Hi all
I've been slowly recapping and modding my Soundcraft 1600 console, and have some interesting measurement results I thought I'd share.
I have done all mods in sets of two channel strips, and measured the results with a MOTU 828mk3 interface using Room EQ Wizard.
By far the biggest sound improvement was recapping the power supply. Do this first if you're recapping an old console for sure! Also I would recommend to replace any TO-3 transistor sockets, I had one that was on the way out (weak contact pressure on the pins) and might not have noticed if I hadn't specifically looked at the socket. The sound improvement was noticeably tighter bottom end throughout.
I haven't been able to hear any improvement in sound with any opamp swaps.
Mods done to channel strips are:
* Recapped electros with Panasonic FC (Green traces)
* Recapped with Pana FC, and also recapped film caps with WIMA FKP2 (Blue traces) Some values are not available so used other brand of non-metallized film cap for those
* Recapped with Pana FC, and swapped out input transistors with ZTX951 (Orange traces)
The red traces are an unmodded channel strip with original 80's components.


where can i upload my pictures online
As you can see, recapping gave me back my bottom end, and everything was calibrated to within 0.1dB when making measurements.
The distortion figures are pretty interesting. Going to Panasonic FCs gave a good reduction in distortion over stock, until we get to the top end which is actually a bit worse.
But recapping the old films to new WIMA films gave a massive improvement, which is pretty audible. It actually IS worth recapping those old film caps in this case.
It looks like while the ZTX transistors have lower noise than the 2N4401 stock, they are a bit more distorty in this circuit.
Hope this helps someone! I'll post the actual cap values I used when I get a chance; I collated several old threads from many sources and ended up with some solid recommendations that improved bottom end response, as shown above. (Edit: see post #140)
Cheers
Darren
I've been slowly recapping and modding my Soundcraft 1600 console, and have some interesting measurement results I thought I'd share.
I have done all mods in sets of two channel strips, and measured the results with a MOTU 828mk3 interface using Room EQ Wizard.
By far the biggest sound improvement was recapping the power supply. Do this first if you're recapping an old console for sure! Also I would recommend to replace any TO-3 transistor sockets, I had one that was on the way out (weak contact pressure on the pins) and might not have noticed if I hadn't specifically looked at the socket. The sound improvement was noticeably tighter bottom end throughout.
I haven't been able to hear any improvement in sound with any opamp swaps.
Mods done to channel strips are:
* Recapped electros with Panasonic FC (Green traces)
* Recapped with Pana FC, and also recapped film caps with WIMA FKP2 (Blue traces) Some values are not available so used other brand of non-metallized film cap for those
* Recapped with Pana FC, and swapped out input transistors with ZTX951 (Orange traces)
The red traces are an unmodded channel strip with original 80's components.


where can i upload my pictures online
As you can see, recapping gave me back my bottom end, and everything was calibrated to within 0.1dB when making measurements.
The distortion figures are pretty interesting. Going to Panasonic FCs gave a good reduction in distortion over stock, until we get to the top end which is actually a bit worse.
But recapping the old films to new WIMA films gave a massive improvement, which is pretty audible. It actually IS worth recapping those old film caps in this case.
It looks like while the ZTX transistors have lower noise than the 2N4401 stock, they are a bit more distorty in this circuit.
Hope this helps someone! I'll post the actual cap values I used when I get a chance; I collated several old threads from many sources and ended up with some solid recommendations that improved bottom end response, as shown above. (Edit: see post #140)
Cheers
Darren
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