BrownDog 4739 Adapter

Almost1

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#1
I restored my dad's original 2000 II with the BD 4136 adapter and OPA2134's fitted along with new muse caps and it sounds fantastic!! I left the 4739 alone since there was nothing viable at the time. FF to now, I have a 4000 II I bought with one dead channel that I'm tracing down to possibly a dead 4739. I've read that someone here has used it though I don't know which amp(s) were tried, but there are mostly the same amp options as the 4136 adapter. What are the considerations when selecting an amp for the 4739, and has anyone had any luck with replacing with one of them with one from BD?
 

laatsch55

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#2
I know in the 2ooo, replacing the 4739 with the Browndog/2134 option may cause oscillations. We're gonna find out for sure this weekend.
I could not say about the 4000 application. Perhaps Joe will chime in...
 

mlucitt

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#3
I know in the 2000, replacing the 4739 with the Browndog/2134 option may cause oscillations.
The Browndog/2134, SKU 1016J ($20.00), is a perfect upgrade to the Z3 RC4136 Quad OPAMP.
PL installed a 350pf cap above the Z1 RC4739 OPAMP to control the overshoot and end the ringing. You can safely put a Browndog/2134, SKU 1025G ($11.50) there. I opted to leave the Z2 4739 in my PL2000 because it only sends signals to the rear channels, which I don't use.
In the PL4000, the audio signal is processed first then amplified in the 4-channel Logic Amp. This board uses discrete transistors GES 97 and TIS 93 in each channel instead of an OPAMP.
WOPL Sniffer can chime in here, he knows about the PL4000 like I wish I did.
 

WOPL Sniffer

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#4
I think the Brown Dog and the associated Opamp is Hype, expensive, time consuming and using bypass cap to eliminate the above issues mandatory. Myself and Grapplesaw documented this quite a while back. Installing these caused havoc in a preamp I was upgrading for a customer. As Mark said, overshoot and ringing was the order of the day. There is like 30 of these in the 4000/4000t and besides the cost of the adaptor and chip (I have about 50 I put back in the box and said to hell with it), the time involved in making them useable, I used the TI RC4136's available from Mouser "Same Day Shipping, No Minimum Order" all for the princely sum of $1.47

The preamp quit acting stupid and I saved a lot of time and headache, not to mention saved money for a couple cases of Hauenstein beer in the process. Best part about it? I was able to get excellent numbers (noise wise), and all was good. Save your money..... Now I order RC4136's by the tube and never looked back. Bob Carver used the shit outta these and he's Mr. Gadget............


https://www.mouser.com/Search/Refin...GGL4R-AOxHe1D9FVmguzEMouZv4npovsaAhRvEALw_wcB
 

Almost1

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#5
Thank you all for the insight!

WOPL just for clarification, you use the RC4136's to replace the original 4136's and not the 4739's correct? Are the pin configurations the same?
 

Gepetto

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#8
If you purchase a blank DIP header it will allow you to swizzle the pins on an RC4559 (which is readily available) to match the unique pinout of the RC4739, you will be able to get an equivalent to the original RC4739 device.

Use a fork DIP header something like this. I used to be able to get the old school phenolic header base instead of this plastic one. The phenolic header was heat resistant to the soldering operations and were more robust.

Aries Electronics 14-600-11

You can also swizzle an OPA2134 although not quite as low noise as the RC4559. The best devices are only offered in SMT packages these days so it makes it more difficult to take advantage of these more modern devices.
 
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mlucitt

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#9
Are the pin configurations the same?[/QUOTE said:
They are not the same pinouts. The 4136 Quad OpAMP gets its + and - power on pins 11 and 7 respectfully (all pins used). The obsolete 4739 Dual OpAMP gets its + and - power on pins 14 and 7 respectfully (pins 2, 3, 4 and 10, 11, 12 have no connection).
 
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