Diamond Bass Comp

snk · Post by **snk** » 22 Apr 2021, 12:13

Hello,
I have built a simplified version of the Diamond Compressor, using Fred Briggs DIAMANTE design, and this layout on veroboard.
I really like what it does

However, there are two little things which I'd like to improve :

1- I'd like to be able to get a little bit more of output volume.
At high compression settings, i'm barely at unity gain, and I wish I could get 3 to 6 more dB at make-up gain. Is it possible (I mean, without adding a booster as a daughterboard) ?

2- The barebones Diamante design skips both the TONE and the INDICATOR LED. I don't need the tone, but now that i've built it, I wish I could add an indicator led. I don't need a fancy bicolor led, but it would be nice to have a led showing the amount of compression, without affecting the tone.
Is there any easy way to add this to the Diamante?

Thank you!

Manfred · Post by **Manfred** » 22 Apr 2021, 23:24

To point 1:
For 2dB more gain decrease R19 to 2.2k and increase C13 to 1.5uF.
For 3dB more gain decrease R19 to 1.5k and increase C13 to 2.2uF.
To Point 2:
An idea would be to insert a LED between +9V and terminal 2 of the VTL5C3 which then maps the current through the LED of the VTL in the illuminance,
but whether this works at all and how you have to redimension the control circuit of the VTL in this case I cannot say without more knowledge about it.

snk · Post by **snk** » 22 Apr 2021, 23:37

Hello, Manfred,

To point 1:
For 2dB more gain decrease R19 to 2.2k and increase C13 to 1.5uF.
For 3dB more gain decrease R19 to 1.5k and increase C13 to 2.2uF.

The 3dB gain increase tip is great, and I will do it tomorrow, thank you!

To Point 2:
An idea would be to insert a LED between +9V and terminal 2 of the VTL5C3 which then maps the current through the LED of the VTL in the illuminance,
but whether this works at all and how you have to redimension the control circuit of the VTL in this case I cannot say without more knowledge about it.

I will try that. The stupid thing is that the original pedal uses a led indicator, but 1- it uses a bicolor led, and 2-the circuit I followed (by Fred Briggs) is quite different than the original Diamond Comp (less transistors, more opamps, etc), so i don't know how to adapt the indicator led portion from it...

snk · Post by **snk** » 24 Apr 2021, 18:17

Hi,
I just checked, and I don't have any 2.2µF Mylar/polyester cap left : should I go for a monolithic ceramic capacitor instead, or for an electrolytic, or even tantalum?
(I often use Mylar for audio path and electrolytic for power supply, but here, i don't know which kind would be best... and if that matters)

snk · Post by **snk** » 25 Apr 2021, 18:15

Hi,
In fact, while the layout I used to build my circuit used a polyester 1µF capacitor, the Fred Briggs design used an electrolytic there : so, I put a 4.7µF instead of the stock 1µF cap, along with the 1.5K resistor, and *bang!*, it's perfect ! Now, the Diamond compressor can compress much more, and I have enough makeup gain, louder than unity gain if needed.
Thank you again for your tip, Manfred, it's much appreciated !

codysorgenfrey · Post by **codysorgenfrey** » 13 Apr 2023, 17:23

Please forgive my ignorance as I'm just learning EE in my free time.

Did you all use 1/4W metal film resistors for most of the circuit? I saw on the Diamond website (http://web.archive.org/web/201807311130 ... s.com/faq/) that the pedal is supposed to draw 20mA @ 18-24V which would call for resistors that can withstand at least 0.36 watts. Can someone explain this to me? Or did I wrongly assume those smaller resistors are 0.25 watt?

UPDATE:
I've done a bunch of research, and now know this is not how you actually determine resistor power rating. If someone would be so kind as to explain how to actually work out what you'd need for this circuit, I would greatly appreciate it! It seems most people online are comfortable with just overestimating by a wide margin so as not to get in trouble.

lietuvis · Post by **lietuvis** » 14 Apr 2023, 19:48

codysorgenfrey wrote: ↑13 Apr 2023, 17:23 Please forgive my ignorance as I'm just learning EE in my free time.

Did you all use 1/4W metal film resistors for most of the circuit? I saw on the Diamond website (http://web.archive.org/web/201807311130 ... s.com/faq/) that the pedal is supposed to draw 20mA @ 18-24V which would call for resistors that can withstand at least 0.36 watts. Can someone explain this to me? Or did I wrongly assume those smaller resistors are 0.25 watt?

UPDATE:
I've done a bunch of research, and now know this is not how you actually determine resistor power rating. If someone would be so kind as to explain how to actually work out what you'd need for this circuit, I would greatly appreciate it! It seems most people online are comfortable with just overestimating by a wide margin so as not to get in trouble.

Hi, for your convenience as a learner start using basic ohms law formula to calculate your current then learn turn your current and voltage to power. Very soon you will learn that 0.25W resistors are more than enough for pedal building, most of these 20mA are eaten by IC's and transistors rather than resistors. In other hand you won't really see few ohm resistor connected to 24V directly.
For example: voltage divider made of 2 x 10K resistors connected directly to 24V will dissipate 0.0288W thats: I (current) = V (voltage) / R (resistance) then P (power) = I (current) * V (voltage) - ( I )0.0012A=24V/20000ohm, ( P )0.0288W=0.0012A*24V
Hope that makes sense for start.
Someone can correct me if I'm wrong
Happy stompboxing

codysorgenfrey · Post by **codysorgenfrey** » 12 Jun 2023, 14:40

Thanks to everyone on this thread! This pedal sounds awesome!

If anyone wants the files for this project let me know. I have the schematic, CAD, PCB gerber files and enclosure design files.