What are the advantages/disadvantages of different amp topologies?

[Atmasphere]

That may be true but the reverse "If they sound good, they must measure good" is not necessarily so and neither is "If they measure good, they must sound good"

Its all about making the right measurements and also knowing what those measurements are telling us. That knowledge is in short supply.

For instance, I said that, IMHO, over-engineering with loads of electronic processes applied between source and speaker, perhaps to correct "measurements" or to cut costs ( such as using a diodes in place of more expensive rectifier tubes), ruins the sound. I also said, IMHO, that designing a simple circuit with the lowest parts number but with the best parts available usually sounds best. Atmosphere, agreed to the simple design with excellent parts idea, but only as a segue to advertise his own OTL amplifiers.

I mentioned them because they have less stages of gain than any SET. SET's are usually trotted out as being the most simple but they are not. Nelson Pass has built amps that are simpler than SETs too.

let me add that “emotion” to me is a function of music. There’s no getting emotional over gear, unless it is one’s sole inheritance from a loved one. From my perspective, what systems “contribute” is distraction, which precludes emotion. So when a drum whack makes me almost leap out of my seat as it would in a live concert, and a tube amp slightly softens bass response, that’s nowhere as decisive as the fact that a drum whack isn’t just bass, and what hinders my emotion is inevitably when my attention is drawn to a part rather than the whole. The musical properties that let us engage with the emotional content, to me are about coherence and timing, and of course tone (which is big when one is primarily a classical music aficionado like me), apart, quite simply, from anything that doesn’t belong there (the very definition of distraction). In general, I can’t bring myself to say that tube gear or solid state does all three better than the other, the point is the tradeoff must not be such that one isn’t connecting to one’s favorite music.

Music is normally processed in the limbic portion of the brain until it finds a problem (such as harshness), at which time the music processing transfers to the cerebral cortex. IMO the goal of the designer should be to keep the processing in the limbic portion as much as possible, so the music will be more engaging with greater emotional impact.

Understanding how the ear/brain hearing perceptual rules work is key. That has to be married to the engineering skill to design circuits that conform to those rules.

 

[morricab]

I owned a First Watt F3 for awhile, it used JFETs for amplification only (not hybrid). To me, it lacked the emotion of a good class A SET amplifier, but could emulate drum wack’s fantastically when driven by the Shindo Massetto pre. What about emotion in regards the Aries Cerat Triode-FET hybrid (Or is it strictly a FET acting like a triode)?

I will let you know when my Protos arrives!

 

[cjfrbw]

I will let you know when my Protos arrives!

Nelson Pass is releasing another First Watt single ended SIT, the SIT-4, made with Tokin SIT rather than his previous radar SIT. Amp is spec'd at 10 watts per channel, but the Tokin device has potential anode dissipation of hundreds of watts (radar SIT had anode dissipation of about 50 or 60 watts). It is both voltage and current amplifier with a mu type MOSFET binary with no feedback fronted by NP's favorite JFET buffer.

Likely due to the massive reserve of the Tokin device, the amp has a lazy distortion curve that goes to about 20 watts @ 5 percent or so distortion, and probably can punch out higher transients than that, so not so lightweight as it seems from basic specs. $5K, so maybe a 'poor man's' Aries Cerat triode transistor type.

NP is also planning monoblocks for heat sinking purposes to push the base power up to 20 watts or more per channel.

SIT-4 – www.firstwatt.com

The owner's manual can be downloaded here: SIT-4 Owner's Manual

www.firstwatt.com

Introducing the First Watt SIT-4 Power Amplifier - The Absolute Sound

Introducing the First Watt SIT-4 Power Amplifier - Tom Martin stops by the Refined Audio room to get a glimpse of First Watt's improved power amplifier, the SIT 4. It's a two-channel Class A, with a Triode tube-like character, it's equipped with Tokin SlTs rated at 400 watts and 30 amps and a...

www.theabsolutesound.com

I suspect this one will be a favorite of the low power high efficiency crowd, if it is anything like the single ended VFET Sony 2SK60 that I built from Pass DIY site.

Morricab's reports will be interesting on the AC units, but I have only read good things about them.

 

[acousticsguru]

Morricab's reports will be interesting on the AC units, but I have only read good things about them.

I’m curious, too. I think Michael made the right move to get a pair of Ianus Essentia. Protos is a manageable size and weight that would be on my short list of amps to demo (if I needed or wanted one).

Greetings from Switzerland, David.

 

[DasguteOhr]

I think it's great when someone builds something excellent with affordable tubes. The Siemens E280F pentode in triode mode thumbs up.
You can do other things too with this tube.

 

[cjfrbw]

My Allnic H3000 phono probably has more than 10,000 hours, so I gave thought to tube replacement. The unit is still strong and sweet, I just wanted spares in case.

I read that the Russian 6j52p was an equivalent to the e810f or D3a tube so I ordered some cheapies from eBay as backup in case a tube fritzed out.

I thought I ordered six tubes, but I received 72 tubes from Ukraine for whatever reason. Probably a good thing as it turned out.

My tube tester tests E280F 7722 tubes, so I used that socket, same pinout and similar specs. Of the 72 tubes, I couldn’t get emissions on half. Of the half that tested strong, maybe a subset of those tested VERY strong. So, I’ll get a couple of sets of four of strong tubes at least.

These tubes from graphs are very linear in triode mode, great curves. I don’t know what the quality control situation was, or if they just had assembly line dumps that were untested before sales. Of course, Ukraine is at war, so maybe they are just shoveling stuff out to sell it.

I guess I’ll find out if and when I put them in the unit, but I wonder if I should, given the strange situation with them. Maybe I should try some more innocuous application to try them out first.

 

[Aries Cerat]

My Allnic H3000 phono probably has more than 10,000 hours, so I gave thought to tube replacement. The unit is still strong and sweet, I just wanted spares in case.

I read that the Russian 6j52p was an equivalent to the e810f or D3a tube so I ordered some cheapies from eBay as backup in case a tube fritzed out.

I thought I ordered six tubes, but I received 72 tubes from Ukraine for whatever reason. Probably a good thing as it turned out.

My tube tester tests E280F 7722 tubes, so I used that socket, same pinout and similar specs. Of the 72 tubes, I couldn’t get emissions on half. Of the half that tested strong, maybe a subset of those tested VERY strong. So, I’ll get a couple of sets of four of strong tubes at least.

These tubes from graphs are very linear in triode mode, great curves. I don’t know what the quality control situation was, or if they just had assembly line dumps that were untested before sales. Of course, Ukraine is at war, so maybe they are just shoveling stuff out to sell it.

I guess I’ll find out if and when I put them in the unit, but I wonder if I should, given the strange situation with them. Maybe I should try some more innocuous application to try them out first.

Hi

6j52: A very nice tube, especially when we use it on TriodeFet.

-------A word of advice for these, a lot of these were made with Pin 1 unconnected (only pin3 used for cathode, not 1+3 ) so proceed with caution ----- Good thing, it is easy to spot which ones have pin1 NC

Best
Stavros

 

[Atmasphere]

Nelson Pass is releasing another First Watt single ended SIT, the SIT-4, made with Tokin SIT rather than his previous radar SIT. Amp is spec'd at 10 watts per channel, but the Tokin device has potential anode dissipation of hundreds of watts (radar SIT had anode dissipation of about 50 or 60 watts). It is both voltage and current amplifier with a mu type MOSFET binary with no feedback fronted by NP's favorite JFET buffer.

Likely due to the massive reserve of the Tokin device, the amp has a lazy distortion curve that goes to about 20 watts @ 5 percent or so distortion, and probably can punch out higher transients than that, so not so lightweight as it seems from basic specs. $5K, so maybe a 'poor man's' Aries Cerat triode transistor type.

NP is also planning monoblocks for heat sinking purposes to push the base power up to 20 watts or more per channel.

SIT-4 – www.firstwatt.com

The owner's manual can be downloaded here: SIT-4 Owner's Manual

www.firstwatt.com

Introducing the First Watt SIT-4 Power Amplifier - The Absolute Sound

Introducing the First Watt SIT-4 Power Amplifier - Tom Martin stops by the Refined Audio room to get a glimpse of First Watt's improved power amplifier, the SIT 4. It's a two-channel Class A, with a Triode tube-like character, it's equipped with Tokin SlTs rated at 400 watts and 30 amps and a...

www.theabsolutesound.com

I suspect this one will be a favorite of the low power high efficiency crowd, if it is anything like the single ended VFET Sony 2SK60 that I built from Pass DIY site.

Morricab's reports will be interesting on the AC units, but I have only read good things about them.

SITs are quite interesting in that they not only have a linearity curve rivaling triodes, but also a soft-clipping characteristic. Too little was done with these devices when they were developed. The Sony VFET amps of the 1970s likely gave them a bad name and so the devices went out of production for the most part. Nelson had a run of them made in the US and of course the Tokin part is still around. Nelson also updated the Sony VFET circuit and offered a kit for it, using up a stock of 2SK82s he had on hand. Those amps made about 20 Watts and were PP designs, sounding quite nice by all accounts.

There's been a bit of experimentation using SITs on DIYAudio.com, where you can also find a massive thread on Nelson's VFET update kit. At least one of those experimentation threads has to do with a Single Ended Static Induction Transistor amplifier that was very simple.

Were it not for recent advances of class D design, I would be a lot more interested in the SIT amps. SITs are at a bit of a disadvantage due to the lack of support in the semiconductor industry though.

 

[cjfrbw]

Hi

6j52: A very nice tube, especially when we use it on TriodeFet.

-------A word of advice for these, a lot of these were made with Pin 1 unconnected (only pin3 used for cathode, not 1+3 ) so proceed with caution ----- Good thing, it is easy to spot which ones have pin1 NC

Best
Stavros

Thank you. Indeed, from the bag of 'non-performers', it looks like several have no 1 pin connection. I will have to look at the others that tested well to compare.

 

[cjfrbw]

At least one of those experimentation threads has to do with a Single Ended Static Induction Transistor amplifier that was very simple.

This is the one I built, mu follower version @ 6 to 10 watts, impedance dependent. Sound is sublime, similar to a 45 or a 2A3 in reveal and imaging but with 'balls' and intensity on brass and transients. It has similar distortion curve up to 10 watts to the published SIT-4.
Of course, with commercial version, you get the security of a warranty and top notch construction, as well as the Nelson Pass herbs and spices from extended toil, whereas mine is a ham fisted home DIY.
I have the VFET 20 watt push pull amp and the Tokin version based on SIT 3, all sound wonderful. I have to admit that the single ended Sony SK60 is special in a mysterious and elusive way that you uncommonly hear in audio.

 

[Atmasphere]

This is the one I built, mu follower version @ 6 to 10 watts, impedance dependent. Sound is sublime, similar to a 45 or a 2A3 in reveal and imaging but with 'balls' and intensity on brass and transients. It has similar distortion curve up to 10 watts to the published SIT-4.
Of course, with commercial version, you get the security of a warranty and top notch construction, as well as the Nelson Pass herbs and spices from extended toil, whereas mine is a ham fisted home DIY.

The so-called 'L'amp'' is far simpler using only 7 parts which include 2 light bulbs as the drain load, capacitively coupled to a loudspeaker.

 

[acousticsguru]

The so-called 'L'amp'' is far simpler using only 7 parts which include 2 light bulbs as the drain load, capacitively coupled to a loudspeaker.

That sounds like fun!

Greetings from Switzerland, David.

 

[Atmasphere]

That sounds like fun!

Greetings from Switzerland, David.

Yes! No feedback obviously. The way people talk about it on that thread has a lot in common with how people talk about SETs.

 

[andromedaaudio]

High power push pull amplification .

Ps sorry i had nothing to do at work , besides aggravating the SET crowd

 

[andromedaaudio]

 

[bonzo75]

High power push pull amplification .

Ps sorry i had nothing to do at work , besides aggravating the SET crowd

Andro with his ex

 

[Rob181]

Andro with his ex

View attachment 131525

What happens when you play with "push pull"....

 

[DasguteOhr]

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To me it always looks like an attempt to combine tube amps with unsuitable speakers. We'll add a few more tubes and it will work at some point. Hope is not a good strategy. I don't want to say that such amplifiers are bad but I would rather invest in the right speakers to protect myself from running costs(tubes).

 

[Atmasphere]

To me it always looks like an attempt to combine tube amps with unsuitable speakers. We'll add a few more tubes and it will work at some point. Hope is not a good strategy. I don't want to say that such amplifiers are bad but I would rather invest in the right speakers to protect myself from running costs(tubes).

Tube amplifier power has always been expensive which is why vintage speakers prior to the solid state era tended to be horn-loaded.

But the simple fact is that any amplifier benefits from not having to work hard for a living! Put another way you might have a power house solid state amp that you can weld with, but making it drive a difficult load (low impedance, low efficiency) isn't the same as saying that amp is sounding its best.

The problem you run into with higher powered tube amps (unless its an OTL) is the output transformer limits bandwidth and introduces distortion. So you run into a practical engineering problem that is best solved by simply using a speaker that's easier to drive, thus allowing for a lower powered amp that can have wider bandwidth and lower distortion.

I don't seen an upside to hard-to-drive speakers- they don't seem to have greater resolution or bandwidth... If you want to get the most out of your amplifier investment, its always going to be best served by a speaker that's not low impedance and has higher efficiency.

 

[Audiohertz2]

Tube amplifier power has always been expensive which is why vintage speakers prior to the solid state era tended to be horn-loaded.

But the simple fact is that any amplifier benefits from not having to work hard for a living! Put another way you might have a power house solid state amp that you can weld with, but making it drive a difficult load (low impedance, low efficiency) isn't the same as saying that amp is sounding its best.

The problem you run into with higher powered tube amps (unless its an OTL) is the output transformer limits bandwidth and introduces distortion. So you run into a practical engineering problem that is best solved by simply using a speaker that's easier to drive, thus allowing for a lower powered amp that can have wider bandwidth and lower distortion.

I don't seen an upside to hard-to-drive speakers- they don't seem to have greater resolution or bandwidth... If you want to get the most out of your amplifier investment, its always going to be best served by a speaker that's not low impedance and has higher efficiency.

There is always an engineering problem , first things first , define higher Efficiency ..?