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+--- Thread: Stereo home audio doctors in the house? (/showthread.php?tid=27993)
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Stereo home audio doctors in the house? - Psurfer - 02-14-2007
Sometime back, I posted about some weirdness w/my old stereo gear. More recently the power amp blew out. I've been loaned a repl amp, and the system's back in business -- Except poor sound from the turntable: very audible distorted highs, even from mono records w/preamp switched from Stereo to Mono -although that & tone controls take the edge off the distortion. All other sources sound fine. Moving magnet Grado in late mdl Dual, to even older orig kit Halfler preamp.
Would this symptom most likely be caused by the cartridge or its connects; or the phono stage in the preamp? The back of the preamp is Hard to access, so I don't want to disconnect anything from it unless I know it's necessary. All mentioned components (other than repl amp now) have been connected, unmoved, for many years.
I had heard the same phono problem a little while before the old amp went out, and I thought it might have related to compromised cartridge pins-to-wires connections at the tonearm. I messed w/those prior to my amp's demise, curing a loud hum that had developed. I don't think I can do any more to those junctures myself, as the wires' connectors do not really pinch down tight enough to completely contact the cart's thin pins. -They never did, but worked fine for years before.
Re: Stereo home audio doctors in the house? - Fritz - 02-14-2007
my bet would be preamp, but it could be a dried out cart or oxidized wires on the connect.
Re: Stereo home audio doctors in the house? - mrbigstuff - 02-14-2007
I bet a lousy connection on your Grado. I had the same happen to me. Also, check your grounding of the turntable.
Re: Stereo home audio doctors in the house? - Psurfer - 02-14-2007
mrbigstuff- good point: grounding- as I should also mention that touching certain of the cart's wires w/my finger causes hum. Is that par for the course?
If you knew what a pita it is to get to the back of the preamp, you'd understand why the same equpmnt has stayed put since the Reagan era... I suppose the easiest troubleshoot would be first to take off the cartr and take it to a shop to be looked at. I should first try to guess the place where a simple tightening or replacement of the wires' little connectors might get done for cheap -or gratis, like if they think I could be a customer for some new component in the future (which I may).
Re: Stereo home audio doctors in the house? - Filliam H. Muffman - 02-14-2007
I would bet it is, in the following order of likelyhood: a bad electrolytic cap in the phono preamp, oxide buildup on switches/gain potentiometer, oxide buildup on pins of the phono cart.
Re: Stereo home audio doctors in the house? - Bernie - 02-14-2007
Older amps had two different sets of inputs for turntables. One for magnetic and one for ceramic. Your turntable may not be compatible to you newer replacement amp if it only has one set of inputs.
Re: Stereo home audio doctors in the house? - Joey Cupcakes - 02-14-2007
[quote Bernie]Older amps had two different sets of inputs for turntables. One for magnetic and one for ceramic. Your turntable may not be compatible to you newer replacement amp if it only has one set of inputs.
Except he replaced his power amp, not his preamp, if I've read the original post correctly; also, routing a MM cartridge to a ceramic or aux input would result in a crappy sounding low-level signal, not a high-level distorted one.
Tighten ALL connections, from the cartridge through the MM phono inputs on the preamp, and check the grounding. If that doesn't fix it, the preamp probably needs servicing.
Re: Stereo home audio doctors in the house? - Psurfer - 02-14-2007
Joey has read the original post correctly. Pre-amp is the original Hafler, which uses these rectangular plastic push switches, which I thought were said to be less suceptible to oxidation troubles, switch either works or it breaks entirely. If the problem does turn out to be in the preamp, what's a good one to get these days (new or used)? -Must have phono section. The amp is now the Adcom 535 II.
Re: Stereo home audio doctors in the house? - Yoyodyne ArtWorks - 02-14-2007
Mistracking often manifests itself as HF distortion so I would first check to make sure the stylus is clean. If that doesn't help, check the tracking force and anti-skating on the tonearm. I would zero out the tracking force and anti-skating dials, then carefully position the counterweight to set the tonearm parallel to the platter and then add the appropriate tracking force and corresponding anti-skating. 1.5 grams sounds about right, though the instructions that came with your Grado should give you the optimum force (or check with Grado). Remember that it is better to err on the side of too much TF than too little, as inadeqaute tracking force causes mistracking and potentailly damages your records.
If the problem still exists, use a protractor to make sure that the cartridge alignment in the headshell is correct. This is a less likely solution, but still worth a look.
BTW, the tonearm on the Dual is dynamically balanced and thus isn't so demanding in terms of your turntable being absolutely level.
Hope this helps!.
Re: Stereo home audio doctors in the house? - Dick Moore - 02-15-2007
It's the preamp. You could do worse than an Adcom preamp to match the new power amp.