Geekslutz DIY Summing Mixer

[Tim Farrant]

I have had numerous emails from people interested in a mix summing DIY kit based on ideas from this thread...

http://gearslutz.com/board/showthread.php?t=30281

I am sorry I did not reply to all those who emailled me, but I now am thinking we can take this a step further and decide on a final design that could be made available to those interested.

First of all, I need a show of hands as to who might be interested in pursuing this. And then we need to come up with a feature set that satisfies everybody. Please discuss.

Cheers
Tim

[Jam]

I'll be the first to admit my DIY activities lack follow through but this looks like a great idea to me !

Jam

[Stitch333]

Im in the middle of this right now.
Heres a couple of links to threads at prodigy-pro:
http://www.prodigy-pro.com/forum/viewtopic.php?t=16188
http://www.prodigy-pro.com/forum/viewtopic.php?t=19426

can I get a 'Buzz Audio' sticker for mine?

[supaheef]

I'm in! Me solder quite good, but not make good understand skematik. If you draw it up, specify the bits, and make me a cup of tea while I butcher the circuit board, I'll be fine.

Are we talking fixed pannng (switched like the Folcrom) or rotary pans? Curious as to other people's preferences. I like the idea of panning out of the box, but that will make mix recall-ability a bit of a hassle. MHB may argue that point though, he says his recalls take about an hour...

heath.

[octatonic]

I'm in....

Are we looking at a completed kit with all the parts supplied or just a PCB and then source your own parts?

I'd be interested in the transformer switchable design, but I'll go with the flow.

[svart]

active? passive? switches? relays? makeup amps? ICs? transformers? powersupplies?

You guys have a whole lot of questions to answer.

Your best bet is summing resistor front ends to a balanced network with differential instrumentation opamp gains stages and transformer output isolation for the ones who want unbalanced outputs. That will be your cheapest and most reliable route.

[WidgetNinja]

I could find use in any of these:
4-16 inputs to stereo outs, just hard left and right.
simple 4 in, mono out

It could be cool if we had switchable/choice of a few different opamps/trannies so we could do something like build 2 different colored busses with fewer inputs that then cascaded to a third unit. A switch ala shadow hills would be coolest. After that, things like faders and pan controls become nice.

Tonally, I'm finding I really don't have any excitement towards new clean gear, except converters to more accurately capture the dirty sounds. Something somewhere between egg-whites and rubber cement in texture... you know smooth out some highs, barely, and add perceived depth/density. The other contrasting flavor would be the faster, crunchy in the top one. Fudge and rock candy.

There's so many middle of the road sounds already. If I'm going to build something, I'd want it to be different, something with a purpose.

[velvetgeorge]

Count me in. With a vote for 16 ins.

george

[synth.ignition]

i'm in if quality is a priority over price.

[stellar]

my vote:

-1-space panel per channel
-fader
-2 stereo busses
-2 auxes
-2520 per
-5-position pan
-mute

I know everyone wants their own thing I'm not saying this is the best I'm just making a suggestion. simple api line mixer with no pres. which is what everyone wants. bet it comes in at around 150 per channel before you add in the housing and psu if you go for less expensive faders. the summing amps for the 4 busses and 2 auxes could all fit on one 2-space panel with stepped outies.

Edit:

kit idea:
-panel with fader slot pre-cut; and means of attaching a perfboard, intended to run a 325 type amp.

so the psu, options, chip, fader, box, transformers, etc, etc, are up to the builder.

certain other parts might want to be included.

maybe even a whole psu board.

[mos]

Originally Posted by WidgetNinja

It could be cool if we had switchable/choice of a few different opamps/trannies so we could do something like build 2 different colored busses with fewer inputs that then cascaded to a third unit. A switch ala shadow hills would be coolest. After that, things like faders and pan controls become nice.

I would be definitely interested if something like this could be included

[ddageek]

Hey Tim here is my $.02 (probably worht less than that)
First what would be IDEAL FOR ME ( eyah it all about me but hey I have a two year old and everything else is about HIM)

1 would love 32 inputs could live with 24!
2 Got to have pan pots!!!
3 mutes!!!! I need mutes!!
4 if at all possible a design that is lets say in modules of 8 that can be expand at a latter daTe to up to 32!
also if another set of modules could be added for an aux send or2 or 3 or 4?

yes I would love something based on the 2520/990 opamp frm but if it sounds good I really dont give a crap whats inside!

Now thinking practical
I think metal work and control layout should pretty much be at the builders discression because everybody seams to have their own preference!

Yeah I want a console on the cheap but don't we all?????

[Tubemooley]

I am totally down with this idea. I can be flexible on the features but pan on each channel is real handy. Minimum of 16 input channels. Expandable at a later date is a great idea also. And as someone else has already mentioned, sound quality is most important to me. 2520's or 990's would be great. The John Hardy 990c's are quite reasonable in price and relatively easy to purchase. The Forssell 990's are great also but they are FET-based and won't drive any output transformers. I follow most of the threads concerning summing mixers on Prodigy Pro. There are a lot of good discussions over there. I have engineering experience and would be more than willing to help out with any engineering grunt work. I've been working on a project like this for a couple of years now (mostly just research; unfortunately, no active building has occurred yet). DW.

[Coyoteous]

- show of hands? I got your show of hands!



(it only let me do 10 - had 100...)

[Zeppelin]

I'm interested in building.
I think the scheme in the other thread looks very doable for us that not are manufacturers, but have some experience with soldering. 8 channels is cool, since they will be pretty cheap you could build two for more channels. I'm I mistaken if I've read that the old Neve's have a opamp and transformer for every 8 channels?
Since otb summing start becoming more useful when you add outboard comps and eq's between the daw and the summer(instead of going d-a-d for processing and then go d-a again to the summer) I think a mono switch would be very very handy. I'm thinking for money tracks like lead vocal, kick, snare and bass which all usually are panned in center.
How is this achieved electrically, by simply splitting the signal l-r or do you have to change the resistor values in the passive network?(suppose there be different levels if not).

I think the most important thing if making a kit would be the PCB(perhaps transformer for convenience), as all else components should be easy find,

Why hasn't Tim replied in this thread for a while?(Hoping the project is not abandoned.

Henning

[AMIEL]

quality sound first here!

16-24 Ch
2Aux
Pan
Mute
solo!! (that would be great!)
2 parallel stereo outputs
master bus control/fader.


extras:
3 ST busses
VU meter with light

[LouD.]

Originally Posted by AMIEL

quality sound first here!

16-24 Ch
2Aux
Pan
Mute
solo!! (that would be great!)
2 parallel stereo outputs
master bus control/fader.


extras:
3 ST busses
VU meter with light

direct outputs for tracking
optional faders
solo in place

[Tim Farrant]

Hi all, sorry for the lack of posting about this.

Ok, the idea was to keep this a simple summing mixer for a DAW - we are not building a console with aux's, solo etc!!

My thoughts are;

16 mono inputs with switches that allow you to select L, R, or both (mono). Inputs would be on DB25 connectors, output on XLR. The circuit would be based on my simple circuit in this thread...

Want to Build Audio Summing Mixer

It might be nice to add an level trim on the L and R outputs. The circuit would use the Sowter 8403X transformers, but this could be optional if some want to experiment, otherwise the kit would include 1U chassis, internal power supply and all other parts.

In order to get a firm price for the kit, I need a show of hands on this idea. Obviously if we get 100 kits made, it's going to be cheaper than 30.

I know some have emailled me expressing an interest in a kit before, and I apologize for not replying to everyone - it got a bit daunting! However, please email me again if interested;

stuff "at" buzzaudio "dot" com

Cheers
Tim.

[Tim Farrant]

After reading this thread a bit more thoroughly, I have additional thoughts;

1] The board could be laid out to accomodate the 990/2520 opamps or standard dual in line IC opamps. It would be up to you to obtain the discrete opamps of your choice.

2] Having a mix buss link arrangement whereby 2 units could form a 32 channel summer would result in too much gain for a single opamp I feel (although the 990 might handle it). However, we could add 2 input XLRs that allow you to feed the output of the first into the second (think of it as a 18 input summing box). But how many people would use actually use 32??

Tim.

[LouD.]

Whatever it ends up being, I vote for AMIEL's avatar for the logo!!

[Tim Farrant]

Originally Posted by LouD.

Whatever it ends up being, I vote for AMIEL's avatar for the logo!!

Hahahahaha!!

[pan60]

Originally Posted by LouD.

Whatever it ends up being, I vote for AMIEL's avatar for the logo!!

[AMIEL]

Originally Posted by LouD.

Whatever it ends up being, I vote for AMIEL's avatar for the logo!!

Hey LOUD!
Not a bad idea at all!!!

[recall]

I would be interested but have absolutely no experience with building things. So I will just watch and see how this thing develops, and then maybe I'll get involved somehow

[nerogtr]

i'm down, depending on the price point of the project. i know that more kits = less money, but can you give an approx ballpark $x to $y range?

[AMIEL]

So Tim..any ideas about how much would cost that kit?

[Berolzheimer]

Originally Posted by LouD.

Whatever it ends up being, I vote for AMIEL's avatar for the logo!!

And what names for the unit does that suggest?

[carloff]

I would be interested for purchasing as well!

[StrykeBack]

I'm very interested as well however the ideas u've thrown out make it very much like a folcrum which is already a pretty low price so what is the ballpark figure on say 50 to 100 kits?

[Tim Farrant]

Originally Posted by AMIEL

So Tim..any ideas about how much would cost that kit?

As I said, price will depend on the quantity we produce. If you are keen, email me and I will add you to the list. When we hit 30 people then I have a definitive. So far, I have about 5. But, as an indicator, it's going to be way cheaper than a built up product.