Meridian 508.24 - modding opamps

recstar24 · 31st March 2010, 01:13 PM

I have tried finding info regarding modding the opamps that are in the 508.24 but found only limited info. I have not popped the top yet, but believe that there are 4 NE5534's, of which two are used for summing the balanced out from the DACS to the single ended output, and the other two are used for the I/V conversion. That is just a hunch, but if anyone had a schematic or knowledge regarding the matter I would appreciate it.

EUVL · 04:44 AM

I have a schematics. You may try to ask Meridian for one if you are an owner with serial number and registered with them.

The opamps are NE5534 (at least on mine).
I have tried OPA627 (sounds good but supply voltage is too low for the 627s), am currently using OPA727 (more suited for +/-5V), and shall be swapping them for LT6230 soon, but need to etch a special adaptor board first.

If you want to try the same, you may get 4 Bungard boards from me at a nominal cost. Send me a PM.
LT6230 you can get from Digikey.

Patrick

EUVL · 1st April 2010, 04:49 AM

Incidentally I also tried increasing the bias of the output transistors, but this made little or no difference, so I went back to the original circuit in the end. But the opamps has been staying there for 3 years now, until I found the LT6230.

Patrick

livemore · 24th February 2011, 05:38 PM

Quote:

Originally Posted by EUVL

Incidentally I also tried increasing the bias of the output transistors, but this made little or no difference, so I went back to the original circuit in the end. But the opamps has been staying there for 3 years now, until I found the LT6230.

Patrick

LT6230 until forever???

EUVL · 24th February 2011, 07:36 PM

Till now yes.

Patrick

livemore · 25th February 2011, 02:27 AM

Quote:

Originally Posted by EUVL

Till now yes.

Patrick

thank you very much!

livemore · 25th February 2011, 02:29 AM

Quote:

Originally Posted by EUVL

Till now yes.

Patrick

have a your 508 mods pic?

EUVL · 25th February 2011, 03:33 AM

No, but it is just replaced opamps.
I have a few spare PCBs if you want to try.

Patrick

livemore · 25th February 2011, 04:12 AM

i seen your email.
thank very much

EUVL · 09:41 AM

As promised some pictures of the opamp adaptors.
A skilled DIYer would have no problem making the same for himself.

(PS The LT-Chip should face downwards towards the Meridian PCB.
....The "closed holes" have pins to replace connections for the DIP-8 Opamp.)

Regards,
Patrick

.

31st March 2010, 01:13 PM	#1
recstar24 diyAudio Member Join Date: Nov 2008	Meridian 508.24 - modding opamps I have tried finding info regarding modding the opamps that are in the 508.24 but found only limited info. I have not popped the top yet, but believe that there are 4 NE5534's, of which two are used for summing the balanced out from the DACS to the single ended output, and the other two are used for the I/V conversion. That is just a hunch, but if anyone had a schematic or knowledge regarding the matter I would appreciate it.

1st April 2010, 04:41 AM	#2
EUVL diyAudio Member Join Date: Oct 2003	I have a schematics. You may try to ask Meridian for one if you are an owner with serial number and registered with them. The opamps are NE5534 (at least on mine). I have tried OPA627 (sounds good but supply voltage is too low for the 627s), am currently using OPA727 (more suited for +/-5V), and shall be swapping them for LT6230 soon, but need to etch a special adaptor board first. If you want to try the same, you may get 4 Bungard boards from me at a nominal cost. Send me a PM. LT6230 you can get from Digikey. Patrick Last edited by EUVL; 1st April 2010 at 04:44 AM.

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1st April 2010, 04:49 AM	#3
EUVL diyAudio Member Join Date: Oct 2003	Incidentally I also tried increasing the bias of the output transistors, but this made little or no difference, so I went back to the original circuit in the end. But the opamps has been staying there for 3 years now, until I found the LT6230. Patrick

24th February 2011, 07:36 PM	#5
EUVL diyAudio Member Join Date: Oct 2003	Till now yes. Patrick

25th February 2011, 03:33 AM	#8
EUVL diyAudio Member Join Date: Oct 2003	No, but it is just replaced opamps. I have a few spare PCBs if you want to try. Patrick

25th February 2011, 04:12 AM	#9
livemore diyAudio Member Join Date: Feb 2011	i seen your email. thank very much

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