[Coco] Audio recording on CoCo

[gene heskett]

On Monday, November 21, 2011 11:20:26 AM Steven Hirsch did opine:

> On Mon, 21 Nov 2011, gene heskett wrote:
> > On Monday, November 21, 2011 12:31:59 AM Joel Ewy did opine:
> >> On 11/20/2011 09:57 PM, Brian G wrote:
> >>> I would like some advice on how to transfer LP music to CD.
> >>> What equipment, software is needed? I have a turntable that I have
> >>> not used in years, so starting from that, what do I need?
> >> 
> >> Computer with sound card.  Preamp to get the LP to line level audio.
> >> Cable from preamp to audio in jack on computer's sound card.  Some
> >> kind of recording software on the PC.  Audacity is Free / Open
> >> Source, and runs under Linux and I believe Windows and Mac.
> > 
> > You forgot what is probably the single most important item, the record
> > turner, and the 'tone arm' and the cartridge mounted in it.  If a
> > magnetic cartridge, you will need a preamp that converts the magnetic
> > cartridges velocity mode output into an amplitude mode output,
> > commonly call an RIAA preamp.
> > 
> > When records were king, there was no better playback cartridge than
> > the Shure RE-15's, but the arm they were mounted in had to be capable
> > of being adjusted to 1.5 grams tracking weight, and so friction free
> > it would follow the recording groove faithfully at that pressure.
> 
> I'll second that recommendation.  I used V15s (consumer version of RE15,
> I believe) for years.  And, yes, they required a "high compliance" arm
> and are not something you'd blindly refit to a low-end turntable/arm
> combo. IIRC, the V15 had a more delicate stylus and would start to
> collapse at about 1.5 grams!  The only other cartridge I bonded with
> was a Dynavector moving-coil unit, but the stylus eventually was ruined
> from clumsiness and the company is long gone.
> 
> I recently went through the exercise of digitizing part of my (large) LP
> record collection.  The cheap phono-to-USB converters I tried were
> simply terrible sounding.  All the hard-won lessons about analog op-amp
> application to audio have been forgotten over the past 30 years or so.

+100

> There's nothing more grating on my ears than an audio stage with
> obvious slew-rate problems (Walt Jung, where are you?).

Or Larry Klein.  That, and crossover distortion, you feel like somebody is 
drilling a hole through your head from ear to ear with a hammerdrill.  That 
slew rate is one of the reasons I have never figured it out why the 5532 
op-amp was considered the gold standard for audio, it was 4 each 741's with 
their attendant slew rate limits due to the 10hz open loop gain rolloff.  I 
had a rack of audio DA's I inherited with WDTV that got pulled out in a 
year or so, replaced with a card I designed that used TLO-81's, about a 
10,000 x wider bandwidth, and all cmos.  You really had to pound on them at 
40 kilohertz to see slew rate limits at 20 volts p-p output, and crossover 
was invisible unless the +- 15 volt supply rails were also exceeded.

Unforch, not very immune to EMP's on their output lines, some of which 
reached several hundred feet, so it was a good thing I had socketed them.  
I kept a couple sticks of them in the closet for obvious reasons.
 
> Ended up taking the "straight line" output from a high-end pre-amp
> (discrete FET input stages - no op-amps!) and running it through a
> Burwen analog tick and pop suppressor into the Intel sound chip on my
> Linux box. When adjusted properly, the Burwen does a noticably better
> job of quieting transient groove noise than the Audacity algorithms.

Yeah, I didn't think those were at all effective.
 
> Then, I used Audacity to clean-up the residual steady-state noise by
> auto-correlation.

Oh, oh, I got stoned and missed it growing that facility.  I have some 
metal cassette tapes that could stand that.  I'll have to look at audacity 
again, thanks for the heads up.

> The results are almost indistinguishable from a
> digital-mastered CD.
> 
> I was fortunate enough to have a Technics SL1200Mk2 turntable left over
> from a previous life in the audio biz.

Some folks have ALL the luck.

> Which is fortunate, because good
> turntables are not easy to acquire anymore without paying stupid prices
> on eBay.

Yeah, after I posted that I went to ebay to check, they have scads of the 
SL1200MK2, which new was $400 or so, worn out, missing parts and still $200 
or more. $400 & up in a DJ carry case & you know those have been beat to 
hell in a bar someplace. The linear drive tables were about $200 more, and 
I wonder how many of those could be restored?  They were not at all 
friendly with service manuals.  And I didn't see anything but AT & Stanton 
cartridges.  AT's weren't all that bad, but certainly not at all comparable 
to the Shures, but the Stantons were absolute junk, both aurally and to the 
records.

> Steve

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene>
Universities are places of knowledge.  The freshman each bring a little
in with them, and the seniors take none away, so knowledge accumulates.