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  #1  
Old 11-08-2011, 12:21 PM
thebuttonfreak thebuttonfreak is offline
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Any of you ever try to build a Bozak clone from scratch?

Hey guys, first post but I've been lurking for months. I have a background in physics and know my way around a circuit board. I got some bozak schematics and was shocked by how simple the circuits were so I decided to start building a clone from the ground up. Looks like I can get everything I need but I have a few questions.

Have any of you tried this? Is there some reason my confidence is misplaced?

Also, many of the parts can be replaced by parts from different manufacturers listed in the schematic, I can't convince myself from a scientific point of view that this would make any difference (the specs are the specs right?). Am I missing something?

Thanks! Any advice or resources would be appreciated as I embark to create my perfect mixer.

ps - anyone have schematics for an isolator?

Thanks and hello!
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  #2  
Old 11-08-2011, 01:38 PM
jnkarrik jnkarrik is offline
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Quote:
Originally Posted by thebuttonfreak
Also, many of the parts can be replaced by parts from different manufacturers listed in the schematic, I can't convince myself from a scientific point of view that this would make any difference (the specs are the specs right?). Am I missing something?


I think this is the great debate, and most audiophile types are going to disagree.

Stilll sounds like a fun project, and would at least give you a starting point for experimenting with some of the key components that may (or may not) affect the tone.

In the end, let your ears decide.

Welcome to the board!
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  #3  
Old 11-08-2011, 02:28 PM
thebuttonfreak thebuttonfreak is offline
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Total noob question here. I have been djing for 15 years and I certainly have my own opinions about what mixers sound good, which ones don't etc... I've had a chance to mix on some rotaries and just loved it so I got a rane mp2016 and now want to build my own. But my technical knowledge is pretty weak so I may come at you with some annoying questions.

When you guys throw the word "tone" around. What do you mean. Just the overall sound of the mixer? How it handles bass, highs, mids....the overall quality of the sound when it plays an audio source and when it mixes audio sources together. Or is there more to that word?
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  #4  
Old 11-08-2011, 02:58 PM
Mistick Krewe Mistick Krewe is offline
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i think most here are referring to the overall sound quality of a particular mixer as a whole... like a musician would refer to the 'tone' of a guitar (or accordion... )

some of the vintage electronic stuff isn't exactly like an audiophile straight wire preamp, maybe tends to throw their own color into the end result....
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  #5  
Old 11-08-2011, 03:20 PM
thebuttonfreak thebuttonfreak is offline
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Correct me if I'm wrong (please!) but there are two aspects to this. The overall sound of the mixer when it's playing a single channel and it's sound when it plays more than one (the mix). It seems like these could be different. From djing experience alone I've often found that a mixer will sound good when just playing one channel and sound like crap when mixing, others seem to mix well but sound shitty when playing a single source.
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  #6  
Old 11-09-2011, 10:02 AM
Estacy Estacy is offline
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there are so many factors as to how a mix sounds. Its not just the mixer. the key and overall sound of the tracks, how the gain structure is handled, EQing, yes or no. they all come into play
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  #7  
Old 11-09-2011, 10:45 AM
wheresmejumper wheresmejumper is offline
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Quote:
Originally Posted by thebuttonfreak
others seem to mix well but sound shitty when playing a single source.
i dunno.never experienced this
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  #8  
Old 11-09-2011, 04:57 PM
thebuttonfreak thebuttonfreak is offline
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Well I just ordered a bunch of parts. I've decided not to care about the manufacturer and just rely on type (ceramic vs coaxial etc...) and specs. I'll keep you posted.
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  #9  
Old 11-09-2011, 06:22 PM
Mistick Krewe Mistick Krewe is offline
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are you going to wire this clone point to point? or make up some PCBs?

have fun with your project!
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  #10  
Old 11-09-2011, 06:55 PM
thebuttonfreak thebuttonfreak is offline
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pcb I think, bread board to build and test. Anyone know of a reasonable place to get pcb's printed?
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  #11  
Old 11-10-2011, 01:36 AM
Pern Pern is offline
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I have spent "a little" time on this also. But if you want to build a 100% Bozak clone then you must use 100% the same components as the original and some of them isn't available anymore or at least really hard to find. I wouldn't focus too much on that it should be perfect Bozak clone, see it as that you are building a discrete mixer based on a great design.

Yes, you can replace the hard to find parts with other brands/models and you also might have to change the schematics a little to make it work 100% with these (If you change Transistor/FET models). As a minimum i would use high quality caps in the signal path and the PSU. I like to use ELNA Silmic II in the audio path and Panasonic FC in the PSU. Also for best performance you need to do some component matching. If you build it i'm sure that you will have a really nice discrete mixer.

When i started with this i first did a SPICE simulation of the Bozak mixer to better understand it and also see how component brand/model/value-changes would affect the design. There is nothing strange about the Bozak design but the SRPP concept was new to me at that time. After that i built a couple of the modules on breadboard and tested them. But i stopped the Bozak Clone approach for a couple of reasons. 1) My goals is not just to build a mixer for myself but to offer them as DIY projects, and finding original parts is really hard. 2) I wanted to extend the functionality, or at least to offer that option.

So my next approach was not to use the same components as the original but the best available today like Toshiba Audio FETs/Transistors and ELNA Silmic caps etc. But since i just couldn't replace the original Transistors/FETs etc with these i skipped the original schematics and designed a new discrete mixer in a similar way as the Bozak (You can check the DM21 project on my website). I also built it on breadboard and it works really nice. But even with this new design i still have the same problem with adding new features, component matching etc. Adding new features isn't hard, but the calculations needed and prototyping just takes too much time.

My current approach for my discrete mixer is to work with discrete OPs. I think this is the best option if you want to have a discrete mixer that is easy to modify/extend. Also when you design your own discrete OPs you can make them work/sound in almost any way you want.
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Last edited by Pern : 11-10-2011 at 09:37 AM.
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  #12  
Old 11-10-2011, 02:40 AM
Laurin Laurin is offline
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Quote:
Originally Posted by Pern
I have spent "a little" time on this also.

LoL understatement of the century!

I-want-this-asap!

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  #13  
Old 11-10-2011, 03:05 AM
Pern Pern is offline
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Quote:
Originally Posted by Laurin
I-want-this-asap!

The plan is to have my second (final) prototype of it finished this weekend.
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  #14  
Old 11-10-2011, 03:39 AM
Laurin Laurin is offline
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  #15  
Old 11-10-2011, 09:35 AM
thebuttonfreak thebuttonfreak is offline
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man, it;s you crawled into my brain or something. This is exactly the sort f thing I'm looking to build. 3 channel though, 2 phono/line and 1 just line.
Quote:
Originally Posted by Laurin
LoL understatement of the century!

I-want-this-asap!

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  #16  
Old 11-10-2011, 09:39 AM
Pern Pern is offline
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That is my M2 mixer described at my website. The M1 is a 2-6 channel mixer.
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  #17  
Old 11-10-2011, 09:40 AM
thebuttonfreak thebuttonfreak is offline
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Thanks for the info Pern. That's a really inspiring project and almost exactly the type of thing I'm looking to do, I'm not set on building an exact Bozak clone. Truth be told I've never even seen one. I am attracted to building a nice discrete rotary knob mixer in a similar configuration as you have now. So it doesn't need to be an exact replica.
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  #18  
Old 11-10-2011, 09:52 AM
thebuttonfreak thebuttonfreak is offline
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Wow, thanks for the SPICE tip. I was going to open up Mathematica and do it all myself.
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  #19  
Old 11-10-2011, 09:52 AM
Pern Pern is offline
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A good start is to start with the summing amp and adding an output amp/buffer and it can be really simple. You can use the summing amp from the Bozak schematics if you want. You can use the Bozak output card also, but i think it has too much gain for my needs.

(But this is my own design.)
http://www.bozure.com/T1.aspx?PID=58
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Last edited by Pern : 11-10-2011 at 11:21 AM.
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  #20  
Old 11-10-2011, 10:03 AM
Pern Pern is offline
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Quote:
Originally Posted by thebuttonfreak
Wow, thanks for the SPICE tip. I was going to open up Mathematica and do it all myself.

I do all my designs as SPICE simulations also (after basic calculations) . Then when i'm finished i do the final calculations.

I use LTspice, free and nice.
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Last edited by Pern : 11-10-2011 at 10:18 AM.
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  #21  
Old 11-10-2011, 11:26 AM
thebuttonfreak thebuttonfreak is offline
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could you explain what those plots mean? Obviously it's voltage out on the x axis. Bit what is on y axis? Voltage in? How do I interpret it? Sorry for the noob questions. I'm a quick study though.
Quote:
Originally Posted by Pern
A good start is to start with the summing amp and adding an output amp/buffer and it can be really simple. You can use the summing amp from the Bozak schematics if you want. You can use the Bozak output card also, but i think it has too much gain for my needs.

(But this is my own design.)
http://www.bozure.com/T1.aspx?PID=58

Last edited by thebuttonfreak : 11-10-2011 at 12:07 PM.
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  #22  
Old 11-11-2011, 01:33 AM
Pern Pern is offline
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First remember that the data quality of a SPICE simulation is only as good as the quality of the models that you use.


Top chart is an FFT with an input sinewave V source set to 1V at 1KHz and pots set so that the output is 0dB (almost).

X-Axis: Frequency
Y-Axis: Output level in dB

First you can see that the noise level is about -142dB. And the distortion generated is mainly 2nd harmonics (-117dB) and a little 3rd harmonics (-138dB).

Second chart: The interesting line here is the one at -56mdB. This is the frequency response and the value itself is not interesting but how flat it is. Here it is about +- 2mdB from 10Hz to 100KHz.
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Last edited by Pern : 11-11-2011 at 03:50 AM.
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  #23  
Old 11-11-2011, 04:37 AM
Richi Richi is offline
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Pern what are you using to generate the 1KHz sinewave at 1v. I'm presuming the FFT is software based?
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  #24  
Old 11-11-2011, 05:03 AM
Pern Pern is offline
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Simulation is done in LTspice.
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  #25  
Old 11-11-2011, 05:16 AM
Richi Richi is offline
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Simulations aside, what does an actual unit measure then?
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