HDTenEightyP/NetNews huggingface dataset:
From: mzk20@spa.amdahl.com (Makoto Kobayashi)
Newsgroups: rec.audio.high-end
Subject: Power amp for Quad ESL 63 Pro.
Date: 14 Dec 92 16:59:45 GMT
Organization: Amdahl Corporation  Sunnyvale, CA
  (5.65c/IDA-1.4.4 for <rec-audio-high-end@ames.arc.nasa.gov>); Mon, 14 Dec 1992 08:59:40 -0800
	id <m0n1J8i-0000GzC@amdahl.com>; Mon, 14 Dec 92 08:59 PST
	id <m0n1J8f-00000fC@amdahl.uts.amdahl.com>; Mon, 14 Dec 92 08:59 PST
	id <m0n1J8z-0000MQC@juts.ccc.amdahl.com>; Mon, 14 Dec 92 08:59 PST
NNTP-Posting-Host: 129.89.7.4
Keywords: Pwer amp, Quad ESL 63
Originator: tjk@csd4.csd.uwm.edu



I have been driving a pair of Quad ESL 63 Pro. 
(equivallent to the US monitor) with a CounterPoint
SA 220 power amp.  The pre-amp is CA SA-5000.  Recently,
I have been wondering how the ESL 63 sound with other
power amps.  Yesterday I visited Audible Difference 
in Palo Alto and was told that many people end up
driving the ESL 63 with Spectral power amp.  I was also
recommended a pair of Quick Silver.  I am also interested
in Mark Levinson 27.5.  I mostly listen to vocals and strings.
I will appreciate any recommendations/opinions.
From: AP201125@BROWNVM.brown.edu
Newsgroups: rec.audio.high-end
Subject: Carmina Burana
Date: Mon, 14 Dec 92 18:29:17 EST
Organization: University of Wisconsin - Milwaukee
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

Someone mentioned Carmina Burana in the last digest. I was wondering if I could
get some opinions on the best recordings available on cd (of Carmina Burana, of
course). I have been dissatisfied with the first three I have purchased (I
don't have the information for them at hand right now). Recommendations
anyone?? (This is all in an attempt to find a recording approaching the magic
of a mystery recording played to us in a college music theory class several
years ago).
And please,- I don't quite yet have the money for a GOOD turntable....

Many thanks in advance.

                                    Kitto Weikert
                                    AP201125@Brownvm.Brown.edu
From: bower@pecan.cns.udel.edu (Ty Bower)
Newsgroups: rec.audio.high-end
Subject: Re: Amplifier specifications
Date: Thu, 17 Dec 1992 23:00:33 GMT
Organization: University of Delaware, Newark
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

Since we seem to like referencing things so much:

Spectral DMA-80 100-W/ch, $2795
1000 V/us slew rate!

Audio by Van Alstine: Omega 240 120-W/ch, $895
500 V/us slew rate

Bryston Model 7B 500-W mono, $1895
slew rate only 60 V/us

Crown PSA-2 275-W/ch, $2095
slew rate a paltry 30 V/us

Forte Model 6 150-W/ch, $1590
Claims pure Class A gain stages,
slew rate 50 V/us

Jeff Rowland Model 8 200-W/ch, $7500
slew rate 50 V/us

What do these number tell me?  I'm not sure.  All of these amps are
clearly high-end, yet seem quite comfortable at slew rates of 
30-60 V/us.  I think this specification isn't quite as important
as some manufacturers would like us to belive.  I guess as long as
the amp can slew sufficiently fast enough, that aspect is not
going to be a performance determining characteristic.  Although
a rate of 1000 V/us may impress your friends, it seems to me that
it may be overkill.
From: hsu@ecf.toronto.edu (HSU TITUS HENG-HSUEH)
Newsgroups: rec.audio.high-end
Subject: Re: Any Apogee Stage Owners Out There ?
Date: Tue, 15 Dec 1992 22:38:38 GMT
Organization: University of Toronto, Engineering Computing Facility
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

I have lived with a pair of Stage for two years now, and I have found a few
things about this pair of speakers myself.  In my set up, the Stages really
didn't like the Tara Lab cables.  I bi-wired the Stages with 4x1 foot length
TFA returns.  The highs sounded rather dry.  I took Jason Bloom's
recommendations and tried the Symo LS-5 cables.  They seem to sound on the
warm side (In my case, anything sounded warm in comparison to the TFA Return).
So I suggest you try some other speaker cables as well.  This pair of speaker
is rather picky, so good interconnect would likely help.  I haven't tried
any other pair of interconnects with my system yet, so I can't tell you
for sure.

As for positioning the speakers, my brother and I had fun adjusting them
for a whole year.  I think you may want to bring the Stages to 4 feet from
the back wall.  Also, Martin Collims said that you seem to be able to pull
the speakers quite far apart, so you may want to try that too.  Also be sure
to play around with the tilt of the panels.  A couple more turns on those
screws can make quite a bit of difference.  If you seem to be losing the
highs, try to tilt it so that your ears allign with the perpendicular
of the tweeter/midrange ribbon.  I found them to be very sensitive to
positioning.  Slightest mistake, and they'll make sure you know.  I set them
up in such a way that it has no toe-in.  If you're going to set them up 
without toe-in, make sure the panels are properly aligned.
From: matthews@eecs.ucdavis.edu (Thomas W. Matthews)
Newsgroups: rec.audio.high-end
Subject: Re: WHAT IS 96X OVERSAMPLING?
Date: 14 Dec 92 22:22:15 GMT
Organization: Division of Electrical Engineering and Computer Science, UC Davis
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu


I thought I'd add a brief note.

When the 44.1 kHz. signal has its sampling rate increased by a factor
of four, it is as if three zeros are added between each sample.
However, these zeros are not output to the DAC.  The signal is then
passed through a digital filter.  The filter's response will assign
values to the samples that were previously zero.  This is like
interpolation, but not straight-line interpolation.  I describe the
effect as an interpolation that takes into account the upper limit of
the signal bandwidth.

Tom Matthews
From: rsd@sei.cmu.edu (Richard S D'Ippolito)
Newsgroups: rec.audio.high-end
Subject: Re: Re: Re:Re: twin triode crosstalk question
Date: Thu, 17 Dec 1992 17:46:24 EST
Organization: The Software Engineering Institute
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu


In article <1gq1tiINNrhl@uwm.edu>, peterca@ento.csiro.au writes:

|> This is where my experience is in conflict with the theory.  I have a valve
|> preamp made locally.  It uses a shunt regulated push pull circuit which is
|> virtually identical to another design I use.  The one difference is that
|> for some reason I can't fathom it uses one half of each of two 12AX7s for
|> each channel with a 6V supply on one half of the filament.  It just seems a
|> waste to me but it works just fine.  I'd love to know why the designer
|> (Laurie Cohen) did this.

A further explanation and correction is in order -- the RCA tube manual state
that the triodes are independent except for a common heater, a statement that
does not appear for all twin triodes.

This is misleading in that, upon my closer inspection, in this case it refers
to electrical independence, and not heater/cathode independence.  This tube
does indeed have TWO heaters with a common connection for a total of three
base pins, so the manual should state that the are two heaters which can be
invidually energize but require a common power supply connection!  Arrgh --
the ambiguity trapped me.  In your design, not energizing the other heater
(NOT the other half of a single heater) saves energy.  Except as I stated
before regarding outgassing and vacuum degradation, the unused (unconnected)
triode is "fresh".

There are tubes with a single heater for one or multiple cathodes that have
the heater center-tapped to allow voltage flexibility, but the 12AX7A is not
one of them.  Again, please don't call them filaments, which have the emitting
coating applied to the heating wire.

Sorry.


Rich
From: Bill Eccles <@usceast.cs.scarolina.edu:eccles@charlie.ece.scarolina.edu>
Newsgroups: rec.audio.high-end
Subject: Re: Dynakit 70 Tube Amp
Date: Wed, 16 Dec 92 17:27:34 GMT
Organization: University of South Carolina EECE
	for info-high-audio@csd4.csd.uwm.edu
	for rec-audio-high-end@speedy.mcnc.org
NNTP-Posting-Host: 129.89.7.4
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Originator: tjk@csd4.csd.uwm.edu

ep502ca@pts.mot.com (CHARLES ACTOR X2922 P7091)

You, my friend, have become one of the lucky few (many? I dunno'.)
At any rate, the amp IS worth keeping. I've got two myself driving a
pair of Klipsch Forte that are going to be my mainstay amps for a long
time to come -- as long as I can get the driver tubes (not the EL34's,
the 6 somethings). From what I've seen around here, some of your problems
can be solved by various companies' upgrades. And people like them. If
you got it for under $250, you're doing well.

(I paid a total of $75 for my pair. One was my dad's, and the other
was in a HI-FI shop where the guy didn't know what he had -- in the
same shop that sold every uppity brand available.)

Keep it, love it, caress it (carefully! they get awfully hot!) and
enjoy the heck out of it for years to come.

Bill
From: <U37426%uicvm.uic.edu@OHSTVMA.ACS.OHIO-STATE.EDU>
Newsgroups: rec.audio.high-end
Subject: McIntosh 275
Date: Thursday, 17 Dec 1992 23:25:03 CST
Organization: University of Illinois at Chicago
 BSMTP id 1014; Fri, 18 Dec 92 03:41:11 EST
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

    I just read in the october issue of The Absolute Sound that McIntosh will
be remaking one of their old tube amps, the 275.  Does anybody have one of the
originals?  When was this amp made the first time?  I would like to here from
 anybody who has this or any other McIntosh amp.  thanks!

by the way....what power rating does the 275 have?
From: dbarker@spang.Camosun.BC.CA (Deryk Barker)
Newsgroups: rec.audio.high-end
Subject: Re: Any Apogee Stage Owners Out There ?
Date: Mon, 14 Dec 1992 21:59:58 GMT
Organization: Camosun College, Victoria B.C, Canada
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

ryo@oakhill.sps.mot.com (Ryo Inoue) writes:
: I recently purchased a pair of Apogee Stages with dedicated Stands.
: I'm driving them with a pair of PSE Studio II (110W) amps and Tara Labs
: Space&Time cables.
: 
: I would appreciate any advice and experiences in setting up the Stages
: for best sound. Right now, the sound is flat and somewhat "unfocused"
: sounding. The speakers are 6ft part and 3 ft from the rear wall.
: The room dimensions are roughly 14ft X 18ft.
: 
: Any hints on positioning, damping material, cable selection, etc will
: be greatly appreciated.

I have a pair (two years old) driven by a Linn LK-270 amp and Linn
LK20 cable, they sound just dandy. Have you expermented with the angle
of toe-in? Mine are unfortunately too close to the rear wall, but
domestic considerations sometimes have to come first! Biwiring made a
fair difference - have you tried that?

When I initially set them up I used the standard position of the
switch on the back (I forget what it's called) and experienced a major
disappointment. Setting it to high made all the difference.

I would also suggest that your speakers are too close together - I was
told 8ft minimum as I recall.

Hope this helps a little.

BTW I don't have mine on stands, just the feet supplied.

--
Real:  Deryk Barker, Computer Science Dept., Camosun College, Victoria B.C.
Email: (dbarker@spang.camosun.bc.ca)
Phone: +1 604 370 4452
From: ep502ca@pts.mot.com (CHARLES ACTOR X2922 P7091)
Newsgroups: rec.audio.high-end
Subject: Dynakit 70 Tube Amp
Date: Mon, 14 Dec 1992 19:09:14 GMT
Organization: Paging and Wireless Data Group
Reply-To: ep502ca@pts.mot.com
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

I have an old Dynakit 70 tube amp that I recently picked up.  All it
took was a new power cord to get it working.  Is the Dynakit 70 the
same as the Dyna ST70 amp that people talk about?  Is this amp worth
keeping or is it boat anchor material?  The only thing wrong with it is
I can't get the bias voltage quite right.  A friend of mine said the
caps in the bias circuit were probably dried out.  If it's worth
keeping, should I change anything with it?  I don't want to spend alot
on it.  A friend suggested replacing all the caps (with what kind?) and
changing the voltage to the preamp tube (plates?) to DC.  How can you
tell when you need new tubes?

Thanks in advance,
Chuck
From: jacek@lakme.East.Sun.COM (Jacek Ambroziak - Sun Microsystems Labs BOS)
Newsgroups: rec.audio.high-end
Subject: Amplifier recommendations needed
Date: 11 Dec 1992 21:42:11 GMT
Organization: Sun Microsystems Inc. - BDC
Distribution: world
Reply-To: jacek@lakme.East.Sun.COM
NNTP-Posting-Host: 129.89.7.4
Content-Length: 584
Originator: tjk@csd4.csd.uwm.edu

Hi everybody,

I think I may be splitting hair, but I'd like to hear your opinions
on Adcom vs. Acurus vs. Hafler amplifiers.

Currently I have Adcom 565/545 II preamp/amp, and I'm looking at 
-- Hafler's  915 or SE-100 preamp + 9180 amp
-- Acurus L10 or DIA-100

I'm not going to use phono anyway so I think I don't need to pay for
the phone stage and may get instead better quality line-level-only amplifier.

At the same time I'm trying to decide between Adcom CD changer and Rotel 965BX...

If you feel you can elucidate me on any of these issues please do so.

Thanks,
Jacek
From: markt@cup.hp.com (Mark Thompson)
Newsgroups: rec.audio.high-end
Subject: Re: Dynakit 70 Tube Amp
Date: Tue, 15 Dec 1992 22:39:59 GMT
Organization: Hewlett-Packard
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

ep502ca@pts.mot.com (CHARLES ACTOR X2922 P7091) writes:
: I have an old Dynakit 70 tube amp that I recently picked up.  All it
: took was a new power cord to get it working.  Is the Dynakit 70 the
: same as the Dyna ST70 amp that people talk about?  Is this amp worth
: keeping or is it boat anchor material?  The only thing wrong with it is

It's an anchor, just mail it to me, i'll give you enough money for postage. 
Just kidding.  It's quite a nice vehicle for mods.  There were so many made
(as you can tell from all the posts) that there are many ideas people have
come up with for improving it.  If you put, say 8-16 hours and $100-200 into
modifying it I would say that it could complete with many other amps on the 
market today in the same output range.  The one problem with the stock amp,
aside from degeneration of parts, is the 7199.  This tube is really hard to
get.  Many mods start with the sole purpose of replacing this tube.  
: I can't get the bias voltage quite right.  A friend of mine said the
: caps in the bias circuit were probably dried out.  If it's worth
: keeping, should I change anything with it?  I don't want to spend alot
: on it.  A friend suggested replacing all the caps (with what kind?) and

In the power supply use electrolytics.  You really need atleast the same
voltage as the original ~500v.  Try digikey 800-344-4539, or Antique Radio (no
number). You don't have to replace all the caps on the input board but if
you do use only high quality film caps like polyproplyne or polystyrine.
The between the driver board and the output tubes should be at least 500v.
: changing the voltage to the preamp tube (plates?) to DC.  How can you
: tell when you need new tubes?

Once you get the power supply working right see if you can get the output
tubes biased.  If it is still stock, all you have to do is put one probe on
the chassis and one in the socket pin on the front that is marked "BIAS".  Adjust
the pot near the power transformer (one in the middle) until you get 1.56v.
If you can't get 1.56v the output tubes are gone.  Thoes are easy to replace.
If you have a manual you can check other voltages on the driver board.  This
may tell if the other two tubes are good.  If not you need to seriously think
about modifying the sucker.  You can also find someone with a tube tester.
It's not very good for output tubes but it can give you an indication on how
well the 7199s are doing.

Good luck.

Mark

PS. If you want more specific info on where to get parts let me know directly.
From: peterca@ento.csiro.au
Newsgroups: rec.audio.high-end
Subject: preemphasis on CDs
Date: Wed, 16 Dec 92 14:45:39 EST
Organization: University of Wisconsin - Milwaukee
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

Here is a summary of the replies I had to my question on the CD
preemphasis:
1)  >...a led indicating whether the...
>de-emphasis circuit is switched in.  It comes on very rarely.  In
>fact the only times I've noticed it have been when playing test disks
>that have tracks with emphasis to compare to tracks without emphasis.
>My collection of disks is approximately 1400 disks, mostly pop/rock.
>Most of these disks were produced/released between 1987 and 1992.
>I think older disks used pre-emphasis more often.

2)  >Although I don't have a figure on the proportion of CDs with
preemphasis
>(the percentage is decreasing daily), most new recordings no longer use
>preemphasis, particularly if they are digitally recorded.  So if you don't
>have many older, AAD or ADD recordings, then you probably won't need the
>circuit.

3)   >Denon and Bis seem to always use emphasis
>Tallis Scholars/Gimmel on older recordings, sim for ASV and lots of other
>small labels
>Philips and DG, never so far as I can tell.

4)  In some literature from Ben Duncan with his CD mods: "CD's (sic)
requiring de-emphasis are fairly scarce.  Most if not all are of Japanese
origin."


What I would now like to know is why the Denon and Bis people and/or
Japanese and/or small lables and and/or older recordings think/thought it
worthwhile.   Is it a good thing but dropped by slack multinationals and
only continued by small lables which care or is it a bad thing and the
small lables just have old gear for recording?

----------------------------------------
Peter Campbell
C/O Div. Entomology, C.S.I.R.O.
Box 1700 Canberra A.C.T. 2601
Australia  (peterca@ento.csiro.au)
Ph.61-6-2464158 (w), 61-6-2516213 (h)
----------------------------------------
From: nasiom@rpi.edu (Milton Peter Nasiopoulos)
Newsgroups: rec.audio.high-end
Subject: OLD TUBE AMPS NEEDED
Date: Mon, 14 Dec 1992 20:45:07 GMT
Organization: Rensselaer Polytechnic Institute, Troy, NY.
Reply-To: nasiom@rpi.edu
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

Keywords: 

HI!, I have (had?) an old tube amp which recently broke.  As it turns out it 
needs quit a few replacement parts which cost a fortune for new.  Does anyone
have an old tube amp which I can salvage some parts from?  If you do can you
let me know how much you want for them (I'll buy the whole unit too)$$$$.  
Some of these are fairly heavy so please include how much you want for shipping
also.

thanks.

milt.

ps.  All I know about the amp is that it's very old (25 yrs?) and it was made 
     by Motorola.  It also uses 6L6's??? and 12AX7???  I think some of these
     also need replacement.
From: mlloyd@ihlpm.att.com
Newsgroups: rec.audio.high-end
Subject: Op Amp App Note by Walt Jung
Date: Wed, 16 Dec 92 17:39 CST
Organization: University of Wisconsin - Milwaukee
NNTP-Posting-Host: 129.89.7.4
Original-From: ihlpm!mlloyd (Michael Lloyd +1 708 713 5497)
Cc: mlloyd@ihlpm.UUCP
Originator: tjk@csd4.csd.uwm.edu

Greetings:

Preamp home-brewers may want to call Analog Devices and ask for 
Application Note AN-232. The title is "Bootstrapped IC Substrate
Lowers Distortion In JFET Op Amps" by Walt Jung. This app note 
discusses a couple of approaches to help reduce the distortion 
increases observed when driving JFET Op Amp circuits from high
high source impedances. According to Walt, a cause of this 
phenomenon is the nonlinear variation of parasitic capacitances 
(associated with the input JFETs) with input voltage. 

VERY briefly, the two approaches are 
1. Balance the source impedances (R and C) at the inputs, and
2. Bootstrap the the amplifier substrate.

Approach 2. uses a transistor and a couple of resistors to vary the 
device substrate voltage with the input signal. Clever!

The accompanying test photos show some significant improvement.
The basic gain stage that this technique is applied to in the 
app note is Walt's popular AD744 + AD811 combo (which, by the 
way, makes quite a good sounding gain block for line amps and
headphone amps!).

A key point mentioned is that this phenomenon exists for all
JFET Op Amps, so the approaches discussed can be applied to
whatever your current favorites are (for example, Burr Brown's
OPA604).

If you want the whole story, don't call me! Call Walt Jung or 
contact your local Analog devices rep and ask for the app note.
The head office in Mass is on 617-329-4700.

The usual disclaimer applies: I'm not getting paid by anyone for 
this (but if you have a burning desire to give me money, I'll take it)!

Michael Lloyd
From: youngd@panix.com (David Young)
Newsgroups: rec.audio.high-end
Subject: interconnect cable
Date: Tue, 15 Dec 1992 15:03:52 GMT
Organization: PANIX Public Access Unix, NYC
	(queueing-rmail) id 141315.16223; Tue, 15 Dec 1992 14:13:15 EST
NNTP-Posting-Host: 129.89.7.4
Summary: recommanded cable to hook up a Melo Preamp to a Krell
Originator: tjk@csd4.csd.uwm.edu


	I am about to get my Melo preamp with balance out and plan
to hook it up to my Krell KSA250. I need some advice on which
cable to get.

	I had 2 cable in mind - Kimber Silver or Audio Quest Lapis.
Anyone out there has any idea on either cable or something else?

	by the way, I use a PS ultralink D/A and the PSB stratus gold
speaker.


dy
From: c.oneill@trl.oz.au (Chris O'Neill)
Newsgroups: rec.audio.high-end
Subject: Re: Amplifier specifications
Date: Wed, 16 Dec 1992 04:34:53 GMT
Organization: Telecom Australia Research Laboratories
NNTP-Posting-Host: 129.89.7.4
Originator: tjk@csd4.csd.uwm.edu

>In article <1g7j10INN1fm@uwm.edu>, gfl@herahera.cc.bellcore.com
>(lenahan,grant f) writes:
>|> Anything under 20 V/uS for power amps is terrible.
>|> 
>|> 4.4 v/uS is fine for a preamp, since 2.2 V rms is typical
>|> maximum Vout.
>|> 
>|> Grant
>
>How comes that slew rate < 20 V/sec is terrible ? My NAD 2155, rated at
>55 W(RMS) is specified to have a slew rate of 5.5 V/sec. It doesn't
>sound terrible at all!
>You''l also rarely find a tube amp with that slew rate.
>
>Malte

Less than 20 v/uS is terrible only if non-linear distortion (transient
intermodulation distortion, TIM) actually occurs if the amplifier output is
driven at its maximum slew rate.  The situation doesn't seem to be well
understood and the idea of limiting slew rate being the fundamentally important
parameter in TIM is a hang over from the days before E.M. Cherry showed that it
is not necessary to have an enormous slew rate capability to avoid TIM.  What
Cherry showed was that TIM can be avoided simply by making sure that the input
(and possibly following) stages are not put into saturation by a square wave
input at maximum rating.  This is done by making sure that the input stage
transconductance is low enough relative to the input stage saturation current.

The fact that many people still talk about the slew rate limit shows that they
do not know about Cherry's finding.

Chris O'Neill
Telecom Australia Research Labs