GDA 700 DAC mods done

soundfreak1

Here's what was done:

12 caps nichicon 100/50
12 caps .1/250
6 ic's TI. Lme49710na/nopb
6 8 pin dip goro gold sockets

Removed adcom ic's (6aa) replaced with ic sockets.
Removed 10 mf caps for +- 17vot rails and replaced with .1/250 stacked metal film paralell 100/50 caps
Removed L500-L503, replaced with jumper.
Removed C510, C511,511,C512,,515 also removed C518,C521
Installed LME49710na. IC'S
Could have used the Bb OPA627BP'S but the LME flat out blew them away on paper and in a/b listening tests.
Base is incredably tight, deeper and outside the cabinetts.
Mids and voiceing is smoother and very clean and silky.
Highs are open real crisp without any harshness at all and all over the room as is the imaging.
Very warm sounding but with a detail in instraments that is amazing.
Bottom line: WOW!!! VERY HAPPY.Picts to follow.

deronb1

Very cool upgrade. Wish I had those skills

soundfreak1

Me too. This was done by my tech.

deronb1

Too funny. Well then, wish I had that cash!

soundfreak1

Wasent that much about 2 bills.

deronb1

not terrible for such a noticable change. I was thinking of having a few things done to my amp. It's old and I am sure it could go for some reconditioning.

soundfreak1

Me too. Im old and could use some reconditioning also LOL too bad it would be more than 2 bills though!

FTGV

Looks like a nicely executed mod.The LME49710/20 (LM4562) are my current faves,as I find them,quiet,detailed and dead nuts neutral not to mention very reasonably priced.

soundfreak1

Yes they were dirt cheep ( my tech told me they are using them in production of so many really highend preamps, dacs, phono pre's ect that production is in the 10's of thousands so the price is driven down nicely. TI also bought burr brown and is building them as well but at about 30. Bucks apiece and not as good as the LME'S.

heiney9

Great, enjoy!

H9

FTGV

soundfreak1 wrote: »

Yes they were dirt cheep ( my tech told me they are using them in production of so many really highend preamps, dacs, phono pre's ect that production is in the 10's of thousands so the price is driven down nicely. TI also bought burr brown and is building them as well but at about 30. Bucks apiece and not as good as the LME'S.

I'm currently using the LME's in a number of projects( active crossover and a couple of DAC's.)The OPA 627 is a great opamp but it's going on a couple of decades old so there has been some excellent sounding, lower cost devices developed since like this series from National (before their aquisition by TI).

heiney9

Fred,

Which LME model could I roll in place of the OPA 627. Might be fun to roll a few in the Adcom GDA600 since I have sockets.

My Keces DAC uses a couple LME's and I agree, they seem to be very neutral and natural.

H9

FTGV

The dual version LME49720 or LM4562,same part just the 4562 was introduced before NS changed their numbering scheme.

soundfreak1

My tech has done a couple of 600 using lme's i will see what he put in them and post later today. A goof friend has one of them and was very impressed.

heiney9

Don't get me wrong, I absolutely love my modded GDA 600, but one will never know if something more current will change the flavor in a positive way. Since they are socketed, I'm going to give it a try.

H9

Dawgfish

Like everything these things always depend on your taste and system, but another one I enjoy is the AD 825. If you are looking for deep bass, this is the one. Having said that, I run the BB OPA 627 most of the time in my MHDT Paradisea + DAC. It's an oldy but goody and sounds the best to me with the most variety of music. The Paradesiea + comes stock with the LM4562 and it's a good sounding op-amp overall, but sounds a little thin and sterile compared to some others. A couple of others I like are the BB OPA 2228 and OPA 2107.

soundfreak1

For my friends 600 he used the lm4562na or could use the LME49860na the diff is the power supply mod needed these chips are jfet as opposed to bipolar like the burr browns and with the TI's you can pull out some of the caps due to the fact that there is no ossilation issues to deal with as they are delt wiith in the chip itself. Accotding to my tech.

soundfreak1

H9 you can roll the ti's in nut to get the full effect the power supply mods are recomended. Just less in the signal path needed with the TI's .

dhart86

soundfreak1 wrote: »

Here's what was done:

12 caps nichicon 100/50
12 caps .1/250
6 ic's TI. Lme49710na/nopb
6 8 pin dip goro gold sockets

Removed adcom ic's (6aa) replaced with ic sockets.
Removed 10 mf caps for +- 17vot rails and replaced with .1/250 stacked metal film paralell 100/50 caps
Removed L500-L503, replaced with jumper.
Removed C510, C511,511,C512,,515 also removed C518,C521
Installed LME49710na. IC'S
Could have used the Bb OPA627BP'S but the LME flat out blew them away on paper and in a/b listening tests.
Base is incredably tight, deeper and outside the cabinetts.
Mids and voiceing is smoother and very clean and silky.
Highs are open real crisp without any harshness at all and all over the room as is the imaging.
Very warm sounding but with a detail in instraments that is amazing.
Bottom line: WOW!!! VERY HAPPY.Picts to follow.

Soundfreak,
Do you think your tech could be interested in doing the same mod to my GDA 700?

soundfreak1

Absolutly, well at least im sure he would. We have been frienda fof years.

soundfreak1

Absolutly, well at least im sure he would. We have been frienda fof years.pmed u his info dhart

dhart86

Thanks man.............very cool of you!!!!!!!!!!!!!!!

soundfreak1

Have had more time with it now and it is even better with more hours on it. Sweet thing!