CL-1B style compressor DIY

Hi All,

i've just read up a little on the CL-1B and didn't realise how different this compressor was:

The Tube-Tech CL 1B compressor differs from many other compressors, in that the gain reduction element is made from a non-semiconductor element, which in itself has a very low harmonic distortion and none of the non-linearity problems involved when using most semiconductor elements. Furthermore there is no long-term degradation of the element thus giving it almost infinite life. This signal processor is placed after the input-transformer of the compressor and followed by an all tube-based amplifier with a gain of 0dB to +30 dB. Thus the signal is not fed through any semiconductor circuitry on its way to the output.

would it be possible to design something similar using a non-semiconductor element? this ideas sound great.

regards

Spence.

An ldr would be a 'non semiconductor' gain reduction element. Use a splitting transformer and you could split the signal to something to drive the LED for the LRD.

non semi conductor??? 

A semiconductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current

Click to expand...

I would say that a LDR is a Semi conductor. under that definition even a neon bulb is a semi conductor. 
LDR are linear just in part of their curve as transistors or tubes.

the only way I can imagine using a conductor to reduce voltage is wire in a transformer and using the saturation of the core but that would be a semi conductor too isn´t?

Well can anyone shed any light on exactly what and how the CL-1B does this?

Regards

Spence.

The TUBE-TECH CL 1B is an all-tube optical mono compressor
So, have a look at any LA2A, or the D-AOC.

Yes, optical.

Despite the general EU ban on cadmium (!?!)

Jakob E.

Jakob have you designed anything like this? G9 valve side and optical?
i'm looking for something CL-1B / LA-2A style but more control of the compression, faster attack / release

regards

Spence.

Spencerleehorton said:

The Tube-Tech CL 1B compressor differs from many other compressors, in that the gain reduction element is made from a non-semiconductor element, which in itself has a very low harmonic distortion and none of the non-linearity problems involved when using most semiconductor elements. Furthermore there is no long-term degradation of the element thus giving it almost infinite life. This signal processor is placed after the input-transformer of the compressor and followed by an all tube-based amplifier with a gain of 0dB to +30 dB. Thus the signal is not fed through any semiconductor circuitry on its way to the output.

Click to expand...

I believe this is marketing speech for 'hey dude,  we built our version of the LA2A - and it sound real cool'. Don't get me wrong, the CL1B is a really great comp, but afaik nothing unique in terms of the basic circuit design.

Michael

do we have a schematic? or a schematic of something similar?

http://groupdiy.com/index.php?topic=50539.0

12afael said:

non semi conductor??? 

I would say that a LDR is a Semi conductor. under that definition even a neon bulb is a semi conductor. 
LDR are linear just in part of their curve as transistors or tubes.

the only way I can imagine using a conductor to reduce voltage is wire in a transformer and using the saturation of the core but that would be a semi conductor too isn´t?

Click to expand...

I still think it's not a semiconductor under that definition. An LDR works as a resistor, and there is no circumstance under which it will not conduct at all. At a very high resistance it might conduct very, very little current, but a diode or transistor in normal usage will conduct in only one direction baring some sort of failure (or reverse conduction threshold). I mean, except for the fact that they aren't perfect and a gig of resistance might be involved.

At any rate, it's clearly an extremely vague definition of an optical comp.

Cadmium selenide is an inorganic compound with the formula CdSe. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type

Click to expand...

same with cadmium sulfide more used on LDRs

https://www2.warwick.ac.uk/fac/sci/physics/current/postgraduate/regs/mpags/ex5/intro/groupii-vi/

GRE looks like some sort of opto chip to me. Here's a comment from Matt Syson at gearslutz. I don't think he would mind me posting here.

"You should consider this unit to be an IC or transistor 'opto compressor' with a valve make up amplifier. All the audio you hear goes through the transformers, opto resistor and valves.
Matt S "

Otherwise, just a different take on an LA2A?

To me it is a really well designed, great sounding opto comp design. Not exactly another take on the LA2A, but a 'modern' approach on the same topic. As modern as it can be for a maybe 20 year (or even older?) design, yet there's nothing I'd like to have changed if I built it today.  It would be really interesting to me to have a similar design for diy, cloning is obviously not in the picture since it is still being built (afaik?) and the gain reduction element is unknown.

I haven't fully understood the situation for LDRs here in Europe, is it illegal now to sell them, or is it only illegal to sell units with them inside? Obviously they will become difficult to buy, I just wonder how soon?

Michael

I still like the idea of having a gyraf g9 style tube side and having some sort of opto, could something be added to the G9 for this? A mod which could be switched in/out so it could be used as micpre or compressor?
Any thoughts?

What about something like this?

http://www.vishay.com/docs/83725/4n25.pdf

Spence.

That's actually a transistor, not a resistor. Unfortunately not the way to go here.

Michael

Could you suggest something's?

The vtlc5xx-family seems like an obvious choice, but since all LDRs have been banned by the EU due to the cadmium (?) used in the process I have no clue about whether any kind of LDRs will be available at all in the future. I haven't had a chance yet to understand the whole topic, it seems rather complex to me. Jakob is not allowed to sell his compressors based on LDRs any more, but LA2As are still being sold - it all makes no sense to me.

As interesting as it would be to have a CL-1B workalike, it seems a rather big effort to develop something like it if essential parts will be unobtainable on the near future. Unless someone here is really fast doing it and we can secure the necessary LDRs in time.

Michael

i was not aware that LDR have been banned!!!!
I have some left over from my LA-2A builds, so could I still use these in builds?
hopefully someone is in the throws of designing something without said substance which has been banned?