Hi Frequency Limiters?

[abbey road d enfer]

The print is a four page fold out IIRC. The inductors are a separate PCB that forms the other side of the module. It may be a separate print.

I had to print it and assemble it in order to make it legible. So far, I see that the signal is delayed, probably in order to apply some predictive compensation, the cross-over has a gentle slope of less than 6dB/octave and the detector has a perfect 12dB/oct slope which precisely matches acceleration, so overall, it's an interesting combo of wide-band and split mode.
Using analog multipliers as gain cells, it is perfectly suited for feed_forward topology.
It's the culmination of analog art, before digital audio wiped the slate clean.

 

[SWAN808]

I don't know how Warmth in FATSO works, maybe some slew-rate limiting. Never used it but the various videos have not convinced me of its value.
SOOTHE is a very nice tool, unfortunately there's no way you can DIY such a thing. DSP and FFT are the words.

Yes I actually wasn't blown away by FATSO Warmth circuit but the concept is similar...what I'm looking for is more of an effect that is being used commonly in certain types of electronic music so for sure it wouldn't necessarily be popular universally...I would plan on also having some clipping saturation alongside as well...so it's more of a creative processor...re Soothe yes understood you can't replicate DSP, again it's just a reference...

It seems like a de-esser is probably the most sensible way forward...I found the XS902 project and a dbx 263 schematic...I wonder how Empirical Labs do the HF limiting on ther Der-esser...

https://groupdiy.com/index.php?topic=46453.0

https://groupdiy.com/index.php?topic=69872.msg891037#msg891037

 

[abbey road d enfer]

I found the XS902 project and a dbx 263 schematic..

They're essentially the same! They replaced the expensive discrete stages with IC's, but the operation AND performances are the same, except if you want to drive a 150 ohms load...

I wonder how Empirical Labs do the HF limiting on ther Der-esser...

I don't know either. I can only conjecture. Since they have honed their soft-clipping circuitry, I wouldn't be surprized if they used it in the HF range.

 

[Gold]

Using analog multipliers as gain cells, it is perfectly suited for feed_forward topology.

I haven’t seen four quadrant multipliers used as gain cells in any other compressor.  It’s something of an art to get the units calibrated.

The older HK66 HF limiters are wideband with a 12K Hz bandpass in the sidechain. They don’t work nearly as well. I use the older VG66 rack the HK66’s came in. I have them hard bypassed.

 

[abbey road d enfer]

I haven’t seen four quadrant multipliers used as gain cells in any other compressor.

There have been a few attempts, but the limitations in terms of noise and distortion were a major issues, of which the datasheet is blatantly silent.

  It’s something of an art to get the units calibrated.

Indeed. I had to do it twice, first when the near new SX74 broke down and I replaced it with the SX68 from the older lathe, and second when we got the repaired SX74. No explanation from Neumann, but soon after, they came and modded something in the rack, leaving us clueless. That was 1976, so I guess they were still learning.

The older HK66 HF limiters are wideband with a 12K Hz bandpass in the sidechain. They don’t work nearly as well. I use the older VG66 rack the HK66’s came in. I have them hard bypassed.

So, no acceleration limiter?

 

[Gold]

Indeed. I had to do it twice, first when the near new SX74 broke down and I replaced it with the SX68 from the older lathe, and second when we got the repaired SX74. No explanation from Neumann, but soon after, they came and modded something in the rack, leaving us clueless. That was 1976, so I guess they were still learning.
So, no acceleration limiter?

There were seven revisions of the circuit. The last number in the drawing number is the revision number. By 1976 it was probably around revision three or four. The major change from the user perspective was single knob operation with the side chains linked. The original ones had separate meters for left and right. Later models have one knob and one meter. The official calibration procedure was never published AFAIK. It was eventually made available but the official translation to English left out a step. A friend had it re translated and figured that out.

I use the Maselec MDS2 as an HF limiter. I like it better than the BSB74.

 

[abbey road d enfer]

There were seven revisions of the circuit. The last number in the drawing number is the revision number. By 1976 it was probably around revision three or four. The major change from the user perspective was single knob operation with the side chains linked. The original ones had separate meters for left and right. Later models have one knob and one meter.

It's so far away for me I don't remember the details, just how much a PITN to set up.

The official calibration procedure was never published AFAIK. It was eventually made available but the official translation to English left out a step.

That's right, we didn't do a full recal, just set it up for the new (old) cutter and back. It was a tad terrifying, knowing that sneezing would probably end up with another burnt cutter head.

I use the Maselec MDS2 as an HF limiter. I like it better than the BSB74.

OK; I would think many modern dynamics would offer a better performance than this 40+ year old technology.

 

[Gold]

OK; I would think many modern dynamics would offer a better performance than this 40+ year old technology.

The BSB74 is still used and preferred by many. These days it can be hard to find SAL racks with BSB74's. They were stripped out of a lot of racks. Much of the 'record sound' is the sound of HF limiters. The BSB74 was the most widely used for the longest period. It could be argued that the BSB74 is the sound of a record.

 

[abbey road d enfer]

No arguing with acquired taste... 

 

[SWAN808]

I found a plugin version of the 902 de-esser and on a full track the results don't seem very useful...I don't know if the release is too fast to cope with complex source but it isn't a smooth sounding process...it should be a fairly accurate emulation because the developer is quite good...

I know it is in plugin world, but sometimes they are based from circuit modelling, but the limiter No. 6 has a HF limiter in it that sounds quite good...I wonder what philosophy that is based on...

https://www.tokyodawn.net/tdr-limiter6-ge/

Im now wondering is a frequency specific soft clipper might be a better direction in the analogue world...

You will have to forgive me but I am from the plugin generation so I do a lot of quite experimenting using plugins to get into the ballpark of what I want...

 

[gyraf]

That's quite surprizing; there's no mention on this effect in the VT7 litterature. Do you think it's a serendipitious effect?

It's the "softer" side of the harder/softer parameter potentiometer.  I had a suspicion that this is what it was doing, sweep sorta confirmed it.

But yes, strange that it's not mentioned in manual or description - perhaps they found it wise not to tell, because it would possibly prevent someone from using it from a theoretical perspective..

And it sounds really really good on a wide variety of slightly-too-hard mixes, much like a simplified/condensed version of what we often like in tube compressor side-effects (note that this is probably a PWM compressor with tube makeup, so it does not give you the tube-compression artifacts on its own ).

/Jakob E.

 

[synthiaks]

EMT also did something like this with the 260, I'm not sure if it was for Radio, cutting or only Deessing. What I do know is that you could change the filter in it so maybe it was a bit of all of the above depending of what was put in it.

/s

 

[Gold]

A BSS DPR-402 can be picked up for under $500 on the bay. That would probably give you what you are looking for. Before the Maselec was available this was a popular choice when a BSB74 wasn’t an option.

 

[scott2000]

does the 404 have the same de-esser as the 402? I thought it was pretty decent.....

 

[Gold]

does the 404 have the same de-esser as the 402? I thought it was pretty decent.....

I don't know. It's been a while and I never used one on a daily basis. The 402 has a few different de esser modes one of which works well as an HF Limiter for cutting.

 

[scott2000]

interesting...

Yes they do look different...

 

[SWAN808]

A BSS DPR-402 can be picked up for under $500 on the bay. That would probably give you what you are looking for. Before the Maselec was available this was a popular choice when a BSB74 wasn’t an option.

thanks for the suggestion I will look into that one...

 

[fazer]

Found a page dedicated to the BSB74. 
https://www.phasebook.org/20131003/records/neumann-cutting-lathe-acceleration-limiter/#.XaZWOS2ZNE4

Complicated piece of gear with all the toroidal inductors and such.  Interesting.

 

[abbey road d enfer]

The BSB74 is still used and preferred by many. These days it can be hard to find SAL racks with BSB74's. They were stripped out of a lot of racks.

That's quite surprizing. Why have they been taken out? They can't be used for anything else, to my knowledge...

 

[5v333]

why is that? is it because it must be connected with a cutterhead? and not just simple in and out operation?

They can't be used for anything else, to my knowledge...