dbx 160vu clone

[abechap024]

Yea its just that a copyrighted LOGO is a lot different than a circuit...From my understanding all you can really copyright in a circuit is the actually drawing. otherwise the guy that invented a differntial opamp input would be a millionaire...And they no longer produce the 160vu, but pretty sure that logo is still what they are known by. Anyway more power to you! Just pretty sure DIY or not, selling something (parts to a DIY product or not) with a registered trademark on it (that you do not own) is seemingly icey ground. Not trying to make a double standard here, we all are "inspired" by different designs.

 

[Biasrocks]

Yes is have seen a real dbx 160. Like I said this is a order that had to satisfy may people and they chose the white on black design.

My reply was directed at SR1200, who was questioning the use of the dbx logo.

Regards,
Mark

 

[sr1200]

Understood, I just dont want to see another purusha incident or another thing like last week with the LA2A chassis... BTW, are there still part kits available.. i never did get around to finishing my 1U 2channel unit.  (the i channel I do have has been gettin a work out lately

 

[abechap024]

... are there still part kits available.. i never did get around to finishing my 1U 2channel unit.  (the i channel I do have has been gettin a work out lately

I better start stocking them again i guess. gotten a lot of requests for them!

 

[canidoit]

Well can't find the other thread....just want to let people know that the REV 3 manual is finished!

www.acsoundstudio.com/manuals/clx_manual_rev3.pdf

Thanks

Impressive manual abe!

 

[SLB]

Understood, I just dont want to see another purusha incident or another thing like last week with the LA2A chassis... BTW, are there still part kits available.. i never did get around to finishing my 1U 2channel unit.  (the i channel I do have has been gettin a work out lately

Please explain the incident. I'm considering changing it. I don't want to cause any trouble.

Regards,
Brezo

 

[sr1200]

as far as i understand it, long story short, a guy was selling chassis for DIY gear that was identical to the "real" gear including logos and everything else... thats a BIIIIG no no. If the site is seen selling items that contain trademarked logo's there is a level of liability that the owner/admin of this site has and could cost him (and subsequently the community on here) dearly.  Now, if you made the meters with cLx in the dBx font... that would be cool. 

 

[dmp]

Very cool project. I've been watching this for a long time and it is great you pulled it off.
It would be really cool to add the attack release of the dbx165 to a next rev.
And make it into 51x too!

My two cents: I think if you want to copy a logo it's best to keep it off the forum. It makes the place look bad.
And shouldn't people in the music business be against stealing someone else's logo??? Take the moral high ground. It will make you feel better when you can't earn a living as a musician because everyone takes music for free.

 

[Kid Squid]

Hi Abe,
Just wondering if you have any spare boards left for sale ?

Best,
Steve

 

[abechap024]

Hi Abe,
Just wondering if you have any spare boards left for sale ?

Best,
Steve

Yes, I need to make another order for some. Just scratching my head on how to do a group buy on here....should start a new thread??

 

[haima]

I have a board left from an earlier run (it might even be one of the very first, prototype runs...?)

I'm not going to get around to it... not much time for DIY these days :'( Send me a PM if interested.

Otherwise wait for the good chap abechap's next run!

Carry on.

 

[alexidoia]

Hi there, is there a new topic ? I am interested in some PCBs.
Thanks

 

[abechap024]

Hi there, is there a new topic ? I am interested in some PCBs.
Thanks

Its codenamed the CLX-vu or just the CLX
There are boards available!

 

[thomasdf]

I'd love to give that comp a try but I need to see if I can make it fit in a spare Eurorack case that I have... What is the board size in millimeters please?

Thomas

 

[David Kulka]

I could get the exact meter remade but people did not won't to spend that kind of money. The same model meter is still available today and is made by Beede. I believe that meter used in UA LA-2A is the same design made by Beede.

Huh?

Several years ago I had a batch of 160 meters made by Beede, but they told me that after my order was filled, no further orders for them would be accepted, because too much set up time was needed. I made inquiries once or twice after that, and was told the same thing. Did Beede tell you that they would make more of these for you?

It's definitely not the same meter as in the LA-2A, not even close. The 160 meter is much smaller, is DC instead of AC, and the needle rests right of center, instead the left end of the scale.

 

[Biasrocks]

The discrete VCA's, and other parts add to that character, but the dynamic feel can be reproduced with the 2252 and the 22uf cap and 909kohm resistor combination (it won't be exactly the same, due to the difference in dynamic resistance characteristics of the charging transistors in the 208 vs the 2252, but will be close). Adjustments for threshold vs input signal would have to be re-calculated with the new components to achieve similar results to the new standard parts.

To answer the parts question, on my 160 schematic, the parts in question are R35 and C15.
jD

Actually, I have a schematic which shows R35 is a 1M 1% resistor in both the 160 and 161. The value of C15 is correct the same.

I'll have to open up the pair of 161's I have here to verify what they actually used.

Mark

 

[Biasrocks]

Schematic pt2

 

[SirNickity]

Thread necromancy!

I've been working on transcribing this (CLX) schematic to something more comprehensible, and I've run into something a bit peculiar.  Take a look at Q7 -- the one right by the VCA module.  This is a PNP transistor with the collector connected to +15V through 470R, the emitter connected to ground, and the base connected to ... nothing.

I assumed this was a mistake, but the CLX schematics show it, the CLX board follows the schematic exactly, and all the old dbx 160 schematics I've seen also show the base unconnected.  (The dbx schematic posted just above also notes that this transistor should be selected with the VCA.)

I did some research on this, since I've never seen someone leave a base floating on purpose (tricks involving photo or capacitive sensitivity notwithstanding), and it appears various (mostly audio?) companies have used this technique as a crude avalanche diode.

So, my question is... is this a good idea?  I'm guessing most people building the CLX are not giving much thought to Q7 selection.  (Indeed, most are probably leaving it out completely, in favor of the 2180.)  For that matter, does anyone know what criteria WOULD be important?  Or wouldn't we rather use a zener or something else more modern?  I'm not even 100% sure what the designers are trying to achieve here, but from what I've read, actual avalanche diodes are more reliable, more stable, and in general appear to be superior to this hack(?) in just about every way.

Any thoughts?

 

[SirNickity]

Found another oddity...

In the output section, the LM301 is being powered through resistors to the +/-24V rails.  This is strange enough, as it is usually advised to provide the lowest possible impedance to the rails -- not add several K-ohms.

Abe's schematic doesn't show what's going on around here very clearly -- some layout issues obscure what is actually connected where, but I've traced the PCB and it seems like V+ and V- are through R85 (2.2K) to +24V, and R95 (2.2K) to -24V.  The original schematics show these as 3.3K, but are otherwise in agreement.

This all seems very sketchy, and is blowing my mind a little bit.  The Rs spec'd are 2/3 the value of the original, and seem to be the only thing standing in the way of frying that poor IC, as the rails are 1/3 higher than the absolute max allowed per the datasheet.  Of course, with that much resistance, the actual voltage present is going to be load-dependent, while also sourced from the *unregulated* DC voltage coming off the rectified transformer secondary, so dependent on mains voltage, secondary ratio, and line/load regulation of the transformer as well.

WTH?   Nothing about this makes sense.

EDIT:  Attached a copy of my work-in-progress schematic.  Main PCB page only for now.  I also have the 200 / 2180 and 208 circuits drawn on separate pages.

 

[abbey road d enfer]

In the output section, the LM301 is being powered through resistors to the +/-24V rails.  This is strange enough

Not strange at all; bootstrapped rails. This a trick that allows a larger swing than the absolute rails of the opamp. The actual voltage seen by the opamp is less than +/-24V because of the drop in R86/94. OTOH capacitors C27/28swing the opamp's supplies in accordance with the expected output.