Soundcraft 800b/1600 & Soundcraft 2400 Micpre & EQ

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Laska

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I've laid my hands on one of these ole beasties & intend to refurbish & maybe upgrade some of the componentry & I'm looking for some new ideas please.
I need some space to host the input strip schematic before I continue......any offers ?
Thread update 8/11/04:
Frank aka nrgrecording has come up with PCB designs for a rack style 2400 preamp & eq!

Regards,
Tom
 

gyraf

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Hi Tom,

Why not get your own free 25MB photobucket.com account?

http://photobucket.com/register.php

Jakob E.
 

Laska

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Thanks Gyraf,

From Photobucket Site:
"Over the next few weeks we will be upgrading our infrastructure to better serve our users.
Therefore we are currently accepting new "free" accounts between 11am-1pm and 11pm-1am mst!

The current time is 2:53 am mst "

Missed out by 1 hour 53 minutes :roll:

By the way; back over on the " Littleweed & Skinny Roadshow" I posted many items & enjoyed so many more in TT...any archives floating around ?

Regards,
Tom
 

gyraf

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I just remembered - we have our "own" GroupDIY image upload section now:

http://groupdiy.twin-x.com/index.php

Jakob E.
 

Laska

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Trying to figure it out (how to upload file) ...I think the year off the net has made me a tad "innorant"!
Tom
 

Laska

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Tried to upload file to this site: http://groupdiy.twin-x.com/upload.php
& received this message ?

"Sorry there is no album where you are allowed to upload files"

What am I missing?

Regards,
Tom
 

Laska

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I would appreciate it if someone could give the schem the onceover & make some recommendations.
The module is packed with TL072s' so I would like to replace some of the channels with alternative opamps etc to pull a different "sound".
The NE5532 gets a good wrap BUT from what I can ascertain it is not a simple swap process to replace the TL072 with it.
Anyway any suggestions would be most welcome.
Regards,
Tom
PS...I did read the topic posted by Greg about his potential A&H mixer mods & he asked the following:
"If I were to do some IC replacing (which I haven't decided upon yet), what would be recommended to replace the TL072 ICs........!"
Hmmm!
 

gyraf

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Use high-quality electrolytics for C1-C2 with 100nF polyester caps in parallel.

C6 - 100uF - at the mic gain pot is too small. Gives poor bass response at high gains. Use good quality 1000uF here, preferably bypassed with a small polyester.

C7-C8 could probably benefit from being 2u2 polyester types.

We'll probably need a DC-blocking electrolytic capacitor between HPF output and EQ input. This will prevent DC offset from upsetting the eq boost/cut pots. Make it 100uF or so. If you mount it before C24, you could get rid of that.

In general, bypass all signal-carrying electrolytics (C1-2-6-7-8-11-23-24-27-33) with 100nF polyesters. There's room for this on the track side of the pcb.

Maybe try with a LM833 for IC3 (high/high-mid EQ). It may be a drop-in in this case I think. It may even make the Hi/HiMid boost function useable.

Start with modifying a couple of channels, and compare to see if it's worth it.


Jakob E.
 

Laska

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Thanks Gyraf,
I'll certainly implement those mods & thankyou for your prompt & generous assistance.
So the mic preamp TL072s' stay ?
Regards,
Tom
 

gyraf

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[quote author="Laska"]So the mic preamp TL072s' stay ?
[/quote]

You could try with a LM833 at that position also, but you may want to evaluate the other (safer) mods first - to get a clear picture of possible improvements/problems..

Jakob E.
 

Bjorn Zetterlund

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Hi Laska!

I've got an 800b that I sometimes experiment with. I don't need it for anything in the near future, so I haven't arrived at a final solution yet, but amongst the mods I have tried are replacing the preamp section with an INA 217, and also eliminating all the electrolytic caps by using DC servos instead. A lot of hassle, and certainly not something I'm going to do on all channels, but it did have much better LF response. It also oscillated with maximum LF boost, but that's just because my servo design skills are shit! Anyway, I would go with all that Jakob recommends, in particular a larger cap for C6, as that is where you get the greatest amount of LF 'wooliness'. Don't forget that this is an old desk; I think mine is 20 years or more. Soundcraft no longer carry spare pots. I have thought of mods that would cost up to 50 pounds per channel, which would be pure folly to implement. Realistically, I shouldn't spend more that 10 pounds per channel at most. You have to consider how much use you will get out of this desk, and how long it will last before maintenance gets unbearable. Having said that, I replaced all the faders on mine, and so far none of the pots have given me any trouble...I'll keep my fingers crossed!

Bjorn
 

Laska

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Thanks Bjorn,
They may be old but they're rugged unlike most of the new medium range gear which, as you know doubt know, has the majority of components mounted on one large PCB loaded with SMDs'.
Bob Dylan runs an even older Soundcraft in his home studio, a 2400 made in 1979.
But then again he has the cash to keep it up & running sweet.
Regards,
Tom
 

nrgrecording

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Ger manley (germany) ;-)
Hi guys.

If someone have a spare psu or even a spare toroid transformer... thats what iam searching for.
I have two 2400, one without a psu. I hacked the pcb layout for the original psu into my computer but i still need the transformer.

What do you think about using 4 transformers instead of the original one with many taps? Would that cause any problems?
this is my psu: http://www.nrgrecording.de/html/psu.html

Modding a soundcraft sounds good :wink:
I thougt about making a new master section, adding flying faders (ucapps and dbx2150vcas circuit), adding ppm meters, mixbuscomp, and i want to make one big console out of two 2400 28/24/2. (56/48/2)

Regards,
Frank.
 

Laska

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nrgrecording hi,
Sorry to hear your trannys' blown.
I'll keep an eye/ear out for you & hope you get lucky!
I'm running a 2400 PS on my 800b/1600 so many of the older model units are interchangeable; specially the toroidal.
I have a full set of schems for the 2400 & I would be happy to email them to you if you need them; these aren't available at:
http://www.soundcraft.com/products.asp?product_category_id=5
Regards,
Tom
 

Laska

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buttachunk,
When you say: "first, TL0whatevers must go.", I assume you mean the TL072s' ?
If so; what to replace them with?
Regards,
Tom
 

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