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Old 17th August 2007, 08:02 PM   #1
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Default swapping BA4560 in phono pre

New member here with a question:

I am looking to mod my Bellari VP129 hybrid phono preamplifier. The four stock IC chips are BA4560s. I have a few ICs on hand that I'm inclined to swap out the BA4560s for:
1 Audiocom AD825
3 LM4562s

FWIW, I also have these:
2 OPA2134PA
1 OPA2228P
1 AD826ANZ
1 AD827JNZ

I may only swap out for the last two IC positions (assuming their numbering corresponds to circuit order).

My question is this: Is the AD825 or LM4562 suitable where a BA4560 is being used?
If so, will this affect my choices when I decide to tube roll (there's one 12AX7 in the circuit)?
I understand that maybe only those familiar with the Bellari VP129 may be able to answer this.

I wish I could bring more information to the table here, but I am still teaching myself the fundamentals of electron flow and have a far way to go before I can more thoroughly understand IC technology.
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Old 12th May 2008, 12:27 AM   #2
faxurda is offline faxurda  Canada
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Did you try this oamp swap? I whant to swap the ba4560 for LM4562.
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Old 12th May 2008, 07:50 PM   #3
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Unfortunately, no. I can't really read tech sheets for opamps (yet), so I will only swap when: a) someone who understands the technicals tells me it will be fine, or b) another person has already tried it in the same circuit safely.

I'm currently over-building The Ripper phono-pre kit Jim Hagerman designed. It employs six op amps, does ADC/DAC via USB (for ripping vinyl to digital and converting digital back to analog) and has a heaphone output. I also suspect the RIAA EQ is probably better than the Bellari's, based off Jim's extensive research on the evolution of the RIAA curve. If you're curious, you can see my progress with this project here.

-Brinkman

p.s.- I just now realized that when I started this topic, months ago, I did so in the wrong subforum. That would probably explain the lack of responses.
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Old 14th May 2008, 05:52 AM   #4
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Hi,

I have been involved in audio equipment repairs for many years and i have come across the BA4560 integrated circuit in many items .

I have successfully replaced it with the NJM4558 or BA4558 Integrated Circuit and it worked perfectly without any problems.

Hope this information would be helpful to you. Please feel free to contact me if you need further assistance

With Regards,

Edmund
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Old 14th May 2008, 06:35 AM   #5
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BA4560s is slightly better than the well-known 741, ancient design but you can also replace it with almost anything.

LME49720 is an extremely good choice but those are also good

AD8620
OPA2227
OPA2228 if gian is more than 5
OPA2134
NE5532

and many more. Check for a dual opamp with standard pin configuration.
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Old 14th May 2008, 11:44 AM   #6
faxurda is offline faxurda  Canada
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Thank to every one.. I will give a try this week-end ...
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Old 24th May 2008, 05:25 AM   #7
faxurda is offline faxurda  Canada
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I put inplace the LM4562NA in UA3 and UA4 (see the schematic) First impression was super but in High volume I hear an hhhhhh sound... not the ground sound.

And I also try to put in u1a and u2a position but I got no sound...

For the moment I got on and 2 lm4562na and the original ba4560.

Do i need change someting to the design ? or try different opamp?

http://avforum.no/forum/attachments/...lari-vp129.pdf
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Old 13th August 2008, 02:10 PM   #8
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At what point does the "hhhhhhh..." become audible; when the gain is all the way? 2/3 way?

Do you think the noise may be tube microphonics or power supply noise? Try rolling a different 12AX7... if it doesn't go away, go back to the 4560s and see what happens.

I will likely install IC sockets in the U3 and U4 positions to help with chip rolling. It looks like these dual op amps are buffers for both the RCA and headphone outputs, right and left channels, respectively. The first two chip positions are for the EQ and should probably stay stock.

Either way, let us know how you're progressing.
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Old 27th November 2008, 03:59 PM   #9
faxurda is offline faxurda  Canada
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I fixed the hhhh problem .. I put capacitor on op amp power.
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Old 11th January 2009, 01:47 AM   #10
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Quote:
Originally posted by impactzone
Hi, I have been involved in audio equipment repairs for many years and i have come across the BA4560 integrated circuit in many items .

I have successfully replaced it with the NJM4558 or BA4558 Integrated Circuit and it worked perfectly without any problems.
I would like to point out that according to the data sheet the BA4560 supplants the 4558 chips with better specs like output current, slew rate, frequency bandwidth etc...

So while these chips can be interchanged, there technically should be a *degradation* in the phono preamp when going 4560 to a 4558. If you are going to the trouble to tweak your phono preamp to get better sound, it seems to me looking for a better replacement op amp is a good idea.
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