SET amp owners thread

[bonzo75]

Here's one of several of my bespoke SET's from Oliver Sayes

6HJ5, 6N7, 5R4WGB
UTC & Lundahl transformers, Duelund caps

nice what are your impressions of the differences of the models you had?

 

[Argonaut]

ok, clueless, many drivers in horns. Altec was never as high priced as GPA made it to be all of a sudden. And what makes you think Goto is better, have you heard any Goto 2-ways? They are almost always 4 or 5 ways as they are narrow bandwidth and have their own complexity

You are quite aware of the point that I am making Kedar …

 

[djsina2]

Love the simplicity of that amp. was is a custom request or an existing build from them? Still Ken?

It’s an existing build. Ken said he worked a long time on this design and it’s his best price to performance 300B amp. It has a toggle to switch between PX25 and 300B.

 

[Kray]

It’s an existing build. Ken said he worked a long time on this design and it’s his best price to performance 300B amp. It has a toggle to switch between PX25 and 300B.

very nice. may I ask how much?

 

[Kray]

nice what are your impressions of the differences of the models you had?

Good question. This 6HJ5 is similar in spec to a 2A3, but i can re-tube the whole amp for under $80. It also sounds VERY close to my Sayes 421a.
Had a 42, 45, & 46 from Sayes as well. Enjoyed them all but prob the 46 the most. It's always hard for me to remember how to compare the sound once they've been out of the house more than a year.

My current favorite is my 307a. tango transformers. Similar to 300B but tightened up bass and more 3D.

• C3M driver
• 5AR4 rectifier
• Regulated DC filament supplies
• 0D3 tube regulated screens
• Duelund copper caps
• DHT wired Tetrode output
• 6wpc
• Lundahl chokes
• Hirata Tango output transformers

 

[djsina2]

very nice. may I ask how much?

$2500 + shipping, no tubes

 

[the sound of Tao]

Here's one of several of my bespoke SET's from Oliver Sayes

6HJ5, 6N7, 5R4WGB
UTC & Lundahl transformers, Duelund caps

Beautiful to see… they look fantastic Kray. Lovely work.

 

[Kray]

Beautiful to see… they look fantastic Kray. Lovely work.

Thank you... obviously i'm a fan of Oliver's work as you can also see under the amp, the dual chassis 37 preamp by him as well

 

[Fishfood]

Good question. This 6HJ5 is similar in spec to a 2A3, but i can re-tube the whole amp for under $80. It also sounds VERY close to my Sayes 421a.
Had a 42, 45, & 46 from Sayes as well. Enjoyed them all but prob the 46 the most. It's always hard for me to remember how to compare the sound once they've been out of the house more than a year.

My current favorite is my 307a. tango transformers. Similar to 300B but tightened up bass and more 3D.

• C3M driver
• 5AR4 rectifier
• Regulated DC filament supplies
• 0D3 tube regulated screens
• Duelund copper caps
• DHT wired Tetrode output
• 6wpc
• Lundahl chokes
• Hirata Tango output transformers

I feel like I need this amp. How do I get one? Is there a website or a way to contact the builder?

 

[Kray]

I feel like I need this amp. How do I get one? Is there a website or a way to contact the builder?

I’ll PM you

 

[morricab]

I feel like I need this amp. How do I get one? Is there a website or a way to contact the builder?

it gave me an itch as well...not ready to pull the trigger yet...I have plenty of good amps...however...

 

[Atmasphere]

hey are of course single ended triode design but they only have a balanced XLR input. I have almost no knowledge of electrical engineering but I do understand how a balanced/common mode rejection design works and thus know that if an amp is single ended, it cannot also be balanced, so I don't understand why such an amp would have an XLR as the input unless it was simply because the designer chose to use that connection for convenience.

I use adapters on my (long) IC cable runs, which are themselves RCA only, as is my pre-amp. I've asked my dealer who supplied the units a number of times but whilst he's given an explanation, I've never quite understood it. He says there is a transformer immediately behind the input which recombines the signal before passing it through the amplification stages. This makes sense but I still don't understand why you would do that rather than just use an RCA input and lose the transformer (which would simply add cost, unnecessarily it would seem).

Depending on how you have the input transformer wired, it can do either balanced or single-ended input quite well.

This is the usual tribute to fashion. Balanced connection is necessary when transmitting weak signals over long distances, for example from a microphone from the stage, or in modern DACs. In this way, the level of noise that occurs in the chip during signal processing in DACs is reduced. A balanced signal can still simplify the design of the PP amplifier. It is not needed at all for the SE amplifier.

Balanced connections are more than just fashion. They allow you to run really long interconnects without degradation (as in a microphone, but at line levels too), which allow you to placed your amps as close to the loudspeakers as possible. With SETs this is important, because they are more sensitive to speaker cables. This allows you to run as short speaker cables as possible (minimizing loss of bass impact and other colorations) without compromise on account of the long interconnects.

Can you give an example of a SE amplifier class other than class A?

Class A SETs come in three varieties, class A1 (which is most of them), class A2 (grid current can be present during part of the signal waveform, which requires a more robust drive circuit) and class A3 (which was recently patented and also has grid current present). To my understanding class A3 offers the most power and the least distortion but the operating point is arcane and not understood by most designers.

 

[LL21]

...Class A SETs come in three varieties, class A1 (which is most of them), class A2 (grid current can be present during part of the signal waveform, which requires a more robust drive circuit) and class A3 (which was recently patented and also has grid current present). To my understanding class A3 offers the most power and the least distortion but the operating point is arcane and not understood by most designers.

Interesting, Ralph. Do you believe A3 offers significant 'base level' advantages as a design approach...so that it has perhaps (or is or will) tempt a designer like you to do an all-out assault design for it? Most power, least distortion...and all Class A seems like a great story.

 

[jeff1225]

$2500 + shipping, no tubes

Excellent. What transformers are in the amps?

 

[djsina2]

Excellent. What transformers are in the amps?

His own. He won’t tell you anything about them. Trade secret.

 

[Kray]

His own. He won’t tell you anything about them. Trade secret.

Ken is a... interesting guy. i've had a couple experiences with him.
Those look like Tango transformers though, anyone else think so? I know he used to use and promote Tango a lot. @jeff1225

You could check underneath and see if you can see the bottom of the transformer.

 

[SVS]

Depending on how you have the input transformer wired, it can do either balanced or single-ended input quite well.

Balanced connections are more than just fashion. They allow you to run really long interconnects without degradation (as in a microphone, but at line levels too), which allow you to placed your amps as close to the loudspeakers as possible. With SETs this is important, because they are more sensitive to speaker cables. This allows you to run as short speaker cables as possible (minimizing loss of bass impact and other colorations) without compromise on account of the long interconnects.

Class A SETs come in three varieties, class A1 (which is most of them), class A2 (grid current can be present during part of the signal waveform, which requires a more robust drive circuit) and class A3 (which was recently patented and also has grid current present). To my understanding class A3 offers the most power and the least distortion but the operating point is arcane and not understood by most designers.

Is it necessary? I have yet to see a home audio system in which the distance between the speakers is 20 meters or more. 3-4 meters between speakers, very long interconnects are not needed.
Loss of bass should be considered when choosing an amplifier. Fist-sized output transformers will never produce quality bass. A balanced connection or long interconnects will not add bass.

If we are talking about a SET amplifier without general feedback, then a large output transformer is needed in order to hear good bass. The lower operating frequency of such a transformer at the level of -3 dB should not even be 20 Hz, but 7-8 Hz, if it is less, the sound will only be better. This transformer should provide a damping factor of at least 3-4.


Class A is when the active element, that is, the tube, amplifies both half-waves of the signal. 1 or 2 or even 3 do not change the principle of operation, they show the mode of operation of the output tube.

 

[Atmasphere]

Interesting, Ralph. Do you believe A3 offers significant 'base level' advantages as a design approach...so that it has perhaps (or is or will) tempt a designer like you to do an all-out assault design for it? Most power, least distortion...and all Class A seems like a great story.

A3 does offer benefit, but Its not a thing in which I have a lot of interest. I like musicality, but since I've done a lot of recording and have been at the sessions I've recorded, I know what they are supposed to sound like, so I'm not a fan of colorations and for the last 50 years have tried to prevent them showing up in my designs. So far, having studied SETs since the early 1990s, I've not found a particular advantage they have over other topologies; for SETs, colorations seem to be the name of the game.

Is it necessary? I have yet to see a home audio system in which the distance between the speakers is 20 meters or more. 3-4 meters between speakers, very long interconnects are not needed.
Loss of bass should be considered when choosing an amplifier. Fist-sized output transformers will never produce quality bass. A balanced connection or long interconnects will not add bass.

The advantage of shorter speaker cables is an advantage; in addition to helping get the bass right, things like vocals will be more easily discerned. Even though the amplifier might have decent bass in itself, its high output impedance might otherwise pose a difficulty, especially if the OPT is used on a lower impedance tap! By using balanced lines, you can eliminate the colorations that so many single-ended cables impose (if you've auditioned two such cable side by side and heard a difference, that's exactly what I'm talking about), and one of those colorations can be a lack of bass; IOW I'm not concerned about adding bass rather not losing it. I play bass (since 6th grade) so I need to be convinced by the system's ability to play bass correctly.

I fully agree with the rest of your comments that I didn't quote.

 

[LL21]

Thank you, Ralph and clear as always.

 

[microstrip]

(...) Balanced connections are more than just fashion. They allow you to run really long interconnects without degradation (as in a microphone, but at line levels too), which allow you to placed your amps as close to the loudspeakers as possible. With SETs this is important, because they are more sensitive to speaker cables. This allows you to run as short speaker cables as possible (minimizing loss of bass impact and other colorations) without compromise on account of the long interconnects. (...)

Ralph,

Curiously it seems counterintuitive. Why would a few tens of miliohms in series with speakers that usually have higher impedance than speakers designed for SS affect the sound of a low damping amplifier?

In fact we see many people using vintage cables of low section with SET amplifiers.