Diamond - Compressor [new gut shots added]  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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culturejam
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Post by culturejam »

Here are a bevy of gut shots provided to the forum anonymously.
====
Attachments
diamond_comp_01.jpg
diamond_comp_02.jpg
diamond_comp_03.jpg
diamond_comp_04.jpg
diamond_comp_05.jpg
diamond_comp_06.jpg
diamond_comp_07.jpg
diamond_comp_10.jpg

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culturejam
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Post by culturejam »

And here are parts values, also contributed anonymously.

Capacitors
Caps 2u2 and higher are electrolytic. C22/23/30/31/32 are ceramic, all other film
C1 47u
C2 47u
C3 47u
C4 5n6
C5 5n6
C6 330n
C7 100n
C8 100n
C9 100p
C10 820p
C11 100p
C12 820p
C13 1u
C14 100p
C15 330n
C16 820p
C17 820p
C18 100n
C19 10n
C20 10n
C21 2u2
C22 100n
C23 100n
C24 820p
C25 3n3
C26 15n
C27 10n
C28 4u7
C29 3n3
C30 100n
C31 100n
C32 100n

Resistors
All metal film 1% except R1 which is carbon film 5%
R1 100R
R2 10K
R3 10K
R4 100R
R5 15K
R6 3.32K
R7 22.1K
R9 15K
R10 47.5K
R11 47.5K
R12 47.5K
R13 47.5K
R15 1M
R16 475R
R17 475K
R18 475K
R19 3.32K
R20 6.41K
R22 100R
R23 475K
R24 22.1K
R25 100K
R26 1K
R27 3.32K
R28 475R
R29 221K
R30 475K
R31 100K
R32 221K
R33 100K
R34 475K
R35 221K
R36 10K
R37 1.5K
R38 10K
R39 Jumper
R40 10K

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Post by analogguru »

:shock: most of the components desoldered in the last picture :shock:

I think this effort deserves a schematic.

first impression:
the routing is insanely complicated - as an example have a look at the rectifier-stage at the lower right corner (D7, D8, R29, R32, C19, C20). That´s one of the worst routings I have ever seen. This area could be very easily done on a single layer with the same component placement. You only have to make the ground connection of R29 and R32 on the other side of the resistor.

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Post by Dirk_Hendrik »

analogguru wrote:That´s one of the worst routings I have ever seen.
Take any BYOC or Roger Mayer PCB and this is heaven :roll:

kudo's for the contributor who has the balls to desolder his Diamond this way. Many would be scared to death to ruin it :thumbsup
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Post by analogguru »

Dirk_Hendrik wrote:
analogguru wrote:That´s one of the worst routings I have ever seen.
Take any ...... Roger Mayer PCB and this is heaven :roll:
I think you mean the new RM-pedals. The routing of the old (vntage) RM-pedals is not so bad.

But you are welcome to trace the schematic. :roll: For the rectifier stage you can start at pin 7 of U1 and go on to R31 and C25.

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Post by analogguru »

Boahh..... The electronic design is similar shitty as the routing - typical "boutique". My impression:
Someone was surfing too much on diy-"high-end"-sites, absorbing everything he could find there - including mojo - and now believes that he is an audio-design-engineer and ready for the pedal-world.

Example 1:
The input buffer doesn´t have a normal emitter resistor to ground, no, the resistor is replaced by a current source to improve the distortion factor from 0,01% to 0,001 % - as if this would be important in a distorted guitar world.

Example 2:
The tone-control is a 100% clone of a "high-end"-diy-design. The basics for this design were published in 1970 in the magazine "wireless world". In the mentioned diy-design there was a switch to bypass the tone-control. This was done with two resistors R12 and R13 which were connected by the switch to the inverting input instead of the potentiometer. The original bypass-function has been omitted but the now unnecesary resistors R12 and R13 are still there.

Example 3:
The coupling caps are 100n film caps in parallel with 820p film caps.

When high-end solder-jockeys meet the pedal-world......

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Post by culturejam »

analogguru wrote:Example 3:
The coupling caps are 100n film caps in parallel with 820p film caps.
What exactly does this accomplish, other than give an effective capacitance of 100.82nF? (assuming the caps actually are at the rated values)

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Post by analogguru »

culturejam wrote: What exactly does this accomplish, other than give an effective capacitance of 100.82nF? (assuming the caps actually are at the rated values)
This technique is normally used with electrolytics. The theory behind this is that every (electrolytic) capacitor has an inductivity too. The result is that the reactance of the capacitor will increase with frequency having the effect of a poorer high-frequency response (above 10 - 15 kHz).

This effect will be stronger with electrolytics. So if you need a 10µF electrolytic for good bass response the high-frequency part of the signal will not be as good as with a 10µF film cap - neglecting the size and price of the film cap.

The solution:
Take a 10µF electrolytic in parallel with a film cap (up to) 1/10th of the value in this case a 1µF film-cap. Some high-end freaks even parallel to this combination a ceramic cap of again (up to) 1/10th from the value of the film-cap. Snake-oil sellers are everywhere.

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Post by culturejam »

Interesting.

So you're saying that for small-value film caps, such paralleling is sort of pointless?

I'm also wondering if after there is a schematic for this monstrosity, we couldn't work up something just as effective but with less parts and a more sensible setup. :)

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Post by Jack Deville »

culturejam wrote: So you're saying that for small-value film caps, such paralleling is sort of pointless?
I'll wholeheartedly agree with the above notion.
Placing caps in parallel can create an unusual (or standard) value, and it is feasible that this is critical for the design of a tuned circuit. In my experience however, the values/construction of the capacitors selected in most common stompboxes can be optimized, often times for an improvement in the performance of the circuit.

Without analyzing the full circuit, it is impossible to say whether or not that is the case in this specific instance, and quite frankly, I'm in no mood to trace a PCB from a few (nice) photographs.
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Post by PmCimini »

but folks, setting all the mojo apart, we all must agree that solid construction and useless practices (lined up components, polyester film caps instead of multilayer and boards with parallel lines), actually make up for a great build and look.... and even if this circuit won't mean much difference afterwards, I always looked at the gutshots with pleasure

edit:
btw, I really -HATE- those cross-connections when a component is soldered into the groundplane. I mean, I know eaglecad does this automatically if you don't change it, but it bugs me so much when working on it... is there any actual function for it?

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Post by Jack Deville »

Yes.
Its a nice and convenient way to run your ground! Plus, it can be used to "shield" some sections of the PCB.
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Post by mictester »

culturejam wrote:Interesting.

So you're saying that for small-value film caps, such paralleling is sort of pointless?

I'm also wondering if after there is a schematic for this monstrosity, we couldn't work up something just as effective but with less parts and a more sensible setup. :)
It's entirely pointless unless you want to make a non-standard value for (say) an accurately tuned filter. It has no audible effect whatsoever.

However, it is a valid technique at radio frequencies - RF power amplifiers need their supply rails decoupled at a range of frequencies, so two or three capacitors are sometimes used - an electrolytic for the lowest frequencies (and to keep modulating audio off the supply rails in AM gear), and ceramic types for the RF.

The clueless Audiophools believe that RF techniques apply at audio frequencies (I can remember being told proudly by the designer of the Naim amplifiers that his output transistors were rated to >20 MHz!).

Incidentally - is the actual performance of this compressor any good?
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Post by cpm »

PmCimini wrote: edit:
btw, I really -HATE- those cross-connections when a component is soldered into the groundplane. I mean, I know eaglecad does this automatically if you don't change it, but it bugs me so much when working on it... is there any actual function for it?
those are "thermal relief pads"
their purpose is to make a physical separation from the signal plane, so when you solder the part, the heat gets concentrated on the pad, instead of spread across the surrounding copper (this would make longer solder times to heat up the copper)

the final purpose is to unify heating time on each pad, for a mechanical process.
it may also help with the risk of damaging a part from overheating.

culturejam wrote:I'm also wondering if after there is a schematic for this monstrosity, we couldn't work up something just as effective but with less parts and a more sensible setup.
sure...
but do you really nedd to look this schematic? i guess we're able to work out from scratch something just as good if not better.

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Post by HEAD »

cpm wrote:
PmCimini wrote: but do you really nedd to look this schematic? i guess we're able to work out from scratch something just as good if not better.
:wink:
Why not? Would be great to show all the boutiquers out there what you can do if you realy got the guts.;)

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Helge

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Post by culturejam »

mictester wrote:Incidentally - is the actual performance of this compressor any good?
Never tried it, but I've heard a lot of sensible people say it's a great compressor.

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Post by toetap »

The performance is a very low artifact style compression. Sounds really nice for this sort of thing. I personally enjoy my Orange Squeezer more. (A little color added.)

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Post by PmCimini »

cpm wrote:
PmCimini wrote: edit:
btw, I really -HATE- those cross-connections when a component is soldered into the groundplane. I mean, I know eaglecad does this automatically if you don't change it, but it bugs me so much when working on it... is there any actual function for it?
those are "thermal relief pads"
their purpose is to make a physical separation from the signal plane, so when you solder the part, the heat gets concentrated on the pad, instead of spread across the surrounding copper (this would make longer solder times to heat up the copper)

the final purpose is to unify heating time on each pad, for a mechanical process.
it may also help with the risk of damaging a part from overheating.

Whoa, thank you for the really insightful answer.... Those crosses always bugged me whenever I tried to reverse a pedal... but at least I can see that they indeed have some utility...

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Post by KB »

Sorry for dragging up this old thread

I was wondering if a schematic was ever completed?

My question is about the Tilt eq. Is it similar to Figure 10 in this link


http://gilmore2.chem.northwestern.edu/ ... al_prj.htm

If anyone can supply any information I would be grateful.

cheers

Kevin

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Post by analogguru »

KB wrote: My question is about the Tilt eq. Is it similar to Figure 10 in this link

http://gilmore2.chem.northwestern.edu/p ... al_prj.htm
It is not similar, it is identical (except that the switch has been omitted) because it is "stolen" from there. The non inverting input connects to V/2 cause it runs on single supply. Rest as described above.

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