ADA Depot - A Forum To Support Users of ADA Amplification Gear
Let's Get Technical => All PREAMP Tech Tips & Support => Topic started by: luffliffloaf on March 11, 2014, 01:14:14 PM
-
I have an early MP-1.
Curious as to what op-amps you guys have put in, and did you only replace U4 and U9?
What about the OPA827, OPA2134, OP270EZ, LM833N, NE5532 instead of the TL072IN's?
Anyone?
Thanks!
-
U4 OPA2604
What U9 do you mean,on the mainbaord or on the midi board?
-
Main board, sorry.
Did you replace both the U4 and the U9 on the main board with 2604's?
My rear board already has an RC4559, which I kept in.
Thanks
-
Also, I did both noise mods 1 and 2 (all large lytics replaced and several resistors upgraded to 1/2 watt 1%), replaced all the 4004's with 4007's, recapped all the 33uf small caps on the tube board, and got 2 vintage usa 12ax7's that test strong on my calibrated Hickok.
And I replaced every jack in the thing (5 of the 7 were broken). That job sucked.
But it's still a bit noisy. Any other suggestions? I think I'll order a few 2604's next.
Loomis
-
Leave U9 like it is,won't help you with reducing the noise.
Do you still have an original non modded mp-1?
-
I've already socketed and replaced (on the main board) U4 and U9, with the TL072IN.
I would like to point out that this unit is still stock basically. it is not modified per se. It has upgraded caps, resistors, and jacks, but it is basically stock otherwise. The op amps are socketed, so I can revert them if necessary.
I might consider switching to the 2604 but I read the current draw is much higher and it's not realistically a drop in replacement?
Do you guys replace the tube board mylar caps with orange drops?
-
The 2604 works very well in a MP-1.At +-15V supply it draws 23 mA,so no problem here.Why wouldn't it be a realistically drop in replacement?
The original NE5534 is a far better opamp then the TL072.
You can use orange drops or mallory 150's.Downside of the orange drops is that they are quite big.
-
Hey MarshallJMP
Have you ever tried stacking op amps/running them next to each other?
Came across an adapter on
http://www.monteallums.com/pedal_mods.html#CA
Was wondering what it would be like to run 2 op amps in the same slot
-
Hey MarshallJMP
Have you ever tried stacking op amps/running them next to each other?
Came across an adapter on
http://www.monteallums.com/pedal_mods.html#CA
Was wondering what it would be like to run 2 op amps in the same slot
I've tried this in a few OD pedals with no noticeable effect compared to a single opamp. Marketing gimmick IMHO.
-
Hey MarshallJMP
Have you ever tried stacking op amps/running them next to each other?
Came across an adapter on
http://www.monteallums.com/pedal_mods.html#CA
Was wondering what it would be like to run 2 op amps in the same slot
I've tried this in a few OD pedals with no noticeable effect compared to a single opamp. Marketing gimmick IMHO.
+1
-
Ok two OPA2604's just arrived, and will try them in place of U4 and U9 on the main board, tomorrow.
-
Put the original LF412 back into the U9 socket.
-
NE5532 vs TL072:
NE5532: (original MP-1)
http://youtu.be/jcCAvESZVu0
TL072: (noise mod)
http://youtu.be/H8-qdDzTXh8
JRC4558 (tube screamer overdrive pedal):
http://youtu.be/s21MmTQaGAc
-
NE5532 vs TL072:
NE5532: (original MP-1)
http://youtu.be/jcCAvESZVu0
TL072: (noise mod)
http://youtu.be/H8-qdDzTXh8
JRC4558 (tube screamer overdrive pedal):
http://youtu.be/s21MmTQaGAc
That's interesting b/c the NE5532 is marketed as a low noise opamp (vs. a JRC4558 AFAIK). The TL072 is a JFET based opamp; I can vouch that It's fuller in the low and high freq. range vs. a JRC4558 in a TS circuit. I'm going to check out those links ASAP. Anyone experimented with Burr Brown opamps? They're premium-priced but I don't notice a significant difference swapping in overdrive pedals.
-
First of all I have to admit that I didn't read the whole thread, lazy me.
That being said, here's what opamps I put in my MP-1. Basically I swapped U4, U11, U15 and U18 for OPA2604 (with sockets). According to my notes U4 was originally a NE5532 and the others were RC4559N. I kept U9 as is (almost, it was an LF412CN and I put an LF412CP, because I mistakenly swapped it for a TL072 in the first place and damaged the original opamp when I removed it).
I chose the OPA2604 over the OPA2134 because some said it was more tube-like whereas the other was more hifi, whatever that means. I'm sure the 2134 wouldn't be a bad choice either.
The bottom line is that I am more than pleased with the results, it's as if a blanket had been lifted (that's so cliché!) and I suddenly had some nice high end coming back at my disposal. And of course the noise went drastically down (but I also changed the caps as per the noise mod instructions).
I also felt that my gain went up too. Previously I had doubts and was considering a gain mod, but no longer now, I get the gain I need, and more (think Bettencourt gain).
-
Another mod is to replace all the NP elektrolytic caps (the yellow ones 10µF/35-50V)with some high quality panasonic NP's.MAkes also quite a difference in sound.But on the other hand,alooooooooooooot of work (around 45 caps).
-
Ooooo
" Kaz Kylheku
Date: 2012-10-21 07:24 +200
To: ada-mp1
Subject: Wow: quite a difference from replacing the EQ section op-amp!
Hi all.
Recently, I've gone on an op-amp upgrading rampage. I basically
got rid of all audio-handling dual op-amp IC's in my ADA MP-1,
and replaced them with NE5532 chips from On Semiconductor.
What a fantastic difference in sound quality, and the unit is
incredibly quiet now. I can put the guitar down with the volume
up even on a high gain setting and the noise is negligible. From
this I learned that the MP-1's reputation for being a noisy
preamp is in fact due to numerous inferior op-amp chips.
Yesterday, I replaced one more op-amp, for which I had to order
the replacement. I kicked out the LF347 in the EQ section and
replaced it with a MC33079 from On Semiconductor. I was not
expecting much of a difference any more, but the difference
made by this "last piece of the puzzle" is quite astounding.
The MC33079 is a very good IC. It has low distortion (with
published distortion figures correlated with frequency and
output voltage). It has an output stage which doesn't
exhibit crossover distortion and is quiet. It is also stable,
being internally compensated for stability at unity gain
with, the data sheet claims, a good phase margin. It's not
a bad match for equipment loaded with NE5532's.
On Semiconductor, a 1999 spinoff company of Motorola parentage,
recommends this part to designers for audio work, along with their
version of the NE5532 dual op-amp and the NE5534 single.
The old chip in the MP-1's EQ section, the LF347, it a ho-hum
part whose datasheet does not recommend it for audio at all.
It is for DC applications only. No graphs of any kind are
given on the datasheet, which is kept very brief.
"Wide bandwidth" is claimed, but it is not stated how wide,
or whether it is unity-gain stable. "Low distortion" is also
claimed, but no figures or graphs are given. I suspect that
this op-amp quite possibly oscillates unless it is carefully
compensated with external components, and undoubtedly introduces
distortion, which has contributed in a big way to my MP-1's
sound quality issues. The LF347 should never have been used
in any quality audio equipment, and would never be used for such
a purpose by any competent designer today.
After I popped in the MC33079 I was surprised with a sound
which has become much more transparent and pure on all tones,
from solid state and tube cleans, to blues crunches to rock
and roll and metal distortions. The best aspect of this new
sound is that there is more musical high end. Previously,
I always struggled with high end. When I dialed in more, there
was something objectionable in the sound, and when I tried to
cut that away, the sound became too dull and blanketed.
Now the "fizz frequencies" sound more pleasant. I'm hearing
what is sometimes calld "bacon frying sizzle", and the high
end is more controllable. I'm guessing that this is because
it doesn't contain nasty distortion products that the
LF347 op-amps were introducing.
Basically, the rig sounds like simple tube amp, except
that it is MIDI-controlled. I.e. this is what it was supposed
to be like, until they screwed it on the assembly line with
sub-par op-amps to save money.
It is poor op amps which cause the MP-1 to be tonally regarded
by some guitarists as a preamp only for "80's hair metal".
Replace all the audio path op-amps with high fidelity units,
and you're in for a big surprise. It literally becomes a
different animal, tonally. And a very quiet one.
You know, if Vito Bratta had had an MP-1 like this,
he might have tossed the BBE "sonic minimizer" in the trash."
-
Mmmm gotta try the NE 5532 swaps.I use a LT1058 in the tonesection.Now only V1 mp-1's used the LF347 in the tonesection,the V2 used a TL074.
-
Zsoli...very interesting read Dude..Thanks for all of the "Input" :thumb-up:
By the way check your pm Buddy....Thanks! Steve :metal:
-
My OP-AMP test TL072 vs 2134 vs NE5532N vs NE5532P vs 2604 - ADA MP-1 (U4)
http://youtu.be/6xRAAWZeC9Q
-
Awesome comparison!!!!
My personal ranking:
1. BB OPA2604 (warmest, most tube-like sound)
2. BB OPA2134 (close 2nd, tad bit more HiFi sounding but harmonically complex, lowest noise)
3. NE5532N (real low noise floor, sound-wise a bit flat, lacks complexity and warmth)
4. TL072 (boring)
5. NE5532P (highest noise, fizzy mess of ice-pick attacks)
YMMV........
-
Honestly I stay away from the Tl072 and Tl074. 2064 is awesome where its needed.