Im building an ECL82 based amplifier and am hoping i can find some output transformers designed for ultra linear operation if possible.
I believe 5K is the correct primary impedance for single ended configuration.
The closest thing i can find is in this ebay here, and its a multi impedance transformer, so may not be as good, its also chinese.
Either way, if someone can point me to a product that is suitable without the expense of going custom wound, that would be great
OT8SE Single Ended Output Transformer 8VA 5K,7Kohm:3.2/8/16 45mA (imported) | eBay
I believe 5K is the correct primary impedance for single ended configuration.
The closest thing i can find is in this ebay here, and its a multi impedance transformer, so may not be as good, its also chinese.
Either way, if someone can point me to a product that is suitable without the expense of going custom wound, that would be great
OT8SE Single Ended Output Transformer 8VA 5K,7Kohm:3.2/8/16 45mA (imported) | eBay
I can suggest this: TTG-EL84SE - Tube output UL transformer [5kOhm] EL84 / 6V6 SE - Shop Toroidy.pl
I have used several OPT's from this manufacturer with good results.
I have used several OPT's from this manufacturer with good results.
Ive been in contact with them, they dont have anything suitable.
OK, they look interesting, I didnt think toroidal OT were that popular for audio use.
They seem pretty pricey, and they are too large for my amp anyway, these are rated at 30W, and my amp only has like 3w max output
Last edited:
Don't buy this type unless you are going parafeed.
I discovered that they are not gapped at all
AUDIO output Transformer for Single-ended Tube amp 6P3P 6P6P EL84 EL34 6P14 type | eBay
I discovered that they are not gapped at all
AUDIO output Transformer for Single-ended Tube amp 6P3P 6P6P EL84 EL34 6P14 type | eBay
OK, thanks for the heads up.
Ive found some NOS philips transformers bang on spec, but they are designed for 5 ohm speakers, annoying because I want to use 8 ohm speakers.
I guess I could get away with 4 ohm on such a transformer, but its ideal to use 8 ohm.
Interestingly enough, some claim that using your 8 ohm speaker on the 4 ohm tap may sctually sound better!
http://www.stereophile.com/content/tube-amps-try-4-ohm-output-tap-better-sound-1
Could I get away with such a transformer?
Ive found some NOS philips transformers bang on spec, but they are designed for 5 ohm speakers, annoying because I want to use 8 ohm speakers.
I guess I could get away with 4 ohm on such a transformer, but its ideal to use 8 ohm.
Interestingly enough, some claim that using your 8 ohm speaker on the 4 ohm tap may sctually sound better!
http://www.stereophile.com/content/tube-amps-try-4-ohm-output-tap-better-sound-1
Could I get away with such a transformer?
Last edited:
I wouldn't be too concerned about the mismatch. I have a little SE here that I am using some Bell radiogram transformers in.
They were designed for ECL86 to 3.5 ohm speakers, but sound great into 8 ohms.
Probably knocks the power back a bit, but un-noticeable.
I think ECL82 likes to have impedance on the high side of 5k anyway.
They were designed for ECL86 to 3.5 ohm speakers, but sound great into 8 ohms.
Probably knocks the power back a bit, but un-noticeable.
I think ECL82 likes to have impedance on the high side of 5k anyway.
OK, interesting, ive been told the opposite by this seller.
His transformers look suitable anyway, new 10W 8KCT to 4 & 8 ohm output transformers for tube amps & other applications | eBay
his message to me was:
Hello, for 6BM8, I'd use 4K on the plate, and 2K to the Screen(Grid2).
6BM8 is similar to a 6BQ5 and half a 12AT7. I've used these for single ended 6BQ5s before.
If it calls for 5K, I much rather have 4K than 6K. 6K just wouldn't get full power out. Thanks, Joe
Either way, for the price, im not going to complain!
6BM8 is similar to a 6BQ5 and half a 12AT7. I've used these for single ended 6BQ5s before.
If it calls for 5K, I much rather have 4K than 6K. 6K just wouldn't get full power out. Thanks, Joe
Either way, for the price, im not going to complain!
A comment from that seller
This is not the first time ive heard about air gaps, other listings on ebay claim their transformers have them, but i dont think its a literal gap, as i dont see how it could physically work.
Is it a type of layering between the windings?
OK, thats along the lines i was thinking, essentially a space between windings.
I know its supposed to be crucial when winding OT to get this right.
Anyway its hard to get transformers here in New Zealand.
I have to order everything from overseas, or get custom wound jobs that cost $$$
Here is one cheap alternative. I have tested this too. It works fine as a replacement for a tube radio opt. There is also an UL tap included.
TGL 5/001 INDEL - Transformer: speaker | TME - Electronic components
TGL 5/001 INDEL - Transformer: speaker | TME - Electronic components
Last edited:
I own some of the larger capacity transformers in this line. I like his transformers and they are good value, but *if* I am doing my measurements correctly, the low frequency response is not suitable for hi fi. Expect around -5dB when you venture down below 100Hz or so. If that kind of low frequency response is acceptable for your application, these are otherwise good transformers.
I've also played around with line transformers a bit, including ones almost certainly a lot better than this model ^^^^^. With the better ones, their single ended performance is acceptable at low power outputs - up to about one or two tenths of a watt. IMD goes up a lot after that. My measurement equipment is limited and crude by modern standards. Some line transformers can be very good low power push pull transformers, though.
The idea that Edcor has nothing suitable for a single ended 6BM8 is wrong. Get an XSE15 in whatever load / speaker impedance you want, and be done with it. Mine go down to 70 Hz at -1 dB.
Win W5JAG
edit: for that matter, the Hammond 125BSE, 125CSE, 125DSE, or 125ESE would be satisfactory. These are off the shelf transformers - someone in NZ might actually stock them.
Last edited:
That particular seller specialises in guitar amp parts, so that should tell you that the frequency range of his transformers is going to be limited. The one you linked to is for push-pull, not SE.
The tube that has the 6BQ5 pentode section is the 6GW8/ECL86. The ECL82 is much more akin to the performance of a 6AQ5, even though the 6AQ5 is a tetrode.
There is a complete kit available on eBay, designed for the 6P1 tube (a form of 6AQ5), that I have built and listened to. It would be easy to adapt that to 6BM8 if you want. The iron in the kit is quite good, although the power transformer runs fairly hot on 230v. Note that it is a full point-point kit including all parts:
6N2 Push 6P1 Double 6Z4 Tube Amplifier Kit Tube Rectifier Amplifier Kit | eBay
PM me if you want to discuss further.
Gary
The problem with the likes of the Edicor XSE15 is that its too large rated at 15W.
Im trying to keep my amp compact and small so it fits on my computer desk.
The hammond transformers are a bit smaller, but for the price of these ones on Ebay, I went for them.
I may go for something better once i test out how this goes.
IDK, it may sound alright.
The seller assured me they sound great in single ended hifi and he has used them himself on a similar build.
Im trying to keep my amp compact and small so it fits on my computer desk.
The hammond transformers are a bit smaller, but for the price of these ones on Ebay, I went for them.
I may go for something better once i test out how this goes.
IDK, it may sound alright.
The seller assured me they sound great in single ended hifi and he has used them himself on a similar build.
"...an air gap is a cut in single ended transformers to give a softer sound" WHAT A CROCK, the air gap is there so that the DC present in an SE amp does not saturate the core. Make it easy on yourself, use a transformer spec'd for PP (cheap and easy) and parafeed it. Best amp I ever built used SE 6C33C tube and a parafed toroidal power transformer as an OPT. Fantastic frequency response, low distortion, and great sound!
Unknown until you try them, but guitar types are available locally:
OP6 Output Transformer New | Trade Me
I have no knowledge of the merits of these either.
Here's my little amp (still not fully finished but running well.
Attachments
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.