Klark Teknik KT-2A Optical Compressor

[12afael]

CE require RoHS compliance. https://www.setra.com/blog/ce-rohs-compliance-what-you-need-to-know

As of July 22, the RoHS exemption for industrial monitoring and control instruments will end. Non- compliant product cannot be CE marked and sold in the European Union or to customers who otherwise require the CE mark.

In other words, the requirements for a CE mark (initially focused around radiated emissions) now include the requirements for RoHS compliance (concerning the content of lead, mercury, and cadmium). If a pressure transducer does not meet RoHS compliance, it will no longer meet the requirements for a CE declaration of conformity after July 22, 2017.

I heard that Electro harmonix paid 450000usd because of an FCC issue but i have not heard of anyone paying any fine because of CE problems.

 

[abbey road d enfer]

CE require RoHS compliance.

It makes sense, which is not so usual regarding regulations.  ;D

 

[[silent:arts]]

I notice the T4B cell shown in the video of the DIY version has a CE mark on it. How does the supplier manage that considering it contains cadmium sulphide?

Just like Avalon, Chandler Limited , IGS Audio, Klark Teknik , Manley,  Warm Audio (all marketed or known as opto compressors, all available from Thomann in the EU).
They just don't care.

 

[ruffrecords]

It's a long time I haven't been concerned with regulations, but isn't the presence of CdS an RoHS issue? Maybe CE is not concerned about it...

ROHS is necessary to apply the CE mark:

https://www.gov.uk/guidance/rohs-compliance-and-guidance

unless we are convinced that professional audio comes under the exempt heading of "non-road mobile machinery for professional use"

Cheers

Ian

 

[Kingston]

I don't think the KT-2A is an exact copy of the circuit. But removing a tube and seeing what happened is fast and worked for me. ;-)

Besides the PSU and transformers its the same circuit.

 

[onder]

KT-2A:

There's one 12AX7 in the signal path, the other one is just for the sidechain. You can find out which one to replace by temporarily removing it (while the unit is turned off, obviously).

The other tube in the sidechain is the 12BH7A.

Sorry for asking but I need to be sure. Does it mean that if I pull out one of the 12ax7 and the unit stop passing signal it's the one in signal path, right?
Or could you describe where in KT2A is the audio signal path 12ax7 located, please?

 

[Rob Flinn]

Sorry for asking but I need to be sure. Does it mean that if I pull out one of the 12ax7 and the unit stop passing signal it's the one in signal path, right?

Yes

 

[onder]

Yes

Great, many thanks!

 

[Tubetec]

Is there also an EL84 voltage regulator , seems to be listed on the manufacturers site ,

Be interesting to see how the psu is done on it ,must be switched .

 

[living sounds]

Is there also an EL84 voltage regulator , seems to be listed on the manufacturers site ,

Be interesting to see how the psu is done on it ,must be switched .

PSU on both tube units from KT (EQ and compressor) are switching types. Filtering could be better, there is more hum than necessary IMHO.

 

[manulaudic]

What do you guys think about upgrading input and output transformers.
Especially to give better clarity maybe with Lundahl?
I found this list : https://groupdiy.com/index.php?topic=6518.0;wap2

Anyone know if the circuit of the kt2a uses same transformers ratios etc?

Manu

 

[living sounds]

What do you guys think about upgrading input and output transformers.
Especially to give better clarity maybe with Lundahl?
I found this list : https://groupdiy.com/index.php?topic=6518.0;wap2

Anyone know if the circuit of the kt2a uses same transformers ratios etc?

Manu

I think the transformers are fine, I'd rather replace the PSU with a linear one.

 

[abbey road d enfer]

I think the transformers are fine, I'd rather replace the PSU with a linear one.
"PSU on both tube units from KT (EQ and compressor) are switching types. Filtering could be better, there is more hum than necessary IMHO. "

It's weird. SMPS don't hum generally; their noise spectrum is at HF.
It would be interesting to substitute a linear PSU and see if it cures the problem.

 

[manulaudic]

interesting, a linear psu should be fairly easy to do. i was wondering mostly if some frequency response and dymanic range would be improved with Transformers.
Manu

 

[abbey road d enfer]

interesting, a linear psu should be fairly easy to do. i was wondering mostly if some frequency response and dymanic range would be improved with Transformers.
Manu

Transformers never improve frequency response nor dynamic range. Many people love what they impart to sound, though.

 

[manulaudic]

I get it, I meant that maybe cleaner ones would improve over those cheap ones. Character is one thing but I believe some transformers do open sound more than others.