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Phono Preamp comparison (horror story)
JonPike
post May 31 2002, 23:50
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Yeah, that's not much.. Uh, you do have the ground wire from the TT to the amp (or computer) chassis hooked up?
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Pio2001
post Jun 1 2002, 00:34
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I wouldn't rely on background noise analysis, because if the record is a little warped, the catridge will pickup the noise of the vinyl vibrating, which is a medium-range noise.
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fewtch
post Jun 2 2002, 02:08
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Hey, has anyone ever heard of "Bozak Madisson" or know anything about this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1356587747

Sounds like a phony company name to me, invented to sound "high end" but who knows...

Thanks (and I'm still looking for a decent, (very) low cost preamp, if anyone has any suggestions)... here's another one I wonder if anyone's heard of...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1355205349


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JonPike
post Jun 2 2002, 05:29
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Have not a clue to the "Bozac" pre.. tried a search to see if this "well known brand" appears anywhere else on the planet?

The other one.. well, it might be a prejudice.. but I'd expect anything that would be marketed in a bubble pack wouldn't have sound quality as its primary design goal..

I saw a likely item for the Quality side of the market.. the Graham Slee Amp 1 or Amp 2..
these are low end (for the Audiophile market) decent quality pre's... but that makes them end up around $130 and $175 USD, shipped.. At least you could trust them to actually meet their specs.. I've seen some good reviews and comments on these, check this site and his other one linked, for more info.. Pretty cheap for real 'phile gear..
Still, probably not quite down with your "cheap" requirement..

http://www.grahamsleeprojects.supanet.com/...eamplifiers.htm

A review on the both.. would sound like the 2 would be worth going for if you're planning on more serious growth in the hobby.

http://www.tnt-audio.com/ampli/gram-preamps_e.html

Hope it helps..

Jon
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fewtch
post Jun 2 2002, 05:43
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QUOTE
Originally posted by JonPike
The other one..  well,  it might be a prejudice..  but I'd expect anything that would be marketed in a bubble pack wouldn't have sound quality as its primary design goal..

To be honest, anything with sound quality as its primary design goal is gonna be out of my price range. What I'm looking for is something better than currently built in to my turntable, which is why I keep asking if people have heard of this brand or that brand.

I couldn't find "Bozak Madisson" anywhere else in a search, but I saw an RCA phono preamp advertised on Ebay too, and also couldn't find that on the Web. It's possible some of these are old stock from the 1980's, or whatever. I just need something that reproduces the frequencies accurately (but am beginning to think "accurately" is in the mind of the listener!)

Edit -- Has anyone here upgraded, and have an old phono preamp you would be willing to sell me? At least then I'd know it was tested as reasonably good. I really can hardly trust my own ears on this, as the sound of vinyl can vary so much between records.

Any opinions on the second preamp listed on this page:

http://www.kabusa.com/Phonpre.htm


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JonPike
post Jun 2 2002, 07:24
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Again.. nothing here.. I also think that the one in your Fishcer amp, or maybe even the turntable, might be the equal of (or better) than the $20 "superbargain" independant.

But I understand your looking for personal reccomends and updates.. You might get some results by throwing the question out in some "fi" fourms..
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fewtch
post Jun 2 2002, 08:23
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QUOTE
Originally posted by JonPike
Again.. nothing here..  I also think that the one in your Fishcer amp,  or maybe even the turntable,  might be the equal of (or better) than the  "superbargain" independant.

Funny, I liked the sound of the one in my Sony PSJ11 the best so far, and that turntable is basically a toy (I opened it up yesterday and it has some sort of plastic gear drive rotating the platter). No wonder the mechanics were so noisy...

I thought about using the preamp from the Sony (separately), but that would involve basically junking the turntable, as everything (including the motor controller) is on the same circuit board... and the preamp runs on 12VAC so I'd have to yank the transformer too. Maybe I'll do that, junk the old turntable, and put the Sony preamp into the Techlink box. biggrin.gif biggrin.gif

Then again, someone would probably pay $50-$60 for the Sony turntable on Ebay... I dunno, considering all I'm doing is recording old Moog records into MP3 format (then putting 'em into storage), maybe it's overkill to even worry about an external preamp. Or, I might try one more time buying a cheap one, & then give up.

Edit... found another one that looks interesting. Needle Doctor carries a cheaper model of this brand. Strange, but the wording here is almost exactly the same as some of the webpages for the NAD PP-1, the specs are the same too:

http://www.btech-usa.com/bt926.htm


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JonPike
post Jun 2 2002, 11:19
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Speaking of the NAD PP-1.. was poking around on TNT-Audio, and found reviews for that, and one of the KAB boxes..

http://www.tnt-audio.com/ampli/nadpp1_e.html

http://www.tnt-audio.com/ampli/kabph1_e.html

As expected.. they didn't exactly dislike the PP-1 ($100), and sorta liked the KAB PH-1. ($150) They did seem happier with the Graham Slee Amp 1, though ($130)..

We're just not finding you that killer $20 preamp, are we?? wink.gif

Maybe the $20 (+$25 more parts) Bugle kit will pan out into something decent.. it has a chance to.. especially if we pick some higher qual parts...

Macdaddy.. you get a package in the mail yet?
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fewtch
post Jun 2 2002, 11:31
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Well, I'm not really looking for "killer" either. Just something that sounds better to my ears than the preamp built into the Denon DP-26F (frankly, it sucks). Even an external $20 preamp might be better, in a $150 turntable... so I'll keep looking around, who knows?

Let me describe the problems with the preamps I have now:

Denon: The sound can best be described as "grating." Highs are not high and lows are not low sad.gif ... too often a sustained high sounds like a screech instead, and cymbals lack detail... at least it doesn't "lose" instruments.

Fisher: Better, but it "smooths" the sound too much. Instruments are lost underneath the bass, and clicks/pops on the record sound more like bass thumps... try cleaning that up with an audio software! rolleyes.gif

Sony turntable: Well, it was flattish (nothing special) and too "warm," but didn't "lose" instruments and so far sounded the best. But the preamp is built into the turntable and I don't want to tear it apart.

Anyway... I've babbled enough, off to get some sleep.


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Bruin
post Oct 30 2007, 23:53
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If I read the Tracer Technologies info correctly, the whole idea is for their phono preamp is to provide the exact sound of the vinyl recording without RIAA EQ - and then to process that through their DC Six (upgraded to 7?) software to provide not only RIAA equalization but to also compensate for cartridge/tonearm/turntable freq responses - as well as room characteristics, clicks & pops - and even personal preferences. So, if you're listening to your records using just their preamp and not the software - of course it sounds tinny & bass shy.
I plan to speak with someone there this week to see if I've got this correct but I'd like to get other people's take on it.
I'll keep you posted on what I find out.

They say: (at http://www.tracertek.com/index.asp?PageAct...amp;Category=6)

"CTP Phono Preamps
These quiet, high quality phono preamps do something that no other preamps do...they give you the audio off of your records...exactly as it comes off of them. No EQ is added, so what you get is exactly the sound your record is generating...with no colorization.
The Software
The idea is a simple one. Your current phono preamp adds an equalization curve to every song that passes through it...even if you don't need or want one there...it's hard coded into the hardware. We simply use the CTP series to deliver a flat signal and then use our software to add a mathematically perfect equalization curve to the audio. The results...the closest thing to hearing what happened in the recording studio the day your favorite group or singer recorded it! These are differences your ears can hear...not just theory!".
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AndyH-ha
post Oct 31 2007, 16:54
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This idea has been discussed to death in various forums, including, I believe, one or more threads in this forum (it gets hard to keep track in my head). It’s a ravenous world and most people have to find some way to make a living. This is their angle, but it is only a snare for the ignorant, just like a lot of audiophile nonsense.

RIAA equalization has been well specified for somewhere around a half century. There are plenty of public domain circuits that do it correctly. It requires a bit of care in selecting component values if you want to precisely meet the specs (i.e. 1% resistors are better than 20% resistors, and selection by measuring actual values is best), but for a competent engineer it is no big deal. Besides, the variable in the vinyl, and especially in your phono cartridge, make it pointless to get too hot and bothered about precision..

Among the other arguments against this approach is that phono cartridge output raises with frequency. Even if their preamp is built to handle the (relatively) high levels at the higher frequency end, your soundcard may not be able to avoid clipping there if you attempt to get good input levels at the lower frequencies where most of the music lives.
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pdq
post Oct 31 2007, 17:13
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Of course, the other obvious disadvantage of this approach is that it only works through your PC.
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Axon
post Oct 31 2007, 17:58
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The soundcard overload argument is a red herring. When you take the RIAA eq out of a phono preamp, all you have left is an overpriced mic preamp with some interesting impedance loading and crappy connectors (RCA) instead of the balanced connectors that the rest of the world uses. Mic preamps often come with 40-60db of gain, making low output MCs fairly easy to record. And there are several reasonably high quality mic preamps with USB interfaces of some kind. I use the EMU 0404 USB for my flat-preamp experimentation.

A bigger issue is that MM cartridges really need the loading that a preamp designed for MM cartridges provides. If you go the flat route with a mic preamp, you're mostly forced to switch to MC.

I prefer to think that the rising sensitivity with frequency is a strength, not a weakness. If you assume that the electrical noise is relatively flat with respect to frequency for both RIAA preamps and flat preamps, then you wind up with 20-40db more SNR in the treble if you record flat.

Pure Vinyl on the Mac supports flat recording too, and the author is a noted proponent of the technique. (His site pointed out to me the connection between mic preamps and phono preamps.)
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2Bdecided
post Oct 31 2007, 18:10
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But most music is spectrally white-ish or pink-ish.

A 20dB+ treble boost, without clipping anything, implies a 20dB+ cut elsewhere. That implies 20dB poorer SNR. More if you're going to stop clicks and pops clipping: these can be _huge_ - 10x bigger than signal peak!

I'm sure either approach can work perfectly well, but the digital RIAA route seems unnecessarily painful to me. As for the advantages: if the the pre- and de- emphasis circuits match, it's a perfect system. Any mismatch and it isn't, but it's the least of your worries. Given that the original curve (before the record was cut) was achieved with analogue components...


Where this _is_ useful is for pre-RIAA recordings. When you are not sure what the EQ is, it makes sense to be able to change it in software later - though even then, some kind of known EQ on recording can be better than none at all.

Cheers,
David.
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Axon
post Oct 31 2007, 19:01
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But the 20db treble boost is at 3khz: where it's most important. The ear's sensitivity at the places where the dynamic range is lowered is considerably more than 20db worse than at the 1-3khz range. Of course, it goes all the way to 40db at 20khz, but in my experience, the energy contribution from that part of the treble is overhyped.

Also note that flat amping allows one to make far more accurate measurements of THD, wow/flutter, or anything else that requires numeric computation and a flat transfer.
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AndyH-ha
post Nov 1 2007, 04:59
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I can allow that lowering the input level to accommodate the hf rise might not be overly significant since good soundcards cover far more dynamic range than LPs can provide. Making measurements against “flat” recordings (hardly flat relative to the audio encoded there on, however) might be interesting, but is not a consideration for more that two or three out of 6+ billion possible listeners. So, what about that advantage in the midrange? Do your experiments find anything that can unconditoinally be called an auditory improvement?
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pdq
post Nov 1 2007, 12:44
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QUOTE (Axon @ Oct 31 2007, 12:58) *
I prefer to think that the rising sensitivity with frequency is a strength, not a weakness. If you assume that the electrical noise is relatively flat with respect to frequency for both RIAA preamps and flat preamps, then you wind up with 20-40db more SNR in the treble if you record flat.

Since most of the noise added by the preamp is in the input stage, that noise will also be subjected to the RIAA frequency curve, so there is little or no difference in SNR whether the preamp does RIAA equalization or not.

Edit: spelling

This post has been edited by pdq: Nov 1 2007, 12:45
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Woodinville
post Nov 1 2007, 20:01
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QUOTE (pdq @ Nov 1 2007, 04:44) *
QUOTE (Axon @ Oct 31 2007, 12:58) *

I prefer to think that the rising sensitivity with frequency is a strength, not a weakness. If you assume that the electrical noise is relatively flat with respect to frequency for both RIAA preamps and flat preamps, then you wind up with 20-40db more SNR in the treble if you record flat.

Since most of the noise added by the preamp is in the input stage, that noise will also be subjected to the RIAA frequency curve, so there is little or no difference in SNR whether the preamp does RIAA equalization or not.

Edit: spelling


Something else to consider. Doing RIAA digitally requires a lot more dynamic range in the ADC. Just take the entire top to bottom range of the curve, divide by 6, and add that many bits to the required capture.

Good luck.

I have to wonder what the odd preamp reported in the OP was doing. Did you ever get any answer?


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AndyH-ha
post Nov 1 2007, 20:06
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Why "add" that many bits and to what do you add them?
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pdq
post Nov 1 2007, 22:28
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QUOTE (AndyH-ha @ Nov 1 2007, 15:06) *
Why "add" that many bits and to what do you add them?

If the RIAA curve is ~40 dB top to bottom then you need ~7 bits more resolution with a linear preamp than a RIAA equalized one (or so the theory goes).
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Axon
post Nov 1 2007, 23:21
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QUOTE (AndyH-ha @ Oct 31 2007, 22:59) *
Do your experiments find anything that can unconditoinally be called an auditory improvement?
Nope. In fact, my current setup requires an outboard box to supply the resistance loading for my MM cart, and between the haphazard construction of that box and the poor shielding on my tonearm cabling, a significant amount of HF crap is leaking into my recordings. However, I strongly believe that is not an inherent problem with the technique, and once I switch to MC carts and get better tonearm wiring, I should see better results. But I'm already getting recordings good enough to listen to on my iPod on a regular basis.

QUOTE (pdq @ Nov 1 2007, 04:44) *
Since most of the noise added by the preamp is in the input stage, that noise will also be subjected to the RIAA frequency curve, so there is little or no difference in SNR whether the preamp does RIAA equalization or not.
True enough, but wouldn't this depend on whether or not the equalization is active or passive?

QUOTE (Woodinville @ Nov 1 2007, 14:01) *
Something else to consider. Doing RIAA digitally requires a lot more dynamic range in the ADC. Just take the entire top to bottom range of the curve, divide by 6, and add that many bits to the required capture.
Which is about 6.5ish bits.. but 70db+40db=110db, and mic preamps with such an amount of SNR do exist. My 040 USB allegedly does 127db, weighted.

If I were to actively try to look for effects of reduced dynamic range due to flat preamp recording, should I just search for a post-RIAA noise spectrum that is inferior to an RIAA-preamped recording, or are there more subtle effects to consider? And if I can show that the surface noise (or thermal noise) is much higher than this level, is that enough proof to say it doesn't matter?
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pdq
post Nov 2 2007, 16:20
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QUOTE (Axon @ Nov 1 2007, 18:21) *
QUOTE (pdq @ Nov 1 2007, 04:44) *
Since most of the noise added by the preamp is in the input stage, that noise will also be subjected to the RIAA frequency curve, so there is little or no difference in SNR whether the preamp does RIAA equalization or not.
True enough, but wouldn't this depend on whether or not the equalization is active or passive?

I'm not quite sure what distinction you are making here. If one places the equalization in the feedback of the input stage (which is how it would normally be done) then the input noise receives the same gain as the signal and both are RIAA equalized. If instead one places a simple gain stage at the input, then passes this through a RIAA equalization circuit, then again both signal and noise are processed identically. The only way that I can see that it would make a difference is if during RIAA equalization the signal level at some frequencies dropped low enough to pick up additional noise in later gain stages. This would obviously be a poor design.
OK, in a REALLY bad design one might place passive equalization before the first gain stage, but I hope nobody would ever make that mistake.
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