Pimp my A-119?

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Reptil
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Pimp my A-119?

Post by Reptil » Sat May 16, 2009 10:01 am

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!

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astroschnautzer
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Post by astroschnautzer » Sat May 16, 2009 10:09 am

This is something I would like to know too.

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Reptil
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big photo

Post by Reptil » Sat May 16, 2009 10:33 am

Image

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e-grad
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Post by e-grad » Sat May 16, 2009 11:10 am

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.

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Post by Reptil » Sat May 16, 2009 12:26 pm

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
:chewie:

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Reptil
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Post by Reptil » Sat May 16, 2009 12:36 pm

yes they are pin and voltage compatible
Image

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e-grad
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Post by e-grad » Sat May 16, 2009 12:41 pm

Bitteschön, gern geschehen.

These should be the direct links. Author is serenadi whom I think a reliable source:
http://www.sequencer.de/synthesizer/vie ... 119#253557

http://www.sequencer.de/synthesizer/vie ... 119#252422

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Reptil
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Post by Reptil » Sat May 16, 2009 12:50 pm

interessant!
:marge: :party:

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Post by Reptil » Sat May 16, 2009 1:13 pm

:guinness:
So, I'll have to change the resistors for the symmetrical input, and will also change the caps for something better..
Last edited by Reptil on Sat May 16, 2009 4:25 pm, edited 1 time in total.

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Reptil
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Post by Reptil » Sat May 16, 2009 4:23 pm


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haven
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Post by haven » Mon May 18, 2009 3:19 pm

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?

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Post by wetterberg » Tue May 19, 2009 3:24 am

very cool.
I'd start with the IC replacement, and perhaps report on the sound change?

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Post by fonik » Tue May 19, 2009 4:04 am

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...
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Post by consumed » Tue May 19, 2009 4:38 pm

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?

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consumed
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Post by consumed » Wed May 20, 2009 2:01 am

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.
Last edited by consumed on Wed Feb 24, 2010 12:08 am, edited 1 time in total.

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Post by Reptil » Sun May 24, 2009 9:54 am

that sounds much better!

I also posted here

maybe there's something out there better than the TLC07x and compatible???

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Post by Reptil » Sun May 24, 2009 10:04 am

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

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Post by e-grad » Sun May 24, 2009 11:49 am

Why you've choosen the LME49740?

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

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Post by Reptil » Sun May 24, 2009 1:28 pm

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:
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.

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Audio Upgrades
so the OP275 is also an option. MOTM sounds good IMHO.

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Post by Funky40 » Sun May 24, 2009 1:40 pm

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

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Post by doctorvague » Sun May 24, 2009 2:01 pm

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

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Reptil
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Post by Reptil » Sun May 24, 2009 3:34 pm

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
:hit:

I want to know
Image

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

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Post by Reptil » Sun May 24, 2009 3:37 pm

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. :party:
thanks!!

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Post by Tim Stinchcombe » Sun May 24, 2009 3:52 pm

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!)
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Last edited by Tim Stinchcombe on Wed Feb 24, 2010 8:17 am, edited 2 times in total.

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Post by Funky40 » Sun May 24, 2009 5:20 pm

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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