Search found 5458 matches

by mediatechnology
Tue Apr 16, 2024 6:24 pm
Forum: Pro Audio Design
Topic: THAT2252 RMS Detector Replacement Using A THAT300 Array
Replies: 38
Views: 51089

Re: THAT2252 RMS Detector Replacement Using A THAT300 Array

The Uno Compressor spawned an improved THAT2252 replacement which is a "0 Vbe-up" design having a 0V output when the input is at the reference current. The gain of 2 amplifiers, which square the log of the absolute value, are level-shifted down by one Vbe. If not for this level-shift, the ...
by mediatechnology
Fri Apr 12, 2024 10:56 am
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

I've updated the drawing - which I'll post later - that includes the audio signal path, metering and sidechain on two sheets. For the moment I'll be pulling out all of the component designators in the drawing and reassigning them from the layout. It's a little tedious that way but it makes manual DI...
by mediatechnology
Mon Apr 08, 2024 6:29 am
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Latest schematic. I added a low frequency single-order high pass filter to the sidechain. With the values shown, the maximum frequency is about 240 Hz. Added series resistance at the Phoenix connector lowers the frequency. When fully open-circuit Fc is about 7 Hz. Jumpers at the output of the Dome f...
by mediatechnology
Thu Apr 04, 2024 3:03 pm
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

The units Paul and I are talking about (e.g. Neumann BSB74, Maselec MDS2) are specific to vinyl cutting and are typically used when the sibilance - or any excessive HF energy - isn't a problem in other mediums. Inverse RIAA, an acceleration-limited mechanical system, cutterhead power limits and powe...
by mediatechnology
Thu Apr 04, 2024 9:10 am
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Updated schematic 4/8/24. I added a simple Sidechain HP filter ahead of the Dome filter. https://proaudiodesignforum.com/images/jpg/Unocomp_Sidechain_Schematic_040824.jpg Though there appear to be a lot of op amps they can all be TL072. No attempt is being made to reduce component count because it's...
by mediatechnology
Thu Apr 04, 2024 9:01 am
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

I've had an interest in a de-esser/sibilance controller for vinyl and have wanted to wrap my head around the BSB74. It would need to be a dedicated box.. Jakob Erland once described it as S&M engineering. With the inductor based delay line. I have the BSB74 literature. If you need anything let ...
by mediatechnology
Wed Apr 03, 2024 6:29 pm
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

I've had an interest in a de-esser/sibilance controller for vinyl and have wanted to wrap my head around the BSB74. It would need to be a dedicated box. I decided to take a look at using a 10K linear pot, wired in a poteniometric configuration, to control the attack-release time and see if it were s...
by mediatechnology
Tue Apr 02, 2024 5:46 pm
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

Thanks! What's nice is that the actual ratios now follow the calculated values. I found that the combined feedback resistance with the trim added was now about 105KΩ or about 5% higher. Some of it is due to the dynamic resistance of the soft knee diode, Q2 of array 3, but most of it (I think) are th...
by mediatechnology
Mon Apr 01, 2024 4:54 pm
Forum: Pro Audio Design
Topic: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"
Replies: 60
Views: 28876

Re: A Quadrature Power-Summed Compressor Sidechain For "The Uno Compressor"

I found that a ratio trim is necessary to compensate for the tolerance in detector, sidechain and VCA control scale. When calibrated at 8:1 the lesser ratios remain accurate and near-infinite compression becomes available. The updated schematic has some additional changes. The current for the soft k...
by mediatechnology
Thu Mar 28, 2024 9:52 am
Forum: Build
Topic: Phono Transfer System Construction Information
Replies: 251
Views: 6616059

Re: Phono Transfer System Construction Information

4.7µF, the max available in PP, should be large enough since it moves the cutoff frequency down to about 2.4 Hz. It varies a little bit as the gain jumper is moved from 10K to 14K3 to 20K for -3, 0, and +3 dB gain. The RIAA path through the first input has two coupling caps - one at the input the se...