Output transformer options in 2021?
- Thread starter StepheK
- Start date
They are far from cheap- but I can say, the Slagle/ Intact Audio SE output transformers are great performers.
Though it's far from its "intended use"... I managed to get some of Dave's SE 2500:8 SE transformers (originally made for 300B), to put out 16 watts using two 6L6s in triode mode parallel, running the transformer into a 16 ohm speaker impedance (which made it act like 5K primary). It made full power down to about 30Hz, and 11 watts at 20Hz, cleanly, using only about 10dB of global feedback.
http://www.intactaudio.com/tran.html
Regards,
Gordon.
Though it's far from its "intended use"... I managed to get some of Dave's SE 2500:8 SE transformers (originally made for 300B), to put out 16 watts using two 6L6s in triode mode parallel, running the transformer into a 16 ohm speaker impedance (which made it act like 5K primary). It made full power down to about 30Hz, and 11 watts at 20Hz, cleanly, using only about 10dB of global feedback.
http://www.intactaudio.com/tran.html
Regards,
Gordon.
maxhifi
Addicted Member
I think over the decades, the term ultralinear has changed meaning from a trade name to a generic term to represent that specific form of screen grid feedback.
I actually believe that it is flattering to the original line of equipment, that the name lives on 60 years after the original products were discontinued, similar to how the term Bass Reflex was once a Jensen trade name, but now is a term which describes a specific speaker enclosure.
^ It's a real concern to some companies. Kodak was worried about dilution of their trade name, so when Paul Simon made a song called Kodachrome, Kodak required that he trade mark it on the record sleeve.
Xerox is probably the most notorious. There were others (e.g. Kleenex). Google is playing out right now.... (Now I'm going to google the other two dozen trade name dilutions...)
Xerox is probably the most notorious. There were others (e.g. Kleenex). Google is playing out right now.... (Now I'm going to google the other two dozen trade name dilutions...)
FlaCharlie
Super Member
I can't help with any OT recommendations, but I gotta ask . . . since you just built a SE KT88 with a 5k "UL tapped" OT using the Edcors, why build an entirely new amp that seems to be essentially the same as the first one?
https://www.audiokarma.org/forums/index.php?threads/building-a-kt88-6ej7-amplifier-thread.940563/
The voltages you posted in the other thread indicate that they're being run at 78mA with a plate voltage of 401v with is a plate dissipation of 31.28w. According to the data sheet, maximum plate dissipation is 35w, so you're at 89% of that now. Squeezing a tiny bit more power out of it will be unnoticeable.
Other than using different OTs what would be so different about this new build? If you're not satisfied with the Edcors, why not just replace them and tweak parts values if you want to try a different operating point? Or drop in a different tube in place of the 6EJ7?
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It's hard to compare changes without listening back to back is one reason. This is a hobby for me and I enjoy the building + is helping me from going crazy from COVID hibernation
This next one, I plan on using an 8 pin 6SN7 driver with various circuits, possibly as monoblock amps, but maybe I should just punch out this chassis and mod it? Or rewire it to try an pair of ECC85 / 6AQ8 tubes? Just exploring options and learning who is still making transformers in 2021 as my search pulled up conflicting info, some of it from a decade ago. Whatever I do, it sounds like some consensus that Electra-print is highly regarded. Maybe I should just venture off into a PP amp...I have just gotten to tube rolling in this new amp and last night swapped in some soviet military 6Ж51П / 6J51P variants of the 6EJ7 and they sound a lot crisper/cleaner than the RCA mesh versions, but maybe a tad too bright? But maybe they just need to burn in some. I have some non-mesh GEs that are too microphonic, and a couple of other version to try out. Not sure exactly how many 6EJ7 variants there really are that aren't just rebranded of the same tube. There are other tube types I could try rolling in as well, but not sure any of these are sonically the equal of a good 6SN7? Trial and error I guess. I also want to try some EL34 tubes and I believe I can also roll in some 6V6GC, possibly needing minor mods. Maybe some combo of tubes will hit the magic balance for what I have already built. Like many things, it seems like the old story of the porridge is either too hot or too cold in search of audio nirvana
This is a deep rabbit hole I have ventured down, I appreciate your help and your question!
Audiophile nervosa. Yup. It’s partly what keeps the big boys in business. Never being satisfied, endlessly upgrading...
For me, simpler is better, so I don’t play the game anymore. My thinking these days is I will only build a new amp if it explores a new concept I have not tried before. It’s not that interesting to me to build essentially the same thing again but with slightly different components. But to each their own....
Some things I’d like to try one day:
1. A Williamson amp, cos I’ve never built one.
2. A SET amp for the same reason. Using 300B or 811 or something.
3. An OTL. Gotta try that one day.
4. A fully regulated monster. Like what ARC did. Not a simple amp so this one would violate my simple is better principle, but still would be a great learning experience.
5. A fully differential amp and preamp just for the giggles of it.
6. A hybrid of some sort just to horse around in that arena a bit.
7. A simple PP amp using a switching power supply. Just because not many people do it, so why not.
For me, simpler is better, so I don’t play the game anymore. My thinking these days is I will only build a new amp if it explores a new concept I have not tried before. It’s not that interesting to me to build essentially the same thing again but with slightly different components. But to each their own....
Some things I’d like to try one day:
1. A Williamson amp, cos I’ve never built one.
2. A SET amp for the same reason. Using 300B or 811 or something.
3. An OTL. Gotta try that one day.
4. A fully regulated monster. Like what ARC did. Not a simple amp so this one would violate my simple is better principle, but still would be a great learning experience.
5. A fully differential amp and preamp just for the giggles of it.
6. A hybrid of some sort just to horse around in that arena a bit.
7. A simple PP amp using a switching power supply. Just because not many people do it, so why not.
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@kward , your item 5 above is a worthy project. I have build a couple of differential power amps with a CCS paired cathode load for each stage. My present amp is is also all transformer coupled. The differential feature gives great detail resolution but you get the advantages of PP. Of course this means a harder clipping point when one tube in a pair reaches the CCS current limit but you get well balanced class A performance. This is my favorite amp so far. K&K Audio has a high power ccs kit that fits the job nicely for an output stage.
John
John
FlaCharlie
Super Member
I would suggest that, instead of building, you should consider setting up a breadboard. This allows you to experiment to your heart's content and, if you come up with something you like a lot, then you can build it.It's hard to compare changes without listening back to back is one reason. This is a hobby for me and I enjoy the building + is helping me from going crazy from COVID hibernation
I have just gotten to tube rolling in this new amp and last night swapped in some soviet military 6Ж51П / 6J51P variants of the 6EJ7 and they sound a lot crisper/cleaner than the RCA mesh versions, but maybe a tad too bright? But maybe they just need to burn in some. I have some non-mesh GEs that are too microphonic, and a couple of other version to try out. Not sure exactly how many 6EJ7 variants there really are that aren't just rebranded of the same tube. There are other tube types I could try rolling in as well, but not sure any of these are sonically the equal of a good 6SN7? Trial and error I guess. I also want to try some EL34 tubes and I believe I can also roll in some 6V6GC, possibly needing minor mods. Maybe some combo of tubes will hit the magic balance for what I have already built. Like many things, it seems like the old story of the porridge is either too hot or too cold in search of audio nirvana
This is a deep rabbit hole I have ventured down, I appreciate your help and your question!
I agree with Kevin, although he's much more ambitious (and competent) than I am.
I stick to simple topologies and I like trying a variety of tubes, especially ones that tend to be overlooked but are still available and (mostly) relatively cheap. So no 300Bs.
Last year most of my projects were built in existing console stereo chassis, which is much simpler (for me, anyway) than building from scratch. I did build a very basic preamp from scratch using 1626s. That project was the end result of trying a large variety (about a dozen or more) of low gain tubes on the breadboard.
There's nothing wrong with modding an existing project either. I recently partially dismantled an earlier build which has used 3 different output tube types over the years (6V6, Russian 6N3CE and 6A5G). It will get a new PS, including a different PT, and the input tubes will be switched from 27s to 6A6s in order to get more drive. I'm copying an existing schematic for that one.
My current breadboard adventure is an SET but in reverse so to speak. Instead of using directly heated output triodes, I'm using some oddball indirectly heated triodes on the outputs and directly heated triodes on the inputs. Keeping it simple by using battery grid bias and SMPS to heat the DHTs.
I'm loving the results so far. My plan is to build two projects, the SET amp and a DHT preamp based on the breadboard results.
That's a really good idea! Thanks.
I *always* breadboard new projects. A nice, thick cutting board makes a great base. Octal relay sockets are very handy:
https://www.grainger.com/category/electrical/industrial-controls-automation-and-machine-safety/relays-and-accessories/relay-sockets?attrs=Base+Style+-+Relay+Socket%7COctal&filters=
These are often available more cheaply in surplus lots on eBay.
Nylon spacers/standoffs make it easier to mount transformers. Again, usually available in surplus lots.
Snap-in capacitors can be secured with 3M mounting tape. Can capacitors can be mounted bottom-side up with standard mounting clamps.
Breadboards are so much fun, you can play to your heart's content--just be careful of all the exposed voltages!
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Lavane
Lunatic Member
I've been very happy with the Transcendar SE output transformers. I've used the chokes made by them also. The company is based in Holister Ca.
Mike Stehr
Poverty Audio
Someone say breadboard...
It's good to have a DC supply to simplify things.
It's good to have a DC supply to simplify things.
AmadeusMozart
Well-Known Member
Must have been due to me singing Transcendar praises on some other websites. Gery is retired, he stopped some years ago and when I found out at the end of 2019 that he was winding agian I immeditely ordered some custom made transformers. Late last year, when I heard about wanting to cut back I immediately ordered some more OPT. (plus fairful he might stop permanently or fall ill with Covid) Don't know what to do with those yet.... (better investment than tubes, still plnety of tubes available and made, but less and less good winders are available) Grab good transformers while you can. One electron look interesting to me, never had the opportunity to use those but nearly bought a pair.
The Transcendar transformers are properly interleaved unlike some others, I was very disappointed with some Hashimoto PP transformers. (also was underwhelmed with some James transformers when they were still around).
I am still waiting on a small choke from Gery to arrive (airfreight is slow these days and ... expensive... Seafreight has been re-instated so I am using that instead), Last choke I bought from Hammond came from China and the thing went into the trashcan. On this note: bec arefull with Hammond power transformers, their specifications have changed over the years from rather specifiying the DC capacity now they are specifying the AC capacity but the documentation guidelines are still based on the old data. So you are likely to end up with too small a PT if running it to the limit. (I found out when I queried after receiving a transformer that ha dhte old rating on it. Must have been sitting in some warehouse for 15+ years..... I was informed that it was still made to the same specifications but that labelling had changed from DC to AC capacity.)
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