Transformerless Vari Mu Compressor build thread

[scott2000]

Also, would it be possible to build a non-mastering stepped version that otherwise works like the pot version in terms of levels and GR selection?

Like Heikki said, the stepped rotary sidechain boards were intended basically to be used as an alternative to the pots for more accuracy/repeatability. Same as when the coarser stepped input controls were added to use in place of pots there.

The highpass and the extended threshold mod is useful regardless even though they were added in/for the mastering version ..imo.

 

[JMan]

Starting to source parts for this build. I found this wall wart (the recommended one from the BOM is out of stock everywhere and one of the retailers helped me scout around for an alternative, and this is what we came up with). Does it look like this will work? It's got 36v/1A output.

https://www.mouser.com/ProductDetail/XP-Power/ACM36US36?qs=w/v1CP2dgqpmeeEKxNJgTw==

 

[living sounds]

The high voltage DC DC converters costs 40-50 EUR and will be availible (maybe) in 6 months...

 

[Heikki]

Does it look like this will work? It's got 36v/1A output.

https://www.mouser.com/ProductDetail/XP-Power/ACM36US36?qs=w/v1CP2dgqpmeeEKxNJgTw==

It should work. Almost any 36V DC supply with 800mA or more max output current should work.

 

[Heikki]

The high voltage DC DC converters costs 40-50 EUR and will be availible (maybe) in 6 months...

TME still has 2 in stock

https://www.tme.eu/details/r24-150b/dc-dc-muuntajat/recom/

 

[living sounds]

TME still has 2 in stock

https://www.tme.eu/details/r24-150b/dc-dc-muuntajat/recom/

Thanks! Ordered it and the other one, too. Have these always been this pricy? I would never have expected that a linear PSU with a transformer could actually be cheaper...

Where can I get the perforated plate you used in your build?

 

[JMan]

It should work. Almost any 36V DC supply with 800mA or more max output current should work.

Thanks, Heikki! This is what I thought, since you had mentioned these specs earlier in the thread, but I really appreciate the confirmation!

 

[JMan]

@scott2000 did I spy purple meter LEDs on your build? Are there any restrictions/parameters for LED colors in the GR meter section? I seem to recall a post saying not to use any high efficiency LEDs, but I can't find it again on a quick scan of the thread and I'm wondering if maybe I am confusing it with a different project.

 

[scott2000]

did I spy purple meter LEDs on your build

Yes. I had used flat top blue,purple and (red at 12dB) but the blue was waaay too bright. There are output specs for the different colors and blue was more compared to the purple color.. Never knew to look.

I think these are the ones.....guess ultrabright should've been a clue..lol

https://lighthouseleds.com/led-component-lighting/clear-top-dip-leds/5mm-led-flat-top.html

 

[JMan]

Blue LEDs are crazy. Did you know that the invention of the blue LED won its creators the Nobel prize in physics?

 

[Heikki]

Where can I get the perforated plate you used in your build?

https://modushop.biz/site/index.php?route=product/product&product_id=299

 

[scott2000]

Blue LEDs are crazy. Did you know that the invention of the blue LED won its creators the Nobel prize in physics?

I did not! Neat..

 

[gyraf]

I'd wish they made a version of a blue led that was not monochromatic. My eyes simply don't agree with the halo effect of the blue..

/Jakob E.

 

[living sounds]

I'd wish they made a version of a blue led that was not monochromatic. My eyes simply don't agree with the halo effect of the blue..

/Jakob E.

I think I used a black marker on any gear that uses blue LEDs... But aren't all basic LEDs monochromatic?

 

[paolomunarini]

News on my build.

I added a vumeter driver circuit + vumeters scavenged from an old sansui receiver. For now the meters are only I/O meters, but I'm planning a mod on the driver meter to add gain reduction metering on the needles.

The panel is made by a guy in my city that does plaques/stamps. He has a CNC mill and a UV printer. I brought him my DXF and the panel from the TME rack chassis.

 

[living sounds]

C2 (2.2u) in the sidechain looks like a timing capacitor. Would it be advantageous to use a tantalum cap here? I often like what tantalums do in timing circuits.

 

[paolomunarini]

C2 (2.2u) in the sidechain looks like a timing capacitor. Would it be advantageous to use a tantalum cap here? I often like what tantalums do in timing circuits.

Following

 

[TheJames]

Anybody have some sound examples of this project? I'm curious about it.

 

[scott2000]

Anybody have some sound examples of this project? I'm curious about it.

1st post should have something..
Maybe depends on what kind of effect one may be wanting to hear though? For another example, just playing around with that BX Townhouse compressor at more extreme settings, it was easy enough to get things reacting/sounding similar imo but with the differences that the 2 have for whatever reasons. noise not being one...

 

[Heikki]

C2 (2.2u) in the sidechain looks like a timing capacitor. Would it be advantageous to use a tantalum cap here? I often like what tantalums do in timing circuits.

I don't know how significantly tantalum caps differ from a perfect capacitor so I can't say if it adds anything audible when using them as timing caps. Maybe tantalum caps will give that sweet sound of conflict minerals.