I received my new Denon turntable today, which has a built in phono preamp.
Since reviews state the Denon preamp isn't that good, I went and bought a separate (Techlink) preamp, which now it looks like I wasted $33 on this piece of crap.
Compare the two. Here first is the Techlink, which seems to be doing no RIAA equalization at all to my ears. Terrible over-emphasis on the highs:
http://home.attbi.com/~fewtchmon/techlink.mp3 (http://home.attbi.com/~fewtchmon/techlink.mp3)
Now compare the Denon, which sounds pretty good to my ears:
http://home.attbi.com/~fewtchmon/denon.mp3 (http://home.attbi.com/~fewtchmon/denon.mp3)
Does everyone agree the Techlink sounds horrible? My god, everybody be sure to stay away from it (www.tracertek.com (http://www.tracertek.com)).
I prefer the sound of the Denon over the sound of the Techlink...
Ditto... there's something wrong with the Techlink's sound. Highs are too emphasized, midrange seems de-emphasized, bass sounds screwy... :rant:
What kind of pickup (MM or MC) is the turntable using?
If the preamp is made for the wrong type you might have those kind of effects.
I don't know, it's a cheap preamp so I would assume MM (which would match correctly with my turntable). Sold for $59 at the website, at least I got a deal on it... maybe I could return it.
To tell the truth, this new Denon turntable has better detail & less rumble than what it's replacing (Sony PS-J11)... but I think the Sony has the better built-in preamp (frequencies are more balanced, bass is better). Maybe I'll have to save up for a better preamp, but I don't know what I would get.
I had never heard of that Techlink preamp, but I can't imagine it sounding that bad unless it isn't working right. Maybe you could ask them if it's supposed to suck...
The NAD is generally considered to be a good little phono preamp, and it sells on eBay for under $100:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1355128981 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1355128981)
BTW, I have never actually seen a turntable with a built-in preamp (although I know they exist), but how can you use an external preamp with such a turntable? Does it have two sets of outputs?
Originally posted by fewtch
To tell the truth, this new Denon turntable has better detail & less rumble than what it's replacing (Sony PS-J11)... but I think the Sony has the better built-in preamp (frequencies are more balanced, bass is better). Maybe I'll have to save up for a better preamp, but I don't know what I would get.
Wow.. sorry to hear that Techlink is such a piece.. hope you can return it.
On the Sony vs Denon thing.. might it be possible to remove the Sony board, and replace the Denon's with it? Hell, it might just fit! ;-) If not, you could put it in a separate box, and make it an ouboard preamp.. and then (assuming the TT has direct and preamp'ed outputs) do A/B tests between them..
That would be probably the cheapest way to go, and you already have an idea of the quality.. Could be a good starting point, till you settle on something better.
Originally posted by bryant
I had never heard of that Techlink preamp, but I can't imagine it sounding that bad unless it isn't working right. Maybe you could ask them if it's supposed to suck...
The NAD is generally considered to be a good little phono preamp, and it sells on eBay for under 0:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1355128981 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1355128981)
It's an idea... the one built into the Denon seems adequate, if a bit lacking in bass.
BTW, I have never actually seen a turntable with a built-in preamp (although I know they exist), but how can you use an external preamp with such a turntable? Does it have two sets of outputs?
There's a simple switch that selects either regular "phono" or preamplified output.
P.S. I'm not gonna complain too loud, this turntable is head & shoulders above the one I had before (just made the nicest sounding vinyl recording to digital I've ever done). But the Techlink preamp was a total waste of money... oh well.
new week, new thread, same usual suspects...
fewtch-I am sorry to hear about your preamp predicament. I'm glad the Denon worked out for you, though-it's probably a very solid turntable...
I ordered the hagtech bugle over the weekend (the developer said it would ship today sometime). I won't know about quality until I build and test-I bought the half kit, so I'm going to have to mess around with getting more parts from somewhere, and I won't know precisely what I will need until the kit arrives. I will then have to construct the thing. BUT it could quite possibly be comparable in cost to the piece you are attempting to return, so if you get your refund, you might want to go down the same road (misery loves company)...
JonPike-warning: you might be getting a pm from me in the very near future (and thanks, in advance)...
Listening to the samples from the Techlink preamp again, it seems to me that the sound follows the so-called "V" equalization curve (rather than flat like it should be). Bass and treble are overemphasized, and there's almost no midrange.
I wonder if this is by design in the Techlink, in order to make cheap speakers sound better? I got an Email back from a rep at the company, stating they've sold over 1000, customers have been very happy, and "it should work with any cartridge." *sigh*...
P.S. Macdaddy... I'd be interested to hear your experiences with the Bugle (the kit aspect sounds like fun too). After quite a successful transfer to digital yesterday, I'm thinking the preamp built into my turntable is adequate enough to preclude spending yet more $$ on a new one.
Macdaddy.. I'll be looking.. good that one of us took the plunge.. I might join you in a bit.. I'll be more than happy to show you sources for parts and help you pick some good ones..
fewtch... I'd try harder to get 'em to take it back.. they probably WISH they sold 1000's.. you might try the "I'm a regular on a audio forums that have a readership of 1000's.. you don't want THAT much bad publicity, do you" approach on them. it might even work.
Sounds almost like (though I'll have to check) a MC optimized pre, as opposed to the Moving Magnet type.. At least I remember the sound as much brighter (high treble), I don't recall if the bass went up too.... I have a switch on the one built in the Yamaha amp, and tried it back when I was first setting things up.
Think these guys know the difference between a MC or MM cartridge?? "it should work with any cartridge." my ass! It's gotta be designed for one or the other, or switch between.. the wrong type is completly inappropriate..
Ask them which it's designed for.. if they act like there is no difference, DEMAND your money back, and call Consumer Affairs.. they either don't know what they're talking about, (but are promising they do) or are conciously misleading people about it..
Worse case... we could turn the TNT-Audio guys on them. They'd likely buy one, (or we send them yours) do a reaming review as an example and warning of people trying to rip off unsuspecting customers... They like that kind of thing.. And what would these guys do, sue 'em? Sorry, wrong country! (most TNT guys are in Italy)
Let me know if you have problems.. I know who to talk to over there.. :diabolic:
Actually, they said they would take it back. Thing is, I have to find the packaging (if indeed I saved it), get an RMA number, plus it's gonna cost another 5 bux postage to mail it (at least), not to mention packing & all that... then waiting for them to credit my Paypal account... on a $29.00 item I'm not sure if I want to expend the time & energy for all this.
I might stick it in the closet to re-sell it some other time on ebay (insert evil grin), give it to someone else who doesn't care much about sound quality but needs a phono preamp, or just use it for parts or something instead. Dunno yet. Minus the main electronics, it could make a nifty "basic switchbox."
I wouldn't swear to the accuracy of this, but from your audio sample it's possible to make a rough frequency response measurement of both units. And looking at that, it seems that the HF RIAA equalisation is completely absent from the Techlink. In other words, they don't know how to design a phono pre-amp!
This is what the approximate frequency response looks like:
Dennon: http://privatewww.essex.ac.uk/~djmrob/mp3board/denon.gif (http://privatewww.essex.ac.uk/~djmrob/mp3board/denon.gif)
Techlink: http://privatewww.essex.ac.uk/~djmrob/mp3board/techlink.gif (http://privatewww.essex.ac.uk/~djmrob/mp3board/techlink.gif)
If you apply an approximation to the HF part of the RIAA equalisation to the techlink signal, you get this:
http://privatewww.essex.ac.uk/~djmrob/mp3b...techlink_eq.gif (http://privatewww.essex.ac.uk/~djmrob/mp3board/techlink_eq.gif)
Like I said, it's not exactly scientific, but I think it implies a design fault in the RIAA equalisation.
This page explains equalisation for gramophone records, and the reason it is necesary for all records:
http://www.rfwilmut.clara.net/repro78/repro.html#eq (http://www.rfwilmut.clara.net/repro78/repro.html#eq)
Cheers,
David.
http://www.David.Robinson.org/ (http://www.David.Robinson.org/)
EDIT: typo
Originally posted by 2Bdecided
I wouldn't swear to the accuracy of this, but from your audio sample it's possible to make a rough frequency response measurement of both units. And looking at that, it seems that the HF RIAA equalisation is completely absent from the Techlink. In other words, they don't know how to design a phono pre-amp!
I figured it was something like that (I know a little something about preemphasis and the need for RIAA equalization, and that's just what the problem sounded like).
And this is what the specs for the Techlink say:
"Frequency response: According to RIAA standard"
:wtf:
Very cool.. I should have thought of running the sound thru the spectral analysis part of some software I have.. (Cool Edit, for one) Which program is that you're using?
And, you've confirmed our suspicions.. these idiots blew it when they designed the EQ!!
Looks like they made a try at the bass enhancement, but even that isn't right... it peaks up somewhat at about 1Khz, then sharply rolls off.. rather than ramping up and staying at the proscribed increase of gain down the spectrum.
These guys must be betting on most of their customers having no experience in listening to LP's... they'll just think they're supposed to sound like that!
"Welcome to the Tracer Technologies Web site. Tracer publishes, manufactures, and distributes some of the world's best audio products."
Maybe so.. but this sure as hell isn't one of them..
Heh.. I like this line in the specs. Isn't really saying anything isn't it? I guess it needs an addendum:
"Specs:
Frequency response: According to RIAA standard" (we fu*ked up)
People like this really piss me off.. I say, more should know the truth about this thing..
fewtch, willing to donate yours to the TNT-Audio review cause?? :diabolic:
Fewtch, you should at least send a link to this thread to the company-David has exposed them pretty clearly. Tell ebay about it, too. These guys are flooding the auction site with these pieces of sh*t, and I'm sure that there are plenty of consumers who have bought the thing. I don't think ebay is down with crap merchandise, I could be wrong. But they should at least know about it...
JonPike-I will know exactly what is needed when the kit arrives. I'll be in touch when I have the instructions and parts list. Thanks again for offering to help.
You guys are having so much fun ripping this company apart that I almost hate to make this post, but I really don't believe that they could be selling a phono preamp that does not follow the RIAA curve. Nobody could listen to that and a reasonable stab at the RIAA eq can be done with a few passive components (so they're not trying to save money). The only reasonable explanation is that fewtch got a bad one (or, there might even be something wrong with the Denon's output in "no preamp" mode).
I've never seen a moving coil cartridge for less than $200 (and most are over $500), so when they say that a sub-$50 preamp works with all cartridges, what they really mean is that it works with any cartridge that anyone in their right mind would hook up to it.
Just my $0.02...
I agree with bryant, in that it can't be proven based on experience with one preamp / turntable.
I do think the company is rather shady (dumping these preamps on Ebay at $29, while still selling on the website at $59.00 is a good indication). And I doubt anything is wrong either with the preamp or the Denon turntable, but can't prove it.
If somebody else does care enough to order one though, and write a review on it, I would be watching with interest. Another thing to point out is I don't think it would be a fair review unless it came straight from the company (not through a third party).
There's still one available on Ebay, btw:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1356838482 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1356838482)
Another idea would be to contact the company and request one to review. My guess is they would refuse though... If interested, here's some contact information:
"curtis crowe" <curtisc@tracertek.com>
"Denise" <denisem@tracertek.com>
Tracer Technologies, Inc.
3600 Board Road
York, PA 17402
(717) 764-9240 Voice
(717) 764-9254 (Fax)
Heh.. well, I guess I agree with you guys as well.. Thinking about it in the cold light of day, (it was late the other night) I've calmed down a bit. We should probably give them A chance..
I get pretty steamed with tactics like this.. and think that they probably are as guilty as we think.. but it very well could be a defective unit missing some EQ parts, and not an intentional liqudation of a flawed design. So maybe we call off the dogs, till they prove themselves..
It would take careful measurement and maybe good lab equipment, to actually measure how closely the EQ matches the RIAA standard.. Though a test record and Cool Edit might do.. anyone know if there are test sweeps for this, on those test records?
Trying to think of a good, honest, easy test.. some kind of calibrated frequency sweep.. that always stays the same amplititude (comes out flat, with perfect RIAA) on a record.. I think you can get such tracks on test records.. I'll check..
2BDecided... having just got my Cool Edit back up and running, I now realize that funny icon I couldn't make out in your program box, was what Cool Edit looks like in XP! I thought the overall look of that box looked familiar.. I'm trying to reproduce your results... and it looks a little different.. is there an averaging feature I'm missing? I'd be interested in discussing settings. (offline, if it's too OT or boring to the rest of the thread)
If anyone REALLY wants to test the Techlink preamp, I'll sell it to you for $20 . Really though, I would like to see a review of it somewhere... if someone wants to contact Tracertek, all the info. is two posts above this one.
The fault could be as simple as a dry solder joint - that's where it looks like it's soldered, but it's actually come loose. A single capacitor lead with a 0.1mm gap in the solder (due to dropping the unit in transit) would be all it would take to wreck the performance.
I said the measurements weren't scientific - let me explain how I did them...
An impulse is a reasonable test signal with which to judge the frequency response of a device - put an impulse in, and FFT the output. This would be perfect (apart from background noise).
Now, on the recordings provided by fewtech there are plenty of vinyl clicks, and these will do as a poor mans' impulse! (!) I just chose one of them (a loud click at a quiet point in the music), set the fft to the lowest value (this gives terrible frequency resolution, but only "looks" at 128 samples - which meant it wasn't picking up the nearest "loud" bit of the music), and used the frequency analysis in CEP, with the cursor on the centre of the click.
Measured this way, the absolute frequency response isn't reliable, because it's contaminated by
a) the spectral characteristics of the click on the vinyl, and
b) the music happening at the same time as the click.
If we don't assume that the Denon is OK, then, because of these possible problems, all that can be said is that the techlink is much brighter in sound. However, the flat-ish Denon measurement indicates that the measurement is quite accurate and/or successful (I'd expect a gentle fall off at around 2kHz which isn't visible, but we'll ignore that).
So, if we assume that the Denon unit is OK, then the Techlink has a huge treble lift, which is both audible, and visible in the measurement. It seems more than coincidence that applying the RIAA curve corrects this huge treble lift. With this evidence, it's likely that there is a fault in the RIAA stage - a more accurate measurement could confirm or deny this.
A useful hint: if there are no isolated clicks on the vinyl, you can scan the frequency response of the run-in groove (using CE or CEP) - this should give you at least a rough indication of the response of the RIAA filter (if present) because without it the background noise on a LP is approximately spectrally white (i.e. you would see a flat line frequency response). You could also see mains hum and turntable rumble in there, so take this "measurement" for what it's worth: a very very rough guide, but better than nothing, and very easy to do.
Cheers,
David.
http://www.David.Robinson.org/ (http://www.David.Robinson.org/)
P.S. As noted by bryant, it's almost more likely that the Denon is doing something strange when you disconnect the pre-amp. So dispite all this careful consideration (which shouldn't convince anyone that I actually know what I'm doing ;-)) it's still unlikely that all Techlink phono pre-amps have a problem. (Will that sentence stop them litigating?)
Check new thread I started: "The last phono preamp thread (?)" .
The Denon turntable appears to be working fine, I found another preamp which I think sound better than the one built in (the only disadvantage is 3.7dB of "extra" 60Hz hum on the right channel, dunno where it's coming from but it's inaudible at normal recording levels).
Well fewtch.. welcome to the "keeps huge amplifier just for tiny included preamp" club..
;-)
Actually I do use mine for amplfying and driving speakers now and then..
As for the hum.. if you're motivated, you might check your grounds (all those RCA plugs making good sheld connection?) or even the internal wiring layout.. possibly there is something too close to something else, and moving wires away from transformers or power leads might help.
2B.. great technique!! A click would be pretty close to a pure impulse, at least to the cart/phono pre system.. You'ld need a track with pure white noise to do it right otherwise, kinda hard to find.. Is it true that an empty groove is pretty close to white? Only thing is, it's (hopefully) pretty low level.. but it shouldn't be too hard to find a fairly worn record..
I noticed in my testing of the mp3 files (yeah, maybe the pac's would be an idea) that you couldn't get a very clear picture, exactly like you said, the music content "colored" the result..
I guess we need nice, nearly silent passages with sharp clicks, rather than music, as our test files!
Off to "ping" my own system...
Originally posted by JonPike
Well fewtch.. welcome to the "keeps huge amplifier just for tiny included preamp" club..
;-)
Actually I do use mine for amplfying and driving speakers now and then..
As for the hum.. if you're motivated, you might check your grounds (all those RCA plugs making good sheld connection?) or even the internal wiring layout.. possibly there is something too close to something else, and moving wires away from transformers or power leads might help.
Thanks... I did some checking last night, and I'm convinced the problem has something to do with the turntable. The hum isn't there (and the preamp output is balanced) when the turntable is unplugged or disconnected, but when I connect it the hum is back. The RCA connections are solid, so I figure a grounding issue (none of this crap is grounded properly, both the turntable and amp have 2-prong plugs!).
Anyway, the hum is at ~-66dB (right channel) and the left is at ~-69.7dB, so it isn't audible anyway.
Yeah, that's not much.. Uh, you do have the ground wire from the TT to the amp (or computer) chassis hooked up?
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.
Hey, has anyone ever heard of "Bozak Madisson" or know anything about this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...item=1356587747 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&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 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1355205349)
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 (http://www.grahamsleeprojects.supanet.com/phono_preamplifiers.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 (http://www.tnt-audio.com/ampli/gram-preamps_e.html)
Hope it helps..
Jon
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 (http://www.kabusa.com/Phonpre.htm)
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..
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.
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 (http://www.btech-usa.com/bt926.htm)
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/nadpp1_e.html)
http://www.tnt-audio.com/ampli/kabph1_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??
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?
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 ... 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!
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.
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) (http://www.tracertek.com/index.asp?PageAction=VIEWCATS&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!".
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.
Of course, the other obvious disadvantage of this approach is that it only works through your PC.
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.)
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.
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.
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?
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
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?
Why "add" that many bits and to what do you add them?
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).
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.
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?
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?
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.