tubes or transformer?

[agedhorse]

Ok, let's re-center this. The post I originally responded to was this.

How would you explain this. Are tube watts louder or might it be because solid state amp tone in general is more consistent from low to high volume.

Maybe it's because he simply preferred the tone/voicing of the larger amp?

I'm not quite that old, but in my recent move one of my HP RPN calcs had the screen damaged. I have another and apps on my phone and PC that emulate a variety of HP calcs, but this was my first and has my name engraved in the inset block on the rear. I almost shed nerd tears, but I'll find a broken one and repair it.

My HP 25 finally broke for good, and yes it was a little sad because my dad gave it to me as I left for college to study engineering.[/quote]

There is your problem. I never bought into the whole Teifenbrun / Vereker world view, even after owning a lot of both of their gear in the early days. The 'high end' audio world is full if so much crap, it would take years to cover it all.

I have a hifi amp design being retailed at the moment by another company. It's my best design, but the amount of crap being used to sell it is embarrassing.

I agree, my first job as an engineer was designing amps for that industry and you are right... the things they would do to sell amps would make a sailor blush.

I don't recall a hifi or pro amp that I've designed or worked on that's cap coupled anywhere, except as a blocker at the input, and not then always. If a DC servo loop is used instead, then a cap is used.

Sorry, AH, not telling you how to such eggs, just using your comment to reply.

Right, but I was talking about capacitor coupled output which is what Will had mentioned earlier. A DC servo can be used in the global feedback loop rather than a shunt cap, both methods have their pros and cons. An input cap is a good idea because we can't control the outside world.

 

[Snert]

Right, but I was talking about capacitor coupled output

I understood that, just should have been clearer in adding that caps are seldom used in coupling anywhere in a SS amp.

 

[ardgedee]

Some of my 30W Ashdowns seem slightly louder than my 50W Ampeg.

Is it possible the Ashdowns are compressing or distorting in a way that makes them sound louder?

 

[Wasnex]

Is it possible the Ashdowns are compressing or distorting in a way that makes them sound louder?

The amps I compared are LB30 Mk1, LB30 Mk2, Ampeg PF50T.

My test was very unscientific, and it's possible my perceptions are wrong. I set the volume just below the onset of audible distortion for each amp, so distortion should not be a factor. I did the test to confirm my initial (surprise) impression that the PF50T was not as loud as the LB30s.

Since the shootout, I also got a Little Stubby. My impression is the LB30s are louder than Stubs.

All four amps sound great, but none of them are what I would consider loud with bass.

 

[byacey]

I understood that, just should have been clearer in adding that caps are seldom used in coupling anywhere in a SS amp.

Actually,in the preamp and tone control stages, coupling caps are very common. The power amp sections in a modern AB are mostly direct coupled. Line level inputs and outputs / FX loops are almost always capacitor coupled.

 

[Snert]

Actually,in the preamp and tone control stages, coupling caps are very common. The power amp sections in a modern AB are mostly direct coupled. Line level inputs and outputs / FX loops are almost always capacitor coupled.

The discussion was power stages. I'm aware of where coupling caps may be used in lower level stages.

 

[byacey]

Older single ended supply power amps invariably used coupling caps on the output. It was the only convenient way to block the DC, and power the bottom half of the complimentary output.

 

[Snert]

Older single ended supply power amps invariably used coupling caps on the output. It was the only convenient way to block the DC, and power the bottom half of the complimentary output.

Show me some SS non hifi single ended amps in mass use in the last several decades.

 

[byacey]

Dukane, Rauland, Bogen, TOA, and numerous other commercial duty amplifiers often used this topolgy. The power supplies were simpler and could even be run off an external battery supply for emergency situations.

Edit: The original Acoustic Control Corporation bass and guitar amps used single B+ power supplies, with a coupling capacitor for the speaker.

 

[definenredefine]

You are looking at this from a risk/reward (or benefit) perspective and IME that is a rare thing these days. There are two thoughts that I feel need more time and attention these days...and they are ones you touched on.

First, just because we can do something doesn't mean we should or that it's a good idea. The second is a little more esoteric and is rooted in a piece of a psychological principle that starts with "all change involves loss". Moving to something new most always means leaving something old behind. Unfortunately some of our "old skills" (a few of which you mentioned) are perishable over time. This can create a total dependence on the new tech unless we stay in practice/keep ourselves and the older resources current.

I think, all too often, that our species loses track of this...

 

[rzero]

I think that the word "transformer" here is intended to mean "output transformer", which (in general) only tube amps have. That said, I believe Marshall made a transistor amp with an output transformer back in the day.

Well, I'm confused. The guy in the video mentions several pieces of solid state gear he likes that contain "transformers."

 

[rzero]

Yes, most solid state amps do not have audio transformers.

What solid state amps have output transformers?

 

[SteveCS]

...
In actively participating as an engineer in close to half a century of all manner of high technology and related design evolutions, I've consistently seen more difference in design outcomes related to "engineering competence with the technology used" than I have to the specific type of technology employed. I've also observed that even a universally praised premiere technology can be poorly integrated into/employed in a design such that the final product's performance is simply awful.
...

This is verging on being a universal truth.

 

[Snert]

What solid state amps have output transformers?

None in MI that I'm aware of but over the years there have been a couple in the audiophile market. McIntosh made/makes some IIRC.

 

[agedhorse]

What solid state amps have output transformers?

I think there was a Hellborg model, but that’s all I can think of.

 

[Wasnex]

I think there was a Hellborg model, but that’s all I can think of.

From the Baer Valkyrie OM:

Engaging the VALKYRIE’s Split/Drive™ tube drive circuit routes the all solid state signal coming from the preamp through our innovative variable tube drive section. This unique design is the result of many months of research and development with one clear goal in mind. Deliver all the dynamics, harmonic overtones and growl that only genuine tubes can bring to your sound, while preserving maximum clarity in the low end. This is not the typical single 12AX7 design found in most tube hybrid bass preamps. Our Split/Drive™circuit utilizes a separate dual tube, push-pull amplifier circuit complete with an output transformer and a few tricks up its sleeves. The result is a tube section that combines the lively response you expect from real tubes with a tight, punchy low end that never loses focus and definition, even at extreme volumes.
​

 

[ardgedee]

What solid state amps have output transformers?

None in MI that I'm aware of but over the years there have been a couple in the audiophile market. McIntosh made/makes some IIRC.

Yup. Elaborated on earlier in this thread.

 

[agedhorse]

From the Baer Valkyrie OM:

Engaging the VALKYRIE’s Split/Drive™ tube drive circuit routes the all solid state signal coming from the preamp through our innovative variable tube drive section. This unique design is the result of many months of research and development with one clear goal in mind. Deliver all the dynamics, harmonic overtones and growl that only genuine tubes can bring to your sound, while preserving maximum clarity in the low end. This is not the typical single 12AX7 design found in most tube hybrid bass preamps. Our Split/Drive™circuit utilizes a separate dual tube, push-pull amplifier circuit complete with an output transformer and a few tricks up its sleeves. The result is a tube section that combines the lively response you expect from real tubes with a tight, punchy low end that never loses focus and definition, even at extreme volumes.
​

That's a driver stage and driver transformer not an output transformer that interfaces directly with the speaker. In this case, the transformer is used BEFORE the output stage.

 

[Wasnex]

That's a driver stage and driver transformer not an output transformer that interfaces directly with the speaker. In this case, the transformer is used BEFORE the output stage.

Agreed, but it is a transformer that is sometimes in the signal path.

 

[agedhorse]

Agreed, but it is a transformer that is sometimes in the signal path.

I was addressing the question "What solid state amplifiers have output transformers"?

This is an interstage or driver transformer BEFORE the power amp's output stage and does not affect the interaction between the load (speaker) and the amplifier itself (which is close to an ideal voltage source). It is not an output transformer. An output transformer is after the output stage.

Interstage and driver transformers have been used before in tube amps (I used one in the Diablo series) and in solid state amplifiers (Hill used them in the DX power amp line).