Author Topic: op amp upgrade (Read 9896 times)

shep · « **on:** March 06, 2007, 03:56:18 AM »

Just plugged in new pair of OPA627AP's to replace the OPA2134's
in my Marantz cdp. Found a guy on DiyForum who "made" them (amazing soldering job-so tiny), Dan from OK. I'm sure they need burning in but from a cold start the dif. is startling: explosive, textured, more colour, better defined sound s. Woopie! my nervosa just got fed a good meal

shep · « **Reply #1 on:** March 10, 2007, 12:16:26 AM »

This is kind of like tube rolling (which I have never done). In spite of being vaunted as the next best think to hot buttered toast, I find myself disappointed. (That's the Nervosa talking) This is really weird because these opamps are obviously more resolving and "better" in every dept. but something is not right. I'm less involved with the music, more critical of the sound. I could be and maybe should be that I did them a mischief. When I first plugged them in I did so backwards (believe me this is easy to do) and got almost not sound at all. So it's just possible they have been compromised in some way; I have asked about this in several places but no one seems to know. Theoretically they should have been fried. (fasted way to burn money I know) A diyer offered me the latest and greatest, the LM4562 to try out. There's got to be someone here who has gone thru this! HELP

WEEZ · « **Reply #2 on:** March 10, 2007, 04:53:42 AM »

shep,

mgalusha is a technical guy..maybe he will chime in. (or, you could zip him a PM)

WEEZ

richidoo · « **Reply #3 on:** March 10, 2007, 05:29:21 AM »

Sorry to hear about your trouble shep. I bet thats not exactly what you had in mind when you decided to mod...

I looked up the OPA627AP on digikey, they are only 18.38 each, in stock. It would be nice to have a set of OPA2134 DIPs so you can compare back to stock. Mouser has them for 2.63.

I have read that the LM4562 is very good. If you go that way, I am interested to know what you think.
Good luck getting it straightened out!
Rich

shep · « **Reply #4 on:** March 10, 2007, 08:33:34 AM »

No it's not what I had in mind! I had the 2134 in place. Pleasant, musical but ultimately boring. I buggered them taking them out. So when and If I get the LM4562, assuming I can put them right way round, I'll report.(or I'll be too ashamed to ever mention them again) All of these, requiring the Brown Dog adaptor, are a nightmare to solder unless you're really really good.

richidoo · « **Reply #5 on:** March 10, 2007, 05:28:43 PM »

OK, I wanna get this straight. The OPA2134s were stock, soldered to the PCboard as surface mount SO8, right? Then you had a modder remove those and soldered on a SOIC to DIP conversion to the PC board and now you are using Brown Dogs 970601 to adapt the SO8 opamps into the DIP socket? Sounds like a few extra steps, I must be really confused. That's normal!

If you need help soldering, I am glad to try, I have some small soldering experience, or I have a great audio tech friend who can do it for you. He is factory authorized service for several high end audio brands, including Marantz. So you could send your player to him if it needs TLC to get goin again. What you need is a DIP socket on the marantz board, so you can plug in 8pin DIPs into the socket without soldering. The opamps you are interested in all come as 8pin DIP, even the LM4652.

Am I missing something?
Rich

shep · « **Reply #6 on:** March 11, 2007, 01:30:17 AM »

Sorry to be incoherant (my natural state) The cdp was first modded in England by a good firm http://www.sercal-electronics.co.uk/. I bought it from Brent, their tecky. So it came with the OPA2134's that pin directly to the board. The 627's I seem to have buggered are mono chips so they had to be soldered to Brown Dod adaptors. I honestly don't know if the later LM4652's I'm supposed to get will also need adaptors or not. If that is the case I'm going to need help.(accepted!) Otherwise it will be a direct swap and bob's your uncle. I sure hope they are as good as stated. I find this a bit unnerving...It must be that these little buggers are ALSO very system dependant. Meaning there's really no way to know in advance how they will sound. My new T-amp will get a dose of 627's but maybe there the sound will be totally different...the cutting edge of Nervosa

richidoo · « **Reply #7 on:** March 11, 2007, 09:04:56 AM »

OK, I got it now. The LM4562 opamps are dual, just like the OPA2134, so they will not need a dual>single adapter. So Bob really IS my uncle! I would tend to try the 4562 before anything else as they are quickly becoming SOTA among modders. http://www.national.com/pf/LM/LM4562.html

Here's some other goodies that might help you along the way:
These adapters http://www.accutekmicro.com/product_detail.cfm?Product=SOIC%20Adapters allows you to plug opamps into a SO8 footprint for easy swapping. You can get AK08SOIC-D300S if you want to plug in 8pinDIP packages, or get AK08SOIC-ST if you wanna be able to plug in SOICs for swapping. The latter will require soldering your SOIC to plug in pin adapter before it is ready to plug in. With these you can swap chips quickly with the top off (unplug and drain PS first) for quick sonic comparison.

I did find a nice little FAQ on how to solder SO8 to your board. This might help if you are soldering yourself:
http://cimarrontechnology.com/index.asp?PageAction=Custom&ID=12

And something to make desoldering small SMD easy:
http://www.emulation.com/catalog/off-the-shelf_solutions/lab&rework/chipquik.html

If you need help from a pro, you could send it to Alex: theanalogstore.com or probably find someone nearby.
Good luck Shep!!!!
Rich

shep · « **Reply #8 on:** March 11, 2007, 10:30:12 AM »

Thanks a lot for all the input! I know where the confusion came from. I didn't realize that he had revisited the board and installed an on-board permanent adaptor (which of course didn't apply to the solo 627's. When the guy who is sending me the new chips asked or rather told me about soldering, it was because he didn't know that. So fingers crossed, I can just plug and unplug. Good thing you sent me that link because I had neglected to let the caps drain out before-hand. Chances are even if I had plugged the 6's in right the first time, I would have screwed them not respecting this rule. ( I'm talking like I know what I'm saying

)

shep · « **Reply #9 on:** March 11, 2007, 10:39:22 AM »

Damn! I looked more carefully. There are in fact 4 possible terminations and only one is a plug-in. The others are solder jobs.

richidoo · « **Reply #10 on:** March 11, 2007, 05:08:35 PM »

The PS caps will drain pretty quickly, just let player sit unplugged for 30 seconds before you start surgery.

You should be able to see pin one marking on any of these opamps. SOmetimes it is just a round indent, or a white ink mark. Something subtle. The socket or PCB should also have a subtle mark noting pin one. This will help avoid killing chips. If you don't know, put some junkers in there that won't cost you if you guess wrong. Then when you get it to work, mark the PCB with a red marker dot so you know where pin one is in future. After frying a chip already I bet you are well sure how they go in now, right?

If your new chips are not DIP (plug in), you should be able to get your own samples from National's website, or just solder the new ones to the board. I bet you will like them! They look awesome on paper, but unfortunately that doesn't say much.

Please report back when you get them makin noise!
Rich

shep · « **Reply #11 on:** March 12, 2007, 01:01:46 AM »

Thanks all. I will surely relay my findings. I honestly can't do soldering this
fine, so will be looking for assistance. The Brown Dog adaptors meant that the chip was turned 90° degrees from the original, hense my mistake.
Otherwise I would have just used the lettering as a guide. Yeah the chip measures the best. I hope the sound follows suit. I still wish someone knew how a "fried" chip can still work. When is fried not fried? (the sound of one hand clapping syndrome)