ECD-1 DAC mod findings - blow-by-blow

audioengr · « **on:** 17 Jun 2004, 06:47 pm »

The ECD-1 has some really strange stuff in it. The digital inputs do not seem to be terminated correctly to 75 ohms. I have found this kind of error in the EMC-1 as well. The selector that selects between the 4 digital inputs is actually an ANALOG multiplexer. This is really stupid. This should be all digital. I guess this was done to maintain the differential signalling all the way to the receiver chip. Not a bad idea, but they used the WRONG chip. This thing puts 90 ohms in series with both the signal and ground of the digital signal. Impossible to match the impedance to 75 ohms!!! This will make the unit very sensitive to different digital cables, and it may not benefit much from a very good cable....

There is a lot of hum from this thing. I know why too. There are ground-loops all over the board and digital input connectors. First, I will just isolate the RCA connectors and connect them directly to the receiver, bypassing the analog selector and going through a pulse transformer/terminator and see if the hum goes away and the image gets clearer. This should help the hum problem and match the transmission-line properly to 75 ohms.

RESULT: Hum is gone now and image is much clearer - I can hear the piano echo off the back wall of my reference recording now. Before, it was veiled. Sounding a bit more dynamic in the High-frequencies as well, probably a result of improved focus due to less jitter.

I found a couple of options for replacing the analog selector. They have much lower impedance and should allow the transmission-line to match. However, neither one of them matches the pinout of the selector on the board, so I will need to build a proto-board on top of the board to adapt them to the socket. This a quite a bit of work and primarily enables the inputs through the AES/EBU and Toslink inputs. If you are never going to use these and dont care if they are disabled, the fix I have in now will be simpler and more effective.

Next step is to improve the high-frequency decoupling on the analog board and improve the post-DAC filtering.

RESULT: Dynamics are very good now. The piano keys sound like percussion and fairly live. Cymbols trail-off nicely and rim-shots have impact. This did not change the mid-range smoothness one bit. Very nice indeed. However, there is still a bit of HF sibilance, probably due to the fact that my P-3A DAC has a modded Superclock2 and the ECD doesn't. This causes guitar strings and piano to have a slightly non-live, in the room with you sound compared to my reference DAC.

Carlman · « **Reply #1 on:** 18 Jun 2004, 01:33 pm »

How hard would it be to have 2 RCA inputs that were seletable? That way you could compare transports.

-C

zybar · « **Reply #2 on:** 18 Jun 2004, 02:51 pm »

Thanks for posting your findings Steve.

What kind of price tag are you thinking for the mods without the SuperClock? I would need the ability to have ALL of the multiple inputs available.

I can't wait to hear Chris' unit. If you keep the midrange and improve the extremes, I will gladly sign up for the mods.

George

audioengr · « **Reply #3 on:** 18 Jun 2004, 08:57 pm »

George - It is looking like $750. $650 for labor and $100 for parts. This is without the Superclock2.

Carlman - I have a simpler solution now for the analog selector. All of the inputs will be selectable, the best being the RCA and the XLR.

zybar · « **Reply #4 on:** 18 Jun 2004, 09:20 pm »

Steve,

Is that price with your analog selector?

George

audioengr · « **Reply #5 on:** 19 Jun 2004, 02:20 am »

Thats with the selector. My early estimate.

lonewolfny42 · « **Reply #6 on:** 19 Jun 2004, 04:58 am »

Quote from: audioengr

Carlman - I have a simpler solution now for the analog selector. All of the inputs will be selectable, the best being the RCA and the XLR.

That sounds good to me ! Thanks !!

( http://www.zildjian.com/ )

audioengr · « **Reply #7 on:** 20 Jun 2004, 04:12 pm »

Next Steps - install modded Superclock2. This turns out to be really squirrely as well. The transmission-line for the onboard clock is really hosed. No wonder it sounds a bit cloudy. Needed to wire the transmission-line externally. Signals look really good now. Off for testing and tuning. Tuning done. Signals look extremely good now, textbook perfect.

Result: Oh my God! I'm not sure I have words to describe this. The clarity and focus on piano tracks is just uncanny - track 4 from Gene Harris, the Concord Years is just superb! The Piano has absolutely no aura, no halos, no artificial echo, no veils. I have never heard it this good. Just like live. Cymbols ring like fine bells. The visceral impact in this track just knocks you out of the chair! Dynamics in spades. Maybe slightly better than my P-3A reference. This is so much fun to listen to, I have to hear each entire track. This definitely matches now my reference, the modded P-3A, plus the vocals are a bit more smooth and natural.

Next, after I get the adapters and analog selector in, I hope this does not degrade anything. If it doesn't, I will have to call this a Turbomod for sure.

Jon L · « **Reply #8 on:** 20 Jun 2004, 06:34 pm »

Steve, do you think after all mods, ECD-1 will become a "better ECD1" or a different DAC tonally.

When I heard it, the one thing I wished for more than anything was a denser, deeper, textured, more-hued, and weighty midrange/lower mids/bass... Do you think the modded ECD-1 gives you that?

audioengr · « **Reply #9 on:** 20 Jun 2004, 06:56 pm »

Jon - I believe the modded ECD-1 is improved in all areas:

1) Focus
2) HF extension and dynamics
3) top to bottom dynamics
4) bass impact and tightness
5) less sibilance, echo and "halos"

lonewolfny42 · « **Reply #10 on:** 22 Jun 2004, 01:54 pm »

Steve,

TheChairGuy · « **Reply #11 on:** 22 Jun 2004, 03:51 pm »

Wolfy,

I took a lot longer than I ever expected for my gear to open up...even tho Steve said he had pretty much burned it in there.

I can't believe it was my mind doing psycho-acoustic tricks on me to the extent it did...but who knows? I know it's full, open, extended and unrestrained now..where it wasn't hour 1-100 or so.

Immediately, however, it was grain free. That may have been the near elimination of jitter (transport) that was immediately apparent right off.

Give it time, lots of it

audioengr · « **Reply #12 on:** 22 Jun 2004, 07:57 pm »

Chris - the Jensen Cap in the transport can take a lot of time to finally break-in. Also any silver wire with teflon insulation... The ECD-1 should break-in within hours.

lonewolfny42 · « **Reply #13 on:** 25 Jun 2004, 04:52 am »

Quote from: audioengr

Chris - the Jensen Cap in the transport can take a lot of time to finally break-in. Also any silver wire with teflon insulation... The ECD-1 should break-in within hours.

Steve, Thanks for the info !!

audioengr · « **Reply #14 on:** 28 Jun 2004, 07:53 pm »

More mods to the ECD-1 to bring it closer to the P-3A reference:

1) Silver wiring to replace long copper circuit traces
2) better filter at the CS4397 DAC chip
3) better decoupling capacitor at the CS4397
4) lots of FRED's to replace rectifiers

It is getting very close to my reference now. Need to play it a while to break-in the Silver wiring. The mod cost has gone up a bit with these changes, probably in the $800 range without Superclock2 now.

lonewolfny42 · « **Reply #15 on:** 8 Jul 2004, 10:39 am »

Any more updates Steve ? Thanks !!

audioengr · « **Reply #16 on:** 8 Jul 2004, 11:56 pm »

Sure - Update: I just added a few more Black Gate caps (they were high-voltage, so I did not have them in stock). Very Very nice now. Even the wife commented how good it sounds. Just found out that the new analog selector chips are on their way to me. Everything else is ready, just waiting on them now.

The new selector sucks power compared to the original one, so I hope the 1.5 amp regulator on the board can handle it. I beefed-up the heatsink, but it still gets fairly hot already. If not, I will need to install a second regulator, which of course I dont stock. Maybe Radio Shack if necessary just to get this puppy out the door.

zybar · « **Reply #17 on:** 9 Jul 2004, 01:02 am »

Bummer.

Guess we aren't going to hear it at my place on the 17th...

George

audioengr · « **Reply #18 on:** 17 Jul 2004, 12:36 am »

On the 17th, probably not. It is done, but Chris' transport is waiting on Superclock2 to arrive.

Update:

My wife and I had the opportiunity today to listen to an unmodded ECD-1 compared head-to-head with Chris' Turbomod ECD-1. Now, the difference is apparent. They both sound nice, but when you hear the modded one, it is like the veils are lifted. Particularly with piano, with the stock unit, there is a kind of reverberation that is not in the music that seems to fill the spaces between the instruments. It is noticable at the mid-frequencies, but not too much at the highs, such as cymbols etc... It prevents anything in the midrange from being very well focused. The modded one has pinpoint focus, top to bottom. My wife says the difference isn't huge, but the modded one definitely sounds more live. Also, piano notes on the stock one just dont have the attack that the modded one has. There is a definite sense of a percussion instrument with the modded one. The stock DAC seems to homogenize the midrange to some extent. Not really musical soup, but resonant halos around each note blending with the next note etc.. almost like tube-created distortion.

zybar · « **Reply #19 on:** 17 Jul 2004, 01:06 am »

Thanks for the update Steve.

Tomorrow I will be comparing the stock ECD-1 vs a Dodson Audio dac. and an Audio Logic dac. I am doing this to see how much the ECD-1 is holding back my system(although it sounded pretty damn good today).

George