Zvex - Box of Metal  [traced]

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Re: Zvex - Box of Metal (gut shots)

Postby bajaman » 27 Dec 2008, 11:16

....... more details - the input also feeds one half of a high variable gain stage op amp controlled by the gate potentiometer.
the output of this is fed to a half wave rectifier and also to the other half of the op amp which is usd as a unity gain inverting stage - the latter also is fed into a half wave rectifier and the two rectifier outputs are summed and these drive the led in the vactrol optocoupler (any numbers on it?? or did Zachie buff them off as well!!!) through an NPN bipolar transistor stage. This controls the resistance of the LDR which is effectively in parallel across the output volume potentiometer.
I am not certain - but there appears to be a p type Jfet in series with the signal from the treble wiper. This is normally a very low resitance when no voltage is applied to it's gate - when the noise gate circuit is not activated. When the noise gate circuit is activated the p jfet gate is connected to the junction of the LDR and top of the output master volume control - depending on the level predecided by the setting of the gate control which as mentioned sets the gain of the detector and hence the rectified DC output level which activates the LED section of the optocoupler.
As a result a varying dc voltage is applied to the gate of the p jfet which increases and decreases its drain source resistance accordingly.
There is also a precision virtual earth half rail 8 pin chip too - this is most likely to be a TLE2426 device from Texas Instruments - the previous mentioned dual opa mp is most likely to be a TL072 or similar - not critical, but you could use a higher speed device if you want to.
more later
Cheers
bajaman
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Re: Zvex - Box of Metal (gut shots)

Postby ShortScaleMike » 27 Dec 2008, 12:13

Absolutely top-drawer work, Bajaman.

And thanks very much culturejam for posting the pictures.
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Re: Zvex - Box of Metal (gut shots)

Postby bajaman » 27 Dec 2008, 12:47

Hi Culture jam
What is the distance between the controls please??
inches or millimetres no problem :wink:
thanks - board layout nearly ready :)
cheers
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Re: Zvex - Box of Metal (gut shots)

Postby audioguy » 27 Dec 2008, 16:42

awesome.... I've got a clear bench this weekend. I would love to give it a go!
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Re: Zvex - Box of Metal (gut shots)

Postby culturejam » 27 Dec 2008, 20:31

bajaman wrote:Hi Culture jam
What is the distance between the controls please??

8mm from the edge of one pot to the edge of the next.

There are no markings of any kind on the opto coupler.

I'm thinking I'd have to desolder the caps to read them properly? I'd rather not have to do that, because I have doubts about my ability to re-solder them properly. :oops:

Would it be possible to measure them in circuit, and then back-calculate the value based on how they are connected to other components?
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Re: Zvex - Box of Metal (gut shots)

Postby DWBH » 27 Dec 2008, 21:40

culturejam wrote:
bajaman wrote:Hi Culture jam
What is the distance between the controls please??

8mm from the edge of one pot to the edge of the next.

There are no markings of any kind on the opto coupler.

I'm thinking I'd have to desolder the caps to read them properly? I'd rather not have to do that, because I have doubts about my ability to re-solder them properly. :oops:

Would it be possible to measure them in circuit, and then back-calculate the value based on how they are connected to other components?


bajaman wrote:
I do have a capacitance meter function on my DMM, but it's only for leaded components. It's just two little slots that you slide the leads into

Just grab some insulated hookup wire - strip, twist and tin both ends with solder - plug into capacitance slots and use the other two ends and place them against the ends of the smd capacitors ( the cream coloured flat slab things).
bajaman


;)
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Re: Zvex - Box of Metal (gut shots)

Postby bajaman » 27 Dec 2008, 21:43

Would it be possible to measure them in circuit,

Yes - should be reasonably accurate to do - make sure the pots are all set at half rotation though :wink:
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Re: Zvex - Box of Metal (gut shots)

Postby culturejam » 28 Dec 2008, 00:10

bajaman wrote:
Would it be possible to measure them in circuit,

Yes - should be reasonably accurate to do - make sure the pots are all set at half rotation though :wink:
cheers
bajaman

I'll see what I can do.
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Re: Zvex - Box of Metal (gut shots)

Postby culturejam » 28 Dec 2008, 03:52

Okay, here's what I came up with. Let me know if you need anything else, Bajaman.
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Re: Zvex - Box of Metal (gut shots)  [traced]

Postby bajaman » 28 Dec 2008, 06:59

Thanks culturejam
I have finished my drawings with the component values etc.
I would not consider this an easy to build project - it would be a lot easier to build in a larger box with veroboard or some other through hole component construction.
I would not bother with the gate etc. - far too complicated for very little useability.
Instead use my earlier sketch (now amended with capacitor values and output volume components).
I think that switching some of the SHO stages out may give a more useable function - use a boost control footswitch instead of the gate. More later
cheers
bajaman

http://freestompboxes.org/members/bajam ... sketch.jpg
http://freestompboxes.org/members/bajam ... taltop.png
http://freestompboxes.org/members/bajam ... bottom.png
http://freestompboxes.org/members/bajam ... verlay.png

PLEASE do not try to build this smd layout - it is for educational reference only - you will go blind if you try and build it :wink: :D
bajaman
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Re: Zvex - Box of Metal (gut shots)

Postby borislavgajic » 28 Dec 2008, 10:45

:thumbsup :applause:

great job

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Re: Zvex - Box of Metal (gut shots)

Postby mike_a » 28 Dec 2008, 11:24

bajaman wrote:PLEASE do not try to build this smd layout - it is for educational reference only - you will go blind if you try and build it :wink: :D
bajaman

I can't imagine why anyone would want to clone this horrible sounding unit :?
it's funny to see that is, in fact, another "original" SHO cascaded "design" from the uber-master of cascaded SHO's ... :lol:

Great job on the tracing Bajaman!
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Re: Zvex - Box of Metal (gut shots)

Postby bajaman » 28 Dec 2008, 11:46

The signal path looks strangely familiar to me - almost peavey 5150 or bogner or mesa dual rectum frier.
Only tubes overload and generate those nice smooth tube harmonics though :wink: - no hissy BS170 is gonna get you there. :lol: Still some folks like them I guess. :roll: Maybe a string of TL072 op amps run into clipping diodes like those backwood D2G guys do - see Briggs Kustom Kretin Drive :wink: Ahhh the Super Hard On - It came to me in a dream :hmmm: :blackeye :lol: :lol: :lol: :lol: :lol: :lol:
I wonder what it would sound like with some of those small Russian pentodes (wired as triodes of course) :wink: - another project for a rainy day - they run nice and cool off 30v dc too :wink: - easily done with a 16v AC power pack supply - (or four 9v batteries :lol: :lol: )
I'm beat - too much Christmas pudding and 27 degree celsius temperatures - too hot to sleep for an old codger like me.
Hope you all had a PEACEFUL Christmas
Peace and Goodwill to all
Do good deeds and do not expect anything in return. You will be surprised when the kharmic wheel turns and repays you for an act of kindness - often when you least expect it.
cheers
bajaman
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Re: Zvex - Box of Metal (gut shots)

Postby moltenmetalburn » 28 Dec 2008, 16:43

Dont feel bad! :hug: Lets just try to stay on topic! :horsey:
"The Humans Will Never Destroy Us"
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Re: Zvex - Box of Metal (gut shots)

Postby borislavgajic » 28 Dec 2008, 17:28

moltenmetalburn wrote:Dont feel bad! :hug: Lets just try to stay on topic! :horsey:


:thumbsup :thumbsup :thumbsup
Yes ,stay in freestompboxes land ....no religion ,politics...........just electronics,and no bad feelings!

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Re: Zvex - Box of Metal (gut shots)

Postby bajaman » 28 Dec 2008, 20:36

my apologies Mike a :oops: - I just do not like seeing ANY innocent people killed for whatever reason.
Back to the Mox of betal.
i shall draw the noise gate section soon (unless someone else beats me to it :wink: )
cheers
bajaman
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Re: Zvex - Box of Metal (gut shots)

Postby mike_a » 28 Dec 2008, 20:45

No hard feelings :thumbsup

Thanks again for your work on the tracing.
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Re: Zvex - Box of Metal (gut shots)

Postby bumblebee » 28 Dec 2008, 22:08

Nice work bajaman!
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Re: Zvex - Box of Metal (gut shots)

Postby Cow4prez » 01 Jan 2009, 22:18

Okay - so here it is - a 5 stage super hard on with a modified Marshall tone stack.

[smilie=eek2.gif]
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Re: Zvex - Box of Metal (gut shots)

Postby Torchy » 02 Jan 2009, 00:33

Polite request -

Can we keep the politics out of stompbox threads please ? Its a multinational board and we all have our own views/opinions. Ta :wink:

Thanks for the B-O-M work so far. I'd be interested in the gate element of this too.
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