Preamplifiers, gain and volume control - is the usual architecture really clever?

[boXem]

Gain staging like in the studio. Running every thing as hot as possible (before distortion) until the final stage minimizes final noise. Im running my DAC into the power amp. I turned the dac volume up to ~%90 then adjusted the amplifier volume to as loud as I would ever listen ( a 350w per channel amp so down 15 db?) , than I use the dac volume control for listening. This reduces any noise from previous stages.

DAC self noise is higher than preamp self noise for an equivalent care of design. If you attenuate at digital level, you do not decrease the DAC self noise so the system noise is higher than when attenuating at amplifier level.

 

[CD2]

Does anyone know who was the first audio manufacturer to market separate preamps and amps?

One indicator is the Heathkit catalog archive here: https://www.worldradiohistory.com/Archive-Catalogs/Heathkit_Catalogs.htm In the early 1970s the main audio business is receivers, with "separates for the purist" meaning a separate tuner and integrated.

Christmas 1975 has the first separate power amp, with a whole page (30) introduing this novel idea. Heathkit was generally a trend-follower rather than an innovator, but this does suggest that the change in the market happened early 70s.

 

[mhardy6647]

ummm... Heathkit (and pretty much everyone else) was selling consumer power amplifiers and preamplifiers in the 1950s. They were at the rarefied end of the hobby, but still part of it in those days.

images above are both from https://www.worldradiohistory.com/Archive-Catalogs/Heathkit-Catalogs/Heathkit-1955-Fall-Flyer.pdf

The hifi hobby took a hard turn to more common household popularity in the second half of the 1950s. harmon/kardon is generally recognized (at least in the US) as being the first to offer an integrated (mono) hifi component with preamp, power amp, and FM tuner all on one chassis, the Fesitval D1000 (1954).

Within a couple of years, such "receivers" were available from almost all of the major brands.

 

[mhardy6647]

McIntosh dates to 1949, if memory serves, and offered both power and pre-amplifiers very early on.
Here's an example of a very early Mac power amp -- and a very early Mac advertisement. Their Weltanschauung was rather different in those days.



The EH Scott (not to be confused with HH Scott) radio consoles of the 1930s were Veblen Goods; the Dusenbergs of audio reproduction. Their amplifiers were works of art.

An extreme example: the Quaranta

48-Tube E.H. Scott Quaranta by Jacques Dubois

Fabulous reconstruction of a 48-tube radio - the E.H. Scott Quaranta (1936)

www.campx.ca

The Quaranta makes Mr. D'Angostino's current efforts look tastefully understated.

Antique Radio Classified--Classic Radios

A more typical EH Scott audio amplifier:

Scott 800-B6 Radio/TV/Phono Console (1948)

eBAY auction image of a fairly typical, but nice EH Scott radio.

 

[PO3c]

In terms of total chain SINAD a more logical approach appears to create a variable gain power amplifier.

BMC Audio C2 and C3 amps use this approach.

With regards to completely lossless digital volume control look into Leedh Processing. Using stepped control we can have approx. 1 dB step using only 20 bit values. Which could ensure there are no truncating even for older DACs.

Remember there are not much use of 64-bit volume calculation if we then truncate the value to whatever format the transport support (24-bit for SPDIF). Better option could be using rounding but stepped control are so easy to implement and if our DAC can actually make use of 24-bit we can have resolution as small as approx. 0.035dB for each step.

 

[CD2]

This is fascinating!

What I grew up around (kid in the 60s) was either tube-based all-in-ones (We had a Grundig radio with phonograph input) or transistor-based receivers. Fancy people had fancier receivers.

Did the people making tubed separates transition to transistor separates?

 

[gwing]

No, Dac straight into power amp. The amp has input pots which isnt common but nice to have.

The difference this make with modern gear (sinads in the 100s ) is probably negligible.

That would be what we call an integrated amp not a power amp?

 

[Ropeburn]

That would be what we call an integrated amp not a power amp?

That continues to be the subject of debate. Personally I wouldn't say a mere volume control makes an amp "integrated". It needs more functionality than that, mostly preamp stuff: input switching, EQ, perhaps phono preamp, or thinking more modern, a DAC.

The other way around, a lot of professional poweramps have all kinds of stuff, volume/gain control, crossover, DSP. Nobody calls those "integrated" just because it's more than a plain power stage.

 

[gwing]

This is fascinating!

What I grew up around (kid in the 60s) was either tube-based all-in-ones (We had a Grundig radio with phonograph input) or transistor-based receivers. Fancy people had fancier receivers.

Did the people making tubed separates transition to transistor separates?

Some did. Some (most) quietly faded away. And of course some folks are still making tube separates, but obviously not the same folks as in the 60s

 

[mhardy6647]

Some did. Some (most) quietly faded away. And of course some folks are still making tube separates, but obviously not the same folks as in the 60s

Luxman and McIntosh have been doing it for a while...

 

[gwing]

Does anyone know who was the first audio manufacturer to market separate preamps and amps?

I used to have a couple of Leak Point one amps which I believe were first introduced in 1945, my examples being a couple of years later than that.

 

[gwing]

Luxman and McIntosh have been doing it for a while...

Read the question carefully. It was asking about 'people' not companies

 

[rdenney]

That would be what we call an integrated amp not a power amp?

Not really. Lots of power amps have input attenuators, which isn't the same thing as having a line-stage amplifier the same as the preamp section of an integrated amp.

For me, an integrated amp needs the same basic feature as a separate preamp--selectable inputs, a processor loop, a line-stage amp with a variable attenuator, and tone controls. (Actually, for me, it requires a lot more than that, but then I like to plug in source devices few others are interested in.)

I know it's splitting hairs, but the input pots on power amps are really designed for a different purpose than the volume control on a preamp.

Commercial amps are customarily provided with attenuators to facilitate setting up an appropriate gain structure, and to limit the system to keep people who fiddle with the volume knobs and faders on mixing desks from destroying things. All my commercial amps are so provided (a Carver PM-300, a Samson Servo 500, and a Crown XLI800). But they lack basic features such as input switching. My home amps don't have attenuators (a Buckeye NC502MP, a couple of B&K Reference 125.2's, and an Adcom GFA535). My Kenwood integrated amp comes with complete controls.

Rick "hair-splitter" Denney

 

[rdenney]

Read the question carefully. It was asking about 'people' not companies

Hmmm. It seems to me that Frank McIntosh was a real flesh-and-blood person, and Gordon Gow after him at McIntosh the Company, until well after the period being discussed.

But if you're talking home-built kits, most of those used tubes because tubes were easy and cheap at the time people were building kits like those, such as the 60's when you were growing up.

Later kits used through-hole solid-state components, but those required more parts and more skills.

Rick "automated PCB construction came later" Denney

 

[mhardy6647]

Hmmm. It seems to me that Frank McIntosh was a real flesh-and-blood person, and Gordon Gow after him at McIntosh the Company, until well after the period being discussed.

But if you're talking home-built kits, most of those used tubes because tubes were easy and cheap at the time people were building kits like those, such as the 60's when you were growing up.

Later kits used through-hole solid-state components, but those required more parts and more skills.

Rick "automated PCB construction came later" Denney

I think that earlier post's use of the word "folks" meant actual, living individuals as opposed to assemblages thereof (i.e., people, not companies). I hadn't read it literally, either -- rather obviously.

Heck, even Sidney Harman's gone -- although he, like Col. Klipsch (and a few others) lived to a ripe old age.