Amplifier voicing: what is it and how is it achieved?

Nelson Pass' is guy who has been designing amp's with relatively few gain stage's and (mostly) class a biased single ended MOSFET for decades. I can imagine how his designs have a fairly consistent "house sound". I always enjoy hearing an amplifier based on one of his designs and reading his comments and articles on sound reproduction. Papa Nelson is a true gift to the DIY community.

Just throwing out an example of the opposite: Jeff Rowland Design Group has made some amazing sounding equipment... but drastically changes their design philosophy 4-5 years. In my opinion JRDG doesn't have any consistent "house sound" over a long period of time at all.

 

I would never buy a Rowland amp anyway - I hate all that shiny bling. Besides, if I'm not mistaken, his amps are Class D?

 

Pretty wild. That’s exactly how I and guitar amp builders tweak the sound as well.
Of course you know which parts to change that affect the voicing. But it’s a recipe in the end.

 

Well for starters it's McIntosh, we're not talking about computers are we?
McIntosh builds their power amps to be neutral sounding, if that's a house sound, good for them.

 

I like to think that it was a term in search of a concept...which was originally just a marketing term, in search of a relevant "go-to" standard, to back it up.

If I wear the same sort of baseball cap every day, and people tend to notice when I wear the same sort of baseball cap every day...am I then a victim of my own "baseball cap voicing"?

If I change to another sort of baseball cap like my friend in another part of the country wears, am I then adopting another "baseball cap voicing"?

Howabout, if I just wear a different kind of cap one day, it's just THAT.

 

During the time he was trained in electronics at a university level and worked for the military and space program in what was then the Soviet Union,

"...Vladimir Lamm continuously refined his thoughts on the design of audio electronics, and at the same time developed a unique model of the human hearing mechanism, based on his research into psychoacoustics. This process brought him to a radical conclusion: There is indeed a strict set of predictable, observable, and repeatable design parameters that correlate with the way people do or do not enjoy reproduced music. Not only that, but these data are hierarchical, in that certain design approaches are consistently more or less pleasing to most listeners. (Lamm observes that single-ended topology represents the pinnacle of amplifier design in this regard.) Lamm has refined his theories to the point where he no longer finds it necessary to design by ear. "I design by pencil," he says. "I don't need to listen. Using words to describe sound is not for me but for the experts."

from a Stereophile review of the Lamm ML 2.1.

 

A bit pretentious.

 

The latest generation that have been out for a few years are Class D. In the previous generation (the Concentra series from 10-15 years ago) he was using the LM3886 chip which isn't Class D or digital but a monolithic power op amp chip like what is used in the gainclones that were being discussed on diyaudio.com at the time. Before that he was just using discrete electronic components

 

After or before? Seems you apply what is learned to products that are to be upgraded.

 

I kind of get what amp designers mean when they say their amps were voiced this way or that. I would assume the term means not only EQ but a whole gamut of terms like space, width, depth, imaging, textures, slam, impact etc.
Knowing what effect different transformers, tubes, capacitors, resistors, transistors and component materials have on each of those sonic terms and by which amounts would help an amp designer to achieve a specific voicing I would imagine.

 

good to see someone paying attention

 

Right, but that is not really what the OP is getting at (I think). Mac and many or most others have a goal of neutral sound. However in an imperfect world, things are not perfect and do not always go as planned. It is inevitable that brands can present a sound that defines them. I have had many tube amps over the decades that are close to neutral, , but each had, on a minute level, their own sound. That is one of the bigger reasons that there are so many manufacturers still in business.

 

I was thinking perhaps @avanti1960 was just looking for an excuse to get a new amp

 

Yep. And just to add to that, there is a perception that some companies have developed a “house sound” over the years. Since this implies repeatability over a long period of time and across many different engineers, part of my question is investigating what measurements these companies use to achieve said repeatability.

So, part normalization of how we define the concept of “voicing”, and part methodology to achieve it.

 

With McIntosh I’ve always felt it was the autoformers that play a part in the SQ of the McIntosh SS amps I had back in the 70’s.

 

Thanks for this! I have been trying to understand the difference between voicing and EQ. What you shared makes a lot of sense.

 

“The following is an interview with John Curl recorded in August 1999.”

 

The Yamaha video is talking about achieving a certain kind of "musicality" which to my mind does not mean neutral, but is aiming for something that is more pleasing to a specific customer base.

JohnK

 

Getting physical textures amplified must take talent. I the first time I heard that quality in an amp. I was like “did I just “see” what I thought I heard?”. It was a cymbal and then a voice, both of which I felt I could have outstretched my arm and grasped with my fingers.

 

No it doesn't, doesn't mean house sound either. imo

 

Every amplifier manufacturer is going to tell you their amps convey a musical sound in some positive manner. They want to differentiate their products from the competition I’m sure most reputable manufacturers really believe in their design capabilities and the products they produce. I believe it isn’t too difficult to find truly dedicated component manufacturers where pride of design, audio quality and satisfying customers rank foremost.

 

Neutral? Nah. Warm and powerfully dynamic. They love their autoformers. That and vintage Mac gear was meant to sound like their tube amps with a better low end and of course the whole no maintenance thing.

Personally I love their integrateds with the autoformers and I dig that they are warm, musical and have explosive drive.

Though all the newer gear is a bit more detailed and clean. Still leans warm and big.

 

Would be great if some of the big amp designers would be members of this forum.
To give their expert opinions and offer insight.

on a couple of the guitar forums I was on, there were around three or so of the best guitar amp designers as members and would offer their expertise in similar questions.
Really was educational.

 

Actually looking at this vid again it seems they are tweaking the preamp section and coupling caps. Putting in different values. That would definitely change the freq in the different gain stages.

 

It should not be 'voiced' imo

output/input = G/0 deg, ie, integer gain with no phase shift at all frequencies

Mac is spec driven, always has been. Get as close as possible to the least amount of signal degradation (or add the least distortion). I do not believe they craft response or intentionally alter the signal. Their sound is a result of this and design compromises, not intentional manipulation.

If the output xfmrs 'smoothed' things that is a byproduct, not the reason. The reason was to load match so the amp could be designed to a tighter tolerance since it would always see the same load with the added benefit of putting out the same power regardless of load.