Bass issues with cart/phono?

2007-12-20 14:39:40

Scenario:

Grado Gold cartridge, SME tone arm on Thorens TD 125 MK II
Grado PH 1 phono stage
USBPre A/D converter
Recording on OS X with Bias Peak.

My main problem is a noticeable loss of deep bass resonance in digital recordings of my records.

Symptoms based on testing:

Comparison 1:

A. Kraftwerk Autobahn recorded two weeks ago when PH 1 had been running 24/7 for weeks. Not sure about tone arm balance at this point. Stylus had been exposed to some scratchy, dirty records. Not much liquid cleaning of stylus.

B. After phono stage had been turned off for a few days, warmed up for 48+ hours, tested Autobahn again, before and after two attempts to recalibrate SME tone arm. Prior to this test and power-off of phono stage (2.5 days), but after earlier recording, I had recorded several scratchy and dirty (soapy residue?)records. I have noticed a reduction in bass in recordings made before the power-off, so that may not matter. As for the records, I cleaned them as well as I could before recording. The residue was due to earlier problems caused by previous owner.

Result of comparison: Original recording has very deep, resonant bass, highs are there. Tests since then, after tone arm calibrations, show decent bass, but lack the very deep bass of the earlier recording.

I'm not sure what the state of the calibration was when I made the first recording, but when I checked it after the power-off, the stylus had gotten "lighter" rising above the record. I wonder if the "bass" may have been due to the stylus riding higher in the groove somehow.

Comparision 2, between recording and lossless digital version of the same musical track (possibly from CD).

The digital shows deep bass, just as the first Autobahn recording showed.

The record recording bass sounds okay, but noticeably lacks the deep base in comparison with the digital one.

This could be due to an old vinyl vs better source, I don't know.

Another strange thing today is that twice now, while recording, the system has suddenly generated 100% white noise. I have no idea why.

I asked Grado about the bass issue, and a knowledgeable source there warned me about using liquid on the stylus (no feedback about phono stage warm up yet). At first he said  just be careful. I was, but later he explained that if liquid should move up the stylus shank into the generating system gradual degradation can occur.

Because of the dirty records, I was concerned that the stylus could have picked up junk that would not come off with just a brush. So I applied distilled water to the brush.

Now I'm concerned that liquid might have made it up to the "generating system" and could be responsible for the lack of bass. I am also worried that the two instances of 100% noise might be a sign of the cartridge failing.

I realize this is a complicated problem/question, so please bear with me. I hope someone can explain this.

I'm doubtful at this point that the phono stage has anything to with it. The SME arm may need some lubrication at this point to be sure it is balancing correctly. I don't know how it got out of wack from the earlier calibration some weeks ago. It bugs me that the arm can be that sensitive. But it is problematic that I can't reproduce the earlier good bass from my first Autobahn recording.

I'm in the process or digitizing a huge collection of records to digital, so I need to get a handle on this! 

Bass issues with cart/phono?

Reply #1 – 2007-12-20 15:37:33

Was the white noise very loud (full volume) or softer?

Bass issues with cart/phono?

Reply #2 – 2007-12-20 16:39:20

Hi pdq,

It was 100%, full volume. Kind of like feedback.

It has happened twice. The first time, I I'm not sure what I did, but the 2nd time I shut everything down. So far, it hasn't happened again.

The biggest change is that I disconnected the phono stage to use a tape deck with the A/D converter. I haven't changed the RCA connectors other than the reconnection.

gritto

Bass issues with cart/phono?

Reply #3 – 2007-12-20 18:00:43

The white noise thing is a driver issue. White noise at exactly 100% volume (not attenuated, not clipped) can only come from inside the sound card.

The water could have conceivably damaged the cantilever suspension, stiffening it; this would result in a higher tonearm resonance. Do you have a test record that you can inspect the resonance with?

I'd be interested in any wav uploads if you can swing it.

Bass issues with cart/phono?

Reply #4 – 2007-12-20 18:20:30

I doubt the phone preamp has anything to do with your bass issue - if it did, that would represent some really awful engineering. Any differences between the sound when first turned on or warmed up for days should be minuscule (and largely imaginary).

Deep bass on phono systems is notoriously inaccurate due to mechanical resonances - it is the easiest difference to spot between turntable setups, and one of the chief reasons I was so glad to see vinyl go away. Most of my old vinyl sounds excessively warm and bass heavy compared with CDs, and it is certainly NOT accurate. Warm, but not accurate.

It seems doubtful that a given cartridge would change much in a few weeks. It would take a lot of liquid to do anything to the rubber suspension, and dirt on the records is far more likely to hurt the vinyl than the stylus.

I would check the tonearm calibration first, as that is the most likely to go out. Stylus pressure, overhang and anti-skate settings.

Also, consider that your first Autobahn recording (with the deep bass you like) may in fact be the least accurate - perhaps it is the fluke, and not your subsequent recordings. It may be that with your SME fully calibrated and a brand new Grado cartridge you get - less bass!

Bass issues with cart/phono?

Reply #5 – 2007-12-22 06:47:04

Hey guys,

Thanks for the feedback. I haven't noticed the 100% noise problem for a while now. I changed the stylus and did some tests. The new autobahn test came very close to the original, so it probably is mostly just a dirty stylus.

I've asked a friend in Australia to send me a Magic Eraser because I can't get it in Thailand where I live now.

I think another problem that may be contributing to bad tracking is that my old SME arm (that I bought used) could probably use some lubrication.

When I balance it, it seems to get "stuck" at certain points (lower or higher than the record) rather than always coming to rest in a spot that reflects the weight setting. I took the arm to Bangkok to be fixed a while back, but all they did was fix a grounding problem.

I can't ask SME right now, and the Internet is not helping figure out what kind of lubricant to use on my SME. For that matter, I should lubricate my Thorens too. So, can anyone suggest the right lubricants to use?

Axon, if after lubricating the tone arm and making sure I have the calibration correct, I still have problems, then it might make sense to upload some comparison samples. Thanks for your interest.

Thanks again to all of you.

Gritto

Bass issues with cart/phono?

Reply #6 – 2007-12-23 15:34:19

Axon,

Well, now I do feel like uploading some samples, but I'm not sure I can do so on this forum.

I replaced my stylus and tested Autobahn again. It was acceptably close to the possibly flawed original. Since then I've recorded a few records, some classical, jazz.

My Art Ensemble of Chicago stuff sounded fine, but I noticed a lack of bass in Basie's Afrique and Art Blakey's "Gypsy Folk Tales". Maybe it's the vinyl pressing, but I doubt it.

I'm starting to wonder about the VTA (vertical tracking angle) with my SME arm, based on some searching. Visually, it's hard to tell but if I had to guess it could be lowered a tiny bit. I thought I had it right. 

I'd be interested in feedback, but I doubt I can upload decent samples.