Hi, here’s my first silly newbie question for diyAudio. Is there an engineering/sound quality reason why more high-end preamps don’t have a gain bypass switch? From what I’ve read, the consensus is that most digital sources can’t benefit from having any gain added. Adding gain with a bit more noise only to attenuate it again can only hurt, right? The only thing I can think of is not wanting the switch itself in the signal path. It’s hard for me to believe that this is the answer considering how much is going on in even the simplest circuits. I do understand (barely) that there’s the separate issue of buffering to deal with impedance issues and whatever else the electron gnomes may not like.
Is there somehow a secondary benefit to gain that isn’t addressed in buffer sections? Is this just an interface decision? Do most commercial producers not want to make the tacit admission that sources needing gain won’t sound as good?
Thanks, Dave
Is there somehow a secondary benefit to gain that isn’t addressed in buffer sections? Is this just an interface decision? Do most commercial producers not want to make the tacit admission that sources needing gain won’t sound as good?
Thanks, Dave
No, and that's correct, in that order. To take the first question a step further, is there any reason to even make a preamp with line stage gain? No, there isn't, except in very peculiar circumstances (e.g., to drive unity gain power amps, of which there might be one or two).
Hi Dave,
It's all about gain structure, if you do a search there is a lot of good info here. The basic idea is to keep the gain in the beginning of the audio chain as high as possible in order to keep noise levels as low as possible at the output. It pretty much boils down to finding the sweet spot somewhere between too much noise and too little head room which can lead to clipping and distortion.
Mike
It's all about gain structure, if you do a search there is a lot of good info here. The basic idea is to keep the gain in the beginning of the audio chain as high as possible in order to keep noise levels as low as possible at the output. It pretty much boils down to finding the sweet spot somewhere between too much noise and too little head room which can lead to clipping and distortion.
Mike
Does the average tuner have enough output to use a purely "buffer" preamp?
Like Mesmerize for instance?
Like Mesmerize for instance?
if the digital source has a gain control you probably don't need another gain control in a preamp. If you have no gain control in the digital source and your system is capable of playing loud then you may want to have a volume control. I have some gain in my pre amp (3x) for the simple reason that one of my sources has a low output volume. I know a couple of people who don't have a preamp and just have a selector sw and a volume control on the poweramp. Many power amps used to have a 0.7 volt input for rated output, now 2 volts input is common for rated output.
Indeed, I thought I'd need gain for my tuner. I'm not concerning myself about that right now. I want to figure out the best design for a preamp working on the assumption that the input will be at least 2v. I wouldn't be more specific regarding the input since I want it to work with any future digital front end.
I'm not sure whether or not I've missed something in MB's reply. I certainly have a lot of work to do learning EE basics enough to benefit from all of the information available online. So, maybe I'll end up with a six chasis design?? You know, Joe Strummer said that they made 'Sandinista!' a three record set because Springsteen's 'The River' was a double album.
I'm not sure whether or not I've missed something in MB's reply. I certainly have a lot of work to do learning EE basics enough to benefit from all of the information available online. So, maybe I'll end up with a six chasis design?? You know, Joe Strummer said that they made 'Sandinista!' a three record set because Springsteen's 'The River' was a double album.
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I don't know what an "average" tuner is, but if it doesn't run at line level (2V), generally changing a single resistor per channel will enable it to do so.
For DIY you could have a preamp with a little gain for lower output (often older) sources and a straight through connection for higher output (typically digital) sources. This would be less necessary if loudness wars had not pushed the typical output from CD up near the maximum output.
DF96, that's one of the likely final designs. But, my question remains. Why don't more high end preamps have a bypass? Do they just think their gain stages are made well enough that there's not enough value in it? That seems hard to believe given the writing about working without gain. Unfortunately, I don't have great depth of experience hearing a wide variety of systems.
Maybe now most mfr's assume people will buy a dac with good preamp functionality if they don't need gain. But, why haven't there been more bypasses for the past 20 years? We know they're not stupid. If they could easily produce a feature that wouldn't cost much and may sound great/get rave reviews, why not?
Maybe now most mfr's assume people will buy a dac with good preamp functionality if they don't need gain. But, why haven't there been more bypasses for the past 20 years? We know they're not stupid. If they could easily produce a feature that wouldn't cost much and may sound great/get rave reviews, why not?
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Traditional preamps don't have a bypass because people needed the gain in those days. Modern preamps don't have a bypass because people like the added noise and distortion - that is why they buy preamps, as the gain is now a nuisance. Gross generalisations, but they contain a grain of truth.
IMO, preamps typically have way too much gain. An X1 buffered output might be good, but I've even gotten away without that for a long time, just a passive stepped attenuator. If you don't need a phono stage, gain control or buffer, I can offer a really world class design for a very small fee. 😀
True, but with low distortion line stages (and there's many of them), I suspect it's really more of a psychological thing- if the fashion audio consumer (or the chimp who's reviewing it for a magazine) has to turn the volume control to 3:00, he is likely to perceive the preamp as lacking "dynamics" and "drive" compared to a preamp that will drive the amp into clipping by the 11:00 setting.
Yes. The funny thing about psychology is that it still applies (perhaps in a slightly weaker sense) even when you are aware of it.
Many old preamps did have a volume bypass it was often called "tape output". In the 70's I mad a pre amp with 3 selector switches. There was the regular one ie phono tuner tape etc, then there was a "record from" and a "record to" switches. I could select from any of the 7 sources and output to any of 5 outputs, cassett, reel to reel, Hi Fi vcr, living room and one spare.
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