Doing the last set of mods to my SC 200 Delta; finally getting around to
the few standard input modules that I have.

The Deluxe modules use TL072s throughout; OP275s and OPA2134s have worked
well as replacements. Neutral sound, much if not all of that subtle 072
screech is gone, and as it turned out no external circuitry had to be
changed.

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.

Any suggestions for a pin-for-pin replacement that's not horribly
expensive and in the 2134/275 performance range?

Thanks in advance,

Frank Stearns
Mobile Audio
--

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.

The OP275 does not have a singel channel version with identical performance.
However, the OP184 comes pretty close to a single OP275. Compared to the
TL071 the pin asignement is the same but the slew rate is somewhat lower -
most likely that won't matter. Noise is a lot lower! I don't know much about
output current supply/sink, but it couldn't be worse than the TL071.

Norbert

Norbert Hahn writes:

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.

The OP275 does not have a singel channel version with identical performance.
However, the OP184 comes pretty close to a single OP275. Compared to the

Thanks, Norbert. I look into that one.

Frank Stearns
Mobile Audio

--

Frank Stearns wrote:
Norbert Hahn writes:

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.

The OP275 does not have a singel channel version with identical performance.
However, the OP184 comes pretty close to a single OP275. Compared to the

Thanks, Norbert. I look into that one.

Frank Stearns
Mobile Audio

--
.
Hi Frank, how's that Masterlink sound? For the fader amp in a standard
delta input, I would use either a LM6171 or an AD825. Replace the 100
pf feedback cap with a 22 pf NPO mono ceramic. Cut the trace from the
fader return to the + input, pin 3 of the opamp. Install a 100 ohm
resistor there. Add a couple of .1 uf mono ceramic caps from pins 4 and
7 to ground. A direct out jack can be installed in the rear, just
attach the ground to the input ground from the other jacks and use a
50~100 ohm resistor in series with the signal output from the fader. If
you still want to use the OP275 type of opamp, (which I don't
recommend), I have a couple of tubes of the discontinued OP-176 single
package opamps if you want to get some.

Jim Williams
Audio Upgrades

writes:

Frank Stearns wrote:
Norbert Hahn writes:

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.
.
Hi Frank, how's that Masterlink sound?

Only had a chance for a quicky playback. Detail and depth is now much
better from HD playback. Woohoo! (The real test would be to mix AND
record, as a PB from a track made on the stock system would only benefit
from PB, as the REC path was on the old parts.)

But CD playback is a little odd. Always been suspicious of that
CD drive given how hot the thing gets. But the HD pb is sweet, but haven't
had time to start mixing to it. That will start later today/tomorrow.

I'll make a more full report next week when I start mixing a new album (as
soon as the artists get their tracks to me!). I really appreciated your
fast turn-around.


delta input, I would use either a LM6171 or an AD825. Replace the 100

Very good, thanks.

7 to ground. A direct out jack can be installed in the rear, just

Sweet. Been needing to do this, too.


recommend), I have a couple of tubes of the discontinued OP-176 single

I might take you up on that, only in the interest of the short term.
Surely the 176s are better than the TL072s?

Thank you yet again for your generous help in this forum.

Frank Stearns
Mobile Audio

--

Frank Stearns wrote:
writes:

Frank Stearns wrote:
Norbert Hahn writes:

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.
.
Hi Frank, how's that Masterlink sound?

Only had a chance for a quicky playback. Detail and depth is now much
better from HD playback. Woohoo! (The real test would be to mix AND
record, as a PB from a track made on the stock system would only benefit
from PB, as the REC path was on the old parts.)

But CD playback is a little odd. Always been suspicious of that
CD drive given how hot the thing gets. But the HD pb is sweet, but haven't
had time to start mixing to it. That will start later today/tomorrow.

I'll make a more full report next week when I start mixing a new album (as
soon as the artists get their tracks to me!). I really appreciated your
fast turn-around.


delta input, I would use either a LM6171 or an AD825. Replace the 100

Very good, thanks.

7 to ground. A direct out jack can be installed in the rear, just

Sweet. Been needing to do this, too.


recommend), I have a couple of tubes of the discontinued OP-176 single

I might take you up on that, only in the interest of the short term.
Surely the 176s are better than the TL072s?

Thank you yet again for your generous help in this forum.

Frank Stearns
Mobile Audio

--
.

We'd love to see some THD or IM or other measurments.

Mark

"Mark" writes:


Frank Stearns wrote:
writes:

Frank Stearns wrote:
Norbert Hahn writes:

Frank Stearns wrote:

But the simpler standard modules use the single channel TL071 for the
fader amp. I don't see a single channel version of the OP275, and the
OPA134 is not a pin-for-pin drop-in (pins 5 & 8 are reversed). This is not
a deal killer, but it is something of a PIA.
.
Hi Frank, how's that Masterlink sound?

Only had a chance for a quicky playback. Detail and depth is now much
better from HD playback. Woohoo! (The real test would be to mix AND
record, as a PB from a track made on the stock system would only benefit
from PB, as the REC path was on the old parts.)

But CD playback is a little odd. Always been suspicious of that
CD drive given how hot the thing gets. But the HD pb is sweet, but haven't
had time to start mixing to it. That will start later today/tomorrow.

I'll make a more full report next week when I start mixing a new album (as
soon as the artists get their tracks to me!). I really appreciated your
fast turn-around.


delta input, I would use either a LM6171 or an AD825. Replace the 100

Very good, thanks.

7 to ground. A direct out jack can be installed in the rear, just

Sweet. Been needing to do this, too.


recommend), I have a couple of tubes of the discontinued OP-176 single

I might take you up on that, only in the interest of the short term.
Surely the 176s are better than the TL072s?

Thank you yet again for your generous help in this forum.


We'd love to see some THD or IM or other measurments.

Jim might have an AP, but I don't.

More important than that, static tests won't always show this stuff.
As has been discussed here every now and then, dynamic test suites need
to be invented or standardized. (Such tests do exist I've heard, but I've
not seen them in wide use. Many manufacturers would have a lot to lose by
such tests, I'd guess.)

I can tell you from my own modest tweaking experience that sonic
differences from various tweaks can be readily apparent. I've occasionally
backed-out tweaks that made no improvement or made things worse.

High-resolution monitoring in a properly-built room makes such things much
easier to hear; ambiguities tend to disappear. (We're running Pass Labs
class-A powered Tannoy SGM10Bs in soffits with Mastering Lab crossovers in
a classic LEDE room. That crossover is a tweak, by the way, but one that
makes a startling difference in that monitor.)

But Jim is an expert with lots of experience, happy to give his advice
here. In fact, it's only after a year or so of implementing his
freely-given suggestions that have worked quite nicely that I finally
decided to hand over a machine for him to improve directly. I'm glad I
did. He saved me time, guessing, and frustration during a time when I've
got some tight deadlines.

Sometimes folks here don't believe that such work is worthwhile, that at
some level stock gear is "well designed" and works just fine. When I hear
that I usually conclude that the monitor/room combination used by that
person might not be ideal, and that such folk might not fully grasp that
good designs by brilliant engineers are sometimes thwarted by accountants
who'll go for the $0.20 TLO72 over the $2.00 OPA2134.

And even with the modest 2134 and no other changes, the sonic difference
is quite apparent. (I've got some channel strips on the Delta setup with
the good machined-pin IC sockets so that various chips can be swapped in
and compared.)

Anyway, didn't mean to get onto a rant, but it is remarkable at times the
corners cut by some manufacturers, and how much someone like Jim can do to
improve things.

Rant mode off. Happy mixing and sonic delights to us all! g

Frank Stearns
Mobile Audio
--

In article ,
Frank Stearns wrote:

[snip]


Sometimes folks here don't believe that such work is worthwhile, that at
some level stock gear is "well designed" and works just fine. When I hear
that I usually conclude that the monitor/room combination used by that
person might not be ideal, and that such folk might not fully grasp that
good designs by brilliant engineers are sometimes thwarted by accountants
who'll go for the $0.20 TLO72 over the $2.00 OPA2134.


I don't doubt you've improved the sound of your 200 Delta. I've been using a
200 Delta for years to do electrocaoustic concerts to a pretty demanding
audience. We have 4 Meyer MSL-3s and 650R2 subs powered by Ashly FET500 amps.
No one has ever complained about the sound. (My only complaint is the 60Hz that
has cropped up on the stereo strip, but we don't use that.)

While yours might not be one of them, there are applications in which stock
equipment IS fully adequate: there is a point of diminishing return for some
of us. There are many quality levels of equipment available for different
applications and most competent users can decide for themselves how much they
need to spend to get the performance level they need. Sure, it's fun to modify
stuff and you can extract more performance in many cases, but these days I
prefer to devote my time to the music and find the sonic performance level of
this particular mixer perfectly satisfactory.

-Jay
--
x------- Jay Kadis ------- x---- Jay's Attic Studio ------x
x Lecturer, Audio Engineer x Dexter Records x
x CCRMA, Stanford University x http://www.offbeats.com/ x
x---------- http://ccrma.stanford.edu/~jay/ ------------x

Right, the stock D200 is a prefectly fine console...

But since most of us buy those things used, a good recap is always in order.

I also noticed that some of the Portugese 072s used in those have a tendency
to go bad for no reason.

The opamp that's part of the mic pre will make a BIG difference in sound
though.
But again, the 072 is fine in that position.
I have something else in there at the moment but I'm not sure what... 275s?

I never really could appreciate any major audible difference at line
level...

That said, I'm fairly certain that the fader buffers in my D200 are 134s.
Probably did hat swap just for the hell of it.

JP

"Jay Kadis" a écrit dans le message de
...
In article ,
Frank Stearns wrote:

[snip]


Sometimes folks here don't believe that such work is worthwhile, that at
some level stock gear is "well designed" and works just fine. When I
hear
that I usually conclude that the monitor/room combination used by that
person might not be ideal, and that such folk might not fully grasp that
good designs by brilliant engineers are sometimes thwarted by
accountants
who'll go for the $0.20 TLO72 over the $2.00 OPA2134.


I don't doubt you've improved the sound of your 200 Delta. I've been
using a
200 Delta for years to do electrocaoustic concerts to a pretty demanding
audience. We have 4 Meyer MSL-3s and 650R2 subs powered by Ashly FET500
amps.
No one has ever complained about the sound. (My only complaint is the
60Hz that
has cropped up on the stereo strip, but we don't use that.)

While yours might not be one of them, there are applications in which
stock
equipment IS fully adequate: there is a point of diminishing return for
some
of us. There are many quality levels of equipment available for different
applications and most competent users can decide for themselves how much
they
need to spend to get the performance level they need. Sure, it's fun to
modify
stuff and you can extract more performance in many cases, but these days I
prefer to devote my time to the music and find the sonic performance level
of
this particular mixer perfectly satisfactory.

-Jay
--
x------- Jay Kadis ------- x---- Jay's Attic Studio ------x
x Lecturer, Audio Engineer x Dexter Records x
x CCRMA, Stanford University x http://www.offbeats.com/ x
x---------- http://ccrma.stanford.edu/~jay/ ------------x

Jay Kadis writes:

In article ,
Frank Stearns wrote:

[snip]


Sometimes folks here don't believe that such work is worthwhile, that at
some level stock gear is "well designed" and works just fine. When I hear
that I usually conclude that the monitor/room combination used by that
person might not be ideal, and that such folk might not fully grasp that
good designs by brilliant engineers are sometimes thwarted by accountants
who'll go for the $0.20 TLO72 over the $2.00 OPA2134.


I don't doubt you've improved the sound of your 200 Delta. I've been using a
200 Delta for years to do electrocaoustic concerts to a pretty demanding
audience. We have 4 Meyer MSL-3s and 650R2 subs powered by Ashly FET500 amps.
No one has ever complained about the sound. (My only complaint is the 60Hz that
has cropped up on the stereo strip, but we don't use that.)

Yup, had the same problem... Something to do with how the headphone jack
jumps into that circuit and/or grounding. By the time I'd gotten a new
jack in there and replaced a few other parts, the hum disappeard and has
not returned. (The new monitor and master looms might have helped too. A
lot of things got better after that.)

As far as the sound, the stock Delta (in good condition with reasonable
caps) does sound pretty good -- right up until you start using better caps
and chips and then it's hard to go back. I set up pairs of strips with
275s and 2134s. On either set of strips, that mild HF crunch of the 072
was gone. Simply lower distortion. The 275s had something of a sound
(pleasant), while the 2134s were more neutral (and also pretty reasonably
priced, along with being a direct drop in). I went with the 2134s for now.

While yours might not be one of them, there are applications in which stock
equipment IS fully adequate: there is a point of diminishing return for some

Sure, agreed completely. (I should have made that clear.) My Grace preamps
are beautifully designed and built and I'd never touch them. I did
initially check, though. At every point where I thought there might be
something useful to do, Michael Grace had already done it as part of his
stock design and build -- plus a lot more things I'd never even known
about and still don't fully understand. I do know that there's purity and
realness to the sound that's hard to describe until you hear it and then
actually work with it. Mixing is faster when the initial sound is that
good.

of us. There are many quality levels of equipment available for different
applications and most competent users can decide for themselves how much they
need to spend to get the performance level they need. Sure, it's fun to modify

Again very true. I think what can be useful is to find a well-designed
mid-to-upper-mid-line piece of gear, such as the Delta, that has an
excellent basic design but was under price-point pressures when it came to
the parts budget.

With this type of gear (excellent design, squeezed execution) much can be
gained by tweaking, and for a rather large net savings. My tweaked Delta
recently produced a mix sounding as good and in some ways better than an
SSL4000 (same source tracks). The result startled even me, the guy who'd
done both mixes on both machines. Made me appreciate the Delta all the
more and how much total bang for the buck I'd gotten. (This was not a
lab-perfect comparison but cross-checking in various ways make me
comfortatble in making that statement.)

stuff and you can extract more performance in many cases, but these days
I prefer to devote my time to the music and find the sonic performance
level of this particular mixer perfectly satisfactory.

Generally, I'd agree; unless I see some major shortcuts in the gear -- and
then I have to weigh time and research costs and what I hope to gain.

Being primarily classical and acoustic music recorders, I always want
to squeeze out that last few percent of "sonic purity", if nothing else
than for my own satisfaction.

But there's also this to consider: the cleaner you start and the cleaner
you can stay thoughout the process (even small amounts cumulatively), the
more "distance" you can maintain below that fuzzy threshold where even
laymen might say, "gee, this kinda sounds better than that," even on their
mid-fi stereo.

Indeed it is a balancing act.

Frank Stearns
Mobile Audio

--

In article ,
Frank Stearns wrote:

Jay Kadis writes:

In article ,
Frank Stearns wrote:

[snip]


Sometimes folks here don't believe that such work is worthwhile, that at
some level stock gear is "well designed" and works just fine. When I hear
that I usually conclude that the monitor/room combination used by that
person might not be ideal, and that such folk might not fully grasp that
good designs by brilliant engineers are sometimes thwarted by accountants
who'll go for the $0.20 TLO72 over the $2.00 OPA2134.


I don't doubt you've improved the sound of your 200 Delta. I've been using
a
200 Delta for years to do electrocaoustic concerts to a pretty demanding
audience. We have 4 Meyer MSL-3s and 650R2 subs powered by Ashly FET500
amps.
No one has ever complained about the sound. (My only complaint is the 60Hz
that
has cropped up on the stereo strip, but we don't use that.)

Yup, had the same problem... Something to do with how the headphone jack
jumps into that circuit and/or grounding. By the time I'd gotten a new
jack in there and replaced a few other parts, the hum disappeard and has
not returned. (The new monitor and master looms might have helped too. A
lot of things got better after that.)


I'll have to check into that.

[snip]


With this type of gear (excellent design, squeezed execution) much can be
gained by tweaking, and for a rather large net savings. My tweaked Delta
recently produced a mix sounding as good and in some ways better than an
SSL4000 (same source tracks). The result startled even me, the guy who'd
done both mixes on both machines. Made me appreciate the Delta all the
more and how much total bang for the buck I'd gotten. (This was not a
lab-perfect comparison but cross-checking in various ways make me
comfortable in making that statement.)


If I had this board at home instead of the impossible-to-modify Ghost, I'd be
very tempted to copy your tweaks, which I've been watching here with interest.
(I have to confess I recently started modifying the Blues Junior I've been
using, so I haven't completely given up on playing with circuit modification.)

-Jay
--
x------- Jay Kadis ------- x---- Jay's Attic Studio ------x
x Lecturer, Audio Engineer x Dexter Records x
x CCRMA, Stanford University x http://www.offbeats.com/ x
x---------- http://ccrma.stanford.edu/~jay/ ------------x