I bought these ebay bargain transformers a few years ago, and originally planed to do an 859 style amp with 3 paralleled 509s, to give about 40 watts. But time goes by, and I packed them away, but still their memory lingered and in their absence I eventually convinced my self they were from an audio note parallel 300b amp. Dug them out again yesterday to do some measurements. I convinced myself wrong. They are made by Trans-tronics.
Anyway what tubes to use, I have fairly modest aspirations, 30 watts output should be adequate, rough calculations would suggest a HT of about 500 volts, and 200mA current. I am thinking triodes would be nice, maybe a couple in parallel, but what.
Pleas help me with some recommendations of something hopefully fairly cheap and maybe directly heated? but not essential and probably not 6c33.
Anyway what tubes to use, I have fairly modest aspirations, 30 watts output should be adequate, rough calculations would suggest a HT of about 500 volts, and 200mA current. I am thinking triodes would be nice, maybe a couple in parallel, but what.
Pleas help me with some recommendations of something hopefully fairly cheap and maybe directly heated? but not essential and probably not 6c33.
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Something like this:
Unison Research Performance Integrated Valve Amplifier at Audio Affair
3xKT88 in parallel with 400V anode voltage you should get 30W easy from UL.
If you go for 450V more.
Unison Research Performance Integrated Valve Amplifier at Audio Affair
3xKT88 in parallel with 400V anode voltage you should get 30W easy from UL.
If you go for 450V more.
I love the 6P45S, pretty much a 509 really, but what about some triodes, obviously the 211 845 GM70 wouldn't really work, I am not really familiar with the power triode, but there are a few that are between the 845 and the 300B in size, 811 type of thing?
If 6C33 is off the table 6C41 or 6336 are viable choices.
You could do PSE with E130L for slightly over 20W of output power, the upside being that these require about 4V RMS to drive in SE, meaning you dont really need a driver if your system has enough gain.
You could do PSE with E130L for slightly over 20W of output power, the upside being that these require about 4V RMS to drive in SE, meaning you dont really need a driver if your system has enough gain.
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I suspect ‘modest aspirations’ of 30W from DHT and 1k5 load is an oxymoron.
Perhaps 6c33 isn’t a bad idea, or something of this ilk.
You can still put a dht in front of it, perhaps a pentode for gain.
Otherwise you’ll have to resort to lots of plate feedback from an output tube to bring down the plate impedance for driving that OPT.
For crazy thoughts, what about a cathode follower output stage, this could give low impedance drive for that transformer ?
Perhaps 6c33 isn’t a bad idea, or something of this ilk.
You can still put a dht in front of it, perhaps a pentode for gain.
Otherwise you’ll have to resort to lots of plate feedback from an output tube to bring down the plate impedance for driving that OPT.
For crazy thoughts, what about a cathode follower output stage, this could give low impedance drive for that transformer ?
Hi Hbc,
George of Tubelab is getting ready to unleash an UNSET design and PCB that could put your 1.5k primary SE transformers to good use - probably using a parallel pair of TV sweep tubes. He got 60 watts output with a 1.5k Toroidy transformer in this configuration. See here:
UNSET is coming?
Maybe a handful of parallel connected smaller pentodes would be an interesting way to use these. 4-5 EL84 or 6V6 per channel would lead an easy life. I've done a 3x3 EL84 triode SE with a single 6SN7 driver before, lovely build and an odd number of output tubes per side would be unique.
Thanks for all the input. It has to be 13e1. Been on my radar in the past, but could not justify buying some just because they look cool..... but now, to late already, some on order...
They are a bit costly, but so is multiplying up others. I like the look of the 3663B as well, but 4 of those or 6 x 6P45ss they are going up in price a bit now (bother).
And it seems there is a bit of prior art, which will grease the wheels of creativity, and is giving results of about where I was hoping to be.
They are a bit costly, but so is multiplying up others. I like the look of the 3663B as well, but 4 of those or 6 x 6P45ss they are going up in price a bit now (bother).
And it seems there is a bit of prior art, which will grease the wheels of creativity, and is giving results of about where I was hoping to be.
This is an interesting question. The details are a bit sketchy in my mind now but, they were made in the UK by Trans-tronic, who make audio transformers for valve amplifiers amongst other things. The ebay seller claimed they were litz wired, but I am not sure they are, but the windings look nice and neat, and I don't think they have ever been used. They are some kind of C core, and they weigh about 5.5 kgs each. I find it hard to believe they will be completely rubbish. They were a bargain to me as I think I paid less then £70 for the both of them, delivered.
We will see. Buying transformers always feels like a bit of a gamble, I would be sensible to test them a bit more before I get too far down the line with this amp though...
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Why don't use a pair of 34 triode connected?
Are cheaper, you stay safe for low frequency and you will get around 12-15 watt.
Walter
Are cheaper, you stay safe for low frequency and you will get around 12-15 watt.
Walter
Thanks, I have a triode connected EL34 amp that I am working on already, its very nice. I am sold on the 13E1, wasn't difficult actually. I confront the amplifier design as not just a functioning circuit, but almost like a sculptural piece of art, for my own idiosyncratic taste of course... the 13E1 is one of the the coolest tubes imo, kind of moody and brooding. It needs to be surrounded by architectural circuit elements..
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