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hollywood_steve 24 October 2001

I have been playing around with the idea of assembling several of my outboard preamp and EQ modules into a small 4x2 console. I still
haven't figured out what to do about the two required summing amps. In general, I am using existing modules for all functions, but summing
amp modules ain't easy to come by. I occasionally see old Telefunken V530 summing amp modules for sale, but not many others. Is this
because the makers of other modular consoles did not build the summing amps into stand-alone modules, but rather just located the circuitry
somewhere in the bowels of the master section? Finding the right summing amp modules would be hard enough even if I had several different designs to choose from. Can anyone think of any other models that might be available on the used gear marketplace? (4 inputs, 1 output would be ideal) I realize that there is a LOT more to
console design than just assembling a bunch of old modules into a frame; but that could be an interesting way to get started.

thanks.

steve
sjp@pacbell.net

Comments

anonymous Wed, 10/24/2001 - 14:33

There are summing bus modules out there. The Trident Series 80/80B/80C/70/Trimix consoles used bus modules that contained all the summing circuitry. I'm working on a Trimix right now, which is totally modular with a passive mainframe. The sub-master and master modules are identical in everything but pin-out.
I'm recapping it shortly and will be trying a few different chip upgrades on the summing buses. I've got two spare subs and one spare master which should make before/after comparisons easy. I hope to end up with a refurbished all original master section plus a couple of swappable fast-clean summing buses for when the Trident "crunch" isn't appropriate. Different concept than what you're talking about, but it does rely on the summing buses being modular units. HTH

anonymous Wed, 10/24/2001 - 15:10

If I understand well, summing amps and mic preamps are very similar technically. For example, Forssell Technologies' JMP-1 module is advertised as both mic pre/summing amp(http://www.forsselltech.com/JMP-1.htm).
Also, vintage Neve summing amps (1272, 3415 etc.) are regularly and easily converted into mic pres, I guess it would be fair to assume that it goes both ways.

Predrag

hollywood_steve Wed, 10/24/2001 - 22:42

Don't API have some, build your own 'modular' system now? Perhaps that might fit the bill?

here it is!
http://www.apiaudio.com/apihomeSet2.html

--------------------

Jules - Producer / engineer Julian Standen

API must have some summing amps to build their Legacy consoles; but I have never seen any summing amp module offered for sale on their website. There ain't one on there now.

Back to API consoles.......this kinda goes back to my original question - does an API console have an actual summing bus module for each group, or are the summing amps buried somewhere inside the console? I don't remember ever seeing an API summing amp module. I'm guessing that there are just a bunch of amp cards packaged together somewhere inside the board - or is there some module that I am unaware of?

steve
sjp@pacbell.net

anonymous Thu, 10/25/2001 - 01:04

Hi Steve-
I've been doing some research on this very topic only I want to sum a larger number of line inputs. I'll try to pass along my findings as best I can with my non techi level of understanding.

It seems that consoles such as Neve and API summed individual channels passively. This method combined channels with minimal circuitry and better fidelity but caused a drop in level. 1272 amps (Neve) were then used to boost this passively summed signal to the needed levels. I spoke to a tech who could custom make something along these lines from 1272 modules, but decided not to take this little project on at this time. If you're interested, I could dig up his number for you.

My apologies if my summing amp description has a few holes in it, but as I said, this is my non geek explanation of geeky subject matter from several discussions I was fortunate enough to have with those who really understand this.

Hope this helps.

Kenny Meriedeth
Melted Media Music

hollywood_steve Thu, 10/25/2001 - 21:19

Mike,

I don't see your email address anywhere, so I'm replying on the forum:

I have heard of WSW on several occasions, but I have no idea what it is. Does WSW stand for something that I might recognize? Is it a fully modular console, or is more of a "strip" console with only one module per input channel? I'd certainly be interested in seeing any photos. Do you have a website to post them to or do you just want to email them?

Also, I don't know if you saw my other thread on this topic, but there is a GREAT article on summing amps on the Forrsell Technology website:

http://www.forsselltech.com/summing%20bus.htm

well worth checking out

steve
sjp@pacbell.net

anonymous Fri, 10/26/2001 - 13:03

Thanks for the Forssell link, it's a helpful description of the challenges of both summing bus designs. The Tridents I referred to are all "virtual earth" designs. The article reinforces what I've found to be the most important upgrade on these boards, adding individual ground leads from each module to a new bus bar, to improve CMRR thereby lowering noise. Here's a good write up of the procedure by Eddie Cilletti/Dan Kennedy:

http://www.digitalprosound.com/2001/01_jan/features/analog_maint1.htm

Another option you might consider is a stand-alone 4x1 passive mixer. I use an Uptown Technologies 4x1 stereo unit that has mute and volume attenuaters on each stereo input. There are no active circuits in it so the insertion loss is 10dB, but a 1272 on it's output would make that up easy... HTH

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