scott2000

Anyone know this Tim Williams Compressor ?
« on: November 24, 2018, 06:29:35 PM »
I've seen some limited discussion on it.....Wasn't sure if anyone here has tried it or could tell me what kind of use it could be good for.



Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #1 on: January 02, 2019, 11:58:08 AM »
Hi,

good question!
i'm also looking for ideas for supressor grid compressors with small signal pentodes.
for me its an good start into the world of compressors.

Re: Anyone know this Tim Williams Compressor ?
« Reply #2 on: January 02, 2019, 12:10:16 PM »
To me it looks like an ESP-esque design, even the CAD drawing style/output looks very similar.. maybe he's a close friend or one of his apprentices.

Is there a way to make it work with transistors?

iampoor1

Re: Anyone know this Tim Williams Compressor ?
« Reply #3 on: January 02, 2019, 12:43:25 PM »
Looks like a design for a ham radio.

I'm 99% certain Tim is active on the eevblog forum. Might be worth asking over there too. 

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #4 on: January 03, 2019, 06:03:54 AM »
yesterday evening i played arround with this.
i cant find tube diodes in my box and simply add two semi diodes.
for the pentode i used an ef80 and the triode i replaces with one system of the ecc82.
i know, thats not the best choice but for the first experience it works.
after i add a signal to it, the idea becomes clear for me.
ttheres many small signal pentodes in my box so i want to see what effects on change the suppressor voltage.

(today i bougth some eaa91 tubes)

at this moment i think about an amplifier i build last year.
in this gear, the signal comes over g2 and not g1
screen grid modulation.
this amp works without any signal path caps.
maybe its possible to use g2 for an compressing like feedback.
the standard pentodes not change her amplification with changes on g3
« Last Edit: January 03, 2019, 10:09:10 AM by Joerg-HH »

scott2000

Re: Anyone know this Tim Williams Compressor ?
« Reply #5 on: January 03, 2019, 09:29:49 AM »
I reached out to Tim over at eevblog .....tx iampoor1

At least I think I did...lol....Have to wait and see...

I'll update with any progress..... Thanks for the responses! I actually went ahead and ordered a couple of the 6HZ6 yesterday and will try to put this together soon....

so far I've only been able to find this bit of info.....

This is a feedforward SE compressor. The input signal is amplified with the input tube and a negative voltage is applied by the 1-sided rectification through the 6AL5 diode and smoothing capacitor
on the 'control' schedule. This shuts off the gain, depending on the average signal just in time. Feedforward, because the control signal * is * adjustable for *
reinforcement element, with feedback the output signal_
used to make a control signal, to control the gain.


Yes, in order to be able to exercise real influence, that grid is wrapped much nicer. This means that a voltage of 0 -> -4 V can 'reduce' 20 dB of voltage gain


I also found another Russian site with a good bit of operation theory of it  earlier in my search but didn't bookmark it ..... When I find it, I'll update...

scott2000

Re: Anyone know this Tim Williams Compressor ?
« Reply #6 on: January 03, 2019, 09:46:49 AM »
yesterday evening i played arround with this.
i cant find tube diodes in my box and simply add to semi diodes.

I read somewhere PRR said this would be a thing to try .... so I'm guessing a good idea...

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #7 on: January 03, 2019, 10:08:11 AM »
good news !

i cant find some 6HZ6 for testing (small price) here in germany.
i make some tests with other pentodes.
i never try to make the g3 more negativ as the cathode.

today i calculate the resistors for other tubes to use.

thanks about the info to 0 -4 volts. thats an point for orientation about the needed gain for the triode.

i dont know what hapens with pentodes like ef80, ef86, ef183 and ef184.
these tubes have seperate pins for g3 and i test these for some similar effects
and maybe its possible to play with the smoothing cap for different release times...

but the pentode first ;)

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #8 on: January 03, 2019, 01:32:49 PM »
okay... some news here.
the ef tubes ignoring negative voltages on grid3
i testes it from 0V to -12V and the output drops 0,5 volts rms

the ech81 needs 0V to -1.5V for the same limitation.
So i use the ech81
after that, i play an track with heavy base and get an output with more less base.
the whole volume are not reduced...

the sound over all ist not bad.
i think its possible to make somthing for small budget with it.

« Last Edit: January 03, 2019, 03:22:36 PM by Joerg-HH »

scott2000

Re: Anyone know this Tim Williams Compressor ?
« Reply #9 on: January 03, 2019, 07:56:27 PM »
I reached out to Tim over at eevblog .....

His reply

"Yeah your evaluation is pretty much the gist of it. I never built that, so I don't know how well it actually works."

Tim



I'm guessing he was referring to the bit of info I posted about it.....



Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #10 on: January 04, 2019, 05:20:00 AM »
Okay... thanks for this info..

yesterday evening i search for more informations and get some what i not known before.
in europe they use for this application pentodes they called "regelpentode"
some from this family calls EF83, EF85, EF89 or EF183.
the pdf shows one schematic who's very similar to your first post.
for me i split it in 2 single lines and at the output i add one cathode follower stage.
in my box are some EF83 and EF183 Tubes.
for the side chain i prefer ECC81 or ECC82.


 

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #11 on: January 07, 2019, 02:18:40 PM »
now, the first test is done.
i replace the ecc91 with an ecc81 and use two semi diodes because the eaa91 today not delivered.
the messurement behind the diods with 1k sinus 0,755 rms at the input are 62,8V + and - 62,8V.
this should not be much lower.
the compression are a little bit to slow but works.
i guess, the 100nF needs to much time to load.
i reduce it for a faster compression later or use one rotary switch to adjust it later.
at this moment, dont know about the reduction in db. This follows after after fix the attack timing.
for more details i have to messure anything completet and listen it with my hornspeakers.
now the dynamic section:
woah!  :P it sounds awesome...
the 3,3 cap between the triode stages prevent it to "overbass" and just "tune" the rest.
you can hear thats not only louder. its really more dynamic.

i like it and want to build one in an old rack chassis.
i have a lot of tracks to record it new.

this based on the schematic i posted before.

greetings from grey cold hamburg ;)
« Last Edit: January 08, 2019, 03:06:12 AM by Joerg-HH »

scott2000

Re: Anyone know this Tim Williams Compressor ?
« Reply #12 on: January 08, 2019, 09:19:14 AM »
Very cool! I'd love to hear it in action....

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #13 on: January 15, 2019, 09:24:13 AM »
Now, im done with testing.
Here you see the backside of the first ready to use version.
in this case i use rca jacks because of using in my livingroom.

i splitt the sidechain to one ecc82 and one eaa91 on each side.
at the high voltage i splitt the b+ to 2 lines with diodes...

one thing i have to solve ist the output level. it needs to be regulate to the 0db level after i adjust the compression or expansion.
here i use one stepped  attenuator with 4 x 23 steps.
2 of them for the 1 meg pot replacement and the other 2 for adjust the output level.
i thinked about an tube based leveling but dont like the idea.
maybe i lose dynamic and silent parts...

this evening the front becomes her laserengraving  8)

 

scott2000

Re: Anyone know this Tim Williams Compressor ?
« Reply #14 on: January 15, 2019, 11:02:04 AM »
Looks nice!!

Joerg-HH

Re: Anyone know this Tim Williams Compressor ?
« Reply #15 on: January 16, 2019, 05:35:49 AM »
thanks scott :)

the laserwork was interrupted by the cnc controllerboard....

the output mosfet died in lot of smoke.... 8)
i have to fix it first.


 

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