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Hey all,
Noob here.
I recently inherited a Catskin SET amp with 6P36S, Russian driver tubes. This was custom-built by a guy that knew exactly what he was doing. He was also meticulous to a fault. So I have a high degree of confidence that this amp is of the highest caliber.
I'm an EE by trade and I understand the fundamental physics involved in vacuum tube operation, but not much of the finer points of actually building something with them. This includes speaker matching.
I understand that doing a SET amp any kind of justice requires pairing with a very high efficiency speaker. Herein lies the rub. I'm really choking on the $4k-$10K prices of these speakers and the bewildering array of speakers available. Not all high-efficiency, of course.
What I'm asking for is some guidance and recommendations for something in the range of $300-$600, or to set me straight if nothing suitable exists at a lower price point. Pun not intended.
Any guidance is much appreciated.
Cheers!
Follow Ups:
I built a pair of Madisound Back loaded cabinets with FE206ne drivers and a couple of old super tweeters I had in stock. Crossover only on the tweeters. $750.
Getting ready to replace the inexpensive supper tweeter with a couple of Fostex 90a suppers which will add another $500.
Using 6A3 monoblocks, transformer coupled....sounds nice with a good source.
Stuben
Check out Hsu speakers at hsuresearch.com.
The HB-1 MK2 Horn bookshelf is very friendly to tube amps and with their subs can be very good for the price. I drive three pair with separate amps in different rooms. They were part of a 7.2 surround but I lost interest in that and just do stereo for now. One tubeCube with a pair of EL84's, one Bottlehead Stereomour with 2A3's and one Bob Latino ST-70 with KT88's. They all sound good and even the little ones can blast the horn loaded Hsu's to pain regions.
Here's a very worthwhile DIY speaker project - cheap as it gets and yet a really good cabinet. It would be better to make a hole in the centre section so you have the full internal volume.
Great box for a single unit speaker like Mark Audio Alpair 10M. Could be used for anything really. All you have to do is put a front and back on it and screw them together.
Building a speaker that small, it would be difficult to find a driver combination or full-range driver that is efficient enough for SET........
I don't doubt for a bit that these would sound Great... However, I'm thinking that these would NOT work with a SET amp... I'm guessing about 88db on these ???I had a pair of Rauna Tyr II speakers that were made in Sweden. The Cabinets were solid Concrete. Not as Porus as Cinder Blocks. And they were also 88 db.
Manufactured in the late 1970s - Early 80s..... The were Monitors about 14 inches high... They were 'Killer'.... Nothing I could find could touch them. I had compared plenty Monitor Speakers (All of the Known Contenders) in my home that Cost around $5 Grand and none of them could beat the Transparency of the Concrete Cabinets of the Raunas. Best ones I could find at any price. (I only auditioned speakers that were less than $10 Grand a Pair). Everything else sounded 'muddied'.
I only got rid of them went I went to Full Range Horn Speakers. Speakers that are 20 times their size!
Edits: 09/24/21 09/24/21
"I had a pair of Rauna Tyr II speakers that were made in Sweden. The Cabinets were solid Concrete"
When I lived in Norway I made speakers from a thick concrete drain pipe 45* curve. They sat on the ground. Fantastically uncoloured. Nothing after was like them. They must make these concrete pipes for freezing conditions that would crack anything else.
But, you would agree that these are not SET Friendly?
google "Wayne Parnham" and 4Pi
Newest version of a great speaker.
95db, 8 ohm
Fully horn loaded (back horn on the mid/bass...floor firing and horn tweeter)
6500 Euro
Bass down to a solid 40hz
https://www.odeon-audio.com/models/rigoletto-2020/
Heard this in their factory in northern Germany and it was very good sounding and so I bought a pair even though I have their old "big boy" version of this design.
Probably really good loudspeakers.... But I don't know if they're "budget"...........
Well, its all relative but well under 10K fits budget by high end standards these days.
I love the cabinetry on the smallish Odeon models, and it's unfortunate they don't seem to have a U.S. distributor. If anyone from Odeon is reading the internet, I think there is a potential future model in the lineup that many audiophiles would love to have.Around the Rigoletto model, the Midas does not use a compression driver and no horn-loaded bass. The Tosca does use compression driver but is bass reflex.
I love 1" compression drivers, but the horn in Rigoletto (and Midas, Tosca) are only about 6.5" so the crossover points are a bit higher (2.3 kHz) than I would personally prefer. A future model with 1" compression driver in larger horn, bit lower crossover point, and keep the horn-loaded bass, and many would dig it IMHO.
Edits: 09/23/21
I hear you: past experiences suggest we'd prefer a lower crossover point. Still, that little 6.5" driver should be good up to and beyond crossover point and I'd need to listen for a while before I knew. I understand that driver was designed by the person who developed the Enviee FR drivers and the wide range drivers used by Sound Kaos.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Edits: 10/16/21
They are carried by Tricell in Ontario which is an importer - they then send them to several dealers in Montreal, Ontario and Alberta. I think they are gorgeous-looking speakers and SET amp friendly - Hope they arrive in Hong Kong one day - not sure why they can't get a dealer here - they make small standmount speakers and have beautiful wood finishes. SET amplifiers and tubes are hugely popular in Hong Kong which also sells to the wealthy mainland Chinese who buy in HK because they don't trust the Chinese dealers who sell the real deal.They sell far bigger (as in physically larger) speakers here so size is not a problem - the rich guys rent manufacturing space here and visit their stereos on the side. And people here can drop $1/4 million US on a pair of speakers no sweat - Hong Kong is home to the highest percentage of billionaires relative to the population. So let's see a dealer.
Edits: 09/23/21
I want to thank everyone for the generous outpouring of helpful information. Last night I picked up a pair of Tekton Lore speakers for a pretty good price.
With that, the original inquiry is concluded. I'll update if/when I am able to find more information on the amp. The guy I bought the speakers from had a good lead for me.
I have used Tekton Design speakers with great results with low power SET amps. Both a 8w/ch 300B amp and a 1.5w/ch 45 amp. The Tekton Lore can be had used for $500-$700.
Thanks. It looks like there is a pair available in my area.
Klipsch Quartets- mini Forte can find from $200-$900. Maybe another more recent Klipsch to get started
Thinking about this a little more...
I don't know the output impedance of the amp and I have no documentation. Are SETs amps limited by design to 4 Ohm, 8 Ohm, or something else?
Is this something that I could determine if I can remove the shield and get the transformer part number?
Thanks again!
There are two resistances to consider - the source impedance and the intended load (speaker) impedance. Most amps are designed around 4, 8, and/or 16 ohm loads, but the source impedance depends on the actual design. The ratio of load impedance to source impedance is the damping factor, and most modern speakers assume it to be very large but it's usually around 3 with SETs. That's why you want a speaker whose impedance does not drop much below the nominal value.
Your tube seems to be a beam tetrode, not a true triode. If the second grid is tied to the plate (usually with a resistor around 100 ohms) then it's a simulated triode circuit. But sometime you'll see a pentode/tetrode design with feedback, or even a screen-driven output stage, especially with high-perveance tetrodes such as you have.
You can measure the output impedance by feeding the amp a sine wave signal and measuring the output voltage unloaded and loaded with a speaker-size resistor. (If you don't have an oscillator, you can download a signal-generator app for a smartphone)
Thank you, sir!
Brilliant information. I noted the unusual choice of driver tube in my own research. Knowing the designer, it makes sense. His knowledge of analog video was encyclopedic. Of course he used a tv tube. He also had a tendency toward altruism. It would be just like him to try to improve a design by reducing the cost and barrier to entry. Hard to beat a $5 tube in an audio amp. The 6P36S must have some specific characteristic that he was after.
I've been hesitant to crack the thing open for fear of messing up some subtle tuning, but it seems that some mysteries can't be solved any other way.
If you're interested, I'll post what I find inside. It will probably be a few days. I have a huge collection of tubes to test for estate liquidation.
I got a lead from the guy that I bought speakers from. With help from the nice folks over at the Decware Forum, I found the original discussion about the amp that I inherited. The builder of the amp is the guy who designed the Catskin. The amp in my possession is the same unit discussed. It sounds like the design was experimental in many respects.
For those who are curious: https://www.audiokarma.org/forums/index.php?threads/catskin-class-a2-set-with-secondary-flux-cancellation.780706/
Thanks again for all of the help and recommendations!
...for the link and info. Very imaginative and creative design!
OK. Here it is. I've talked this amp up. Now it's time for the big reveal.
I've posted a video about the amp and what's inside, here -> https://youtu.be/ikAjMVTd5b4
Inside, the amp is about what I expected; complex but elegant. This is definitely not the 15-20 component-per-channel SET amp that I see in schematics online. This amp is more sophisticated.
Two mysteries were solved. The output transformers are 8 Ohm and the driver tubes are pentodes that are configured as triodes.
New mysteries have been discovered. Why were dual triode tubes used in the first gain stage? They aren't wired in parallel or push-pull configuration. What are the devices on the heat sinks? Maybe linear regs?
More sleuthing is required, but at least I can be certain of the output impedance now.
It would indeed be interesting to see what a video designer would come up with for an SET!
Thanks for the suggestions!
I like the kit build idea. Ebay does come through sometimes, but is risky for anything electronic. There is a great hardwoods store nearby and I might have just enough carpentry mojo to pull of something convincing.
It occurred to me after posting that my inquiry would be better suited to the speakers category. I'll start a new thread there for future questions.
Glad everybody beat me to it--was going to suggest 2pi towers if possible as very tough to beat bang per buck. It's a particularly good design to get some bass out of lower-watt deal but they'll take some power too. Built a kit for a friend some years ago and you could listen to everything on them.
Mostly posting to say increment count +1 for interest in seeing the amp details.
Numerous reasons not to use hardwoods to build a speaker. You want good quality plywood. And don't fret over all the opinions you'll find about overly expensive Baltic Birch or Apple Ply or any of the other types better suited to building something expensive.
The Big Box stores all sell $50 a sheet 3/4" plywood that's good enough and unlikely to have voids with loose internal veneers that could rattle. For that matter, quality builders like Bill Fitzmaurice advocate 1/2" plywood with adequate bracing but I'd stick to 3/4" because fancy bracing requires woodworking skills that may be beyond you.
The 2Pi speaker is oh-so-simple to build and sounds better than the $ investment with excellent bass and an easy to drive impedance curve. The 4Pi is comparable to the very best speakers at any price but requires a much higher Dollar investment. Breaking all the rules here, I have a used set of 2Pi drivers, woofers and tweeters, sitting on a shelf I'll offer up for $100 plus whatever the shipping costs might be. I'm not certain but I think I recall that a single sheet of plywood is all you need.
Do your research and PM me if interested.
There's no virtue in being old,
it just takes a long time
OK. I'm stumped. I can't figure out how to PM you. I'm probably missing something obvious.
Click on the (A) after my moniker and at top right you'll find 'Send E-mail'
There's no virtue in being old,
it just takes a long time
Thanks. I tried that. I get "This user does not accept unsolicited email" in big, red font. When I click on "Send email" nothing happens. Maybe I need to fiddle with my security settings.
No wonder no one calls or writes.
Thanks Rod. That's talented amateur IT, fix one thing break another.
There's no virtue in being old,
it just takes a long time
For some reason, the Asylum seemed to default to "This user does not accept unsolicited email" for some of us, and we've had to go back in and set it where we want it.
Only Klipsch besides Klipschorns that cost a fortune are Klipsch Cornwall. Unlike the other Klipsch mentioned, the Cornwall will accurately reproduce the SET audio without distortion. In other words, why own a SET with poor speakers.
You do have to have a Table Saw to build these speakers? Correct? -- Miter Saw won't do it, Correct?
I deal with this all the time. All it takes to build box speakers on the tightest imaginable budget are:the very good Skil $35 Jigsaw
Reinforced Packing Tape in lieu of clamps
Some coarse sandpaper for sanding to the lines you stayed just outside of when using the Jigsaw.
Carpenters glue.
And whatever cheap cordless drill Harbor Freight is giving away that day.
I've done it inside an hour at demonstrations. It works, although likely not for the-windshield-wipers-on-headlights crowd who will debate all day long on diamond vs. ceramic sharpening stones. Present company excepted of course.
There's no virtue in being old,
it just takes a long time
Edits: 09/18/21
Thank you for the advice. I sincerely appreciate it.I spent many years building with just a jigsaw and a few hand tools. I can do a little better these days. I have table saw, miter saw, router, mortising machine, various jigs and clamps. I've been experimenting with draw-bored, through mortise and tenon joinery. Well, I was until lumber lumber prices got the COVIDs.
I appreciate having my lumber assumption corrected. I take it then that the fancy cabinets of high-end speakers are veneers. My favorite hardwood store also has those. Maybe I can find something blemished and marked down.
I can afford to give a little attention to visual presentation. The amp in question is visually modest, even austere, but elegant nonetheless.
Cheers!
Edits: 09/18/21
I've been using NBL (no black line) veneer from Tape-ease for over 20 years.
You'll find Flat Cut Cherry, Maple, and Walnut for around $60 to $75, 4'x8' sheets, as well as many tropicals. NBL is perfect for contact adhesive and, stout as it is, easily bends around 3/4" radii.
There's no virtue in being old,
it just takes a long time
Yeah. Thanks. That looks quite nice.
We've had the cabinets sitting in our garage for almost 20 years. Included with our order were several sheets of finish veneer. When we finally decided to put them in ourselves we weren't sure about using the veneer.
It was a) a PERFECT match for our cabinets b) easy to work with and apply (had a 3M adhesive backing still in perfect shape) and you cannot tell which sides are finish veneer and which are cabinet shop finished! My wife did the hard work, cutting and scraping, and it looks great. A big sigh of relief for us. Who knows how long it will last, but it did the job for now.
I'm no woodworker, I wish I was, but I put in some kitchen cabinets over the pandemic. This was a great little tool.
Very easy to use. Of course eventually I had to move to the bigger one, but I did lots of work with it. $129 with 2 batteries. I found it much easier to use than the jigsaw for purely straight cuts, even 3/4" bevel cuts. They also make a nice 12V jigsaw that uses the same battery.
I think Dewalt makes one as well.
You might get lucky with Forte's or Hereseys, or even Altec, but it would take luck and time. Maybe a kit. But for a lark, for 'something completely different' to tide you over...
I built the Bottlehead Stereomour 2a3 amp, that pushes maybe 8-9 watts/side and I ran it with my 93 db Ohm 3-ways. This isn't supposed to work, or at least not to sound very good, but I was mighty surprised.
I ran them this way for quite a while before transferring to my Valencias, and prior to, they sounded quite good and with good volume..
Sure, they sound better on the Valencias, but that's $40 and a re-cone vs $$$. Just sayin'...
Have fun, -K
A small correction - the Stereomour 2A3 puts out 3.5 watts; it's the Kaiju 300B that puts out 8+ watts.
I guess I was thinking about peak output for the tube.... -K
You could scour the local Craigslist or Ebay offerings for a pair of used Klispch Speakers, especially the Heritage Series..... Cornwall, Forte, Heresey, Quartets... You could pick up a pair in that Price Range with less than perfect cabinets, but if you audition them and they sound great and the Drivers are intact... A bit of refinishing, could bring them back to Glory.Like these on E-Bay
Edits: 09/16/21
"What I'm asking for is some guidance and recommendations for something in the range of $300-$600, or to set me straight if nothing suitable exists at a lower price point."
You might get lucky with Craigslist finding used Altec or similar high efficiency speakers.
Nothing new of high quality comes to mind at that price point.
DT667
If you're into do-it-yourself projects, Pi Speakers is a good option......
The 2Pi Studios and the 2Pi Towers work well with low powered SE tube amps, I've heard both with several amps and all were nice. It's really a simple carpentry project.
nt
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