Sound Skulptor forums

Build help and troubleshooting => CP4500 Stereo Bus Compressor => Topic started by: herrturtur on November 10, 2021, 10:41:22 PM

Title: DMM says 0.3 VAC instead of 3.0 VAC
Post by: herrturtur on November 10, 2021, 10:41:22 PM

Here is where I am: Setup Channel 1, Step 6.

Signalflow: line level XLR from my USB Audio interface > into Monitor Controller > into Heritage Audio OST-4 V2 lunchbox > CP4500 connected via XT500 extension.

Doublechecked the CP4500:
Threshold +15
Makeup 0
Mix 100%

From Pro Tools Signal Generator, I am already sending 0dBFS and a fair amount of gain through my Monitor Controller into the lunchbox > CP4500. Can't get the DMM say 3.0 VAC staying within reasonable output gain of the monitor controller. DMM reads 0.3 VAC. Trimmers + Threshold + Makeup Gain work as expected.

I am new to DIY (and admittedly, using a DMM as well) - so just to doublecheck: The DMM should be connected to pins 2 (+) and 3 (-) of the XT500 (TP positions "2" and "4") / respectively of the XLR output pins of the Lunchbox..? I tried each combination, but no 3.0 VAC with makeup gain at 0.

Not sure If i can proceed to the next PCB like this :(

Thanks in advance!

PS: in case the pictures below show as gigantic as on my screen, with shift + mousewheel I am able to scroll right where you can see the pins etc.

(https://i.imgur.com/kOKefuI.jpg)

(https://i.imgur.com/HZZvDlS.jpg)

Title: Re: DMM says 0.3 VAC instead of 3.0 VAC
Post by: herrturtur on November 11, 2021, 11:34:08 AM

really strange: I went through the testing procedure "In case your CP4500 doesn't work as expected".. and everything was fine (except for the voltage not reading 3.0VAC, no matter how hard I cranked the output of my interface). Since I am not in the studio building the compressor, I use my home desktop USB interface which is a Roland Rubix22.

I then threw an Apogee Groove Dongle USB Interface at my mac and all of a sudden I get 3.0 VAC. I wonder if the interface is really suffering from output power or if there could be another reason for not getting enough volts...? So far so good. I will proceed with the setup guide :)

Cheers!

Title: Re: DMM says 0.3 VAC instead of 3.0 VAC
Post by: JPK on November 11, 2021, 03:48:50 PM

The specs of the Rubix22 say 8dBu maximum output. This is 1.95VAC at 0dBFS.
So it is not surprising that you could not reach the 3V.

Title: Re: DMM says 0.3 VAC instead of 3.0 VAC
Post by: herrturtur on November 15, 2021, 10:33:24 AM

Thanks for maintaining the forum so well! I did not expect the rubix to be that "weak". Completely assembled the CP4500 and tested in the studio, I am really happy with it! Cheers :)