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Pimp my A-119?
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3, 4, 5, 6  Next [all]
Author Pimp my A-119?
Reptil
hai guys,
eeehmmm Doepfer A-119
not so good (sonically)
to put it mildly

how can I pimp this module for better sound quality and more headroom?
the ICs they are TL062cn (Texas Instruments)
but looking at the datasheet of a TL062CN (or CP) these are 8 pin and not 16 like used in the A-119
I guess that's where it starts.. better IC?
different resistor values?

I don't care much for the mic level input
the line in (unbalanced) is what I use

thanks!
astroschnautzer
This is something I would like to know too.
Reptil
e-grad
This was discussed on German list a while ago. IIRC it'll help to use the big jack input only.

edit: Just checked the postings on the forum mentioned above: You should change the TL064 for an TL074 (I GUESS they have the same pin out but pls CHECK before swapping) and use the Symm. In.
Reptil
where was this discussed? (german language no problem for pirate)

the symmetrical input has the wrong impedance (it's for mics)
change the resistors?

ah ok the TL072 is the quad version of the TL074 (figures)
here it says the TLC072 is even better
http://www.me.umn.edu/labs/hmd/lab/electronics/ic.html

Dankeschön
Chewbacca
Reptil
yes they are pin and voltage compatible
e-grad
Bitteschön, gern geschehen.

These should be the direct links. Author is serenadi whom I think a reliable source:
http://www.sequencer.de/synthesizer/viewtopic.php?p=253557&highlight=a 119#253557

http://www.sequencer.de/synthesizer/viewtopic.php?p=252422&highlight=a 119#252422
Reptil
interessant!
Marge Simpson w00t
Reptil
Guinness ftw!
So, I'll have to change the resistors for the symmetrical input, and will also change the caps for something better..
Reptil
21" rims

http://www.vishay.com/company/press/releases/2008/080507foil/
haven
once you have done this could you post a summary of all the mods? It would be great to have it all in one place for the english only crowd (like me).

My A119 would like to be pimped as well... I wonder if the A138D Insert module can have an IC swap as well?
wetterberg
very cool.
I'd start with the IC replacement, and perhaps report on the sound change?
fonik
the TL064 is just a low power version of the TL074 ant it is 3 times noisier. channel separation and noise is almost the same for TL074 and TL084.
i would use a TL06x only for battery powered devices...
consumed
i just babelfished serenadi's posts and still could understand only half of it.
i know that the tl074 is a direct and superior substitution.
are there any mods (resistor or cap changes) that will work best with the tl074?
consumed
good news--ive tested using the TL074 and it is definitely an improvement.
found that signal level was lower AND the noise higher with the TL064.
i set up an A/B test swapping the TL074 with the TL064 and all else equal.
the TL064 was socketed so the swap was really quick.
here's the results:

606 through TL074 16/44.1 wav
606 through TL064 16/44.1 wav

i set up the test using the TL074, turning the 606 volume all the way up, and the 119 gain knob set to where the overload light was just barely flickering on one 16th note only. i used the asym input (the sym input introduces ground hum in this case). these recordings are completely dry, no compression or eq, and gain set carefully along the signal path.

EDIT: i performed this test using the ASYM in, which ive learned/discovered is the BAD input, and therefore much easier to notice the noise as in these recordings. make sure you always use the SYM in to keep the noise to signal lowest.
Reptil
that sounds much better!

I also posted here

maybe there's something out there better than the TLC07x and compatible???
Reptil
the National LME49740 seems totally compatible!
now let's have a look at how many are needed
quantities from 100.. maybe a group buy?
http://www.national.com/pf/LM/LME49740.html
e-grad
Why you've choosen the LME49740?

The typical OPAmp for the audio path within synth cicuits is the TL072 while MOTM uses OP275GP IIRC.
Reptil
e-grad wrote:
Why you've choosen the LME49740?

The typical OPAmp for the audio path within synth cicuits is the TL072 while MOTM uses OP275GP IIRC.


AFAIK pin and voltage compatible (have to check thouroughly but everything looks fine)
recommended by Jim Williams (the uncrowned king of clean) hihi

Quote:
072's are problematic for me in EQ's. There is too much noise to use them for HF boost. They have only 40 db open loop gain at 10k hz, add + 15 db of HF boost and that opamp has 25 db of loop gain left to push down distortion. That creates high THD.

Better choices (if housecleaning work like phase compensation and power supply decoupling is done) are the National LME49720NA or the Analog Devices AD8599, the LT1358, the OP-275, the BB OPA2134, AD8512, etc.

Some of those have 80 db open loop gain at 10k hz, 40 db less dirt. Compare the AD8599 .9 nv/hz/sq noise to the 072's 22 nv noise.

Jim Williams
Audio Upgrades


so the OP275 is also an option. MOTM sounds good IMHO.
Funky40
OP275 or 2604 are the choices you find everywhere.
Go for these if you like to exchange and don't know things.
For CV circuitry LT1013

all same pinlayout as TL072
doctorvague
Funky40 wrote:
OP275 or 2604 are the choices you find everywhere.
Go for these if you like to exchange and don't know things.
For CV circuitry LT1013

all same pinlayout as TL072


yep the OP's are a common upgrade
I agree this module don't sound so good as it maybe could
better opamps couldn't hurt

thanks for the clips
Reptil
Funky40 wrote:
OP275 or 2604 are the choices you find everywhere.
Go for these if you like to exchange and don't know things.
For CV circuitry LT1013

all same pinlayout as TL072


hey I'm all ears Band
trying to gather nice info about upgrading some workhorses
throwing ideas around
why not OP285
POW!

I want to know


please note this is also about quad opamps (2x2 in one package)
which ones?
why?
I'm trying to match the specs of the 275 to the quad ones (??!)

Analog Devices OP482 orrr???
that National LME49740 again? -- slew rate is near the OP275
Reptil
Consumed can you please post an unprocessed recording of that 606
(straight into the converters?) it can then be used as reference to try and find differences.
null test and the noise differences are appearant. w00t
thanks!!
Tim Stinchcombe
Hi folks,
Saw this in passing, and couldn't resist running a few simulations. Looks to me like the main problem with the TL064 is both its limited open-loop gain, and its bandwidth. For the 'asym in' at max gain (about x20 = 26dB), the thing essentially acts as a low-pass filter with a cut-off somewhere around the 1kHz region, so it could well sound pretty 'muddy' - see attached traces. (The low down high-pass effect is almost certainly due to the large back-to-back electrolytic caps at the input, but I didn't look at it in any detail.)

Replacing the '64 with a TL074 increases the bandwidth quite a bit, and using either a OP275 or an LME49720 looks like it will give the same sort of improvement again (the trace for the 49720 is ambiguously labelled as the SPICE model at the product page was actually for the LME49680, but I assume they know what they are doing, and hence that it is equivalent...). The datasheets for both the OP275 and LME49720 show a much higher unity-gain bandwidth than the TI chips, which I assume should help considerably in improving the overall quality of the amplified signal.

Tim

Edit: CAUTION! The OP275 is only a dual op amp package, so is not a 'drop in' replacement! (I originally did this chart before anybody realised that it wasn't a quad part!)
Funky40
uhhh, OP275 is dual, all i mentiioned is dual.
I have no idea about quad OP amps. Interested too to know


i had a A-119 by myself. was very dissapointed by this module.
What you describe Tim fits good how it sounded.
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