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What's Wrong With My Cartridge/Setup?

Please help this newbie sort out a problem with my cartridge, tonearm or installation.

Here's my system: Shure V15VxMR Cartridge mounted on an older Rega Planar 2 Turntable with glass platter into either an Audio Experience Concerto Tube Phono Preamp or a Conrad Johnson SC-22P SS FET Phono Preamp (in a homebrew box) into a CJ Preamp and Anthem Amp-1 tube amp. This system is new to me (most parts are used with the exception of the cartridge which was bought with 'only a few hours use' and the phono preamp (which I ran for 30 hours burn-in).

So here's the problem: My LPs sound like crap. The highs are badly attenuated, the lows are a weak and the entire sound lacks punch. The sound field is totally flat. I've compared a number of vinyl LPs to CD releases of the same material played on my Music Hall CD-25 and the CDs sound considerably better than the vinyl.

I've played with some of the mechanical parameters of the cartridge (tracking alignment, VTA, weight, anti-skating) using a test LP and a scope (as well as my ears). The changes generally have a audible effect but are small compared to the magnitude of the problem. The loading the cartridge is 'seeing' was measured to be very close to the spec of 47K ohms and 250 pF. The two phono preamps I've tried sound pretty similar, so the problem would appear to be with the cartridge/turntable/tonearm setup.

Any ideas? Could cartridge break-in account for such a major sonic impact? Is it fair to compare an LP to a CD of the same material? Help!!!

.... Brian
odourboy

Showing 4 responses by odourboy

odourboy OP
4 posts
 
Thanks all fo your ideas. I'm at least glad to hear that it's fair and reasonable to use a CD as a reference against my vinyl and the assumption that the vinyl should sound at least as good - and probably better if I'm set up properly. I can tell you so far what it is NOT. I've tried a couple of the easy ones:
1) The wiring sure looks right and I even buzzed it out with an ohm meter from the cartidge to the RCA conncetor.
2)Reversing the polarity of one side of the system did not help.
3) I was really hoping that the stylus was not seated properly, but alas, I removed it and reinserted it and engaged in a very satisfying manner, but did not solve the problem.

Still many things to check. I'll report back if/when I get this thing licked.

Cheers, Brian
odourboy OP
4 posts
 
Here's an update... It would appear that there are a couple if things going on: First, the cantiliver on my cartridge looks like it's bent a bit. This makes alignment kind of tough. (Gawd knows what it's doing sonically!) But I think I've got cartridge installation fairly close which has allowed me to uncover what I think is the real culprit. I was hasty in believing that my new Audio Experience Concerto Tube Phono Preamp was working well. It would appear that it's not. With my CJ FET phono preamp, my vinyl is now 'almost' indistingushable from a CD. With the tube preamp - the highs are still audibly attenuated which of course makes evaluating the sound field difficult. Bass seems to be pretty good now, so the cartridge alignment was initially contributing to the problem.

I suspect the Shure cartidge is not operating up to snuff so I probably got screwed buying used (through Audiogon no less!). But I'm pretty sure the tube preamp has some serious problems. It uses 12AX7s and I've tried new tubes including Electro Harmonix, EI, 9th gen. Chinese as well as NOS Matsushita - none of these signficantly 'take the blanket off' the tone. I'll be contacting the manufacturer regarding this issue once I'm absolutely sure it's the problem but if anyone has any experience with these Audio Experience Concerto preamps, I'd like to hear your comments.

... Brian
odourboy OP
4 posts
 
I've spent a fair bit of time trying to align the cartridge and I can't seem to get it in the sweet spot - so I think it's screwed. Ouch! Time for a new stylus or cartridge. :-(

As an aside, I contacted Chui at Audio Experience and he insists I need to let it fully break-in (100-150 hours) before passing any judgement. I am dubious, but I'll give him the benefit of the doubt.

Curiousity got the better of me so this morning I dragged out some gear and did some tests. I graphed the response curve of the CJ FET phono and found it was within 0.8 dB of the standard RIAA curve and just slightly on the 'hot side' at both ends. (Easily within my error of measurement). The AE tube phono was at worst 4 dB below the line on the bass side of the curve and surprisingly, slightly over 1 dB (at worst) below on the treble side - suggesting slightly accentuated upper mids. So this would seem contradict my own listening tests - but more likely, I messed myself up by changing back to the original noname chinese tubes before running this test. I am an EE and fairly well equipped when it comes to test gear.

Dopogue - I am curious where you saw the less that stellar reviews on the AE Phono Preamp. If you can, please point me at them. Everything I read on Audiogon, Audio Asylum and Ebay feedback was positive so I'm really curious.

Cheers, Brian
odourboy OP
4 posts
 
Marakantz - To answer your question, with the AE Concerto turned off, the input measures 47K with a DVM. With the unit powered on, this drops to about 9K resistance. I don't have a schematic (so I'm not sure what I'm measuring) nor do I know if the DVM can provide a valid measure with the preamp turned on (tubes are funny things), but there may certainly be a loading issue here. Can you comment?

The CJ on the other hand is nailed at 47K regardless of whether the unit is off or on - but this is no surprise given the very high input impedence of a FET, so I'm basically measuring the input resistor.
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