Soundcraft 800b/1600 & Soundcraft 2400 Micpre & EQ

[blakbeltjonez]

i worked for a sound company that had a couple of 800B F.O. H consoles and 500 series for monitors a few years back, and a popular mod that worked well was star grounding all the modules - significantly cut down on noise and cross talk between channels. it works well for any of the old Soundcraft 400/500/600/800 series consoles. i liked those old boards, to me they sounded a lot better than some of Soundcraft's later stuff like the Ghost which to me was a little bit thin sounding EQ-wise

 

[nrgrecording]

[quote author="Laska"]
I have a full set of schems for the 2400 & I would be happy to email them to you if you need them
Regards,
Tom[/quote]
Hi Tom. I have a copy of the schematics here but a pdf version could be very nice because the copy isn't really clear readable.
(also soundcraft writes 7.5k instead of 7k5 which sometimes looks like 7 5k because of the the copy)
(my email adress is [email protected]) thx!

[quote author="Bjorn Zetterlund"]
...I have tried are replacing the preamp section with an INA 217[/quote]
Isn't the ina217 a single opamp? What was your way to wire them to your soundcraft? Small pcb? Double stacked ICs?[/quote]

[quote author="buttachunk"]
IMHO the OP2604 sounds MUCH better.[/quote]
What about changing the power supply from +/-17v to +/-24V and change all opamps to OPA2604? Hmm and there could be enough space for a selfmade 990c... at least in the mastersection? :roll:

Regards,
Frank.

 

[Laska]

Frank,
Sent the schems.
Congratulations on the work & dedication you're putting into restoring the 2400...great job!
I like the "Soundcraft 2400 Channel Strip" in a box!
Can you tell us a little more about it?
I agree with you & buttachunk: the specs look good on the OPA2604.
Regards,
Tom

 

[nrgrecording]

[quote author="Laska"]Frank,
Sent the schems.
Congratulations on the work & dedication you're putting into restoring the 2400...great job!
I like the "Soundcraft 2400 Channel Strip" in a box!
Can you tell us a little more about it?
I agree with you & buttachunk: the specs look good on the OPA2604.
Regards,
Tom[/quote]

Thank you very much for the schems!
The channelstrip was just an idea. Someone wants to put channels into a 19" box so i'd done a panel. But if there is a real interest i could do a pcb of the mic preamp and eq. (i don't need channelstrips because i have 56 input channels yet) :wink:

It could also be a nice idea to collect some information about modding these old soundcrafts. I would be glad to collect some tips on my site. :wink:

 

[Laska]

Frank said: "But if there is a real interest i could do a pcb of the mic preamp and eq."
Tom said: "I'm verrrrry interested".
The thought of 56 channels makes Frank a happy man, hey! :wink:
Regards,
Tom

 

[hitchhiker]

I've been given the Soundcraft Series 1s input and master modules .

Can anyone show the schematics for this console?

What's the skinny on these boards. When I was a kid starting out in music
it seemed the better local bands often used these consoles.

The inputs have xformers, but I don't know what their ratio is.(1:2 or 3?)

Are these worth modding in a similar way to what Gyraf has described?

thanks
Lance

 

[nrgrecording]

[quote author="Laska"]Frank said: "But if there is a real interest i could do a pcb of the mic preamp and eq."
Tom said: "I'm verrrrry interested".
The thought of 56 channels makes Frank a happy man, hey! :wink:
Regards,
Tom[/quote]

Hi Tom.
I started to hack the pcbs into my pcb program today. I need to
check for errors and put in the component values. It fits on two
160x100 pcbs.

here are the specs:
+/-15dB @ 12Khz shelving (switchable, either 8Khz or 16Khz)
+/-15dB from 600hZ to 10Khz peaking/dipping
+/-15dB from 150Hz to 2.4Khz peaking/dipping
+/-15dB @ 60Hz shelving (switchable, either 60Hz or 120Hz)

highpass filter 50Hz to 800Hzr 12dB/oct.

balanced mic preamp (impedance 2kohm)
-70dB to -30dB (with 30dB max gain range: 70dB)
switchabel 30dB pad
unbalanced line input -10dB to +20dB
switchable 48V phantom power
phase switch

http://www.nrgrecording.de/2400channelstripPCB1.pdf
http://www.nrgrecording.de/2400channelstripPCB2.pdf
http://www.nrgrecording.de/2400channelstripPCB_layout.pdf

Regards,
Frank.

 

[Bjorn Zetterlund]

Hi Frank and everybody!

My INA 217 mod was on a bit of stripboard by the input section. Nothing worth copying or developing as such, although I imagine it can be done if someone really wants to. I'm planning to mod all my input channels to only take a balanced line input, as I'm planning to use only external pre's from now on. On the 800b that can be done fairly easily using the opamps that are already there. Ultimately, only the XLR input allows for a balanced input to the desk channels, which is why I dedided to take this route.

My INA 217 channel also contains DC servo circuitry and no de-coupling caps in the signal path. I replaced all the TLO72's with OPA 2604's also. I haven't really put in much time with this mod yet, as I have already decided that I'm not going to have mic-pres on my channels, but the 800b channels certainly leave room for improvement on the low end of the mic pre. My first listening test on the modded INA 217 channel was with cymbals...and I didn't notice a difference in the top, but rather in the bottom end/low mid! Further tests have yet to be conducted (if ever) but certainly the mic pre on the 800b could do with a more solid bottom end.

And yes, grounding is another issue on these old beasts. Will have to do the grounding mod at some point. As far as the PSU goes, I have the soundcraft 'big desk' supply for a 32 channel 800b, which means I have more current than I'm meant to have anyway. Should take a look at it really, but it works and therefore hasn't attracted enough attention yet.

Bjorn

 

[Rob Flinn]

With all this talk of changing op amps I have to bring up the subject of the extra strain on the PSU. If you plan on changing all the TL072`s in this desk, be careful to consider the extra current draw. Many of these "upgrade" op amps can draw several times the current of the humble TL072. Soundcraft designed their PSU`s with not a great deal of headroom if the one for my 200b was anything to go by, which always ran very hot.

Whilst you maybe OK when experimenting with one or two channels, if you plan on extensive substitutions be warned.

 

[Laska]

hitchhiker:
Sorry I can't help you with the schems but I'll keep my eye out.

Bjorn said:
"I have thought of mods that would cost up to 50 pounds per channel".
Care to share your ideas?

Frank:
Soundcraft 2400 Channel Strip PeeSeeBeez...hoooweee! :grin:
I'm greatly impressed with the effort & speed you put into producing these; let alone the talent!
I'm sure there will be much interest!
Many thanks,
Tom

 

[Laska]

General discussion on reservoir caps but mostly about power supplies.

http://recforums.prosoundweb.com/index.php/m/23554/0#msg_23554

Regards,
Tom

 

[nrgrecording]

I have added all componentnames and values today. (see the mic preamp schematic for component names) http://www.nrgrecording.de/soundcraft2400_schematic1.jpg

If someone wants to make a partlist... that could be nice. :wink:

http://www.nrgrecording.de/2400channelstripPCB_componentnames.pdf

http://www.nrgrecording.de/2400channelstripPCB_componentvalues.pdf

http://www.nrgrecording.de/2400channelstripPCB_layoutV1.pdf

 

[Laska]

Great stuff Frank...as usual! :grin:

Re the line regarding values that I have just deleted........

Parts list...give me a little time Frank.
Once again thanks for all the effort...I for one greatly appreciate it.
BTW...what software do you use for the PCB layout etc?

Stargrounding a Soundcraft Console:

http://www.tangible-technology.com/articles/200b.html

Regards,
Tom

 

[Laska]

Hi Frank,
Currently working on the parts list.
I'll post it as soon as it is complete.
Regards,
Tom

 

[nrgrecording]

Hi Tom.

Thanks for the link about eddis stargrounding infos!
I use sprint layout for the pcbs. Costs about 40€ and probably
the easiest pcb layout editor (http://www.abacom-online.de/uk/html/sprint-layout.html)

Frank.

 

[tmbg]

[quote author="gyraf"]
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.
[/quote]

What does this achieve?

 

[gyraf]

shunting the electrolytic's ESR at high frequencies. It's a simple mod, but often sonically much more obvious than changing opamps and soforth...

 

[tmbg]

interesting...

Is there some way of measuring ESR? Or is it listed in datasheets? or what

 

[gyraf]

You use an ESR-meter to measure that.

And yes, the ESR is given in data sheets. But the sound - or lack thereof - in an electrolytic is not easily specified - look around this forum, there is several "favorite" electrolytic series, like ELNA Starget, Panasonic FS etc.

The parallel'ing trick is a very simple upgrade to less-than-perfect electrolytics

 

[Laska]

Hi people,
Franks been busy over at his NRGRECORDING site.
Check it out!

http://www.nrgrecording.de/html/2400channelstrip.html

Regards,
Tom