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In Reply to: RE: Electro-Voice Regal lll posted by DaveV on January 10, 2017 at 12:20:26
Dave,
What you and Paul are discussing is over my head but I do enjoy the puzzle. I went to the crossover calculators posted but they were for 2-way systems, shouldn't it be for 3-way systems? I found this one:
http://www.kbapps.com/audio/speakerdesign/calculators/ThreeWayCrossoverSchematicCalculator.php
Do L1 and L2 represent the coils? Do they affect the capacitor values? It's too bad the calculator won't let you input the knowns to determine the unknowns.
What started out in my mind as a fairly simple DIY restoration has become an intriguing puzzle. Rather than replacing the caps with the same values why not use what the calculators suggest? Not knowing what the coils measure, yet, they may need to be replaced.
Craig
Follow Ups:
Craig
The Kbapps calc is better than the other ones we started with here for the job at hand. While it also warns about avoiding a less than 3 octave spread, you can just enter the numbers and ignore the warning which comes up by just closing it. The concern for avoiding a less than 3 octave spread in the crossover is due to the effect of rising voice coil inductance in the driver as frequencies rise, which will show itself as a rising driver impedance as the frequencies go higher, with the possibility that the low and high inductors will interact with this and/or each other. While rising voice coil inductance could be a concern with the woofer in the Regal (and there are ways to address this), the mid and tweeter are horn loaded where the rules are different, and the acoustic resistance of the horn will dominate the driver impedance.
So punching in a 3500 Hz high pass for the 8 Ohm T35B, the calc gives the familiar 5.68 uF cap. With the 1000 Hz high pass on the 8 Ohm mid it gives an 18.41 cap, which is not far from the math derived 19.89 uF I came up with, but also note that the calc changes the higher frequency to 1080 Hz and the lower one to 3240 Hz. which explains the different results.
So what to do?
I would start by checking the midrange presence L-pad with your DMM to see that it's appropriate for an 8 Ohm driver, with attention to see if there is a series resistor somewhere there which would justify the rather low cap value in the mid. If there is, then this would explain the mystery, but I would junk the original crossover (and L=pad too if inappropriate) and build a new crossover. I originally suggested a 2nd order crossover because EV later used them (likely mainly for driver protection with the encroaching higher powered transistor amps), but I would go with a 1st order crossover like the originals seeing as you are using a tube amp.
From the previous math: C= 159,155/F (Z) we get C1 as 5.68 uF, and this is where F=3500 Hz and Z= 8 Ohms. For C2 we get 19.89 uF for a 1000 Hz high pass with the 8 Ohm mid.
For the inductors (L is the symbol) we use: L=159.155(Z)/F. This is where L= the inductor value in milliHenrys, Z= driver impedance in Ohms, and F= the crossover frequency. So for the low pass with the 4 Ohm woofer we get 0.63 mH which agrees with the calc. With the 3500 Hz low pass for the 8 Ohm mid we get 0.36 mH which is not far from the 0.39 from the calc result.
If you decide to "roll your own" crossovers use only air core inductor coils. and definitely not iron core ones. The original ones are air cores. Also be sure to orient them at a 90 degree angle to each other like the originals, but don't crowd them like the originals, as you'll likely just mount them on a wood board and you will have plenty of room.
Wth a first order crossover you have the option of configuring the drivers as a parallel crossover )like the diagram in the calc), or a series crossover, as the parts values will be the same. See Rod Elliot's excellent study of the parallel vs. series crossovers on his website, and I would go series.
Note that the 159 constant has a comma following in the C version, but a decimal following in the L version.The wrong parts could cost a lot of money.
Keep us posted on the project either way you decide to go
Paul
Paul,
This is mostly over my head so pardon my question and my simple way to express it. My understanding is the T35B tweeter is 16 ohms. That's what is printed on the horn. The mid is 8 ohms(?) and the woofer is 4 ohms. Using the calc with 1000Hz, 3500Hz, 16ohm, 8ohm, 4ohm. The C1 tweeter cap is 2.84 and matches what is in the crossover. The C2 mid cap is 18.4 and doesn't match the 5.7uF in the crossover.
It's to bad we can't input the 1000Hz, 3500Hz, 16ohm, 2.84uF & 5.7uF and have it calc the other values.
Do you know where I can get the cap holders & terminal block like Crites use in the Klipsch crossovers?
Craig
Craig
The measurements you posted here on 1/12 listed the T35B you tested at 7.8 Ohms. If the driver actually was a 16 Ohm unit it should measure about 11 to 12 Ohms with a DMM. The diaphragm in that T35B has apparently been replaced with an 8 Ohm one at some point. The replacement diaphrams for the T35/T350 have gone through a spotted history. There were some off-shore copies around with dubious quality. EV sold the original tooling to make them to Great Plains in Oklahoma some time ago, but last I heard they had trouble sourcing the phenolic base the voice coil is wound on, and they were not offering them until they could solve that.. Bob Crites had been offering some 16 Ohm ones he claimed were original old-stock EV, but you need to send the driver to him for a replacement. This begs the question of whether your other T35B also has an 8 Ohm diaphragm. You figure the crossover based on what's actually in the driver, so the crossover specs I supplied for a 4 Om woofer, 8 Ohm mid, and 8 Ohm tweeter should be valid. The power of 1st order crossover design is now in your hands, and you probably have a calculator on your cell phone that can do the arithmetic. Forget the online calculators for this.
You'd have to contact Bob Crites about the cap holders ( a hot glue gun is used by many ; ) and the terminals. You'd have to ask him if he'll do a T35B and what it'll cost. I'd just keep the 8 Ohm ones if they both match.
Paul
Paul.I was searching the Internet trying to find the EV's my friend had with the rather uncommon looking EV midrange horn.
It turned out to be the EV Four but I can't find any EV data on that one.I did find an E-Bay sale for MR-10 horn mids that look like the ones Craig has and the sellers DCR reading also fall into the 8 ohm range like Craigs reading did.
Just thought you'd like to see these because you were wondering what the midrange horn was.
http://www.ebay.com/itm/Pair-Electrovoice-EV-MR-10-Midrange-Horn-Speakers-/122235831559?hash=item1c75d2c507%3Ag%3AtAIAAOSwcLxYMneN&nma=true&si=%252B%252FQDIrHPr2tU85kgL0c%252FVn2VX9c%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557I think the sellers wording id misleading using "driver". Maybe what they wanted to say is that the diaphragm is the same as a T35 8 ohm because I found a pic of an opened MR-10 an it could be.
Here's another one with the MR-10 and CR-10 Xover.
http://www.canuckaudiomart.com/details/174580-electrovoice_mr10_midrange_driver_and_cr10_crossover_network/images/222051/Also found a reference to The MR-10 and CR-10 being EV kit MF-1.
All these do sound familiar to me.
Edits: 01/12/17
Dave
Thanks for shedding some further light on some of the more obscure EV horns. Attached here is a page from my early/mid 70's How to build and Electro-Voice Component Speaker System catalogue. The MF1 horn/ driver is pictured (viewed from the front) along with the Michigan 1000 Hz crossover and the Wolverine CR35 3500 Hz crossover, all of which are 1st order. The budget tweeter is the TW35. All of the drivers in the catalog are 8 Ohms at this point, even the woofers. Note the budget crossovers are 1st order, which was common at this point as the 1st order type has fewer parts. R.H. Small published his AES paper Constant-Voltage Crossover Network Design in 1969-70 which elevated the 1st order series crossover to the top of the food chain, but the need for driver protection persisted in keeping the higher order crossover networks dominant, until the SET craze started here in the 90's with Sound Practices magazine. One of the ebay ads implies that the T35 diaphragm is used in the MF1 horn, and is still available from eBay suppliers, but I dunno how true this is. Note the black paint on the upper end EV stuff and the grey paint on the budget stuff. EV bought the University speaker company at some point, and products which had been superceeded by newer ones got down graded with a grey paint job and the University badge. Some budget stuff was badged Michigan, and the budget Wolverine stuff seemingly started to disappear at around that time.
Note the smiley face sticker I added to the scan, which transforms the copyrighted material into an artistic collage where fair use doctrine applies.
Paul
Paul,The slow death of another company from the "golden years "
of audio.Back around 1978 I was in the market for speakers and always admired the EV line BUT they no longer had the good old drivers.
I ended up with the new versions. An SP15 something with a hidden 1 ohm resistor behind one of the basket ribs, 1823M mids that had replaced the T25A, metal 8HD horns, and the T35 tweeters that appeared to be the same except that they were 8 ohm. And I bought all the new xovers to go with the drivers.I had them all mounted in proper size if not a bit larger cabinets using the EV quide for woofer port.
I did everything I could to make that combo sound good but I ended up selling the drivers and xovers off and buying a pair of EV Regency's with the 15W, T25A, the original fiberglass 8HD horns and T350 tweeters. They were 16 ohm all the way and the xovers had all original caps. What a big difference for the better.Maybe someday I'll come into some disposable money and go after a pair of the earlier Patricians, the ones without that 30" woofer.
Edits: 01/13/17
Dave
As for stories of golden age companies, EV was acquired by Telex some time ago. If you want to see a dumb stare just ask a young person what a Telex was. If you don't remember, the Telex was an electric typewriter which was hooked up to a phone line, and you composed a type written message on one end, and it would be received and typed at the other end by another Telex machine. Kind of like email the hard way, and it's interesting that the Telex company still exists, and it now owns an audio equipment company like EV. Apparently Telex has invested wisely in other tech companies.
I've never heard an EV Regency, and it's interesting that you would prefer them to the EV SP15, 1823M, T35 rig you built. You must have had the same catalog I had as seen above. I would put my money on the EV rig however, and I would have hammered at them till they worked, but that's just me.. The weak point in that combination was the 8HD mid horn which is shown in the catalog pic mounted correctly with the long dimension in the vertical position. Many people (like me) mounted them with the long dimension horizontal because they fit better into what you had, and they are very beamy that way. If you get them out of the front of the baffle mounting as shown in the catalog, you can then get them in phase with the woofer by moving them physically until they're dialed in, and then do the same with the T35. Well that's a different animal of course, and I'd expect such a rig could run against an Altec 19, and that's really saying something.
Paul
Here is my drawing of the wire connections. I don't know how to draw a proper schematic. Maybe someone could convert this into a proper schematic for posterity since one doesn't seem to exist for the Regal III.
Actually Craig, that was a good job because it's all understandable even thought it's not a conventional schematic.
But because you didn't enter any color code that may be on the mid and tweeter, like the red and black on the woofer,it doesn't show if all the drivers are wired in phase or not.
It seems pretty straight forward to me otherwise until we get to the 5.7 cap for the mid and why your reading on a tweeter is lower than would be expected for a 16 ohm unit.
Did you measure the other one like Paul Suggested? Measure the other mid driver too.
The mid & tweeter do not have color codes. I have not measured anything in the other speaker. Because I am a newbie I was going to do one speaker at a time so I always had one as a reference.
Measured the other speaker:tweeter = 8.4 ohms
mid = 7.4 ohms
woofer = 2.4 ohmsAlso measured caps:
2.84 cap = 4.94 and kept dropping
5.7 cap = 8.63 and kept dropping
Edits: 01/16/17
2.84 settled in around 4.3 4.5
5.7 seletted in around 7.7-7.9
Craig,I was going to say that all you need to do is pull one wire off of the mid and tweeter to take a DC ohms reading so you can't get the two connections mixed up. But I see you already got the readings.
The cap readings are in UF or microfarads on your meter and not DC ohms?
I'm not sure if I would use "settled in" readings or not. For a film and foil cap I use the number that comes up in the first 10 seconds. For an electrolytic it's not really the same when using a digital meter so I also use an old 1950's cap checker with an eye tube like the tuning eye tube on old console radios to zero in on the value.
Ideally the drivers would read pretty much the same but in the real world they really don't. They aren't that far off and when dealing with that low of a resistance other things come into play like how well the meter probe makes a clean resistance free connection to what your measuring so to me it's a judgement call.If the voice coil got hot from being over driven, some windings could short together but that's just guessing and I'd think if that happened, the driver would be cooked and not working rather than being an ohm or two different. But that is just my an opinion.
If I were you I'd just replace the 2.84 and the 5.7 and not try to second guess the design or if the drivers are bad or if the diaphragms in the tweeters were replaced. Again, just my opinion.
Because the 3 ohm 12W woofer and that mid weren't items that were used in their previous and larger speakers with a 12db per octave xover at their more conventional xover points, I can only assume that they did what they had to do to get the desired result.
The use of 4,8 and 16 ohm drivers like in the Esquires is already pretty unconventional without any added mysteries or "tricks" they used.
Edits: 01/15/17
Caps are in uF on meter. Not ohms. Edit/correction made in original post.
Edits: 01/16/17
Craig,With the red and black markings now known it looks to me like the drivers are wired in electrical phase with each other. All reds go to plus or red input and all blacks go to the minus or black input.
The Tweeters started out as 16 ohm units as did most of the other EV drivers but over the years the tweeters were available in 8 or 16 ohm and they should be marked accordingly.
I know my two 16 ohm T35's measure around 12-13 ohms so your reading of 7-8 ohms is really a mystery if the diaphragms are original.
You have two opinions so far. Mine that was just replace the 2.84 and 5.7 and see what that does and Paul's that said he would replace the pots with pots that were meant to be used with 8 ohm drivers and I take it that would also mean replacing the 2.84 caps with another 5.7 or 5.8 for what looks like the closer to 8 ohm tweeters.
I see where he's coming from about the existing tweeter pots affecting the xover point depending on where they are set but in my view that's going to happen with different pots too, but to a lesser degree because in theory you have a mismatch to start with.
We are both going on the readings you supplied from the drivers and because both sets seem to be not all that far off, it would seem logical that those are the real readings.
To me, the only truly fixed xover is an electronic one like in a bi-amp setup where the xover point won't change with different signal levels or a different driver impedance.
We were both confused about the 5.7 cap for the mids and those would remain in either case unless you changed out the mid drivers and at that point, at least in my opinion, you might as well get different speakers because now you'd also probably have to change the xover parts for the woofer too.
I'm thinking that you like the RCA sound better because it's not as bass or lower mid heavy. In listening to my Esquires I find that somewhat annoying and it does sound like they aren't very open but they are what they are.
Edits: 01/16/17
Does the differant measurements mean I need new voice coils?
Mid 1 = 4.8
Mid 2 = 7.4
Tweeter 1 = 7.3
Tweeter 2 = 8.4
Craig
Measuring low resistances becomes tricky, as you can check by shorting the test leads of your DMM together and see what reading you get. When set with a range low enough to read typical speaker impedances even the resistance of the test leads becomes a factor, as well as how clean the speaker terminals are, and how good a connection you have on them. So we're talking Ohms in the above test? It seemed like you switched uF for Ohms in one of the other posts. With the readings you have here it seems that the T35B's (which you previously stated were labeled as 16 Ohms) have both had their diaphragms replaced with 8 Ohm ones. The mids also appear to be 8 Ohm units. It looks like the original crossover is not appropriate anymore, and certainly the tweeter L=pad/treble control will not be either if they are 16 Ohm units, as turning it up or down will actually change the crossover frequency as well as changing the volume of the treble. The terminals on the mid and tweeter should be marked, look for the color of the washers at the base like on the woofer (though they may be faded by now). Some EV drivers are marked T1 (+) and T2 (-), some had push open spring loaded terminals with red or black plastic caps.
A correctly designed crossover and appropriate L-pads will certainly improve the sound of these speakers.
Paul
I made a mistake and put uF instead of ohms. Made a correction to the original post. Shorting the test leads of the DMM gave me a reading of 0.2 about a second later it read 0.1 and then a second later it read 0.0 I did clean the contacts with sand paper to get a good contact. The washers were painted over. I scraped the paint and there is a red and black washer. In my diagram the red is on the left side of both horns. So mid horn has green wire to red contact and black wire to black contact. Tweeter has yellow wire to red contact and black wires to black contact.
I am confused to say the least. EV literature says the T35, T35B & T350 tweeters are 16 ohms.
http://www.cieri.net/Documenti/Istruzioni/Electrovoice%20-%20Tweeter%20T35,%20T35B,%20T350.pdf
But replacement diaphragms are 8 ohms.
http://www.simplyspeakers.com/ev-replacement-speaker-diaphragm-89486a.html
Craig
This has been an interesting mystery as many pertinent details have been difficult to arrive at. I have: T35's here (in both 8 and 16 Ohm versions); T35B's (only 8 Ohm versions here); and T350's (only 8 Ohms versions here). The diaphragm is nominally inter-changeable between them (though there have been detail changes and refinements though the years). It's what you have in the driver now that counts and not what a spec sheet says, or even what it says on the driver. Back in the day The Grateful Dead had a sound system with an array of multiple T350's which got blown from too much power, so this is not an unusual problem with these drivers being over driven. From your DMM measurements you have presently: a 4 Ohm woofer; an 8 Ohm mid horn driver; and an 8 Ohm tweeter. Tomorrow I'll post a schematic for a new crossover (based on the data you have supplied) and hopefully this will help. I've never heard the Regals or any of the variants, but Dave has and he can give you his opinion as to how they would stack up against similar vintage speakers. IMHO If they're EV's they are worth fixing, but I grew up listening to EV horns. My main rig now are 6 ft. tall 300 lb. EV monster horns, so I'm coming from a hard core perspective.
Paul
Craig
From the info you have provided I would go with a new crossover following this schematic. Note that the part values are just ideals, so use the next nearest standard value available. Also note the L-pad which is pictured with the shaft pointing away from you, and with the solder lugs pointing down. The L-Pads would be inserted at the X in the schematic, and I left this separate from the schematic for simplicity.
Paul
Paul,
Thanks for the schematic! Just curious, what did you use for the low and high crossover frequencies?
I was hoping I could keep the speakers original in design but update it with new caps. That's not turning out to be the case. I checked with Bob Crites. He says he has NOS 16 ohm T35 diaphragms but wants $100 each installed. Through my research I have come to believe the MR-10 horns were 16 ohms in the Regal III. That would make the 5.7uF mid cap a little closer to what is expected. Since I'm not willing to drop $200-$400 on new 16 ohm diaphragms and since mine measure 8 ohms and new 8 ohm ones are readily available it makes sense to change the crossover & L-Pads to work with what I have.
What is the reason for the 16 ohm and why did 8 ohm become common? The following are the parts I'm considering. The L-Pads have me a little confused. There are different wattages & mono vs stereo.
https://www.parts-express.com/dayton-audio-dmpc-56-56uf-250v-polypropylene-capacitor--027-425#!
https://www.parts-express.com/dayton-audio-dmpc-20-20uf-250v-polypropylene-capacitor--027-436
https://www.parts-express.com/jantzen-audio-037mh-18-awg-air-core-inductor-crossover-coil--255-222
https://www.parts-express.com/jantzen-audio-065mh-18-awg-air-core-inductor-crossover-coil--255-236
https://www.parts-express.com/speaker-l-pad-attenuator-15w-mono-1-shaft-8-ohm--260-250
Craig
Craig
The schematic I posted uses 1000 Hz for the low end and 3500 Hz for the high end like the original crossover did, and it's also a 1st order crossover. The parts you link to for C1,C2,L1 and L2 should be fine. I'm not sure how a "stereo L-pad" applies here, as you want a separate mono L-pad on each mid horn and horn tweeter. Dave wanted me to remind you that the L-pads for my schematic should all be 8 Ohm units, and it looks like you are aware of that. You pay more for higher Watt L-pads so budget according to the amp you are using.
16 Ohm speaker drivers were more common in the vacuum tube amp days as tube amps had an efficiency advantage with higher resistance drivers, while transistor amps had an efficiency advantage with lower resistance drivers. The Regal seems to come from that time in the late 60's when the transition from tubes to transistors came about in the market.
Does the schematic make sense? Note that when a wire crosses over another wire, they are not connected to each other at that point unless there is a dot at the cross road. I used the schematic format from one of the calculators we discussed here for the sketch, and I corrected an error where they omitted a dot where the mid minus connects to the amp minus. It's a trivial point but it may have confused someone not used to reading schematics.
Hope all this helps
Paul
I haven't taken the time to try and decipher the schematic. I'm guessing it is the same way the speaker is currently wired.Mystery Solved?
I was looking around the Great Plains Audio website and discovered this:NOTE 2 - When the original 24 ohm impedance is not required, use the diaphragm manufactured for the Altec Lansing 299-8A, Altec original part #25884 (8 ohms), or the diaphragm manufactured for the Altec Lansing 299-16A diaphragm, Altec original part #25885.
I had no idea speakers went above 16 ohms. When I first found the KBapps calculater I played around with it trying to get the cap values to come out to the numbers I had on the caps. If you make the tweeter = 16 ohms, mid horn = 26 ohms and woofer = 4 ohms you get a C2 value of 5.667265. It also shows L2 = 0.63662, so I might be able to reuse one of the original coils if I could verify the value.
Edits: 01/20/17
Another newbie question. The woofer surround has separated from the cone in two places. How do I re-attach the surround to the cone? I got some cloth surround sealant from Vintage-AR but now I'm not sure if this is what I should be using. It seams this sealant is used to keep air from flowing through the cloth surround. Does it also attach the surround to the cone? If it does attach the surround to the cone do I apply it between the cone and the surround?
Craig
Try a bit of the surround sealant and see how it works. In the past I've made my own speaker dope for this when the surround on one of our Pioneer CS88 in the HT started to separate. I used some DAP silicone rubber in a tube, and I thinned it with xylene as is said on the label, and it worked fine. Silicone rubber comes in different colors (looks like your project would need clear) and can be thinned with various things. I used the DAP because of the xylene which seemed a milder solvent than acetone, and I didn't want to melt the rubber surrounds on the Pioneers, but this is likely not that much of a concern on the accordion surrounds on the EV woofers.
I love the smell of rosin core solder in the morning! It smells like music!
Paul
Paul,
Crossover parts are on order. The smell of rosin core solder in the morning will be soon. Any recommendations on solder? Any reason to replace the wires in the speaker? What do you think of the possibility of the mid horn being 24-26 ohm originally; makes the calculator work.
Craig
Craig
Solder has tended to go lead-free in recent times. Radio Shack has (or at least they used to) Lead- Free Silver Bearing Solder 96/4 # 64-025 but ti's difficult to work with as the solder joints tend to look "cold" (read: not nice and shiny). So it can make an impatient expert into an amateur. I have a lifetime supply of good old Kester "44" Sn 60 which always gives good results, but I dunno if you can still buy it.
Wire: Monster XP is good, reasonably priced and easily available.
A check with your DMM of the original L-pads may reveal more of the mystery, though you should disconnect them first. A reading between the center lug and one of the other ones should reveal either a very low reading or the maximum value of the L-pad as you turn the knob to the end points. Also look for a resistor added to the L-pad which may affect the circuit impedance. To re-iterate: you stated that the T35B's are marked as 16 Ohms units, but measurements show them to currently be 8 Ohm units. If the L-pads don't match the driver they will actually change the crossover frequency as the knob is turned up or down, and it's difficult to imagine EV designing it this way.
Paul
PaulI measured both L-Pads. The low readings are 0.2 and 0.7 ohms. The high readings are 104.2 and 103.8 ohms. Both are disconnected.
Craig
Edits: 01/26/17
Measured my new L-Pads 0.1 to 7.5 ohms
Craig
This starts to explain some of the mystery of why the parts values n the original crossover didn't seem to make sense, and the nominally 100 Ohm L-pads seem to account for the missing Ohms to match the parts. As to why they did it that way I can only speculate. In the page of the 70's EV catalog I posted here they were expecting that DIY'ers would use a "building block" approach which would mean starting with a "full range" woofer in a suitable box which would be made. Later you would add a tweeter for some highs. After you had that awhile you would add a midrange horn for "presence". The mid horn and tweeter were presented as add on tone controls.
As you'll be nearing a time when you can compare the new crossover to the old one, it might be time to move this up page to a new thread, as we're stretching the limit of how far we can go to the right down here. Hopefully the speakers sound better!
Paul
Did you notice that the two caps are connected (in series?). Is that usual?
First, I forgot to mention that 8 and 16 ohm diaphragms were once available from EV`for the T35 but as far as I can tell they discontinued the 16 ohm more than 20 years ago.EV was bought out and so went the 8 ohm diaphragms too. But if Great Plains Audio did get the jig to make them, they are the best bet but they would be 8 ohm as far as I know. You could call to see if they do offer the 16 ohm and when they might have some. Forget e-mail. They aren't good at answering them.
Any new T35 diaphragms you see on line are cheap generics unless they say NOS or new old stock.
The 16 ohm T35 and T35B are a fairly common item on E-bay but unless your lucky I wouldn't expect to see a pair for under $100 and then it's risky unless the seller gives a DCR reading for each or you may end up with another headache.The T35B is just a less efficient version of the T35 with a smaller magnet and it was used with other drivers that were less efficient than some of their other drivers.
No sense in cutting back a T35 like crazy with a pot when the T35B was already less efficient.The T350 used the same diaphragm but it was more efficient than the T35 with a bigger yet magnet and it has a larger horn. Some consider it to be one of the best vintage tweeters even if it doesn't go much beyond 15KHZ like modern tweeters. What it does do it does well.
The caps aren't really in series. Yes, one end of each is tied together but that's the plus input to each and not a series connection. A real series connection would the two caps wired like they are BUT without the third connection that feeds both caps.If they were in series the resulting value would be about 1.90uf. And since you need a cap for the mid and a cap for the tweeter that would leave you with only one cap.
I do see that the 2.84 has one wire on one end and two wires on the other end. The two wires are tied together and because the cap is marked 2.84 that can only mean that there are two 1.42 caps in that bundle in parallel that adds the two values. The other end would be a common connection for the two caps.
Edits: 01/16/17
Here is the actual crossover.
Inside the pot.
Craig,
The calculator link I posted was for Paul to see how I was getting the 2.84 value for the tweeter by assuming the tweeter was 16 ohm and knowing that the standard crossover to an EV T35, T35B or T350 tweeter was 3500HZ.
And that 2-way calculator was for the 6 db per octave that is in the Regal with just a cap in series with the tweeter.
Your link and two others I tried for a three way system wouldn't accept a calculation for xovers of 1000 and 3500 HZ. The xover points had to be 3 octaves apart.
The one I used went from 2-way 6 db per octave to a calculator for 3-way 12 db per octave so that didn't help either because with just two caps and two coils you have 6db per octave.
Yes, the "L's" are the coils or inductors.
No, it's not possible to calculate cap or coil values just based on one or the other. They are chosen based on the parameters of the drivers used, the actual crossover frequencies and the slope being 6,12 or 18 db per octave.
The xover can says 1000 and 3500 but I question the 1000 being the actual xover frequency at which point the woofer higher frequencies start to fade out and the lower frequency of the mids start to kick in.
Not being an engineer, what I see is that we aren't dealing with a text book speaker system where everything should fall into place better.
They tried to make a full range system in a small box with woofers that were meant for a vented enclosure or much larger enclosure and they jury rigged it from there to the midrange.
I can believe the 2.84 cap for the 3500HZ xover to the tweeter BUT that reading you came up with of 7 point something is a bit on the low side. I would have thought if the tweeter was 16 ohm the reading would have been at least 10 ohms. Although Paul did find that blurb about actual impedance at the xover.
Paul suggested a diaphram being replaced but those caps sure look factory original to me and I've seen the insides of several old EV and Altec xovers. Plus you had to unwrap them and the pic you first posted looked like a neat untouched factory package.
If EV used a non standard impedance T35B of something other than 8 or 16 ohms, those caps still look original and making the 2.84 the midrange cap would be even more of a mystery.
At this point I'd say it is what you see and go with the cap values that are in there. Measuring the coils for inductance would add missing data but I'm not sure if that would solve the mystery or not.
You said the speakers didn't sound all that good so you should change the caps to see if new ones make an improvement.
I know what the Esquire 200 sounds like but not the Regal 3000111.
I suspect the Regal with the 8" cone mid might sound better to some people but I wouldn't think EV would have had their next up in line from the Esquire not sound as good even it it had that horn mid.
Judging by the other speakers you mentioned, these may not be your cup of tea but they should sound better than RCA console speakers.
Some other things I have been considering in this restoration is:
Cabinet sealing, bracing, damping, & stuffing. Re-wiring & terminals. This speaker has no sealer caulk, damping material or stuffing.
And what about the horn diaphragms? Do they slowly go bad or just go until they quit?
I am considering taking the crossover out of the can and mounting it on a board like Bob Crites does and I am leaning toward the Sonicaps that he uses.
I know this is Sacrilege to the purest. I am not dead set on doing this. My motivation was to add current knowledge & technique to maximize the original.
What are your opinions on these subjects?
Craig
Craig,My "opinions" regarding anything audio are based on working for three audio equipment companies and one speaker manufacturer. All well known, plus having the field as a hobby for over 50 years and having had and worked on more equipment and speakers than I care to list.
You bring up some valid issues but IMHO it's not worth the money or effort to do all those things with those speakers unless you just want to see for yourself what each "improvement" may or may not do. If you want to spring for those caps for peace of mind then go ahead. I'm just saying that I don't think you should go nuts with those speakers with a mind set that all those things will make them something are aren't.
When I saw the name Crites, the first thing that came to my mind was that he has a business selling parts and mods to people that aren't happy with their Klispch Speakers as they came from the factory. But being bigger more expensive speakers with some good bones to work with, it probably makes more sense to swap out parts to your liking than to buy new ones.
Many times people like something about a speaker but learn to hate something else about it and there you have it.But to address your list:
1.Anything electrical should require a mechanically strong, clean and well soldered or well fitting connection.
2.Cabinet leaks alter the low frequency response and overall function of the woofer to some degree depending on the woofer design. My Esquires don't have a gasket on the lip where the back panel rests but the backs fit snug and tight so I never went any further.
However, if your upgrades prove to be successful in bringing about a sound your more pleased with but the bass seems a bit flabby or off,that's the time to try better sealing. But the woofer, xover and cabinet size are what they are and they have limits.3. Damping on a horn may or may not be needed and you may or may not hear a difference. Depends more on the material the horn is made of and how it's mounted.
4.Stuffing changes how the woofer responds in the cabinet and at the very least there should be some sound absorbent material covering the back speaker panel to help cancel standing waves from the back of the woofer. Adding stuffing where there was none can change the sound depending on how much you add and it may sound better or worse to you.
5.Bracing will change the inherent resonace of the cabinet and that may or may not sound better even if in theory it's correct. When your marketing a $10,000 speaker you better mention bracing because it's expected but with a bookshelf speaker that's not an acoustic suspension design that's driven at high levels I don't put much importance into it as long as your working with a cabinet that isn't coming unglued at the seams and the back panel is tight.
6.Cap brands and types to me are like what flavor ice cream you like or how much you think you have to spend for a tire for your car. Crites deals with horns so maybe he found that the Sonicap flavor works well with horns. Others may tell you that horns need paper in oil caps.
As above, new expensive speakers sold to a niche market are expected to have caps that are perceived to be better or "auiophile" grade caps. That holds true with the electronics too.7. Not knowing what diaphrams are in the mid horns I can't say if they go slowly or all at once. If they are phenolic like the T35B I'd say that they either work or they don't. But the voice coil is attached to it so if the coil has some shorted windings it can change the impedance of the driver and can change the performance.
8. Your not working with a "Classic" that has a big resale value in original condition or with one of those outstanding Japanese reworks so making a new breaboard xover or "Bob Crites style" is fine. Just make darn sure you take pics of the connections or don't take the other xover a part and use that for your pattern of connections or you can blow the mid or tweeter with wrong connections.
Five other people can do what I just did and disagree with me on some or all of my opinions but that reflects how diverse opinions are on what you believe to be true and/or your own experience.
Edits: 01/11/17
I hooked-up the one speaker that is still intact to my RCA tube console and gave it a good listen. It does sound much better than when I had it hooked-up to the Marantz receiver in the office. Does it sound better than the RCA? As I said before, I like the sound of the RCA. The RCA is not your typical console with left and right channels in the same cabinet. It is not boomy like others I have heard from the 60's & 70's. It was one of the first (1958) if not the first to offer a stereo option. It could be purchased as a single mono/stereo unit with the option to add on a second speaker cabinet to allow it to do stereo.
The console is a little more open/airier in its sound. The EV is more powerful with punchier bass. The EV does have that box sound; the RCA less so. I do like the EV and I am more excited to complete the restoration.
I really appreciate your wisdom regarding the other upgrades I listed and I completely understand what you are saying about "it's not worth the money or effort to do all those things with those speakers unless you just want to see for yourself what each "improvement" may or may not do." As I said before this is my 1st DIY project. It's a learning experience for me and it's a hobby/project for me to do during the Minnesota winter. I have already refinished the cabinet and will replace the grill cloth and caps. I probably will add some foam liner and fill just to see what happens.
Thanks again to DaveV, Paul and all that have contributed.
Craig,What your saying doesn't really surprise me.
My Esquires sound better with a tube amp too and the debate continues as to why that is but I really never got involved with that because I've always preferred the sound with tubes so that's a useless debate for me to take part in or worry about.
I have two transistor amps, one 60 watts per channel and the other 200 watts per channel that only come out of the closet when I want reconfirm that I prefer tubes and so do the speakers I have.My Esquires sound "full" all the time like there's upper bass that never goes away. With real deep bass in the source they sound like they are going deeper than they really are and the effect is quite convincing.
I attribute that to the overall design and trying to get a reasonably full ranged speaker at a price point into a small sealed box.
The T35B Tweeter with the pot at full should pierce through all that and give some "sparkle" or a sense of air but the full sound is still there.
Maybe the new caps will change that?Without seeing the RCA speakers and how they are in their enclosures I can't comment on those other than to say that I'm not surprised that you say they sound somewhat more open or airy. But you'll probably find that the Regals are more capable of doing real deep bass better.
The renewed interest in the AR3A bookshelf speaker with a pair going for $1000 plus is an example of a speaker that I wouldn't call open or airy but it does deeper bass well and it has a sound that some may call linear because the bass, mid and treble blend well for a smooth sound without anything jumping out. You could also call the boring or un-involving.
There's a compromise in lots of speakers old and new and some companies pulled it off better than others. The Infinity Qb bookshelf speaker comes to mind from around 1978 that compromised the deeper bass while retaining a good bass presence that sounds clean and fast, the mids are open and clean and the highs come through with detail without harshness.
On another topic, but one that is directly related to how your speakers sound, if your Marantz and RCA still have all their original components they probably aren't doing what they could do.
In the Marantz at least the power supply caps would be suspect and in the tube RCA it would be power supply caps, the rectifier and related cap in the output tube bias supply if there is one, output tube coupling caps and the tubes themselves.So basically you want to have the amp provide the punch and available power it was meant to deliver and without the distortions due to parts that have passed their useful lifetime. In this case we are talking about electrolytic caps and output tube coupling caps ARE a candidate to change even if they are film and foil because if they fail your going to lose output tubes.
Edits: 01/12/17 01/12/17
DaveV,
The Marantz was purchased second hand and I wouldn't doubt it needs work. The RCA was professionally restored about a year ago. I pulled the tube pre/amp/tuner out of an old Magnavox console and have wanted to box it up like a receiver; another project. I'd like to learn how to work on these my self.
Do you know where I can get the cap holders & terminal block like Crites uses?
Craig,What he uses for the cap holder is really a cable tie with a mount. Some of those mounts are self adhesive and that's ok BUT you want ones with a hole in the center too so you can screw them down to make sure they stay down.
See the link below for great pics of them so you can see what they really are. They sell them too.Took me a while to find those suckers because I haven't ordered them in years and back in my day everybody knew them as tie wraps.
The connector is a common barrier strip and Mouser Electronics is one likely source. And there's Allied Electronics and tubesandmore.
I checked and Mouser has the ties too but I had to search for "cable tie locking" to come up with the right ones.
They have the mounts too as "cable tie mounts" but I hate their website sometimes and this is one of those times because it's so hard to keep scrolling to find what you want and the way they show them is confusing.
Edits: 01/12/17
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