Want to Build Audio Summing Mixer - Page 2

**Tim Farrant** · 12th May 2005

Thanks for all your input there George. Everything you suggest is possible but the idea with my circuit is to keep it simple.

The transformer takes care of the common mode rejection and eliminates another active stage. It also adds a bit (note I said "bit") of colour - the Sowter is pretty damn clean really - and this should make the unit sound phat-ish.

Tubes would be nice, but this will make the power supply overly complicated and expensive.

Our products generally have a wide frequency response and people like the sound of them, so I'm sticking to that concept. It's not so much about the frequency response itself, it's more about preserving transients. I do not believe that wide frequency response results in "bad tone" or thin sound - quite the opposite.

The design is not intended to be for a mixing console with alot more inputs, 16 inputs would be the maximum I would recommend with that circuit. The inputs are intended to come from a DAW, it's not a console mix amp.

Cheers
Tim.

cannikin · 12th May 2005

good stuff

Nutmeg II. · 13th May 2005

So finaly you do the "Mix Buzz1.1"?

ballast32 · 14th February 2007

So i'm looking at designing a passive summing mixer and i've got the layouts all figured out, but I'm wondering about impedances... I understand how to design the circuit to have a certain input impedance depending on the number of channels to achieve an output impedance, but I'm wondering how the output impedance will be affected if not all inputs are used. Is the input impedance absolute or does it change based on the number of loads you are currently using?

WidgetNinja · 18th February 2007

Quote:

Originally Posted by Tim Farrant

Perhaps we could make a kit version of this circuit - how many would be interested?

Cheers
Tim.

Add one more here. It would be especially nice if it was designed with a simple transformer daughterboard/screw-in panel that we could swap out to play with different transformers without opening up the chassis.

Actually It'd be nice to see some manufacturers "settle" on something like that with pres. I see Little Labs and SE doing different swapping things, but a standard little card interface would be cool. That way too if we had a more designer pre with a desirable component, we could just steal it for a few minutes in something else.

Matt Syson · 18th February 2007

Hi
A 'standard' pinout or board would not be feasable because someone would want it 'a little different'. Standards only work in a monopoly situation and even then you change your mind!
Tim, Did this 'project' get off the ground at all or just a good collection of ideas?
Actually there is a Velleman kit which could be configured to do this job. It is supplied with a TLO72 I think and the circuit would need slight 'attention'.
How about a 'superbal' input I hear they are pretty good?
Matt S

**Tim Farrant** · 23rd February 2007

Yes, it's only one channel. I've started a new thread about doing a kit for this here...

Geekslutz DIY Summing Mixer

Tim.

andre tchmil · 23rd February 2007

look here.
I want to trade this baby to anyone with a decent offer.
sounds excellent, but I have a 101 input mixing desk now, so I can part with it.
Summer has 18 Lundahl trafo's on board.

andre tchmil · 23rd February 2007

more pictures from the inside.

12th May 2005	#31
Tim Farrant Moderator Joined: Jun 2002 Location: New Zealand Posts: 2,410	Thanks for all your input there George. Everything you suggest is possible but the idea with my circuit is to keep it simple. The transformer takes care of the common mode rejection and eliminates another active stage. It also adds a bit (note I said "bit") of colour - the Sowter is pretty damn clean really - and this should make the unit sound phat-ish. Tubes would be nice, but this will make the power supply overly complicated and expensive. Our products generally have a wide frequency response and people like the sound of them, so I'm sticking to that concept. It's not so much about the frequency response itself, it's more about preserving transients. I do not believe that wide frequency response results in "bad tone" or thin sound - quite the opposite. The design is not intended to be for a mixing console with alot more inputs, 16 inputs would be the maximum I would recommend with that circuit. The inputs are intended to come from a DAW, it's not a console mix amp. Cheers Tim. __________________ "Come on, make my day" Dirty Harry (Clint Eastwood) Visit Buzz Audio

14th February 2007	#34
ballast32 Gear interested Joined: Feb 2007 Posts: 28	bringing up a seemingly old topic So i'm looking at designing a passive summing mixer and i've got the layouts all figured out, but I'm wondering about impedances... I understand how to design the circuit to have a certain input impedance depending on the number of channels to achieve an output impedance, but I'm wondering how the output impedance will be affected if not all inputs are used. Is the input impedance absolute or does it change based on the number of loads you are currently using?

18th February 2007	#36
Matt Syson Lives for gear Joined: Sep 2004 Location: UK Posts: 4,822	Hi A 'standard' pinout or board would not be feasable because someone would want it 'a little different'. Standards only work in a monopoly situation and even then you change your mind! Tim, Did this 'project' get off the ground at all or just a good collection of ideas? Actually there is a Velleman kit which could be configured to do this job. It is supplied with a TLO72 I think and the circuit would need slight 'attention'. How about a 'superbal' input I hear they are pretty good? Matt S __________________ Matt S www.mseaudio.co.uk

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12th May 2005	#32
cannikin Gear maniac Joined: Sep 2003 Location: San Francisco CA Posts: 220	good stuff

13th May 2005	#33
Nutmeg II. Lives for gear Joined: Jan 2003 Location: GEARmany Posts: 985	So finaly you do the "Mix Buzz1.1"?

23rd February 2007	#37
Tim Farrant Moderator Joined: Jun 2002 Location: New Zealand Posts: 2,410	Yes, it's only one channel. I've started a new thread about doing a kit for this here... Geekslutz DIY Summing Mixer Tim.

23rd February 2007	#38
andre tchmil Lives for gear Joined: Sep 2002 Location: always on the move Posts: 750	look here. I want to trade this baby to anyone with a decent offer. sounds excellent, but I have a 101 input mixing desk now, so I can part with it. Summer has 18 Lundahl trafo's on board.