Phono pre-amps
Jun 8, 2015 at 4:54 PM Thread Starter Post #1 of 25

safulop

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So, given that the conventional wisdom among the "objectivists" is that all amplifiers sound alike, what do we think about phono stages and pre-amps, step-up transformers etc.  Some of these trinkets are $$$$$$, but the question is, will a dedicated phono pre-amp "improve the sound" of a high-end turntable versus the MM phono stage in a comprehensive integrated amplifier at a modest price point (e.g. Onkyo 9050A)?
 
Does the "amps are all the same" mantra extend into the esoteric realm of cartridge impedance matching and phono pre-amplification?
 
What if I use a low-output MC cartridge?  Then I am forced to buy something on this wild west marketplace - what is the best choice?  A simple step-up transformer from Denon can cost over $2K, and you can't even adjust the gain.  Meanwhile I could buy a complete phono pre-amp that can handle low-output cartridges for <$300, bypassing my amp's phono stage entirely.
 
What to do?
 
Jun 8, 2015 at 5:56 PM Post #2 of 25

Speedskater

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I think that many of us will accept the possibility that any phono cartridge/pre-amp combination may sound different than some other phono cartridge/pre-amp combinations.
 
When it comes to transducers (phono cartridge, microphone, loudspeaker or headphones) it's hard to make different designs sound the same.
 
Jun 8, 2015 at 9:43 PM Post #3 of 25

sonitus mirus

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I don't believe that all amps sound the same, but any audible difference is most likely measurable without the need of an ABX for confirmation.
 
Speaking of ABX, I did manage to find a link with some ABX data for a couple of phono preamps.  Doesn't prove anything, but I thought it was interesting and worth sharing.
 
http://djcarlst.provide.net/abx_data.htm
 
Feb 27, 2020 at 5:27 PM Post #4 of 25

bmichels

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Now I need to find a decent Phono-Pre to connect to my Thorend TD160 equiped with a MM Shure V15 III cartridge !

I am considering this Coffman G1. Has someone heard it ?


G1-Signature COFFMAN.jpg
 
Feb 27, 2020 at 7:53 PM Post #5 of 25

bigshot

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I have that turntable. I use a $50 preamp I got from Garage-A-Records. It works great. Applying the RIAA curve and bringing level up to line level isn't rocket science. You don't need to spend a lot (though some people go crazy on satiating their OCD by spending way too much). Slapping tubes on top of LP will certainly give you a nice rich, thick soup of distortion, if that's what you're looking for.
 
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Mar 18, 2020 at 2:48 PM Post #6 of 25

bmichels

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A new Phono-Preamp joined the team: the EAT E-GLO Petit. A perfect martch with my "vintage" Thorend TD160 + SME Serie 2 +Shure V15 III....

3585071


3585072


3585073


And some brand new vinyl arrived to feed the system.... All remastered Audiophile versions, some being LP 45 rpm....

3585070


3585074
 
Mar 18, 2020 at 8:08 PM Post #7 of 25

bigshot

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I have a really good one I got at Radio Shack for $40. Works perfect.
 
Mar 21, 2020 at 5:55 AM Post #8 of 25

pinnahertz

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Now I need to find a decent Phono-Pre to connect to my Thorend TD160 equiped with a MM Shure V15 III cartridge !

I am considering this Coffman G1. Has someone heard it ?
The V15 III is notorious for being sensitive to loading issues known, at one time, as "cartridge inductance interaction". The load the cartridge "sees" is a combination of the cable C, and the complex input impedance seen at the first stage of the phono preamp. Yeah, they all have that 47K terminating resistor, and perhaps a hopeful 200pf cap, but that's not the whole story. The real impedance is affected by the topology, including feedback and the RIAA EQ network within the amp. The V15 III was particularly sensitive, so anything outside of the expected 47K/200pf "pure" load with cause HF response issues. The cart actually has an internal HF rise that is expected to be rolled off by the termination. If only it were that simple.

The only way to correctly verify the end result is to use a test record with response tests made without RIAA EQ, then measure the deviation from the ideal RIAA de-emphasis curve at the preamp output. The procedure is a little tedious, but worth the time and effort if you really want your system to play properly. Oh, and nobody does this anymore, so whoever does has a major leg up on everybody else.

Or use a cartridge without so much cartridge inductance interaction. I like the V15 V.

Now, isn't this fun? BTW, this is not new information, but it's only about 40+ years old, so still young in audio years.
 
Mar 21, 2020 at 6:27 AM Post #9 of 25

bmichels

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The V15 III is notorious for being sensitive to loading issues known, at one time, as "cartridge inductance interaction". The load the cartridge "sees" is a combination of the cable C, and the complex input impedance seen at the first stage of the phono preamp. Yeah, they all have that 47K terminating resistor, and perhaps a hopeful 200pf cap, but that's not the whole story. The real impedance is affected by the topology, including feedback and the RIAA EQ network within the amp. The V15 III was particularly sensitive, so anything outside of the expected 47K/200pf "pure" load with cause HF response issues. The cart actually has an internal HF rise that is expected to be rolled off by the termination. If only it were that simple.

The only way to correctly verify the end result is to use a test record with response tests made without RIAA EQ, then measure the deviation from the ideal RIAA de-emphasis curve at the preamp output. The procedure is a little tedious, but worth the time and effort if you really want your system to play properly. Oh, and nobody does this anymore, so whoever does has a major leg up on everybody else.

Or use a cartridge without so much cartridge inductance interaction. I like the V15 V.

Now, isn't this fun? BTW, this is not new information, but it's only about 40+ years old, so still young in audio years.

thanks for all those infos.
 
Mar 21, 2020 at 7:28 PM Post #11 of 25

bigshot

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I had an amp with both MM and MC preamps in it, so I said, What the heck and bought an Ortofon MC cartridge. I got it home and it didn't work with either preamp setting. I went back to the store and told them I wanted to return it because it didn't work, and they said it did work but only with Ortofon's preamp. They wouldn't let me exchange it for a cart that used standard preamps. They made me shell out another $85 for a dumb dongle. That was when I learned to hate non-standard gear.
 
Mar 21, 2020 at 9:40 PM Post #12 of 25

old tech

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I had an amp with both MM and MC preamps in it, so I said, What the heck and bought an Ortofon MC cartridge. I got it home and it didn't work with either preamp setting. I went back to the store and told them I wanted to return it because it didn't work, and they said it did work but only with Ortofon's preamp. They wouldn't let me exchange it for a cart that used standard preamps. They made me shell out another $85 for a dumb dongle. That was when I learned to hate non-standard gear.
You must have weak consumer protection laws over there. Normally, a customer would be entitled to a refund if something so relevant as the cartridge requiring a same brand amplifier was not disclosed.
 
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Mar 21, 2020 at 10:13 PM Post #13 of 25

bigshot

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They said since I had taken the cartridge out and installed it on my turntable I couldn't return it. They may have been lying. I've been lied to before in high end audio stores. Needless to say, I never went back to that one.
 
Apr 8, 2020 at 7:56 AM Post #14 of 25

Sterling2

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I don't know a thing about phono preamps and I can prove it; yet, an understanding has not been necessary since my Shure V15V-MR with Jico SAS stylus delivers a distortion free sound in all manner indistinguishable from CDs of same music. Thus, I am satisfied with my LP playback system as a whole. Interestingly enough, my phono preamp is a Sony TA-E9000ES Pre-Pro feature, described by one reviewer as having merely an adequate phono preamp, a speculation based on an assumption that Sony did not need to address serious LP playback desires on a product which likely would never be connected to a turntable so long after the LPs demise. At any rate, the Sony's MM preamp seems to perfectly complement my Shure cartridge. Perhaps I got lucky. One thing for sure, I'm not throwing any more money at it for any perceived gains, since Apple Music downloads of music I have on LP sounds better than my LPs, precluding any interest in listening to them, or digitizing them for convenience and/or to filter pops.
 
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Apr 8, 2020 at 8:27 PM Post #15 of 25

old tech

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I don't know a thing about phono preamps and I can prove it; yet, an understanding has not been necessary since my Shure V15V-MR with Jico SAS stylus delivers a distortion free sound in all manner indistinguishable from CDs of same music. Thus, I am satisfied with my LP playback system as a whole. Interestingly enough, my phono preamp is a Sony TA-E9000ES Pre-Pro feature, described by one reviewer as having merely an adequate phono preamp, a speculation based on an assumption that Sony did not need to address serious LP playback desires on a product which likely would never be connected to a turntable so long after the LPs demise. At any rate, the Sony's MM preamp seems to perfectly complement my Shure cartridge. Perhaps I got lucky. One thing for sure, I'm not throwing any more money at it for any perceived gains, since Apple Music downloads of music I have on LP sounds better than my LPs, precluding any interest in listening to them, or digitizing them for convenience and/or to filter pops.
Just curious as to which CD(s) of the same music sound indistinguishable from the LP. It is exceptionally rare to find an LP which is indistinguishable from the CD version or vice versa as they typically have mastering differences.

I have never found different but reasonable quality pre-amps to make much difference to LP playback when set up correctly except with MC cartridges, but even then it is not a major difference.
 

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