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The Opamp thread - Page 303

post #4531 of 4693
Man got so many questions don't know where to start.

Ok what is the purpose of having 2-6 dual or single opamps in the output stage of some vintage high end CDP's?

What is the best opamp for the I/V converter section of CDP's?

Although discontinued what can be a single suitable drop in replacement of a MC34072 opamp?

A dac which uses 4 LME47920's and 2 LME49710's can take dual or single OPA627's?

To be edited
Edited by DefQon - 11/20/13 at 4:55am
post #4532 of 4693

My parcel reached the main post office. May be able to try out Muses 1 and 2 this morning.

post #4533 of 4693

Could someone please suggest a quality dual channel op amp to replace the OPA2134 in my FiiO A1?  I'm looking for a slightly brighter and more lively presentation to add a little more sparkle to my Energy C-100 bookshelf speakers.

 

Thanks!

post #4534 of 4693
Quote:
Originally Posted by SoulSyde View Post
 

Could someone please suggest a quality dual channel op amp to replace the OPA2134 in my FiiO A1?  I'm looking for a slightly brighter and more lively presentation to add a little more sparkle to my Energy C-100 bookshelf speakers.

 

Thanks!

 

What do you think, guys?  

 

OPA1612?

post #4535 of 4693
LME49990 or the 49720/10's.
post #4536 of 4693

I almost said LME49990, but the OPA1612 is a little brighter, if that's what he's looking for...

post #4537 of 4693
Quote:
Originally Posted by zilch0md View Post
 

I almost said LME49990, but the OPA1612 is a little brighter, if that's what he's looking for...

 

I'm looking to add a subwoofer to my setup so bright is what I'm looking for.  Thanks for the recommendations guys.


Edited by SoulSyde - 11/21/13 at 3:50am
post #4538 of 4693

Can someone please answer my previous post if they can? Mad Max where are you?

post #4539 of 4693
Quote:
Originally Posted by DefQon View Post

Man got so many questions don't know where to start.

1) Ok what is the purpose of having 2-6 dual or single opamps in the output stage of some vintage high end CDP's?

2) What is the best opamp for the I/V converter section of CDP's?

3) Although discontinued what can be a single suitable drop in replacement of a MC34072 opamp?

4) A dac which uses 4 LME47920's and 2 LME49710's can take dual or single OPA627's?

To be edited

My understanding is limited, so I invite others to chime in, but here goes:

1) The Output stage can be thought of as your current gain stage, so op-amps with higher current outputs are preferable in the output stage and stacking them in parallel yields even more current. You can find current output specs in an opamp's data sheet (PDF).

2) The input voltage gain section is where you need to exercise more finesse in selecting an op-amp - going for the sound signature you prefer. Try the LME49990 or the more expensive MUSES02, but understand that you should really try to learn what the current opamp's specs say about supply voltage, for example. If the current opamp is designed for a 3 to 5V supply, there's no point in trying an op-amp that requires a 9 to 18V supply. It's actually quite risky just plugging in anything that fits the socket. Try to learn as much as you can about what you are replacing.

3) I don't know...

4) Find the data sheets for the LME47920 and LME49710 to confirm this, but I believe the -20 is a dual and the -10 is a single.

Mike
post #4540 of 4693
Quote:
Originally Posted by zilch0md View Post


My understanding is limited, so I invite others to chime in, but here goes:

1) The Output stage can be thought of as your current gain stage, so op-amps with higher current outputs are preferable in the output stage and stacking them in parallel yields even more current. You can find current output specs in an opamp's data sheet (PDF).

2) The input voltage gain section is where you need to exercise more finesse in selecting an op-amp - going for the sound signature you prefer. Try the LME49990 or the more expensive MUSES02, but understand that you should really try to learn what the current opamp's specs say about supply voltage, for example. If the current opamp is designed for a 3 to 5V supply, there's no point in trying an op-amp that requires a 9 to 18V supply. It's actually quite risky just plugging in anything that fits the socket. Try to learn as much as you can about what you are replacing.

3) I don't know...

4) Find the data sheets for the LME47920 and LME49710 to confirm this, but I believe the -20 is a dual and the -10 is a single.

Mike

 

Thanks for that Mike, appreciate the effort in your response. 

 

I've measured the points in my CDP where I've taken out the existing BB OPA2132 opamps and it's around 14vdc one of the points and another 5v. I think throwing in a OPA627 should be ok.

 

So from what I understand the I/V converter stage needs a good detail, revealing or neutral opamp, where as the opamps for the analog outputs in the output stage can be rolled for whatever flavor in sound you want?

 

I've always confused dual and single opamps, by single I'm assuming single mono like a SOIC8 627? And dual is stereo is in other words 2 mono opamps in a single DIP8 package?

post #4541 of 4693

Muses 01 is huge in soundstage and a lot more neutral compared to 02. I am liking it a lot more. Whole day I am listening to same collection and rediscovering everything on a whole new level.

 

Will try to spend more time listening to Muses 02 but Muses 01 has the WOW factor I was looking for.

post #4542 of 4693
I can tell from my experiments with the iBasso PB2 that buffers (opamps in the output stage) certainly influence the sound signature, just as the I/V opamps do, but you want to concentrate on selecting opamps that put out a lot of mA (output current spec) here in the output stage, where the output current spec doesn't matter so much in the input voltage gain stage - where you can play with a wider selection of opamps to get the sound you want (without concern for their output current specs).

This is my understanding, at least, and I remain ever-ready to be corrected if someone wants to educate me. :-)
post #4543 of 4693
Quote:
Originally Posted by DefQon View Post

Man got so many questions don't know where to start.

Ok what is the purpose of having 2-6 dual or single opamps in the output stage of some vintage high end CDP's?

What is the best opamp for the I/V converter section of CDP's?

Although discontinued what can be a single suitable drop in replacement of a MC34072 opamp?

A dac which uses 4 LME47920's and 2 LME49710's can take dual or single OPA627's?

To be edited

 

really old CDP may have complicated, high order 20 kHz analog active filters for the "brick wall" reconstruction filter - needed because of low/no oversampling in the early DAC chips - before today's higher OS ratios, digital filtering

 

some may even have the RedBook deemphasis shelving filter in a op amp active filter

 

 

DAC I/V choice has many "moving parts", "best" is an engineering judgment - intelligent rolling requires taking into consideration at least  DAC chip, feedback, power supply, high frequency layout quality...

 

 

the only MC34072 "discontinued" I see are the old Pb plated parts - helps to know ON-Semi is the continuation of Motorola's analog  business and then you can see the product status, read the datasheet

 

as a 4.5 MHz bjt op amp it boasts jfet input level slew rate and a quasicomplementary output stage that swings a bit closer to the supply rails than some others of its class/generation, also has the somewhat unusually high 44 Vmax supply - check the ps V on the board before choosing replacements

 

but its input V noise is horrible so any jfet input op amp beats there while matching the slew rate, more modern outputs in "isolated" semi processes with good npn/pnp speed matching are easily better today if designed for low output distortion

 

"better" modern chips shouldn't be hard to find on all specs - just don't go crazy on GBW - I wouldn't recommend more than double the speed without an oscilloscope fast enough to see any possible oscillations in the replacement


Edited by jcx - 11/21/13 at 11:52am
post #4544 of 4693

Can you guys check my understanding of my Op-Amps and Adapters with the orientation on the PCB socket (Creative ZXR)?

 

This is how I think it is supposed to go:

 

http://cdn.overclock.net/3/36/900x900px-LL-3645296d_ZXR-Op-Amps-Decoded.jpeg

 

(Red = Pin 1 Location
Green = TO-99 Key Orientation)

 

So for a normal Op-Amp the circle or indention goes towards the half moon/cut out of the PCB socket. For the TO-99 style like the OPA627SM and the adapters above the metal tab will go on the same side as the half moon/cut out PCB socket due to the tab key being in the same direction as the pin 1 white circle indication.  The MUSES01 will obviously go with the indention towards the cut-out end of the PCB socket.

 

Besides the MUSES01 and 2x OPA627SM I am also using a Dual DIP8 to Single DIP8 adapter for the rear channel (or maybe the center/sub depending on the MUSES01 performance) so that I can utilize the LM49710's for the rears.  So my total 5.1 setup will go like this.

 

Fronts: OPA627SM

Center/Sub: MUSES01

Rears: 2x LM49710's

 

Can I get verification I have the above right on  the orientation and any opinions?  BTW I did not pay outrageous prices from Digikey or Mouser's, I used Ebay and I am waiting the 10 or so days for this stuff to arrive.  Prices were as follows (this includes shipping):

 

MUSES01: $32.99

OPA627SM (pair): $28.60

Adapters: ~$17.00 (I went with high quality 2oz copper adapters) 

-----------------------------------------

Total: $78.59, around the price of a single MUSES01 from DigiKey

 

Here are the adapters I went with, Single DIP8 to Dual DIP8: http://www.ebay.com/itm/170921295768?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

TO-99 to DIP8 (2x): http://www.ebay.com/itm/181236559628?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


Edited by NCSUZoSo - 11/21/13 at 8:07pm
post #4545 of 4693

I found OPA627 to be more thick sounding and colored compared to MUSES 01.

 

Right now main amp section uses MUSES 01 and output stage has AD8620. OPA627 takes up the EQ stage which can be bypassed.

 

So far, the best combination I have heard. MUSES 02 goes into the bag.

 

Thinking of ordering 2 more MUSES 01 from same ebay seller just in case the price increases.

 

@ gibosi, thanks for the ebay link.

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