Any other SS amps with output transformers out there except Hellborg?

[Mr. Foxen]

Don't assume bandwidth limiting is a bad. It is way handy for keeping drivers from overworking in the lows and taking the nasty edge off harmonic distortion in the highs.

 

[BadExample]

Don't assume bandwidth limiting is a bad. It is way handy for keeping drivers from overworking in the lows and taking the nasty edge off harmonic distortion in the highs.

Sometimes called compression, right?

 

[B-string]

Sometimes called compression, right?

Not really, compression is headroom limiting. Taking quiet and loud signals, averaging them to a narrower range of signal strength. You could think of a four lane highway with evenly spaced vehicles, feed them into two lanes tightly spaced instead.

 

[agedhorse]

Nobody here or any MI amplifier manufacturer is using constant voltage distribution systems for bass. If they showed up in bass amplifiers it would be a Gimmick.

Maybe, but a transformer can also be used within the feedback loop and it's phase response can alter the way the amp recovers when overdriven... and it forces some global feedback choices that would not be considered otherwise. This does in fact have an effect of the sound and the feel of an amplifier.

I myself do not favor output transformers in a solid state amplifier, BUT I do understand why they were used historically in the early days, and exactly what they can (and can not) do to performance because I have studied and designed and tested a variety of such topologies over the years and can see where some topologies might benefit. For example, the transform ratio may not be the same for all levels and all frequencies which can add some interesting response profiles to the output, and this goes hand in hand with my comments about specific limitations in what can be done with global feedback.

It's not a clear cut "gimmick", but one of many design choice that a designer may choose from. Done with the right understanding, I can see some interesting possibilities, though so far not my particular flavor (but who am I to say it's nobody's flavor?)

 

[seamonkey]

Don't assume bandwidth limiting is a bad. It is way handy for keeping drivers from overworking in the lows and taking the nasty edge off harmonic distortion in the highs.

I'm not saying it's bad, I'm saying it can be done with EQ

 

[KF2B]

Yeah.

It's all placebo and gimmicks. Sure.

Anyway... I would still love to hear if there are other SS amps out there with output transformers?

Anyways, I'd also like to add that Jonas Hellborg does not appear to me like a guy who would sell out for marketing gimmicks in order to sell a few more amps with his name on htem. But then again I do not know him. Would love to though as he appears a no-corners-cut kind of a guy.

 

[Mr. Foxen]

Sometimes called compression, right?

Compression is dynamic range reduction, rather than bandwidth.

EQ only helps stuff if you can insert it after the source of the problem, which is why you can't eq out the nasty top of amp distortion and need to use speakers that limit the bandwidth on guitar. Understanding the limits of eq is important.

 

[Steve Dallman]

A bass player friend I knew in the late 70's/early 80's had an early GK that had an output transformer. He didn't sound all that good.

 

[B-string]

A bass player friend I knew in the late 70's/early 80's had an early GK that had an output transformer. He didn't sound all that good.

Sent me to look through my schematic cache. Would have been a mid '70s 100 G/B, 200 G/B, 210G or 212G series. @rag could shed more light of course. The original 226 from late '60s was OTL so interested about the use of an OT for a short period of time before dropping the idea.

 

[beans-on-toast]

Some current audiophile solid state products such as the McIntosh MA6700 employ output transformers:

• patented McIntosh output Autoformers ensure every connected speaker receives full power regardless of its impedance

This allows them to market the amp, listing it at the maximum power that it is capable of delivering at either 2, 4, or 8 ohms.


Invalid Link Removed

 

[Rick James]

Some current audiophile solid state products such as the McIntosh MA6700 employ output transformers:

• patented McIntosh output Autoformers ensure every connected speaker receives full power regardless of its impedance

This allows them to market the amp, listing it at the maximum power that it is capable of delivering at either 2, 4, or 8 ohms.

The flip side of that coin is that it won't put more power into a lower impedance load than it will into 8 ohms.

 

[walterw]

wouldn't said output transformer have to be as big as the one on an SVT in order for the amp to even produce as much power as an SVT and still have real low end?

maybe not? boogie 400+ amps weren't as heavy and supposedly produced similar power.

 

[Mr. Foxen]

wouldn't said output transformer have to be as big as the one on an SVT in order for the amp to even produce as much power as an SVT and still have real low end?

Would if life was simple. But can save some weight by using toroidals and generally high quality transformer construction, not gonna be far off. Being light doesn't tend to be a design goal for McIntosh though,.

 

[agedhorse]

wouldn't said output transformer have to be as big as the one on an SVT in order for the amp to even produce as much power as an SVT and still have real low end?

maybe not? boogie 400+ amps weren't as heavy and supposedly produced similar power.

Yes, unless an auto-transformer was used. Somewhat different characteristics.

 

[beans-on-toast]

Solid State OPT

The output transistors see a constant inductance rather than a varying reactive load. They make their OPT for solid state amps sound like the best thing since sliced bread. Perhaps better on paper than in practice.

 

[popcat]

Tube designs use an output xfmr for impedance matching to the speaker load, which typically isn't necessary with class AB transistor amps that inherently have a relatively low source impedance and makes the output xfmr just an unnecessary expense. Simple beginner/practice amps of relatively low wattage class A designs would use an output xfmr (sometimes connected to the high-side instead of ground), but the xfmr is accordingly smaller and less expensive. A lot of the more modern SS amps are now class D (switching), and this design may use output inductors but not a xfmr. During the transition era from tube to SS amps, there were many hybrid designs including SS amps using an output xfmr because of power xstr quality/availability at the time (and sometimes the attempt to emulate the tube output power sag/clipping feature), but again, it is usually a more expensive topology that is no longer needed.

For example, here is an old Vox output section (note transistors on secondary side):

 

[agedhorse]

Solid State OPT

The output transistors see a constant inductance rather than a varying reactive load. They make their OPT for solid state amps sound like the best thing since sliced bread. Perhaps better on paper than in practice.

Unfortunately, their description is not how transformers work. They are neglecting the reflected impedance of the load, which by nature is reactive. A transformer can help mitigate SOME of the effects of capacitive load but not all of it.

Also, their comments about not needing DC protection circuits because DC can not get through is incorrect... unless you are ok with DC across the transformer primary saturating the core and probably taking at least something out in the process (maybe the transformer itself, a VERY expensive "fuse")

I wish marketing guys weren't allowed to write ad copy without an engineer (a real engineer) reviewing it for accuracy. A LOT of ad copy would disappear overnight

 

[popcat]

Unfortunately, their description is not how transformers work. They are neglecting the reflected impedance of the load, which by nature is reactive. A transformer can help mitigate SOME of the effects of capacitive load but not all of it.

Also, their comments about not needing DC protection circuits because DC can not get through is incorrect... unless you are ok with DC across the transformer primary saturating the core and probably taking at least something out in the process (maybe the transformer itself, a VERY expensive "fuse")

I wish marketing guys weren't allowed to write ad copy without an engineer (a real engineer) reviewing it for accuracy. A LOT of ad copy would disappear overnight

They always ask for new buzz words; so you tell them something like new "Transconductance Velocity Multiplier" circuitry, or "Multi-cadence Co-phasing Loop" and they go goo-goo. drool

 

[agedhorse]

They always ask for new buzz words; so you tell them something like new "Transconductance Velocity Multiplier" circuitry, or "Multi-cadence Co-phasing Loop" and they go goo-goo. drool

When I give them buzz words, they get all red in the face

 

[Jeff Bonny]

To the original question:
Bryston 3B and 4B.

To the hijack:
Scientific data is essential as a baseline for understanding how a piece of audio equipment functions. But the quality of that data is limited to the quality and intent of the measuring equipment so lets not mistake it for an accurate representation of what a particular individual may or may not be hearing. The auditory cortex is the most complex brain system. The mechanical system of the ear differs in functionality from person to person. Basing an argument on the premise that everyone's ears and auditory cortex work the same seems incredibly sophomoric.