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Calling E-mu 1212M modders

post #1 of 13
12/3/09 at 1:03pm
Thread Starter 
I've recently bought a second hand E-mu 1212M after my 0404 broke down. It measures well, so I don't think it's anything wrong with it. It sounds more balanced than the 0404 which I found too forward and aggressive sounding.

But... in spite of the state of the art CS4398 it doesn't sound any better than my iRiver IHP-120. My modded Zero Dac sounds better in every aspect.

Please give me some input of your mods, what it did to the sound, how much trouble it was etc. And please show some pictures if you can.
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post #2 of 13
12/3/09 at 2:54pm
Congrats on your purchase. I love my 1212m!

I haven't done any mods (yet ), but this thread is a good one to start with:

http://www.head-fi.org/forums/f46/fu...-so-far-71333/
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post #3 of 13
12/3/09 at 5:41pm
Thread Starter 
Thanks for the link. It's inspiring Too bad the pics aren't there anymore.

Is there a schematic somewhere? I wonder if it's the usual arrangement with DAC -> caps -> opamp, balanced to unbalanced, filtering -> buffering opamp and maybe an output cap?

Things to do:
1. Roll opamps, I don't know what to use, those that are easily available to me are LME49720 and OPA2132. None of them are my favourite, but they should be better than the stock opamps. Maybe I'll order AD8599 which I like better.

2. Remove and bypass electrolytic coupling caps, or change them to polypropylene.

3. Decoupling caps. What caps make an impact on the sound? Analog or digital section?
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post #4 of 13
12/3/09 at 6:38pm
Quote:
Originally Posted by diditmyself View Post
Thanks for the link. It's inspiring Too bad the pics aren't there anymore.

Is there a schematic somewhere? I wonder if it's the usual arrangement with DAC -> caps -> opamp, balanced to unbalanced, filtering -> buffering opamp and maybe an output cap?

Things to do:
1. Roll opamps, I don't know what to use, those that are easily available to me are LME49720 and OPA2132. None of them are my favourite, but they should be better than the stock opamps. Maybe I'll order AD8599 which I like better.

2. Remove and bypass electrolytic coupling caps, or change them to polypropylene.

3. Decoupling caps. What caps make an impact on the sound? Analog or digital section?
Be sure to read through the whole thread. Somebody found pics and posted them on later pages. As far as opamps, the consensus seemed to be (if I remember correctly) that the existing opamps are pretty decent, actually, and doing upgrades/changes in the caps made more significant differences. I'd start there first.
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post #5 of 13
12/3/09 at 7:23pm
Thread Starter 
So I guess there's four electrolytic coupling caps between the CS4398 and NJM2068 (L/R pos and neg), and two coupling caps between the two NJM2068(L/R). Is it safe just to bypass them? I couldn't see that anyone measured DC offset after the mods.
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post #6 of 13
12/4/09 at 12:28am
I have my 1212m modded this way (four coupling caps are bypassed). The card has stock opamps in it.

I measure a very modest DC offset at the unbalanced outputs: 7.6mV and 1.9 mV for the left and right channel respectively. At the output of my headphone amp (M-cube) connected to the EMU at the normal listening levels (I use HD650) DC is even smaller: 1.3 & 0.3 mV.
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post #7 of 13
12/4/09 at 7:32am
Thread Starter 
Quote:
Originally Posted by Malvin View Post
I have my 1212m modded this way (four coupling caps are bypassed). The card has stock opamps in it.

I measure a very modest DC offset at the unbalanced outputs: 7.6mV and 1.9 mV for the left and right channel respectively. At the output of my headphone amp (M-cube) connected to the EMU at the normal listening levels (I use HD650) DC is even smaller: 1.3 & 0.3 mV.
Thank you Malvin. I'll try this mod.

Regarding decoupling caps, I wonder if I should just bypass them with small filmcaps like Wima MKS 0.1 uF (cheaper and easier) or change them to OS-CON SVP in the digital section and some "audio approved" ones in the analog section. Does anyone know which caps make the biggest impact?

I'm going to desolder a NJM2068 from my broken 0404 and compare it to other opamps in one of my headphone amps.
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post #8 of 13
12/4/09 at 4:28pm
Thread Starter 
Now I've tried NJM2068 in a headphohne amp, and it isn't bad sounding. There's not a great difference between LM4562 and NJM2068, but I prefer LM4562. It's smoother and more detailed. Now I wonder if it's worth the buck and trouble. It doesn't seem so easy to desolder the opamps from the board, or what do you say?
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post #9 of 13
12/4/09 at 6:12pm
Thread Starter 
I just ordered three LM4562s and some Panasonic 0.1 uF filmcaps, and I'll start from there. Rolling opamps, bypassing the decoupling caps with filmcaps and the coupling caps with wires.
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post #10 of 13
12/9/09 at 5:21am
Thread Starter 
I bypassed the four coupling caps and rolled in LM4562 in U6 and U7 positions. Since there already are ceramic decoupling caps in parallel with the electrolytics, I can't see the benefits of adding film caps. I just see the risk of adding inductance and messing up the circuit.

The difference is significant. Much better clarity and space between instruments. Before I couldn't hear any difference between the sound card and the headphone out of iRiver IHP120, but now the sound card is much better.
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post #11 of 13
12/9/09 at 4:05pm
Quote:
Originally Posted by diditmyself View Post
I bypassed the four coupling caps and rolled in LM4562 in U6 and U7 positions. Since there already are ceramic decoupling caps in parallel with the electrolytics, I can't see the benefits of adding film caps. I just see the risk of adding inductance and messing up the circuit.

The difference is significant. Much better clarity and space between instruments. Before I couldn't hear any difference between the sound card and the headphone out of iRiver IHP120, but now the sound card is much better.
Did you do this all at once? Do you think more of the difference is due to bypassing or the opamps?
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post #12 of 13
12/9/09 at 5:16pm
Thread Starter 
Quote:
Originally Posted by Zaubertuba View Post
Did you do this all at once? Do you think more of the difference is due to bypassing or the opamps?
I'm afraid I was too eager to hear the final result. I did it all at the same time. After rolling opamps in one of my headphone amps I can say that LM4562 is better than NJM2068, and 2 x LM4562 vs 2 x NJM2068 should make even more difference, but not so much it should explain the whole difference. From earlier expereiments I've found that electrolytic caps in the direct audio path is bad for fidelity, even BlackGate NX Hi-Q. Like stated before there's "no" DC-offset (only a couple of mV's probably from the LM4562).

CS4398 seems to be livelier and brighter than AD1852, but I can't be sure since I'm comparing this modded soundcard to a modded Zero DAC (no electrolytic caps in the direct audio path, rebuilt filter, some OS-CONs and AD797).
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post #13 of 13
12/9/09 at 11:52pm
FWIW, I prefer OPA2211A over LM4562 in the output of my Echo Gina24. More detailed, better lows, and more natural, IMO. Found NJM2068 a bit murky, and not up to the level of recent high performance op amps.
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