SET amp owners thread

[Don_Camillo]

If I remember correctly it was:

1. Tango
2. Tamura

3. James

4. Trafo Baule
5. Lundahl
6. Gerd Reinhöfer

7. Thöress

 

[VinylSavor]

If I remember correctly it was:

1. Tango
2. Tamura

3. James

4. Trafo Baule
5. Lundahl
6. Gerd Reinhöfer

7. Thöress

Hi Rolf,

let me correct before the myth about the sound of brands is fuelled even more.

The brands are totally meaningless if the type of transformer is not mentioned as well.
We had two Tango transformers in the race, one made it to number one position and the other was among the worst sounding. There was no Tamura in the contest. Second winner was Lundahl based on consent of all listeners. Then came the rest with James having a slight edge over the remaining ones.

But it is worth mentioning: This was about 17 years ago! The contest was anything else but a scientific comparison. It was a quick and dirty change between transformers without measurements or adjustment for gain since transformers tend to have different winding ratios. And highly subjective since such tests depend on the entire system.

Also worth noting: I do not remember if the Tango iron was Hirata Tango or ISO Tango, both of which don't exist anymore. Lundahl developed an array of new output transformers which far surpass the old ones we used. Especially after he received feedback from me about his output transformers. Yet this old trans made it to second place.

Also worth mentioning: The amp used a Lundahl interstage transformer for all tests. Only the output transformers were swapped. The IT used is not the best for interstage use and Lundahl developed a better one a few years later which I then used for this type of circuit.

I am amazed how the SQ of parts tends to be judged by brand alone. I recently received a comment on a photo which I posed on FB. it said: Wow good driver tubes! I was surprised since the type of the tubes was not visible in the photo and I asked how he knew. The response: They are RCA. Other comments followed saying that the brand is more important for the SQ than the tube type. That is peak audiofoolery.

But anyways if anyone wants an amplifier with Tango or Tamura iron. I still have plenty in stock ;-)

Tango Trandformers

Best regards

Thomas

 

[DasguteOhr]

Yes, Thomas and me started this project for Roehren & Hoeren back in that days. The picture was taken at one of the shootouts with several variants of the schematic and some variants of compoents used. We tested e.g. output transformers from James, Tango, Lundahl, Gerd Reinhöfer, Thöress and others but also combinations of the driver stage with different power tubes (6CB5A, 12E1, 300B, 45).

Ach kiek ma der Rolf aus München ...Servus
I've been there since 2010 in this forum, taking my first steps with tubes. I've always received excellent support and help.

 

[Don_Camillo]

Hi Thomas,

thanks for correcting me. 17 years since then. Time flies

We had two Tango transformers in the race, one made it to number one position and the other was among the worst sounding.

ISO Tango, if I remember correctly, models XE-20s and U-808 whith the XE-20s rated first, the U-808 worst. James was the model JS-6123S

 

[bonzo75]

ISO Tango, if I remember correctly, models XE-20s and U-808 whith the XE-20s rated first, the U-808 worst. James was the model JS-6123S

Yes the U 808 is usually the worst rated. Thanks for the model mentions

 

[Don_Camillo]

Yes the U 808 is usually the worst rated. Thanks for the model mentions

I don't think you can say that in general. For the U-808, it was probably the wrong application – as an output transformer for a tweeter amplifier in an active multi-way setup, the result would probably be different.

 

[bonzo75]

I don't think you can say that in general. For the U-808, it was probably the wrong application – as an output transformer for a tweeter amplifier in an active multi-way setup, the result would probably be different.

A tweeter amp is very specific. But for general amps, the U808 usually rates behind all, and the XE series a coupple fo N models rate higher. DIY audio has many of these compares. While some can be subjective between top models of Tango, Tamura, etc, this seems more consistent.

 

[MrC.]

Why do so many people use 2A3 or 300B. My amp also has a lot of Monolith iron. Its a KT PP amp. I asked about a 300B or 2A3. I was told they are good tubes, but an 811 can be an even better tube.

If your speaker is efficient enough, or if you listen low enough, the 2a3 is an amazing sounding power tube, in my mind far better than the 300b. The mids are richer and the bass is fuller. Why this is I cannot say but the 2a3 amps I have heard bested anything single ended, save a Komuro 845 I heard once and only once at a builders show at a warehouse. Many swear by the AN Neiro which use two of the tube in parallel fed by an IT, and claim it to be the best of their offerings.

 

[Atmasphere]

If your speaker is efficient enough, or if you listen low enough, the 2a3 is an amazing sounding power tube, in my mind far better than the 300b. The mids are richer and the bass is fuller. Why this is I cannot say

Actually you're describing how much better the output transformer works when you don't have to make as much power.
The more power you have to make with an SET, the less of the 'magic' of SETs. This is why the type 10 and type 45 power tubes are considered more highly than the 2A3. It has little to do with the characteristics of the tube and a lot to do with how the output transformer performs.

 

[MrC.]

Actually you're describing how much better the output transformer works when you don't have to make as much power.
The more power you have to make with an SET, the less of the 'magic' of SETs. This is why the type 10 and type 45 power tubes are considered more highly than the 2A3. It has little to do with the characteristics of the tube and a lot to do with how the output transformer performs.

Is that a function of current, voltage or a combination of the two? I’ve heard good sounding high voltage set’s but each had an enormous output transformer and likely used a current figure similar to the 2a3.

 

[Atmasphere]

Is that a function of current, voltage or a combination of the two? I’ve heard good sounding high voltage set’s but each had an enormous output transformer and likely used a current figure similar to the 2a3.

It has to do with the DC magnetic field caused by the current of the power tube being drawn through the primary winding of the transformer. This induces a DC magnetic field and is a function of current. To get around this problem there is a saw cut in the core of the transformer which vastly reduces the DC saturation issue. The less current the less DC saturation; the gap thus made has to be larger when more current is present. That gap also affects low frequency bandwidth!

So the lower power tubes don't need as much current; the gap can be smaller which increases inductance at low frequencies- you get wider bandwidth on both extremes of frequency.

 

[godofwealth]

If your speaker is efficient enough, or if you listen low enough, the 2a3 is an amazing sounding power tube, in my mind far better than the 300b. The mids are richer and the bass is fuller. Why this is I cannot say but the 2a3 amps I have heard bested anything single ended, save a Komuro 845 I heard once and only once at a builders show at a warehouse. Many swear by the AN Neiro which use two of the tube in parallel fed by an IT, and claim it to be the best of their offerings.

My favorite SET at home with my Klipsch La Scalas is the Oliver Sayes' designed 421a. The Western Electric 421a is just a miracle tube, which I like far more than the 300B or the 45 (both of which I have as SET amps as well). One power tube for both channels simplifies the design of the SET even more. The 421a has a bit more power than the 45, about 3-4 watts. It's just got that magical midrange to it, and no one did it better than WE. You can also use the Tung Sol 5998, but that doesn't sound quite as magical in my opinion.

The 421a is the sleeper tube of the century. You can still buy NOS versions without paying a king's ransom (unlike the NOS WE 300Bs).

There's a reason why direct heated triodes are also a bit noisier than the 421a, but I'll leave that discussion to the folks who build SETs. There are a few others who design 421a amplifiers as well, and these show up on AudioMart from time to time.

Glow in the Dark Audio - Oliver Sayes Western Electric 421a

Glow in the Dark Audio showcases Kevin Davis’ personal collection of small-scale, DIY and one of a kind hifi audio gear, with a focus on single ended and push pull tube amplifiers and full range open baffle speakers.

glowinthedarkaudio.com

 

[MrC.]

My favorite SET at home with my Klipsch La Scalas is the Oliver Sayes' designed 421a. The Western Electric 421a is just a miracle tube,

Is it direct coupled?

 

[Atmasphere]

My favorite SET at home with my Klipsch La Scalas is the Oliver Sayes' designed 421a. The Western Electric 421a is just a miracle tube, which I like far more than the 300B or the 45 (both of which I have as SET amps as well). One power tube for both channels simplifies the design of the SET even more. The 421a has a bit more power than the 45, about 3-4 watts. It's just got that magical midrange to it, and no one did it better than WE. You can also use the Tung Sol 5998, but that doesn't sound quite as magical in my opinion.

The 421a is the sleeper tube of the century. You can still buy NOS versions without paying a king's ransom (unlike the NOS WE 300Bs).

There's a reason why direct heated triodes are also a bit noisier than the 421a, but I'll leave that discussion to the folks who build SETs. There are a few others who design 421a amplifiers as well, and these show up on AudioMart from time to time.

Glow in the Dark Audio - Oliver Sayes Western Electric 421a

Glow in the Dark Audio showcases Kevin Davis’ personal collection of small-scale, DIY and one of a kind hifi audio gear, with a focus on single ended and push pull tube amplifiers and full range open baffle speakers.

glowinthedarkaudio.com

The 421a has specs similar to the 6AS7G but with greater mu. A single one of those tubes is good for 10Watts in class A with the right load if you have it wired in push-pull (its a dual triode so this is possible).

Put a few of those in parallel and you don't need an output transformer if you have the right circuit. We've been doing that for decades now with the 6AS7G.

The downside of using this tube in an SET is the tube runs relatively low plate Voltage and relatively high plate current. The plate current is high enough I imagine this would be challenging to design an SET output transformer for it.