Strange bass emphasis in recording of vinyl record

[Windrose]

This is prob. in the painfully naive category, sorry in advance.

I'm trying to make digital recordings of some old LPs. I don't have the detailed hardware specs right here at the moment, but the basic setup is an old Kenwood KD2070 turntable with an old aftermarket AudioTechnica cartridge going into the phono input of a Pioneer stereo tuner/amp thingee, and then the tape/DAT recording output from same going into a computer sound card line-in. (A Turtle Beach card in a Intel 64-bit dual core system running OpenSUSE 11.3, for whatever that's worth.)

Here's the issue: On the couple of test runs I've done so far on, e.g., the original LP recording of "Muswell Hillbillies" by the Kinks (yes, I know, not the album of choice for a test run...) the audio spectrum is heavily skewed to the bass. Heavily. If it weren't for the fact that it makes no sense, I'd say that the RIAA post equalization correction had been applied two or three times in a row. Does this sound like any obvious problem I've overlooked?

Thanks,
MAAB

[steve]

The recording set-up sounds like it should give very good results.
How have you set it up for playback? Turtle Beach Line Out to Pioneer Tuner-Amp Tape in?
What does it sound like when you play it back?

[Windrose]

It sounds pretty much the same as the direct signal from the turntable, rather muddy and heavily bass. But you maybe need to know that for playback from the computer I'm going from the sound card out into the Pioneer Tape/DAT in, so it's going through the same amp?

maab

[billw58]

How does it sound if you play the turntable through the amp and speakers without going through the computer?

-- Bill

[waxcylinder]

Just a thought: your Kenwood TT does not by any chance to change the output between line and phono settings? I.e does it have it's own internal pre-amplifier?

If so if you can either set it to Line out put (which would use the internal pe-amp) - or set it to Phono and use the Pioner amp.

From what you describe it certainly sounds as though the RIAA EQ is being applied twice.

WC

[Windrose]

No, the Kenwood is a pretty much no frills, direct-drive, variable speed TT. You can select the base speed -- 45 or 33-1/3 -- and frob it up or down a trifle with an adjust knob, but that's it.

One possibility, not to be ignored, is that I'm simply over-reacting and its basically working properly and the original recording in fact is kind of bass heavy and muddy. Attached, for those who understand these things, is the frequency spectrum of the very beginning of Frank Zappa's "Willie the Pimp" from Hot Rats, just as I recorded it a little while ago with the above mentioned set-up.

maab

[billw58]

For comparison, here's the first 6 seconds of Willie the Pimp from the Hot Rats CD:

WillieSpectrum.png (127.74 KiB) Viewed 2074 times

I'd say there's something wrong somewhere.

-- Bill

[Windrose]

Herrrm. It is in me to wonder if it might have something to do with the frequency response of the undoubtedly aging needle and cartridge. Maybeso I should break down and replace them.

maab

[steve]

The significant difference between those two plots is only really clear in the very high frequency range (above 5 kHz) which just shows a relative dullness to the the vinyl recording. That dullness could easily be the result of a worn stylus, a worn record, or a tone arm that is not set up correctly (has the tracking weight been checked?)

If the plots were shown using a log scale for the frequency it would give a more clear view of tonal differences through the 0 to 5kHz range and that would reveal if there are other problems (such as double RIAA Eq).

[billw58]

What you can see in the first plot is a "nice, smooth" 12 dB/octave roll-off above 3 kHz or so.

Yes, a log frequency plot would be better.

-- Bill