gswan
Well-known member
jdurango said:
Not really. It's fairly primitive and won't have a great sound. But that might be the 'colour' you are after, who knows?
Carbon resistors and 741 op amps, reminds me of the 1970's!
Determining power supply needs for custom-built preamp
- Thread starter jdurango
- Start date
Help Support GroupDIY Audio Forum:
Not really. It's fairly primitive and won't have a great sound. But that might be the 'colour' you are after, who knows?
Carbon resistors and 741 op amps, reminds me of the 1970's!
gswan said:
Horror Audio Story!
gswan
Well-known member
Whoops said:
Good noise sources though
gswan said:
I'm definitely going for a very oldschool sound...but this mixer cost $1100 + shopping + cost to fashion a power supply. I'm just starting to wonder if I'm better off with something else....especially since this has pretty limited features, no EQ's, etc.
gswan
Well-known member
jdurango said:
You would need to create a schematic to check how the op amps are configured and identify loop gains and compensation networks. With that much cable I would expect a fair amount of compensation would be required for modern op-amps. You can probably vastly improve the sound by replacing the 741's with 5534A devices. Then again, the circuit looks so simple that you may be better just replacing the input module with a new PCB and a better design. The input strips look like a transformer feeding a single-ended transistor stage and 3 x 741 op-amps to provide buffering to busses.
gswan
Well-known member
jdurango said:
Well the transformer input is a good start for that, and it does not look like there is any phantom power from the desk. I'd probably consider a 2 or 3 transistor single-ended input stage with the transformer followed by 5532 buffers for the busses. Should be an easy design to do and give reasonable results.
Then you can work out the master section and sends/returns etc.
PRR said:
It actually looks like more of a 60's design, which is what drew me to it....but the junky preamps are disappointing. As far as mixing, it does everything I need (I can insert 500 series EQ's or Pultecs)....i only need one aux for reverb. I'm doing oldschool 50's/60's style production.
In fact, the more I think about it, I'll be using outboard pres 90% of the time, probably even for mix down as line ins (CAPI VP28's give an amazing color for mixing!)
So yeah, I'm not really even concerned about the mic pres. Maybe some day I'll pop some fancy pres in there if the mood suits me.....but as a mix down or tracking, I can use my 500 series pres and EQ, and use this for transformer balanced i/o, routing, effects or headphones sends and VU metering. Plus it'd be so easy to mod if I need to add features.
I think this actually may be prefect for me, as long as I can get the power supply/transformers sorted out!
So yeah, I'm not really even concerned about the mic pres. Maybe some day I'll pop some fancy pres in there if the mood suits me.....but as a mix down or tracking, I can use my 500 series pres and EQ, and use this for transformer balanced i/o, routing, effects or headphones sends and VU metering. Plus it'd be so easy to mod if I need to add features.
I think this actually may be prefect for me, as long as I can get the power supply/transformers sorted out!
jdurango said:
Not really it's a 70's cheap DIY design.
741 opamps were only available in 68.
jdurango said:
So you need something completely different.
for 50s/60s search for this units, you can still buy some of them or Build them yourself:
-EMI REDD.47
- Spectrasonics 101, 110A
- Langevin AM16
- Altec 1567A tube mixer
- Altec 470A, 475A , 9470A, 9475A
- Universal Audio 1108
In contrast to more modern in-line consoles, with preamps and EQ's and tons of routing and features, all mixing consoles in the 50's, and most in the 60's were very basic transformer balanced with simple routing, VU meters and high quality pots and switches. They often used external preamps, EQ's, comps, and the console was really just for routing. That's what I'll be doing with this. I have external pres and EQ's that give me the sound I'm going for, mostly tube (although surprisingly, the Hamptone JFET is one of my favorite for "that" sound...and I often prefer my solid-state Pultecs over tube ones).
This console uses quality 60's era components (pots, switches, even knobs, even carbon resistors), is all transformer balanced with 60's era iron, 60's era VU's, 60's era transformers on ins AND outs, has an aux bus for headphone mix during tracking and reverb for mixing....even the knobs look like those on my 60's Quad Eight....but it's not huge and heavy like my quad eight....and it cost about $1,000 (probably $1,300 after I get the power supply sorted out) which is FAR less than my Quad Eight....or anything else that fits all these needs which I've found.
The modules you listed are great, but I need a console for tracking to and mixing from 1" 8-track tape.
Plus I think it's really cool that if I ever DO want to add decent preamps (probably 990 DOA based) it'll be really easy to breadboard some and throw them in. I can even have 8 x 990 and 8 x Neve or something else....or all 16 could be different.
Anyway, I'm really not worried about the 741 mic pres as I won't be using them.
This console uses quality 60's era components (pots, switches, even knobs, even carbon resistors), is all transformer balanced with 60's era iron, 60's era VU's, 60's era transformers on ins AND outs, has an aux bus for headphone mix during tracking and reverb for mixing....even the knobs look like those on my 60's Quad Eight....but it's not huge and heavy like my quad eight....and it cost about $1,000 (probably $1,300 after I get the power supply sorted out) which is FAR less than my Quad Eight....or anything else that fits all these needs which I've found.
The modules you listed are great, but I need a console for tracking to and mixing from 1" 8-track tape.
Plus I think it's really cool that if I ever DO want to add decent preamps (probably 990 DOA based) it'll be really easy to breadboard some and throw them in. I can even have 8 x 990 and 8 x Neve or something else....or all 16 could be different.
Anyway, I'm really not worried about the 741 mic pres as I won't be using them.
gswan
Well-known member
That's great.
Since you are using external preamps, you really only need buffering in this case, and a simple set of discrete transistor buffers should do it.
Since you are using external preamps, you really only need buffering in this case, and a simple set of discrete transistor buffers should do it.
gswan
Well-known member
At a guess from the topology in the photographs I'd say there is a single transistor amplifier after the transformer, followed by 3 buffers, probably feeding the quadraphonic and solo busses. It's hard to say without tracing a channel out and seeing where the various controls connect.
gswan said:
Thanks! There are 3-way switches for each of the 16 channels, labelled MIC, -15dB and LINE. I supposed I'd just follow the leads from the LINE position and see what kind of circuit they lead to. That's really the most important audio path for me, so if I do any upgrades or mods, it would be in that path first. I'll check back here when I take receipt of this console. In the mean time, THANK YOU VERY VERY MUCH for all the help! If you're ever in Seattle or Honolulu (I bounce back and forth between both) I owe you beers! Aloha!
