660 Variation

[analag]

I have just finished running some simulations (for tonight) on a 660 type compressor. I'm using part of the PM660 but pairing it up with a 60 watt solidstate power amp (also a part of my reference amp).
I'm toying with the idea of increasing the power of the sidechain amp as this time I will be using (8) triode sections and I also want the flexiblity of driving a bunch of different time constants.

I will post the schemo soon....for a short time only?
analag

 

[chrissugar]

:thumb: :thumb: :thumb:

chrissugar

 

[Svart]

ready when you are..

 

[analag]

As promised for a few days?
As promised but it was a few weeks.

analag

 

[Larrchild]

You're almost home. Rowan. Now vary the bias of the 1st sidechain stage to move it into class B on demand to adjust ratio. more class B= more peak limiting. Class A = compress.

Also, straddle the cathodes of the mu tubes with a large NP cap. =)

 

[Kit]

Expensive compressor....probably good.......but expensive.

 

[Larrchild]

Yeah, expensive, heavy..all that. But when one seeks that sound, and one builds every variation of what this isn't, first, one ends up here.

I'd rather have the tubes in parallel than in series. Thats worse. So makeup gain is either gonna come from cascaded stages or a bunch in tandem.

The method of driving the control voltage, after one tries every shortcut, usually ends up as some form of power amplifier.

This looks good!

 

[chrissugar]

Maybe you can reduce the number of transformers by using at the sidechain input an instrumentation amp circuit. Probably this change will not affect the sound in any significant way, and would be cheaper.

chrissugar

 

[Svart]

edcor. about 40$ worth of trafos not counting the PSU trafo.

 

[Larrchild]

And one need not use Gucci transformers in the sidechain. The original Fairchild output xfmr for the SC was a PA-grade item.

 

[Kit]

edcor. about 40$ worth of trafos not counting the PSU trafo.

Are they any good and if so were can i get some?

 

[analag]

[quote author="Larrchild"]You're almost home. Rowan. Now vary the bias of the 1st sidechain stage to move it into class B on demand to adjust ratio. more class B= more peak limiting. Class A = compress.

Also, straddle the cathodes of the mu tubes with a large NP cap. =)[/quote]

 

[Svart]

Edcor is plenty good for most applications. Fairly clean sound. not what you want if you are looking for the iron sound but great if you want cheap and clean iron for the I/O of rack gear.

www.edcorusa.com

I don't know where they ship to but I don't think they should have a problem shipping overseas.

 

[analag]

[quote author="Svart"]Edcor is plenty good for most applications. Fairly clean sound. not what you want if you are looking for the iron sound but great if you want cheap and clean iron for the I/O of rack gear.

www.edcorusa.com

I don't know where they ship to but I don't think they should have a problem shipping overseas.[/quote]

I have a total of ten Edcors in my studio and they see daily use. They are not effects transformers, they are clean transformers, the cost performance ratio of these line level beauties are unparallel. Precaution must be used when installing them because of the lack of shielding.

analag

 

[tardishead]

Hey guys I have transformers to build a 670 clone. That is for the signal amp at the moment. I wanted to experiment with different tubes 6ba6, 6bc8, 6ES8.
Is it possible to use a normal 10-15watt power amp and rectify the output to act as the sidechain amp. Will need a 4:600ohm transformer to drive the recification circuit. This would be an easy way of making a makeshift SC before I decide on how to go about the SC.

Also what are the specs for the meters in the 670. 0-30maDC?????????

 

[Larrchild]

I wanted to experiment with different tubes 6ba6, 6bc8, 6ES8.
Is it possible to use a normal 10-15watt power amp and rectify the output to act as the sidechain amp.

I think that is a great idea. :grin: Should work fine. Use the 16 ohm out if it is a tube amp. or better 70v.

 

[tardishead]

how about the meter is it 0-30maDC?

correct me if I am wrong but on the 670 the DC offset is varied to achieve different compression and limiting?

 

[Larrchild]

The GR meter current will be a function of how many tubes at what idle current you choose.

DC offset? elaborate a little. Where?

 

[skipwave]

I like the image title/model number. It's the Comp of the Beast. :thumb:

 

[tardishead]

what is the idle current and minimum negative grid voltage for the Fairchild. What are the readings with no gain reduction? I am sure all this has been discussed somewhere but I cannee find it