New Hybrid Single Ended Power and Stereo Amplifiers - Feedback/Poll needed

[Aries Cerat]

If I understand the design right, the answer is right in this graph:

Check on the left where the response is linear (flat line). At low input currents you basically have a tiny region which will not allow much swings around 2 volts. Push the input current way high and you get to the top graph where you now can have a healthy swing around 2 volt. Just like a class A design, you are having to bias the transistor with tons of idle current which goes to waste and needs to go some place. You also have pretty small voltage swings. Careful selection of FETs may provide a better center voltage but still, between the high input current and low voltage swings, making high power version of this will be tall mountain to climb.

Maybe a better picture would clarify

 

[DaveC]

Hmmmm, I've seen something like this before...

http://www.tubecad.com/2009/12/blog0178.htm

 

[DaveC]

Hmmmm, I've seen something like this before...

http://www.tubecad.com/2009/12/blog0178.htm

Sorry to kill the thread... It certainly seems like this is the topology, if so it seems like a really good idea. Broski is a quite adept at understanding circuits, I have two preamps based on his designs. The super-triode configuration makes a lot of sense and I may try it instead of spending huge $$$ (that I don't have) on a big SET amp. I think this amp makes a lot of sense as a big-SET alternative as it has the potential to be much less expensive and sound a lot like the "steering" triode.

 

[Believe High Fidelity]

Sorry to kill the thread... It certainly seems like this is the topology, if so it seems like a really good idea. Broski is a quite adept at understanding circuits, I have two preamps based on his designs. The super-triode configuration makes a lot of sense and I may try it instead of spending huge $$$ (that I don't have) on a big SET amp. I think this amp makes a lot of sense as a big-SET alternative as it has the potential to be much less expensive and sound a lot like the "steering" triode.

Not at all. We just got back from CES so we will resume this at sometime in the next week :thumbs up:

 

[Believe High Fidelity]

So we have decided to kind of combine a bit of both side of the coins. We will be releasing a 30W and 75W stereo and integrated in our Prestige line (ie more affordable) late Q3/Q4.

Thank you all for your feedback

 

[DonH50]

I am not sure Amir's plot of Id vs. Vds is the same transfer function Aries Cerat showed -- those look like different topologies being measured. Either saturation is very high, or the latter is Id vs. Vgs (?) Probably irrelevant to all but geeks...

I always thought an interesting variant on the SET would be a SET with an emitter- or source-follower output. That would provide a class A output, should not really impact the SET sound, but provides a low-impedance output that better handles typical speaker loads. I suppose the big caveat is that amp-speaker interaction is one of the reasons for tubes in the first place...

 

[DaveC]

I am not sure Amir's plot of Id vs. Vds is the same transfer function Aries Cerat showed -- those look like different topologies being measured. Either saturation is very high, or the latter is Id vs. Vgs (?) Probably irrelevant to all but geeks...

I always thought an interesting variant on the SET would be a SET with an emitter- or source-follower output. That would provide a class A output, should not really impact the SET sound, but provides a low-impedance output that better handles typical speaker loads. I suppose the big caveat is that amp-speaker interaction is one of the reasons for tubes in the first place...

Yup, click the link I posted to see what the circuit looks like. Broski calls it Super-Triode.

 

[DonH50]

Thanks, missed that! On lunch break and waiting on a test so I skimmed it. Very much what I had in mind but much better fleshed out. I did something similar ages ago but took the extra step of using +/- B+ rails and a simple feedback circuit for DC-coupled outputs (since that was all the rage a few decades ago, a trend I was happy to see die, after several speakers did...) Close to one of the circuits in that blog but with a single SET instead of stacked devices. (I did build an amp using push-pull tubes stacked similarly to what the blog shows, again with +/- B+ rails and an opamp DC feedback loop). The DC servo got complicated when I started adding stuff to handle possible failures like open or shorted tubes and output devices; never really wanted to plop +/-150 V DC (for my amp) across the speaker terminals...

I don't recognize that name but sense a kindred spirit...

 

[amirm]

I am not sure Amir's plot of Id vs. Vds is the same transfer function Aries Cerat showed -- those look like different topologies being measured.

Yes I was corrected above but I did not acknowledge it as I should have .

 

[DaveC]

Thanks, missed that! On lunch break and waiting on a test so I skimmed it. Very much what I had in mind but much better fleshed out. I did something similar ages ago but took the extra step of using +/- B+ rails and a simple feedback circuit for DC-coupled outputs (since that was all the rage a few decades ago, a trend I was happy to see die, after several speakers did...) Close to one of the circuits in that blog but with a single SET instead of stacked devices. (I did build an amp using push-pull tubes stacked similarly to what the blog shows, again with +/- B+ rails and an opamp DC feedback loop). The DC servo got complicated when I started adding stuff to handle possible failures like open or shorted tubes and output devices; never really wanted to plop +/-150 V DC (for my amp) across the speaker terminals...

I don't recognize that name but sense a kindred spirit...

Yeah, I just made a preamp using Broski's Aikido cathode follower with +/- rails and finally decided on an output coupling cap anyways, good copper foil caps are really good and no need for a DC servo, which has it's own drawbacks imo.

The super-triode looks really nice, I'd like to build one for the speaker I'm working on, it's 102 dB efficient (mid/high section) but can play very, very loud so I need a pretty decent amount of power for it to be able to keep up with the woofer.

 

[Aries Cerat]

Hello there
Excuse my late reply to the thread.

Our circuits is not like Broski's ,though share some common principles.

Broski's circuit sounds excellent BTW!!

Our way of implementing the Triodefet creates a three terminal "black box" which it's transfer curves are even closer to a true triode.

Since we tried some variations of the Broski's circuit and compared it with the Triodefet,i can state with the same type of tube-FET components we achieved 10X lower output impedance as well.

We wanted to expand the use of the Triodefet to simple tube-like circuits,like our parafeed SE stages, and it's sound exceeded my expectations.I did not want to make a amp just because....


Final product launch hopefully within 2016

 

[Audiophile Bill]

How did it go at CES, Mr Aries? I saw some photos with your horns also.

 

[Aries Cerat]

How did it go at CES, Mr Aries? I saw some photos with your horns also.

Hello Bill

The show went fantastic. We had a great room and even though CES's attendance is much lower than Munich,it had quality over quantity.

Very stressful and tiring,as well as a 10-hour jet lag but we managed

It was a real pleasure meet Amir as well.

Stavros D.

 

[Audiophile Bill]

Hello Bill

The show went fantastic. We had a great room and even though CES's attendance is much lower than Munich,it had quality over quantity.

Very stressful and tiring,as well as a 10-hour jet lag but we managed

It was a real pleasure meet Amir as well.

Stavros D.

Oh great - congratulations.

 

[Believe High Fidelity]

Hello Bill

The show went fantastic. We had a great room and even though CES's attendance is much lower than Munich,it had quality over quantity.

Very stressful and tiring,as well as a 10-hour jet lag but we managed

It was a real pleasure meet Amir as well.

Stavros D.

You're supposed to say what happens in Vegas stays in Vegas remember?

 

[amirm]

You're supposed to say what happens in Vegas stays in Vegas remember?

Nothing happened in Las Vegas....