EMI RS124

[gary o]

Typo yes sorry for confusion 390K silly me

 

[joe-electro]

Since you mention the oscillation looks like a square wave on the oscilloscope it seems to me it's a circuit wiring issue. Somehow you're feeding the output of the unit back to the input.  I haven't looked at this circuit for a while, but if it involves a feedback loop check the values of the feedback resistors and coupling capacitors.  Also, make sure the tube cathodes are connected to ground (through whatever components that are supposed to be in their path to ground).  Alternatively, start a new thread and call it the new analog tube oscillator project!

Joe

 

[gary o]

Thanks Joe ....yes there are 39K feeding back from OP to IP tube .....not present in an original 436.....il remove 7 fiddle with them i think ...thanks...

 

[JayDubrek]

Changing the tubes has stopped mine from whining...back in business now. Thanks chaps!

 

[rotheu]

Thanks Joe ....yes there are 39K feeding back from OP to IP tube .....not present in an original 436.....il remove 7 fiddle with them i think ...thanks...

Just swap the 39K connections to the IP tube plates, you are sending a positive feedback, which makes it an oscilator.

 

[emrr]

Improper grounding can cause chirpy thumps during compression too. 

 

[gary o]

JayDubret,,,,cool glad yr up & running,,,,,,,sounding good ?....Emrr I think my grounding ok, its not just popping constant horrible noise....

Rotheu are you saying I have my 39K feedback resistors round wrong way....I have them between the pin 1  to pin 1
& pin 6 to 6 as schematic....

I have my VK1 wired up for some experiments...Im goin to bit by bit turn it into this Rs124 its pretty close as it is anyway but here goes....

so far I have swapped all tubes around to varify I didnt have a tube problem with my RS124....

Ive re arranged the input of VK to be same as RS124 & original 436.....daul 50K pot straight to grids.... so far so good...


Things to do.....

Gonna re wire the side chain to be as Rs124....
Will try 39K feedback resistors instead of VK1s 100Ks
Im wondering what difference if any changing the resistors that go to te grids of the poutput tube ??.....stock 436 has none VK has 220R Rs124 has 270R
I also may leave alone the VKs 470R res & 100R pot to cathodes on the output tube...
Prob also leave alone the 22K & 1K potplate resistor setup of the VK1......unless someone thinks it would be better to change it...

heres link to VK1 that I did a P2P version of that I refere to in this post...

http://purusha.smokinggunrecording.com/XVXDY/1schems.pdf

 

[JayDubrek]

This comp has turned out to be very smooth...far less aggressive than the others in my studio. I've already used it in a couple of sessions but it's not suitable for every job. I'm also part way through building a PTP VK1. I'd be very interested to here how your experiments turn out...

 

[gary o]

Hi Jay.....Im literally fiddling with my VK1/Rs124 circuit right now.....Its almost the RS124 now....but when I added the RS124 side chain it sounded worse compressing a lot too much, so I have put the VK side chain back i have more control this way....tho Im getting thumps if I have a the attack pot set for fast attack......I only build my compressors for recording vocals when I sing a bassy B sound into mic I get this kinda double thump plus the B if on fast attack.......its definatly usable tho & I think I preffer it as the so called Rs124 rather than VK tho  ithink the VK is trying to be the RS124 but really they both are still basically a 436 a great little circuit to play with & learn from but i doubt its the abbey road circuit interesting tho.....my problem is so far nothing I build ever lives up to my beloved RCA BA6A diy of coarse is F***ing awsome! but il keep my VK12436 as a fun tool

 

[dustbro]

Winston... hit me back asap

 

[Biasrocks]

Welcome back Winston,

How about spilling the beans then?

Mark

 

[seavote]

winston, hopefully your friend will direct you to some more threads here!!
redd47!! ua610!!

 

[desol]

A person could spend years and years trying to recreate this unit and be none the better in the end...and have done just that...lost a bunch of time. Equipment is meant to be used...

I'll be busy writing and recording songs, with the compressors that i have. If i do have the cash someday, and it seems worth it, maybe i can get one! Until then, it will remain somebody's secret.

 

[Winston OBoogie]

A person could spend years and years trying to recreate this unit and be none the better in the end...and have done just that...lost a bunch of time.

If it's a unit built from the schematic here then I'm sorry about that.  However, I didn't post this and, as I've said, it's wrong.

How about another hint: I think we can assume that the real genius "someone in the know " who drew this, did so by measuring things in circuit. 
Go back to first principles and extrapolate.  Thévenin's theorem is your friend.

And yes, compressors are meant to be used.  Go with what you've got if it's good.

Winston... hit me back asap

It'll be a while but working on it, haven't forgotten. 

 

[Niketouille]

Hummmm...
Do you have left part of the schematic ??
Regards
Nkt

 

[MagnetoSound]

Blimey!

 

[haima]

Niketouille - i'm pretty sure that schematic shows everything needed...?

maybe a bit of the output attenuator isn't shown but that shouldn't be hard to figure out.

Thanks Winston!

 

[Marcocet]

winston:

THANK YOU

 

[Biasrocks]

Very cool.

Mark

 

[JayDubrek]

It would be nice to see someone knock up a PTP version of this.....