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Topic: Vinyl to Digital: Preamps and Amps (Read 6325 times) previous topic - next topic
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Vinyl to Digital: Preamps and Amps

Hello!

I'm building a vinyl-to-PC digitization system. My turntable will be an SL-1200MK2, and my cartridge a Shure M97xE.

1. Do I need an amp? (as opposed to just a phono preamp)
2. If so, which budget (around $100) solid state amplifiers would you recommend? Does sound quality in SS amplifiers increase w/price?
3. If not, which budget SS phono preamps would you recommend?
4. What's the difference between a phono preamp with a volume knob and a full-fledged amp?

Thanks!

[edited for clarification]

Vinyl to Digital: Preamps and Amps

Reply #1 –
Maybe some confusion here.

High end audio often has seperate power amp and pre-amp. The pre-amp in this case has the volume and tone controls etc. and drives the power amp that provides the grunt. Most domestic amps have the two parts integrated in one unit.

What you are probably thinking of is a phono pre-amp(also known as an RIAA/Equalization pre-amp), this takes the very low level signal from a cartridge and matches it to the input of your other equipment.

Whether you need one or not depends on what equipment you already have.

Some turntables have a phono pre-amp built in, this will plug straight into the line-in on your soundcard.

Some soundcards have one built in. The turntable should be plugged straight into this input .

Many amplifiers(particularly older ones) have one built in. The turntable should be plugged into the phono input of your amp and the line-out of the amp to the line-in of your soundcard.

Obviously, only one pre-amp should be involved in the chain.

If you have none of the above available, or are not satisfied with their quality, then you will need a seperate unit that sits between the turntable and the soundcard. The sky's the limit with these things, prices range from £20-30 to several grand. Buy something that matches the quality of your other equipment.

UJ

Vinyl to Digital: Preamps and Amps

Reply #2 –
Note that I've owned precious few phono stages in my life; this is based on what I'm perceiving online.

With increasing price you're usually going to get lower noise, possibly reduced distortion, and support for MC cartridges. It's such an audiophile field that really objective results are hard to come by, and there are stinkers out there that cost a lot of money.

Off the top of my head, I'd say that you're probably going to see significant differences in phono stages up to about $200-300; everything after that is somewhat dubious. The parts cost for a top-shelf opamp phono stage is $50-100; the parts cost for a top-shelf discrete stage is probably going to be the same once you factor in the additional power supply costs.

You're almost certainly going to find deficiencies in a $50 phono stage. But you're going to need to listent to them yourself to see if they really matter.
 

Vinyl to Digital: Preamps and Amps

Reply #3 –
I have the older version of this: Parasound Zphono

It's a nice preamp for the money.  I used it to plug my turntable directly into my sound card for the same reason.

Robert

Vinyl to Digital: Preamps and Amps

Reply #4 –
While the ideal signal path is phono cartridge to phono preamp to soundcard line-in, there are significant variations in cartridge-out signal level, phono preamp gain, and soundcard input requirements. It is not unusual that either a mixer or a line level preamp is required between the phono preamp output and the soundcard input to either amplify or attenuate the signal from the phono preamp.

Vinyl to Digital: Preamps and Amps

Reply #6 –
fwiw

AudioXpress Phono Preamp Review

don't forget that a good soundcard, balancing and aligning the turntable/cartridge, and placement of the truntable and preamp are critical to good vinyl digitization.

Vinyl to Digital: Preamps and Amps

Reply #7 –
Quote
What you are probably thinking of is a phono pre-amp(also known as an RIAA/Equalization pre-amp), this takes the very low level signal from a cartridge and matches it to the input of your other equipment.

Yes, that's what I meant. I suppose my question should really be this:
I've heard that connecting a phono preamp directly to a sound card can cause clipping. Is an amplifier necessary to avoid this, or can I use another device/method? Is it even true?

Quote
While the ideal signal path is phono cartridge to phono preamp to soundcard line-in, there are significant variations in cartridge-out signal level, phono preamp gain, and soundcard input requirements. It is not unusual that either a mixer or a line level preamp is required between the phono preamp output and the soundcard input to either amplify or attenuate the signal from the phono preamp.

Ah, thank you! So what's the difference between a mixer/line level preamp and an actual amplifier?

Quote
Off the top of my head, I'd say that you're probably going to see significant differences in phono stages up to about $200-300; everything after that is somewhat dubious. The parts cost for a top-shelf opamp phono stage is $50-100; the parts cost for a top-shelf discrete stage is probably going to be the same once you factor in the additional power supply costs.

Pardon my ignorance, but what's an opamp?

Vinyl to Digital: Preamps and Amps

Reply #8 –
"Amplifier" is a very general term. Any circuit that increases signal level amplifies. Used without qualifying adjectives, amplifier probably most often means "power amplifier," the device that drives the output transducers (speakers or headphones). A power amplifier's purpose is to deliver power (significant current such as that need to cook food on an electric range) , most other amplifiers only deliver an increased signal level (voltage) at a very low power.

An opamp (operational amplifier) is an integrated circuit. As an integrated circuit it saves a great many parts, design effort, construction effort, device space, and cost. It is, in one form or another, perhaps the most common analogue electronics active component.

Vinyl to Digital: Preamps and Amps

Reply #9 –
I see! In that case:

* What frequency range is generally considered baseline "good"?
* What S/N ratio is generally considered baseline "good"?
* Does gain generally introduce distortion?
* Should I use a mixer or a line level preamp? Is there any advantage to using one over the other?
* Are the preamps @ phonopreamps.com any good?

Thanks once again!

Vinyl to Digital: Preamps and Amps

Reply #10 –
Quote
* What frequency range is generally considered baseline "good"?

20hz - 20khz is fine.
Quote
* What S/N ratio is generally considered baseline "good"?

Most SNR numbers are something like 70-90dba, but in my experience, those types of numbers are easy to fake. A lot of it depends on how clean your local power is, and how good the stage is at rejecting power supply noise. I'd suggest not taking too much stock in this number and measuring it yourself.
Quote
* Does gain generally introduce distortion?

Phono stages inherently have a very great amount of gain (100-10 000). Increased gain will improve some numbers and compromise others, depending on the circuit type. Noise generally goes up with higher gain.
Quote
* Should I use a mixer or a line level preamp? Is there any advantage to using one over the other?

I would suspect there's no real difference; the preamp might give lower noise. A standalong passive preamp might be the best bet. Again, this is something that will probably require trial and error.

If you know the exact attenuation you need, you could probably solder together an inline attenuator that will definitely be the cheapest option ($10 in parts) and will have the lowest noise.
Quote
* Are the preamps @ phonopreamps.com any good?

No. The TC-750 I bought had a ridiculously bad wall-wart power supply driving an all-discrete stage with virtually no power supply rejection. The actual phono stage seems ok, but you're going to want to shell out more money on a power supply mod if you buy from them.

Vinyl to Digital: Preamps and Amps

Reply #11 –
The best idea is to connect TT to phono preamp to soundcard and see what happens. Every part is a significant variable. With about 450 albums recorded, I have never had any clipping (a very few albums have peaked within -0.2dB on the very loudest parts), so I've never needed any attenuation. Other people with the same soundcard have complained that every LP clips badly.

Some albums I've recorded have maximum peaks below -12dB. Occasionally those few -12dB peaks are way above everything else. Those albums could probably use a little extra amplification, but my system noise is low enough that there really has been no problem (24 bit soundcard). Some people's setup, without a mixer or line-level preamp, just doesn't give enough signal to make optimal use of the possibilities for quality recordings.

In other words, until you try recording, you will have no idea what else you may need. A passive preamp would definitely be a poor investment if you find that you need more gain than the phono stage provides.

Vinyl to Digital: Preamps and Amps

Reply #12 –
assuming the preamp is RIAA accurate, and has the correct RIAA gain (+40db), and the soundcard has a true line-in, a typical moving magnet cartridge (~4mv) should give about 0.4v output at the preamp. Plenty below before it will clip the soundcard input. If its still clipping they are probably doing something wrong somewhere (or everywhere). Common mistakes are connecting MM cartridges to MC inputs of the preamp and/or not adjusting the soundcard mixer input(software) correctly.
suggest you use an external soundcard like the new NX and battery power for both the preamp and soundcard.

Vinyl to Digital: Preamps and Amps

Reply #13 –
I've never seen a standard for "RIAA  gain;" 30 to 40dB is typical for MM.
Only a tiny fraction of phono preamps provide MC operation until one is above the price range of 97% of the population.
It is not possible to adjust for input clipping via software since the clipping occurs at the hardware level -- except possibly on some gaming cards. The correct adjustment of software control panel input  levels it at maximum, i.e. not reducing the bit depth of the digital signal you've just converted from analogue.
There is nothing wrong with external soundcards, but there is no quality advantage to be had there for vinyl transfers either.
There might be a few not too expensive battery powered phono preamps available, but it is very easy to get excellent performance without that bother.

my personal example.
    * PCI Audiophile 2494: noise floor -98dB
    * add phono preamp section of $300 receiver: noise floor -89dB
    * add TT (with some internal wiring difficulty that adds a measurable, but not hearable, amount of hum): noise floor  -80dB
    * add background noise of typical LP as recorded to disk: -56dB[/li]
Any rational considerations says the source media noise is too high to worry about the rest.

Vinyl to Digital: Preamps and Amps

Reply #14 –
Thank you!