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In Reply to: RE: Foil Project for IIIa's posted by computerman on February 01, 2012 at 12:55:45
Hey, great, I'll be eager to hear how it works.
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Hello Everyone. I just wanted to post an update on the progress of my IIIa's. Yesterday we laid down the wire on the second speaker, duplicating the layout of the first speaker. We just have the foil to do on this one speaker and of course the soldering on both. Is there anything special I need to know about the soldering other than it is aluminum wire? I have the solder that Magnepan sent with the IIIa rebuild kit, and Sheila said to use that as it is for aluminum. Once that is done, then it is on to the crossover and mounting to the frames. My friend is just about finished with the frames as well. I also need to replace the "buttons" on the second speaker. Has anyone had any experience with that? They do not include them with the kit, but it is near impossible to replace the wires without breaking them. We drilled out the rivet on both with no damage to the speaker, so I expect I will have to get some from Magnepan. Can anyone tell me what they are for?
I am getting real excited to hear and see what the final project will look and sound like. I do understand that there is a break-in period as well and I am anticipating that. I feel like a kid again waiting for Santa to appear. :-)
I also need a reasonably priced amp that will fit my budget for the tweeters. I could use some advice on that as well. I thought I would search Audiogon once I have an idea of what might be appropriate. I have had good luck for the most part, purchasing equipment from there and any help with that will be appreciated. Perhaps someone here has one for sale. I will search the ads here as well.
As an FYI, as this is a big part of the final sound, I had my Technics SL1200 Mk5 rebuilt by Kevin Barrett. He did an incredible job. He rewired the tonearm with Cardas wires, installed an external power supply, put a switch in for the strobe so that I can eliminate that to reduce electronic noise, plus installed RCA phono plugs in place of the wire connector so that I can use quality innerconnect cables. I also installed his tonearm fluid damper. In addition, I can now record 78's as I had it modified to add that speed. I am using Cardas innerconnects as well to my line level preamp with an impedance matched adapter for input from Pure Vinyl. I am using a custom built moving magnet cartridge from KAB. The next step is to upgrade to a moving coil cartridge. The recording is done through a TC Electronics Impact Twin through firewire to a Mac using Pure Vinyl software which is a pretty impressive piece of software. As I am now digitizing and restoring vinyl as a side business. I am able to write off some of this which helps with the financial end of it. I get a pretty awesome recording now. It is much fuller in general, plus all of the audio spectrum is greatly enhanced. I don't have the knowledge to express the result correctly.
After taking one of these apart and rewiring the tonearm myself, plus researching the subject, I am convinced that this is one of the best turntables ever built. I know that I will get a lot of arguments for that statement, but I would be hard pressed to believe otherwise, especially after the mods. Anyway, I just wanted to include this for information.
Thanks again to all for all the help so far. You are an awesome bunch!
You might want to practice a bit with the solder and flux on a scrap piece of aluminum before risking the ribbons.
The tuning dots control resonances. The stretched mylar resonates like a drum. By dividing the diaphragm up into tuned sections, the resonances can be spread over a broader frequency range to smooth and tailor the frequency response.
I think Satie's the go-to guy on amps, don't know if he's seen your post but he has an encyclopedic knowledge of what's out there that might fit your budget.
Funny that you mention modifying a turntable for 78's, I did that with a Philips 212 when I was a kid. I still remember those cool capacitance switches with the glowing lights . . .
Josh - I had planned to practice with the foil before I solder anything. I should have mentioned that. I will call Magnepan today and try to get the tuning dots. I hope Satie sees this post. He did recommend some amps when I was looking for my pre/pro and he sure does seem to have the knowledge in that area. Is it possible to plan the crossovers out before purchasing the amp, or do I need to have the amp before planning them? I could start putting that together as well while waiting for the dots and frames. Any ideas on that? I know we talked about a PLLXO and perhaps using the TDM active XO for the bass. I would appreciate your ideas on this as well. Thanks again.
What did you do with the turntable?
For starters, just use your current active electronic XO to tune your XO points. You need to find out how sensitive the new midrange comes out, and how resolving it is vs. the ribbon - which will play into where you want to XO. You will also want to measure the FR, at least with a Rat shack SPL meter.
As for ribbon amps, you want either a class A SS amp or a high biased SS class A/AB with stability into 2 ohms and MOSFET or JFET output. as the ribbon is ruthless in revealing the grain and thinness of bipolar transistors. These amps don't need to be more than 25 watts (8 ohm - they will have higher output into the 3ohm tweeter). You can also use a tube amp and a 2ohm resistor to raise the load impedance In which case you need at least 50W.
The better choices are the Pass Aleph series amps, XA 30 and its successor. Classe have high wattage amps rated for 2 ohms that have a highish bias into class A. The older Classe DR series amps designed by David Reich are my favorites for bang for the buck. The older DR 3 and DR3VHC will likely need a refurbishing since they run hot and tend to cook their caps in relatively short order - but would be the best for the role. I use a DR-9, and the model 10 is similar. These give you 8-10 watts of class A and really good class AB for the rest.
A cheaper Pass design is the Forte 4.
If you are willing to put fans in your amps, quite a few can be biased up to provide unbelievable improvements in their sound, but they are not designed to dissipate so much heat, so must have fans installed. These would include the older PS
Of the Class D amps, Wyred 4 Sound would be a good choice for you since it was reported to have less of the top octave TIM that plagues so many of these amps. Besides which, your high frequency hearing loss makes it more likely to work for you. The PS Audio GCA series class D amps may do well too, but may require a mod (see at cullen circuits for options) if the high freq TIM is audible to you,
Go look at the lists I put together for other options at lower price points. Just search for them.
Once you have chosen an amp and checked out the options for XO freqs we can help you build a PLLXO.
If you want the flexibility of a digital device, get a behringer DCX 2496 and have it modded at Endler audio (the most cost effective).
Satie - Another inmate pointed out that there is a sale on the Monarchy SM-70 Pro. It meets the wattage requirement you mentioned and it is a great deal at 40% off, and I would really like to get one, and perhaps add a second and run them as monoblocks in the future, but the one caveat I have is that the lowest signal it should see is 2 ohm intermittent and 3 ohm continuous. Do you think this would work without a resistor?
Satie - There is a pair of Monarchy Class-A mono amps for sale on the Asylum for sale page. Would these be worthy enough to drive the ribbon tweeters? thanks!!
http://trade.audioasylum.com/ca/listing/Amplifier-SS/Monarchy/SE-100-Deluxe/Class-A-mono-amps/54247
I found a couple and was wondering if they could qualify. One is a Classe DR 15 and the other is a Cairn 4808 Class A Integrated Amp. Would either of these fit the bill? Thanks!
Have you ever soldered foil?
How would the modded Behringer DCX 2496 compare to a PLLXO?
Depends on your sources. If you have a really good analog source, the modified Behringer will come up short on mids and highs compared to the PLLXO.
If you are going all digital, then the modified Behringer should provide you a very good DAC and a good clock (if you chose the upgrades) and sound very good. That is because the Crystal DACs that are compatible with the DCX can do 1V output, so you can forgo an output stage, and simply use coupling caps or output transformers. These will sound better than most active output stages on a CD player - even a seriously good one.
Satie - I contacted Scott Endler and he says he is too busy to take on any work. I assume he is the only one that does the mods correct? If that is the case, I guess we have to go with the PLLXO as I cannot afford an expensive electronic crossover at this time. I replied to his message asking him if he would let me know when he might be available. I have not heard back from him at this time.
Do you know what I should use for binding posts on the new frames my friend is building?
I am kind of balking at purchasing a class A amp because of the amount of currant they draw constantly. The Monarchy amps seem real nice, but I found online that they draw 300 watts each at idle. That is a lot of juice and I can just see the meter rotating at high speed. I would most likely leave them on all the time as I have my system connected to my TV. It will all be in my living room. Any ideas on this? Thank you!!
Re busy Endler
I can't do anything to clear up Endler's schedule, so try Rick Schultz at Tweakaudio.com for his turnaround. He is very good to work with and does terrific work. I have a Nuforce ref 8.x amp that he modded and fixed for me after a lightning incident and they are astoundingly good in the midrange and bass.
Re binding posts,
For Bananas - what I use, since it is minimal mass:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=091-1160
I bought a set of these expensive ones and tried them out without drilling for them and they were no better than the bananas so long as you use bananas. The do sound better if you use bare wire - since you skip the banana connector, but not by much, so I skipped them and use the above el cheapo banana jacks:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=093-562
I actually tried out the prior version of these.
Re PLLXO, I can calculate it out for you for various amp options and it is really simple, but you do need to know the amp input impedances and preamp max voltage out for the calc..
Re class A amps
You can keep them off and it takes only 30-40 min to come on song if you keep your house above 70F. That is because they heat themselves up with those 300 watts at idle.
Keeping them on during the winter is nothing much for me since we have electric heat, so what we generate in one place is compensated with the other. Things don't work all that well in summer as the extra heat bakes you in no time at all and the AC must be engaged to remove the heat.
Satie - I want to be sure I understand this correctly. Presently I am using a Mac for a music server using the program Pure Vinyl outputting through the TC Electronics Impact Twin. That goes to my tape input on the Sunfire TGP-5 to the TDM electronic XO. I believe this is a digital; setup correct? If that is the case, then the Behringer would be the way to go correct?
In your description of the Behringer, it appears that you are saying that it gets modded to become a DAC? Am I totally misunderstanding you?
I am not sure if you saw this but I found a few amps to consider. They are as follows; a Classe DR 15, a Cairn 4808 Class A Integrated Amp, a pair of Monarchy Class A mono amps, and a McIntosh MC1700. Would any of these fit the bill for the tweeters? Thanks again!!
Yes, Since you digitize your analog, it is an all digital system.
The Classe DR15 should have no problem with the tweeter. I don't know the Cairn and it is not spec'd for 2 ohms, so I would ask first. The Monarchy SE100 are very nice for their price point, and should work fine. I would contact CC Poon at Monarchy to ask if it is ok into 2 ohms, or you should use a resistor to raise the load it sees to 4 ohms. In any case, the high class A bias means that you will remain in class A for the entire signal likely to reach the tweeter. The Classe and the Cairn will not be operating in class A that far up in power if you need to put in a resistor, (you don't with the DR15, you may with the Cairn).
The old Mac receiver is not workable without a resistor and is not a great value unless you need to fix it and are capable of doing it cheaply (DIY fix). I don't think these SS receivers are that great.
I found a Proceed BPA-2 and checked the manual online. It lists as output impedance .05 ohm. Are you familiar with this amp?
Generally, Proceed amps are very good. I have not heard this one.
sorry, didn't notice your post before.
Satie - I wanted to report that all soldering is done on the speakers to the foil and wire runs. All that is left is to do hookup wire to the XO box that is being built. I took a reading on both runs and they are as follows: foil midrange = 4.2 ohms; wire bass = 4.3 ohms. It looks as if they are right where they should be correct?
Did you see my post on the Monarchy SM 70 Pro? If not they have a special online for $588 plus shipping. They are good to 2 ohm intermittent and 3 ohm continuous. Will this work for the tweeters? If so I have narrowed down my selection to the SM 70 or possibly a Factory Built Class D 4 channel (2XSDS-254 modules) which is bridgeable. There is one on Audiogon for $700. I have a Maggie center speaker to throw into the mix as well. It would be nice to be able to use it. Once again thank you for any input!
Yes, these appear to be appropriate values for the bass and mids.
You asked elsewhere about the use of a cheap tube amp. Though it is possible, you are talking about having a 2 ohm tap or enough power to take a resistor's wasted out of the equation, neither of these things make for a cheap tube amp.
Thanks for all the info Satie. I will begin looking for the amp and let you know if I find something of interest. I do have the ADA Audio Designs Associates PF-200 which is MOSFET and will go down to 1/2 ohm. I had a nice conversation with the factory and the amp's designer and he stated that the amp is happier when it is really taxed to a lower ohm load, so I don't think there would be a problem in that area. If I used it for the tweeters, then I could purchase something for the midrange, which may be less critical. What are your thoughts on that approach?
That is perfectly fine.
The midrange would require higher power than the tweeter, particularly since you lose some efficiency from the use of a foil. You would want something rated at least 100W into 4 ohms. You definitely can use the better class D amps, including the BelCanto designs. And you can add in the Tweakaudio/EVS modified nuforce 8 and 8.5 amps to the list in addition to the ones already mentioned. The Wyred 4 Sound ST or STI 250 would also be very useful here.
There are the NAD 208, the Parasounds - the old 2200 (not the "classic" current production) and the A21, The Jungson 88 (its integrated so would have a very handy volume control for PLLXO down the road).
I should add the PSE Studio V and a little less so the Studio 4. The hybrid amps from Monarchy audio, Counterpoint hybrid amps, particularly the Evolution series, and Vincent hybrids. The Musical Fidelity A3CR and 1008.
Again, go over my recommendations from prior posts, I put together a number of lists for various price points.
If you're going to be using a PLLXO, you have to wait until you know what amp you're getting because the component values depend on the amp's input impedance. (It is possible to get around this using variable resistors but I don't think it's worth the effort, it's easier and better to order the caps when you know what amp you'll be using.) I suggest you put the caps on clip leads to start, in case you decide you want to change the crossover point. You can solder the caps in when you're happy with the results.
Anyway, Satie knows more about the behavior of these drivers than I do, and more about what active XO's are available, so I'd defer to his advice.
I'm trying to remember what I did with the turntable. I know I got it when I was 17 because it replaced an AR turntable that was stolen that year, and I know I replaced it when I was 22 or so with a TD-125 Mk II and a Rabco SL8-E. But I can't for the life of me remember selling it. Maybe I gave it to my Mom? She had one and I don't remember how she came by it. In which case it would have been sold after her death by my drug-addled brothers.
I do remember cutting classes the day I got the Rabco. :-)
Does anyone know how or had experience with soldering foil? I soldered one pair, and it seemed to work OK, but I am not sure if I did it correctly. It is difficult to heat the foil as it wants to break. I tinned the connection with the solder Magnepan sent me, and then laid the foil on the tinned connector. As I tried to solder it, it kind of "melted" into the tinned connector. I have a connection as I tested it with my ohm meter and I applied power to it with my DC power supply and I got a typical reaction, but is this the best way to do it?
Thanks!
I'm afraid I'm not the best person to ask on this, since I've never done it. I know there have been threads on soldering the wire, but I'm not sure if I've seen one on soldering the foil -- though I know some others have used it.
Or.....How about...Mr Gunns crossover...have fun
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