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Analog mixing desk - Soundcraft series two
Old 15th October 2014
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Analog mixing desk - Soundcraft series two

Hi, I'm new here and I have a request.
I recently bought a Soundcraft 16/08 series II (early 70's). It's a beautiful one but it needs some repair (some knobs, potentiometers, XLR-s are missing or broken).
Does anyone have such mixer to sell for parts? Please let me know ([email protected]).
What I need most is the power supply. I wouldn't expect to get an original one but I'm going to order a new replacement. Could anyone give me full parameters of it (power supply)? I know it's 40V DC + 48V for "phantom". How many Ampers and Hzs does it need? Any other details do I need know to make it work with no surprises? Greetings from Poland. Tomek
Old 10th January 2015
I believe you are good with 40 +/- 1 volt.
I know that when touring bands used them in the 70s they could strap 3 car batteries together to power the concert and it would sound fine. Which I think is 39.1 volts.
When that power supply went bad,...actually it was usually just a solder joint or two. I don't believe it was ever actually a failed component (I've had one for 30 years or more).
I would suggest checking your solder joints. Then buying a VARIABLE bench power supply off ebay. I did this for power once when I thought mine had failed. I just bought a PSU that an electronics technitian would have around. made sure it was overkill. Set it for 40 volts and it was fine. You can probably find one for forty least you could in those days. But you want a real PSU, I don't think you will want a swiching power supply...which I think maybe they might use for some things nowadays. Also, The old crown amps would do direct current. So if you bought a DC300, and fed it with a battery on the input, you could use one of the outputs after you set it to 40 volts. You would just need a VOM to check your voltage,...and then tape or glue the knob in place. I have moved recently and I do not yet know where are my manuals are, but I do have a manual for that. Also, I'll bet you a million bucks if you call Harmon/JBL in northridge, CA (I think they still own soundcraft) they will email you an owners manual. I got mine from them when I lived down there...they were awfully easy to deal with once I got them on the phone. If you are in So.Cal ever. Just go to san fernando valley, go west on Roscoe from where the 405 freeway intersects Roscoe, then in about a mile turn Right on Balboa.....and Harmon International is on your right within a mile...can't miss it.
Old 12th January 2015
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This was my problem with a Soundcraft Series One. Same rail V+

But before we get into that, get the manual here:

Soundcraft - [Products]

That's the original with the schematics and everything. I know this console well, I mixed on one and tech'd it for years - very cool, except ..... in addition to PSU-age, you'll need to recap the channels/groups/OPs and replace the transistors too. Also, it's a good idea to change the op-amps for something a little more contemporary, like a JFET lo-noise audio IC.

I copy here from my Tape Op request for help for PSU-age for my Series 1

"40V is a somewhat irregular value.
A good option would be to find a 48V Power One linear series, and adjust the trimpot downwards to 40V. They turn up on Ebay regularly.
Relevant part numbers are:
The number between the hyphens is the amperage rating."

This is the one I got:
Analog mixing desk - Soundcraft series twoPower One HE48 4 A Power Supply Used | eBay

After I adjusted the voltage down to +40 V (easy tweak!), it transformed the Series 1 from a vintage noise machine into a real console with headroom! But try rebuilding your own first, I'd say. Those Power One's are steady! It stays on 40 and does not move!

I would also contact Soundcraft re spares first - you never know, they might have some. I gave my Series One a full refader and they had the exact size!
Old 14th January 2015
I looked at mine and near the fuse it says 2.1 amp. So I'm guessing you need something rated at 2 amps or more. +40 is an odd voltage I agree. But if you get everything going going well you won't believe the headroom you have.
Old 14th January 2015
Gear Maniac

CFB4, why do you say the transistors need to be replaced?
Old 15th January 2015
You don't necessarily have to replace the transistors. Just depends. I've heard a lot of arguements either way. Maybe there were different batches or something. If yours has sweeps, you'll have ic's in the sweep section. And I've heard arguements either way on that one also. The original 1970s soundcrafts are rare , especially nowadays, it's hard for a person to say...well, I've heard a lot of them and can tell you that they all will improve with new ic's, etc.,
Mine has sat in it's case for ten or fifteen years, it's been a long time and I am not about to fire it up right now and venture a super current opinion. But last time I used it there would have been no point in replacing stuff. Soundwise, it was all I needed or wanted (but for bells and whistles, I could give you a long list of what I would like). So I was good with that,..Most stuff I remember being involved with was API, some Neoteks, a crapload of 80b consoles, even a Trident DIAN board at one time (think it was one of two in the world), and only a couple neve's.
If my noise floor is not horrible, and wrecking everything in point.
Maybe to make my point I'll just say,...there are all these newbies in the business last 20 years,...and they will badmouth something just because they know a lot of mixing desks with a lower noise floor (etc., etc.,)..when they really have NO IDEA, what a wayyyy coooool studio or mix sounds like. I mean, they'll whine about a noise floor and then forget that half of the stuff they have in their VERY OWN studio has tubes...which really have a pretty bad noise floor compared to anything transistor. Anybody who's played a Super Lead Marshall or DR103 Hiwatt (turned up to 11) knows that part of the equation is noise. (Usually so much noise that your mixing desks noise is really not something you need on the priority list. But somehow, if they are in front of you, are not about to grab your modeler????? It's like margarine vs. butter. They are both oK to anyone who's never tasted butter,...but once the butter is tasted, the cat is out of the bag.

Get your SERIES II powered up and see how it does first. Then move on from there.
Old 3rd June 2017
Gear Nut
Beefyblue's Avatar
An old thread I know! But we have a 70s 16/8 Series II coming our way. I know it's got the transformer coupled pres, but not sure which version of the eq it is yet. I was just wondering if anyone had any info on the monitor section of the desk. Was trying to work out if we'd need to buy a stand alone monitor controller if it's not up to scratch.

We're currently using a Focusrite C2802 to run some M&Ks with sub, NS10s and an Auratone.
Old 15th January 2019
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Trying to start an instagram group for Series II owners/fans. @ Soundcraft seriestwo

@ Soundcraft seriestwo

Last edited by BobbyButterfield; 15th January 2019 at 05:27 PM.. Reason: Linked my words out of context
Old 15th January 2019
I recently rebuilt a series II input that had issues. The transistor preamp was redone with low noise transistors. That worked out vey well. The quad opamps were replaced with NOS LME49740NA. The rail spit caps were also replaced.
Turns out it had bad trim pots in the EQ. The wipers had poor connections.
Old 16th August 2019
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Hi, a question about Series Two channel upgrades. On the swept 'IC' version, what is a good replacement these days for the 741 Op Amps. I have two Series Twos here that I'm about to refurb!
Cheers, Rich
Old 17th August 2019
OPA1641 is the easiest single package opamp to use. SOIC only like all the good stuff. You may need a feedback cap where missing and some local psu bypass caps.
Old 19th August 2019
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Thanks Jim, I'll buy a few adapters and audition!
Old 20th December 2019
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First of all I would like to express my gratitude to all of you that generously share your time and knowledge to this great community.

I have recently purchased a Soundcraft Series Two which definitely needs some tlc. Although I have been involved with quite a few hardware gear over the years, including some medium to large scale mixing desks, I have never had the chance, or time, to practically involve with electronics at least in the experienced level that this thread's users are.

Therefore, the desk is going to the hands of a fellow engineer who will help with the restoration process. To begin with, I have disassembled the last four channels that have the swept IC eq (red knobs).

Any rough suggestions you might have in changing the caps, op amps, psu etc. so I could buy the parts and pass any info to my fellow engineer? What could be the sound result when installing the OPA1641 as has been suggested by Jim? How far or close is the sound of a modded Series Two compared to a modded Delta?

I will post some pics of the desk soon.

Hope I didn't bore you with my long post..
Thanks for your time.

P. S.
I have tried to contact Soundcraft twice, asking for any kind of info they might have (manual, schematics, product info etc.) but I have received no answer from them. I would be grateful If anyone would like to share anything that might help.
Old 20th December 2019
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Here are a few photos of the board:
Attached Thumbnails
Analog mixing desk - Soundcraft series two-5.jpg   Analog mixing desk - Soundcraft series two-4.jpg   Analog mixing desk - Soundcraft series two-3.jpg   Analog mixing desk - Soundcraft series two-2.jpg   Analog mixing desk - Soundcraft series two-1.jpg  

Analog mixing desk - Soundcraft series two-2.jpg   Analog mixing desk - Soundcraft series two-3.jpg  
Old 31st December 2019
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I too am working on a Series Two.

First thing is the Power Supply. Four bigger caps. Then check all the transistors.
Mine is problematic as it was rebuilt at some point and is/was running on 35v.
Yours should ideally have 40v across output pins 3 and 4.

I have pulled every card. Cleaned all pots and faders. That alone takes a good while.
These cards were nasty. The bottom cover of the console is gone, so it has had a lot of exposure.
I fully recapped (electrolytic) 4 channels. The other twelve I just did the bigger caps.
I just wanted to get on with seeing if this thing is worth keeping.
I’ll go back and get picky if this console holds up.
I also recapped the Echo, output, and busses.

For awhile I had some popping in the line/mic switch of a channel. It also was a little screwy otherwise.
A friend suggested a leaking cap. As I had replaced everything electrolytic, I checked out the tantalum as they are directly in the preamp path.
These are wildly out of spec and seemed bad. I know folks say they don’t go bad and never change them in a Neve etc. That’s probably usually true.
Just keep it in mind.

Your console has obviously been customized a bit and luckily has a simpler EQ, although the low end looks custom to me.
Mine has the full sweep EQ. It’s a bit screwy and pointy but works well if you are judicious. I don’t imagine matching channels quickly but I would probably just use outboard or plugs. The good thing is that there is an off switch for the EQ. I plan to use that.
That said, the filters are great. Very extreme. They might come in handy.

A couple of oddities I discovered:
Unity level through the busses to the Remix is only achieved by having the bus faders full up! Not sure about this yet.
The Remix button on the channel bypasses the bus buttons. Might need to change that for parallel purposes.
The busses do not have inserts. That’s not odd but it is something I would really want to have if I was going to mix with this thing. It looks easy enough to grab the signal before the fader. I have not tried this yet. I’m planning to test inserts with and without transformers.
The busses also do not have mute switches. It might be worth adding to keep garbage out of the Remix.

The basic size and form of the board is really great. P&G faders helps a good deal to start.
The preamps seem fine. To what degree they ‘compete’ with others I don’t know yet. There’s sixteen!
For modern summing/stem mixing it should be excellent, if it holds up.

I mainly worry about the pots going bad and/or needing constant cleaning.

I would be interested to hear of others findings! Anyone?

BTW I do have a manual with schematic. PM me and I’ll try and get it to you.

Old 1st January 2020
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Have you got the original manual that was supplied with the desk? It was probably me who tested the desk.

Last edited by Ade65; 1st January 2020 at 10:03 PM.. Reason: added text
Old 3rd January 2020
A 40 volt supply is too high for the 072 opamps that are limited to + - 18 volts. 35 volts is safer and longer lasting. Each opamp uses a voltage divider to split the rails. Those rail splitter caps usually need replacements as do the trimpots in the sweep EQ. I've used low noise LME opamps in those and it made the console silent.
Old 4th January 2020
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I only have a PDF.
A couple of pages are missing but it’s mostly readable.
Old 4th January 2020
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I have just found a set of series ll and series 1s schematics, also found schematic for the EX4S crossover.
Got a pic somewhere of me testing a series ll at Sutton Street, also got some pics of the last ever series ll desk that was built and not by Soundcraft, I acquired all of the old series ll parts and built a custom 32 channel desk for a studio in south London
Old 4th January 2020
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When replacing components be aware that some of the pcbs were double sided but not plated through holes so make sure that you solder the component leg on both sides where applicable. The box type silver capacitors made by Siemens are sometimes top soldered but be very careful not to overheat these.
Old 6th January 2020
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Happy new year to all!
Thank you all once again for keeping this thread alive.

John, I really appreciate taking the time to share your experience and advise! I will definitely PM you for the manual and/or schematics as this will be of great help!

As I said before I am no expert in the electronics so any parts needed I will have to order myself and pass it to someone else for fixing/changing.
Considering this, could you guys give me any recommendation on specific parts that I should have a look at in view of the power supply and individual channels? I think that I will possibly have to order them online as it might be quite difficult to find them in my country.

John, what have you used for replacing the big psu caps and also for individual channels?

I am having second thoughts on the back of my head of swapping the Series Two with a Delta and then begin replacing stuff... Any thoughts on that? Soundwise? I know that Jim has a lot of experience with the Deltas and Soundcraft in general, I would be grateful if he could share his opinion in this.

Ade65, that sounds like a lot of work in order to build this custom desk! How would you describe the sound of the board?

Also is it safe to turn on and use the console while a few channels are disconnected?

Many thanks!
Old 6th January 2020
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By the way, I found the preamps to be quite different to what I am already using, at least at the state that the console is right now. In comparison with Soundsculptor Neve 1073 and Api 512 clones I found the Series Two to be more mid forward in tone but in a musical way, not harsh or of significant lesser quality. Maybe it could be quite useful in electric guitars or vocals / mic combo which lacks some upper mid frequencies.

Just a rough first opinion using Blue B1 and B6 capsules recording some acoustic string instruments. I am planning to make some more tests with electric bass, guitar, percussion and vocals as soon as I find some spare time.
Old 6th January 2020
Modern, low noise Japan transistors and some cap changes opens up the mic preamps and gets rid of the hiss.
Old 6th January 2020
Lives for gear
Got any suggestions for good transistors that are available these days from good distributors? I’m almost out of my stash of 80’s transistors.
Old 7th January 2020
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Hi Jim, thanks for chiming in.

Any particular brand/model of transistors and caps you would recommend for this desk in particular?

Thanks a lot!
Old 7th January 2020
Toshiba and Renesas make the lowest noise, fast bipolar transistors. Hitachi used to make them. I used Toshiba 2SC3329BL for the NPN, Renesas 2SA1084's for the PNP's. Mic preamps are then quiet and rather open sounding.
Old 8th January 2020
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Great, thanks! I'll find them online and order some to get going.

Any idea, anyone, if I can carry on working with the desk even if I have pulled out some channels?
Old 9th January 2020
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crosscutred's Avatar
Originally Posted by bagomusic View Post

Any idea, anyone, if I can carry on working with the desk even if I have pulled out some channels?
Yes, that's fine.
Old 13th January 2020
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Bago and all,
As usual, Jim W. would probably have the best idea of what parts might be best.
I’m more musician than electrician. I like to think I’m doing some badass refurb on vintage gear...until I break something, which is happening regularly on this project.
I replaced the electrolytics with Digikey stuff. No eBay NOS stuff! Bad idea.
I used mostly Panasonic caps.

A couple of notes if anyone is interested:
I have three bad meters. I’m assuming they cannot be easily repaired. Sifam IS making a replacement. I saw them at Don Audio exclusively as far as I can tell.

The more I work on this thing the more I find funny solder cracks here and there. You experts know about this. I’m just learning how to look at everything with the magnifying glass! Careful!

I bought a Power One 48v supply and dialed it back. It does inspire confidence. Something beyond me has blown the original and I’m going to have an expert get that back to spec soon. Power One also makes/made a 38.5 volt one. I imagine that would work well too.

Just thoughts...

Questions I have:

1. Anyone attempted inserts on the busses? Ideas? Think transformers are likely advised?
2. Anyone (Jim!) give me a better rundown on the bypass scenario on the opamp swaps. I’m a Luddite.
3. Is there a practical way to get the channel line inputs dead on consistent for tape returns? As in bypassing the gain knob, kind of like a slightly more modern board. I know this is a bit of a niggle but it would be nice if it was just ‘right’.
Old 13th January 2020
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crosscutred's Avatar
Originally Posted by hnbcstudios View Post
I have three bad meters. I’m assuming they cannot be easily repaired. Sifam IS making a replacement. I saw them at Don Audio exclusively as far as I can tell.
It's quite unusual for the meter itself to break (without obvious physical damage)
It might be worth checking the driver circuit before buying new meters.
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