Burson op amps for MH DAC23.2

[Luvin Da Blues]

I ran across this interesting thread on Canuck Audio Mart. This looks like a promising upgrade for my Music Hall DAC. Does anyone have experience with these or have any comments? Thanks in advance - LDB

•http://www.canuckaudiomart.com/forum...p?f=21&t=12887

[Feanor]

I ran across this interesting thread on Canuck Audio Mart. This looks like a promising upgrade for my Music Hall DAC. Does anyone have experience with these or have any comments? Thanks in advance - LDB

•http://www.canuckaudiomart.com/forum...p?f=21&t=12887

As audiophile tweaks go, the Burson discrete opamps look like a relative bargain. It's speculation on my part but I suspect you'd hear more difference installing a Burson opamp than you might upgrading you interconnects to various mid-range models that cost several times as much.

On the other hand opamps tend to get a worse reputation than they deserve largely, I gather, because the early ones were relatively awful. Current ones are much better.

A few common opamps I've heard of, (I'm no expert) are:

• NE5532 (dual) or NE5534 (single) -- a decent, very commonly used, unit targeted at audio application.
• OPA2134 (dual) or OPA134 (single) -- a step up, according to some, for audio application.
• OPA627 (single) -- considered by some the "ultimate" audio opamp. The OPA627AU costs a relatively exhorbitant US$24.95, (see Parts ConneXion). I have seen pairs of OPA627 mounted in an 8-pin DIP adaptor (to replace a dual such as the NE5532) for under US$30 on eBay.

I'm a cheapskate but I'd be inclined to try OPA627's before springing for the Burson. (Note that the OPA627, even a paired module, will fit in tight spaces that the Burson will not.)

[Luvin Da Blues]

Thanks Bill,

The OPA627 at $25 is quite a bit cheaper that the $63 each the OP paid for the Bursons. I'm sure both would be consideable upgrades.

[Luvin Da Blues]

I would imagine that this would void my warranty. I should probably wait until the one year expires in December.

[02audionoob]

My MH CD-25 has the 627's. I have a hard time remembering what the dang thing sounds like without my PS Audio DLIII. But then again, I spin so much vinyl, I'm beginning to forget the DLIII, as well.

[Luvin Da Blues]

My MH CD-25 has the 627's. I have a hard time remembering what the dang thing sounds like without my PS Audio DLIII. But then again, I spin so much vinyl, I'm beginning to forget the DLIII, as well.

Did you change to the 627s or are they stock units. I would think that the DAC would come with the same opamps as the CD player.

[02audionoob]

Did you change to the 627s or are they stock units. I would think that the DAC would come with the same opamps as the CD player.

It's a Parts Connexion mod. Stock is 2604.

[Feanor]

I would imagine that this would void my warranty. I should probably wait until the one year expires in December.

I'm just curious: are the DAC25.2 opamps DIPs in sockets or DIPs soldered directly to the board? Or are they surface mounts? Personally I'm not sufficiently confident of my soldering skills to attempt to swap surface mounts.

Of course Parts ConneXion will mod you Music Hall for you with OPA627s or Bursons -- but not for cheap.

[Luvin Da Blues]

I'm just curious: are the DAC25.2 opamps DIPs in sockets or DIPs soldered directly to the board? Or are they surface mounts? Personally I'm not sufficiently confident of my soldering skills to attempt to swap surface mounts.

Of course Parts ConneXion will mod you Music Hall for you with OPA627s or Bursons -- but not for cheap.

My next step is determining the mounting configuration. I haven't opened the DAC up yet. I'm hoping for sockets but I have no problem with board level soldering. I'm not a cheapskate but wouldn't pay someone money for something I have time, equipment and skills to do.

I found this video but nothing new here.

[Luvin Da Blues]

Here's a pic of the innards. Looks like sockets but at this resolution it's hard to confirm.

[Feanor]

Here's a pic of the innards. Looks like sockets but at this resolution it's hard to confirm.

Yeah, looks like sockets which makes swapping really easy of course.

Bursons presumably can't be installed in place of surface mounts. The video shows them being mounted through the board, and I notice that this is what Burson recomments unless sockets are already in place.

[Luvin Da Blues]

I think I go with your advise and start with the 627s. Would be nice to hear a modded one first but what the heck, you only live once.

02audionoob, did you buy your MH CD-25 already modded or did you sent it in after purchase? I'm curious in your opinion of the sonic improvement if you had a chance to hear it unmodded.

[02audionoob]

I think I go with your advise and start with the 627s. Would be nice to hear a modded one first but what the heck, you only live once.

02audionoob, did you buy your MH CD-25 already modded or did you sent it in after purchase? I'm curious in your opinion of the sonic improvement if you had a chance to hear it unmodded.

I bought mine modded, so I haven't heard it without the 627's. When I got it I opened it up to look at the mods and my memory is they were in sockets.

I think this CD-25 sounds beautiful and I might eventually take it off of the DAC. My original reason for the DAC is more for the DVD player. I love my concert videos.

[Luvin Da Blues]

Thanks gents,

I'm in no rush to order these but I'll post my findings after the swap.

[Luvin Da Blues]

Just took a look inside. Appears to have two 2134s and one 2064. Forgive my ignorance, but are the two 2134s to allow for the inverted balanced signal? Should I replace all three?

[02audionoob]

I don't know anything more about this stuff than you, but - given that that CD-25 has two op-amps and no balanced signal, maybe it's the 3rd op-amp that is for the balanced signal. The summaries of the mods at Underwood Hifi indicate the replacement of three op-amps, but it makes sense that you could do just the 2134s. Maybe you could get some free advice from the seller of the op-amps.

[Feanor]

Just took a look inside. Appears to have two 2134s and one 2064. Forgive my ignorance, but are the two 2134s to allow for the inverted balanced signal? Should I replace all three?

LDB, did you mean 2604 rather than 2064? Methinks so.

To my very limited knowledge both the 2134 and 2604 are opamps designed with audio in mind and aren't to shabby, especially the 2134. But, N.B., both types are dual opamps and can't be replaced with single OPA627's.

Almost certainly the 2134's are for the balanced output circuitry. I don't know but would guess that the 2604 is upstream of the 2134's and thus might be first priority. If you want OPA627's you'll need a pair of OP627's and a special adaptor. I believe Parts Connexion sells the adoptors but note that the adaptors might require the surface mount version of the 627 and these are extremely tiny and difficult to work with I dare say.

02audionoob's suggestion is a good one. Email Parts Connexion and ask them if they can upgrade your DAC and what they suggest -- quaranteed they will say 'Yes' and suggest a lot of stuff, likely including the opamps. Ask them specifically about the opamps mentioning what you did here.

A possible source for the pairs of 627 in adaptors is Gigalab on eBay. Assuming they aren't fake 627, these look like a bargain at around US$30 per pair on the adaptor, shipping included.

[Luvin Da Blues]

I think I found it. Is this what your talking about?

http://cgi.ebay.ca/2x-Mono-to-Dual-O...d=p3286.c0.m14

Looks like a dual "pair". Should I replace the 2134s with these and move one 2134 into the 2604 slot?

[Feanor]

I think I found it. Is this what your talking about?

http://cgi.ebay.ca/2x-Mono-to-Dual-O...d=p3286.c0.m14

Looks like a dual "pair". Should I replace the 2134s with these and move one 2134 into the 2604 slot?

I was thinking of this one from Gigawork, (sorry not Gigalab), but the one from Vintage Audio Lab should be the same.

[Luvin Da Blues]

I was thinking of this one from Gigawork, (sorry not Gigalab), but the one from Vintage Audio Lab should be the same.

Ordered the burr-browns from Gigaworks, for this price what's a fellow got to lose.. Thanks guys, I'll post my findings later.

[Luvin Da Blues]

Just planted the Burr-Brown OPA627s into the rig. The 627s replaced a pair of 2134s for the balanced output signal. Improvements were heard immediately. I have to listen more but my intial impressions are;

Overall the presentation was more "fluid" if you may while at the same time sharpening the attack time of instruments. Tonal balance was fuller and a bit more natural. The width and depth of the soundstage increased on all the tracks I've heard so far. Detail is easier to distinguish, absolutely effortless on my better recordings albeit a tad bright sometimes. Overall, for the minimum outlay I couldn't think of a better way to improve a digital signal.

Since I had two 2134s left over, I decided to change out the remaining 2604 chip. Gotta say this was a huge disappointment. Basically not only undid everything the 627 improved but made things flatter. I put the 2604 back in and I'm going to leave it there. Not sure why the 2134 didn't improve things but I am very happy with the 627s so all's good. Cheers

LDB

[02audionoob]

This is good to know. Now I can assume the 627's are helping the sound quality of my CD player like they're helping your DAC.

[blackraven]

The 627's can dramatically change the sound. I changed the OP amps in my Music Hall 25.2CDP and it changed the sound of the player from a very open and airy sound to a more aggressive and forward sound with less transparency. For me the mod did not work out.

[Feanor]

The 627's can dramatically change the sound. I changed the OP amps in my Music Hall 25.2CDP and it changed the sound of the player from a very open and airy sound to a more aggressive and forward sound with less transparency. For me the mod did not work out.

Which goe goes to prove that you need to try them with an open mind. LDB's experience with replacing 2134s with 627s was positive, but replacing the 2604 with a 2134 was negative despite the generally better reputation of the latter.

In LDB's DAC, since the 2604 and 2134 are not dissimilar in price, it is probably because overall circuit exploits the subtle qualities of the former, and that's presumably why the designer used it in the first place.

But the use of a 2134 vs. a 627 is another matter, given the latter is several times more expensive than the former. That is, the designer might compromise best design in this case only to save money.

LDB, you might consider replacing the 2604 with a 627 pair and see what happens.

[Luvin Da Blues]

.....LDB, you might consider replacing the 2604 with a 627 pair and see what happens.

Just what I was thinking.