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-   -   My new DIY Rotary Mixer (http://www.wavemusic.com/community/showthread.php?t=12090)

Pern 07-22-2011 10:04 AM

My new DIY Rotary Mixer
 
Just finished my new DIY Rotary Mixer.


Functionality:
- Can be used as a 2 Ch - 6 Ch mixer.
- FX Loop.
- Cue - Master Headphone Blend.
- Tape out.
- VU Out.
- Booth Out (unbalanced).
- Master Out (balanced).


Components:
- OP: ST TL074/TL072, NE5532.
- Caps: ELNA Silmic II, WIMA.
- Resistors: Carbon Film.
- Pots: ALPS RK27

Internal wiring: Mogami






The reason for the veroboards is so that it can be used in any enclosure 19", desktop etc. And use any brand and models of pots and switches.

Here is the functionality:






More info about it is on my website and faceBook.

jnkarrik 07-22-2011 10:40 AM

:eek: :eek: :eek: Looks great Pern! You've been planning this mixer for a while now, so its really nice to see it come together. How do you like it so far?

Pern 07-22-2011 10:51 AM

Well, i don't think i ever will use another mixer :)

Lime Twig 07-22-2011 12:54 PM

Wow! Congratulations, Pern, you actually built it!

It looks fantastic, really top notch. Any plans to run some bench tests on it, better yet, with comparisons to the Bozak and Urei? I'd love to see how the new design stacks up against the originals that inspired you.

(I admit though, you'll have to explain whatever data you provide, I don't know what the most important tests are that you run on a mixer!)

Still looking forward to the day you built an external EQ circuit - i'll be your first customer!

Mistick Krewe 07-22-2011 01:04 PM

superb execution!

congrats!

Disko Ole 07-22-2011 03:10 PM

I've been following your project @ facebook and your blog Pern! Nice to see the result!

Maybe I'll try this myself when all the details are available, would be an interesting project!

Pern 07-23-2011 05:32 AM

Quote:

Originally Posted by Lime Twig
Wow! Congratulations, Pern, you actually built it!

It looks fantastic, really top notch. Any plans to run some bench tests on it, better yet, with comparisons to the Bozak and Urei? I'd love to see how the new design stacks up against the originals that inspired you.

Still looking forward to the day you built an external EQ circuit - i'll be your first customer!



The only problem is that i don't have access to a Bozak and original UREI, not even sure there is a Bozak here in Sweden. But i will do an detailed description of what the differences is from the UREI and why i did these.

Re: The External EQs. This is one of the main reasons why i did the core functionality so close to the Bozak/Urei. So when i do anything external to connect to it (external EQs, Effects etc) it should also work with Bozak/UREI etc. I'm just finishing my Compressor/Limiter/Leveler project, then will i start directly with the 2 External EQ projects.

Pern 07-23-2011 07:47 AM

One interesting thing that i realized after testing it for a while now is, if a TL074 based mixer sounds bad it's not due to the OP. Then i think it's due to bad design/components/internal wiring and/or bad grounding.

I used a high quality cable inside and about 95% is shielded. Also used star grounding with separate ground wires to everything. The back panel actually have 3 separate ground wires. 1: Inputs, 2: FX Loop, Tape, VU, 3: Outputs.

I was planning to do another TL074 based mixer also even more optimized for better THD and SNR (at least theoretical). But since it sounds so nice i think i will skip that and my next mixer project will be a discrete design instead. But that will be a 2012 project.

Estacy 07-23-2011 09:58 AM

Looks awesome! very sleek, nice and simple. an engraved faceplate would finish it.

Fred Bissnette 07-23-2011 02:44 PM

nice work man looks killer

diy is the way to go

georget 07-24-2011 12:07 AM

The mixer looks cool, but it would be better if you could add EQs per channel.

wheresmejumper 07-24-2011 03:55 PM

looks sweet.really nice cue system

minpud 07-24-2011 05:10 PM

Nice Work, looks very cool thanks for sharing it. Impressed with all the features you have included.

Was wondering is there any control over the send & return?

:)

Pern 07-25-2011 02:50 AM

Quote:

Originally Posted by georget
The mixer looks cool, but it would be better if you could add EQs per channel.


I'm doing 2 different external shelving EQs (one Bass only and one 3 band) and these can be used with any mixer. But they can also be internal by using a larger enclosure.

The reason for the Shelving Bass only EQ is:

1: I always liked the idea of the HP filter in the A&H Xone S6&V6 mixers, but i prefer this filter type.
2: I mostly use the EQ section for BASS EQ Mixing.

So a Bass only shelving filter + an ISO is the perfect combination for me.





Pern 07-25-2011 02:52 AM

Quote:

Originally Posted by minpud
Nice Work, looks very cool thanks for sharing it. Impressed with all the features you have included.

Was wondering is there any control over the send & return?

:)



Not by default. But this is so easy to add so i might do it as an extra option later.

georget 07-25-2011 08:58 AM

looks good with the EQ section. I use the three frequency bands to mix. EQ mixing is the smoothest way to mix music. Don't get me wrong, I can mix with an Urei and Bozak mixer, but I am limited somewhat.

Lime Twig 07-25-2011 11:04 PM

This is exactly what I want too, a bass-only shelving EQ. I've said it before, Pern: I'll be your first customer! Happy to be a DIY customer too if you decide to sell PCBs or some combination of half-built units!

Quote:

Originally Posted by Pern
I'm doing 2 different external shelving EQs (one Bass only and one 3 band) and these can be used with any mixer. But they can also be internal by using a larger enclosure.

The reason for the Shelving Bass only EQ is:

1: I always liked the idea of the HP filter in the A&H Xone S6&V6 mixers, but i prefer this filter type.
2: I mostly use the EQ section for BASS EQ Mixing.

So a Bass only shelving filter + an ISO is the perfect combination for me.






Lime Twig 07-25-2011 11:08 PM

One suggestion:

If you want to design these EQ units to potentially sell them to Urei/Bozak owners, I'm wondering if you could put a socket in them to accept the phono cards? Otherwise you would need to modify the mixer with a channel insert, right?

Would it be as easy as having a socket in the unit and then just using the phono card from your existing mixer? I guess you would need a jumper to replace what you had removed from the socket in the mixer...

Quote:

Originally Posted by Pern




Pern 07-26-2011 01:10 AM

For all of my DIY projects, at the moment i will offer:

1: Bare PCBs
2: PCB Kits
3: Built and tested PCBs

It's the enclosure drilling and internal wiring i'm trying to avoid since this would take to much of my time at the moment. And this only require very basic soldering skills.
But i will later also do http://www.frontpanelexpress.com versions of the front panels, so these can be ordered from them.

The reason for the DIY approach is that these are not commercial products. I'm doing it all on free evenings and weekends. But if/when i have some extra free time i might
do a very limited number of finished units also.

I'm doing 2 different Phono amps myself and are also looking for sources for Phono card sockets for both Bozak/UREI. So, i'm trying to keep all options open.

Pern 07-26-2011 08:20 AM

Even if i describe both my planned EQ projects above, i still haven't decided if i will do my ISO before or after EQ2. It might be before since i already done some work on it.

For the ISO i have at the moment 2 different designs and haven't decided 100% yet which to use. One is 100% TL074 based and the other is a combination of TL074/JFETs.

DjFioreC 07-26-2011 10:06 AM

Hi pern, why didn't you build a gain stage?

Another question, when are you going to start to sell pcb, kits, other?

KR

PS. Your work is Amazing! :D

Pern 07-26-2011 10:39 AM

I like this "clean" look better :) If you want to have gain/trim you can just add the pots and connect it "almost" as in the original 1620 + Change 2 resistors.
Also unity gain is 3 o'clock on the pot, so you already have some extra gain there.

But i'm also doing some "optional" PCBs for the mixer, and the first will have 2 * stereo line level trim. So you can compensate the levels between for example 2 CDs and 2 turntables with RIAA amps.


I'm just finishing a new internal PSU card for the mixer, then the PCBs etc will be available.

Pern 08-01-2011 05:31 AM

Here is the new internal PSU card for the mixer.

Regulators: LM317/LM337

Caps: Panasonic FC / WIMA



Pern 08-05-2011 05:26 AM

The new internal PSU card is now installed.


charles0322 08-08-2011 08:08 PM

Beautiful! Congratulations! I would love to hear it in action. Thanks for sharing all of what you do. Peace


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