Replacement OpAmps for Allen & Heath GL Series console

[ThePaloverdeBeetle]

Haven't done anything like this for awhile but one thing to be aware of is that the replacement op amps may draw more current than the stock ones in the board. Not a big deal for one opamp but cumulatively it may cause you problems down the line ie: a whole bunch of replacement opamps may draw more current than the power supply for the board is prepared to deliver. You can probably replace the power supply with something larger then it is also possible that the board will get considerably hotter than it originally did.

[Nick Sevilla]

Haven't done anything like this for awhile but one thing to be aware of is that the replacement op amps may draw more current than the stock ones in the board. Not a big deal for one opamp but cumulatively it may cause you problems down the line ie: a whole bunch of replacement opamps may draw more current than the power supply for the board is prepared to deliver. You can probably replace the power supply with something larger then it is also possible that the board will get considerably hotter than it originally did.

Hi,

That was one of the first things I looked for.

All three op amps I am testing in my case are rated a little below.

Cheers

[ThePaloverdeBeetle]

Whoops, sorry. I guess it's more of a concern with your typical chock full of TLo72s board of this vintage.

[Nick Sevilla]

Whoops, sorry. I guess it's more of a concern with your typical chock full of TLo72s board of this vintage.

Please use the word "vintage" more appropriately.

My console is not vintage. It is only 2.5 years old.

Cheers

[ThePaloverdeBeetle]

Ahh, again forgive me, My attention span is sometimes a little short, mostly due to lots of work and family life. I'm assuming then that A&H is still making consoles without surface mount components, good to know.
I have modded an older A&H console that is full of tlo72s to good effect. Though people seem to buy these older boards for a vintageyer sound which the tlo72s impart.

The power consumption thing is a good thing for prospective console modifiers to be aware of before jumping into a big project specifically with boards that make use of a large amount of tlo72s.

[Nick Sevilla]

Ahh, again forgive me, My attention span is sometimes a little short, mostly due to lots of work and family life. I'm assuming then that A&H is still making consoles without surface mount components, good to know.
I have modded an older A&H console that is full of tlo72s to good effect. Though people seem to buy these older boards for a vintageyer sound which the tlo72s impart.

The power consumption thing is a good thing for prospective console modifiers to be aware of before jumping into a big project specifically with boards that make use of a large amount of tlo72s.

Hi,

No problem. Sorry for bringing out that misuse of the word...

Anyways, this console of mine, is a GL-2800-32, which has from the factory, TL072 opamps, 5532DD opamps, and also some surface mount components, mostly in the master sections, and a little on the stereo channels.

Surprisingly the mono channels are pretty much all through hole construction, which is great for modifications.

Right now I am finishing a 24 hour burn in on the new opamps for the two test channels, and then I will start the laborious process of doing an oscilloscope comparison at key test points on the circuit, specifically around the places where I have replaced opamps.

So far I have left the TL072 opamps in, and only replaced the three 5532s.

Later on I will switch this around, and ultimately do a test where I do replacement of only one opamp, and other wild combinations, until I find the optimal place to start.

Then I'll look at what other components might need replacement to optimize the new configuration.

So far, there are not so subtle differences with two of the opamps I chose to test, but until I fiddle around some more, I cannot possibly quantify what is going on, and then put that to simple words for anyone to understand.

In the end I am looking to make the board more accurate, for recording. If I want a "vintage"(sic) sound, I do have outboard mic preamps.

It's just that having 32 channels in front of me, I do want those to be clear and accurate, so when I decide to mangle a sound, it will be easier, knowing what the console is and is not doing precisely to the sound.

Cheers

[Nick Sevilla]

Update :

Some pictures of the innards of the beast, showing the new op amp sockets :









Cheers

[Andy Peters]

... then I will start the laborious process of doing an oscilloscope comparison at key test points on the circuit, specifically around the places where I have replaced opamps.

When you do this, be absolutely sure that your 'scope probe ground is connected to a point very near where you're measuring. Connecting it on the next board or to the chassis isn't correct.

This is especially important if you're hunting for high-frequency oscillation.

-a

[Nick Sevilla]

... then I will start the laborious process of doing an oscilloscope comparison at key test points on the circuit, specifically around the places where I have replaced opamps.

When you do this, be absolutely sure that your 'scope probe ground is connected to a point very near where you're measuring. Connecting it on the next board or to the chassis isn't correct.

This is especially important if you're hunting for high-frequency oscillation.

-a

Thanks Andy, I will do so.

[Brian]

Merry Xmas! FYI, I'm watching this thread with anticipation, having modded my board with OPA2134's and AD797's, looking into the mastering section for LME49720's.
I also just got my hands on 10 UTC H100X trannies and might mod a few channels or the master out my board with those and switches to insert them or pull them out.
Muwah ah ah, ah ah. Just thought I'd mess with your head while you could still pull it off yerself, Nick.

Happy holiday,
Brian.

[calaverasgrandes]

I picked up some TI opamps recently as well, damn tiny form factor!
Where did you get the tiny to small dip adapter? frys?

[Nick Sevilla]

I picked up some TI opamps recently as well, damn tiny form factor!
Where did you get the tiny to small dip adapter? frys?

http://cimarrontechnology.com/surfacemountadapters.aspx

I bought them here. Not cheap, but correct pinouts.

I am installing the surface mount ones this week, and testing further.

Cheers

[calaverasgrandes]

Wizard! They even have the dip to sip adapters I would need to mod my PM180 to more modern opamps. I was thinking about attempting a homebrew adapter but shoot $3 is cheap compared to how much time I would spend cursing at tiny wires and heatshrink tubing. besides the free op amp samples from TI makes up fro buying adapters to fit them. It seems the free sample program doesnt extend to hobbyist friendly full size dips.

[Brian]

Check ebay, you can get adapters there too, maybe cheaper, but, since you know what you're looking for, I'm sure you're fine.

[Nick Sevilla]

Wizard! They even have the dip to sip adapters I would need to mod my PM180 to more modern opamps. I was thinking about attempting a homebrew adapter but shoot $3 is cheap compared to how much time I would spend cursing at tiny wires and heatshrink tubing. besides the free op amp samples from TI makes up fro buying adapters to fit them. It seems the free sample program doesnt extend to hobbyist friendly full size dips.

This case, it is better NOT to skimp on these components. Get the best you can afford. It pays to think more $ is better, because, generally in these situations, it is true.

Or fry your board.

Happy New Year!!!