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Post by b2 on Aug 26, 2013 6:36:09 GMT -6
Hey Gary, here's my first step in Doa......some years ago.. just to compare... My "poor" experiment... my first 2520 and 1731 .........they were doing the job but nothing to compare with yours. Cheers,Bruno. Attachments:
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Post by gar381 on Aug 26, 2013 18:58:05 GMT -6
Hey Gary, here's my first step in Doa......some years ago.. just to compare... My "poor" experiment... my first 2520 and 1731 .........they were doing the job but nothing to compare with yours. Cheers,Bruno. Thanks Bruno Yours still look pretty and I bet they sound great.  Playing around with DOAs is fun and thats how we all learn about these guys. Best Gary |
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Post by b2 on Aug 28, 2013 9:30:15 GMT -6
Hi All! Working on my varimu prototype.....I spend time on the "release"... Doing maths to calculated ...the time response with a R-C combination...from 0,2s to 2s with a pot as in 436 or other. BUT ....I was interested to experiment ...the "same "type of release switch used in R124....HeHe!! Doing maths to calculated ....the time response with this kind of switch...will give from 0,2s to 4,7s. After trying to understand this kind of swith and the "Hold" step... I just want to know if people have fix this kind of switch in a varimu..?? What I trying to understand is...the "Hold" position that's the tech at Emi have done..seems very interesting.This "hold" position give a long recovery time (infinite.....very long....) between the both position of fixed time ....  My goal will be ...to fix a simple switch on the front plate ..to get in One position the release by a classic pots...Or in the second position the "R124" type switch with "hold" function... I didn't know if my words are clear... ? But I try to explain what I've got in my small head.. Any experience with this,will help me !! Bouhouhou!! All the best,Bruno. |
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Post by b2 on Aug 30, 2013 6:15:14 GMT -6
Hi All!
Anyone is working on DIY varimu compressor....??
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Post by svart on Aug 30, 2013 7:41:42 GMT -6
Unfortunately no. I've always wanted to build a DIY 670 though. Maybe someday.
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Post by b2 on Aug 30, 2013 7:55:20 GMT -6
Unfortunately no. I've always wanted to build a DIY 670 though. Maybe someday. Hi Svart, 670......The Incredile Holy Amazing compressor! For sure yes..Nice comp to build (I think....BUT when I take look at the schematic..Glups..If a "Heavy" one ...lots of transformers inside and The 6386...tube too. People says that's "its an great sounding one ...amazing on many things ..as used on bus.." For me ..as you may one day.. For this time ..I try to build a "simple varimu" to see..what's going on He he! |
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Post by b2 on Aug 30, 2013 14:26:46 GMT -6
About my humble investigation in the "varimu world,I think that's a this kind of compressor can do a great job when using great components as transformer in/out, matched tube for the (one for the reduction gain stage,and one or more for the amplifier stage but matched).
A simple signal path with great capacitors,a well matched pot or attenuator for the "input" and nice balanced plate voltage for the reduction tube stage and cathode balanced too.
seem that's very good results can be done with by this on the reduction tube stage in my case ...ecc189.
will see after fire up my prototype !May be after this I will do some experimenttion around the release mods..("Hold" function) to see what going on with He He!
and may be after...a Dual unit!
all the best,Bruno!
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Post by tonycamphd on Aug 30, 2013 14:33:12 GMT -6
About my humble investigation in the "varimu world,I think that's a this kind of compressor can do a great job when using great components as transformer in/out, matched tube for the (one for the reduction gain stage,and one or more for the amplifier stage but matched). A simple signal path with great capacitors,a well matched pot or attenuator for the "input" and nice balanced plate voltage for the reduction tube stage and cathode balanced too. seem that's very good results can be done with by this on the reduction tube stage in my case ...ecc189. will see after fire up my prototype !May be after this I will do some experimenttion around the release mods..("Hold" function) to see what going on with He He! and may be after...a Dual unit! all the best,Bruno! sounds great Bruno! let us know how this turns out, i love the attention you give to detail, i'm sure your studio MUST sound amazing!! T |
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Post by b2 on Aug 31, 2013 8:18:26 GMT -6
Hi Tony,
Thank's!
Well I often see that's some diy gear can sound very nice if you paid attention of components and buildind ..(Many people know that's..)
Some gears need voltage calibration too as I said for the varimu comp or others tube gears ..In the 1290 preamp...If you want to have a fine "1290" sounding preamp you have too take care of the components at first ...the soldering.....and need to do a great voltage calibration for the last 2n3055 bipolar HeHe!! That's important!
For me the ...The more DIY you have to take care is ..(it's my humble experience..) the Tube Mic..
Taking care of each components is very important...polarisation of the tube is important....the firts grid resistor is important...If you take a look at a "u47" type schematic..
There's not so much components..but each one is important (capsule+tube+transformers....capacitor ...resistors) the voltage ...and more the design of the psu too!
I have not my personnal studio, I've friends who have studio with my DIY gears inside and used them for some years!
My friends do session and test for me too!
I'm the designer and builder ...my friends are the users He He!
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Post by b2 on Sept 17, 2013 8:19:33 GMT -6
Hi All !! Some days has passed from my last post...  But I was on holidays ! So now coming back ...after some hours working on my varimu compressor.... Resume: A transformer for the input 10K:10K (an edcor wsm 10K:10K) A tube stage for Gain reduction based on the ecc189 tube..... A Gain stage tube with 6189 for driving the output transformer (an edcor XPP1....) A 12al5 for the GR side chain Pots for input attenuator. 600 T-pad for the Output Attenuator (...coming from Capi  ) Pots for attack....release.....Treshold.. and pot for cathode balance (inside the rack) and pot for plate balance (10Turns fix on the frontplate) A vu meter for GR Good caps Paper for audio path...Wima for GR sidechain 1% resistor for ecc189 plate...grid,etc.. A filtered PSU for heat and HT . At first...Always check your wiring at first! FIRE UP  . Measuring the voltage.. VHT:160v Ecc189 Vplate :48V VCathode:1.2V Calibration of the minimum voltage drift for thr ecc189 plate with the 10 Turns pot...(0.04 V drift on both plate) doing the same for the Cathode with 100R pot inside the rack. This is very important to have the best symetrical calibration for the best result in GR . I've put a 4K7 pot for adjust the "0 dB" of the Vu meter. etcc,without the GR side chain Av:34dB Get -0.5 V for GR voltage at first,plug a 1K sinus wave at -20B to +4dB. Rotating the treshold pot.....and....  ......GR ...GR...moved  ! Going more with the input signal....and GR voltage go from -3V to ...-7...-8V.....and more -10...-12V .. So: I've passed time to measured voltage for the ecc189 plate during the GR mode..this go from 48v to 132v ! So it's important to have a nice psu which can do this nicely! I've passed time to "see" the interraction between the coupling caps on the audio path and the coupling caps caps that's feed the 12al5 for the GR side chain...in my case I've fix 22nf/400v paper caps. The ecc189 is a nice pretty tube to work with to understand and began a varimu compressor ,with a GR voltage from -2,-3v to -10V the ecc189 do a great job in reduction stage . I've passed time in adjusting by soldering....and De-soldering   components...to see what's going on...it's for me the only way to get something great... Now,I will passed time to take pics of the "Spaghettis wiring"....the Vumeter in GR ...and more! After ....I will redraw the schematic by hand on a paper..take a picture of it...and post it May be some of you will be interested..... More to come... All the best ,Bruno. |
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Post by b2 on Sept 18, 2013 1:31:36 GMT -6
Hi All ! I've take pics last night....  ...So Let's go ! At first here's pics of the start... You can see The components fix in the rack,the Edcor transformers,the Varimu pcb,the Psu , the power transformer........the pot located on the left inside for ecc189 cathode balance... The frontplate with the pots...left Input Attn....middle Threshold,attack,release....VUmeter and under calibration pot for "0", and the Outupt Attn. Attachments:
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Post by b2 on Sept 18, 2013 1:37:27 GMT -6
Next step ....wiring ,connections,soldering .. The psu .... |
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Post by b2 on Sept 18, 2013 1:48:12 GMT -6
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Post by b2 on Sept 18, 2013 1:50:24 GMT -6
...The Pots....the pots....and the pots... The Input Attn and the 10Turns Pot for ecc189 Plate calibration...with the Blue banana Jack for dc measurement drift..across ecc189 plate.. The pot for ecc189 cathode balance.. The GR sidechain pots....Threshold,Attack and release.... |
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Post by b2 on Sept 18, 2013 1:58:56 GMT -6
The Output attn.......6OO Ohm T-pad from.........capi (Thank's Jeff )!! My tube box...ecc189,6189 and 12al5. It's important for good result to have matched triode tube!  Attachments:
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Post by b2 on Sept 18, 2013 2:03:07 GMT -6
and now......FIREUP the Baby!!! After some test last night...I've reached -14v control voltage for GR..HeHe!! Seems to work great and doing nicely the job. Now ....it's time to go in studio (friends) to test it ....with audio and not only sinus wave and sweep frequencies!! ...All the best ! Bruno. Attachments:
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Post by b2 on Sept 18, 2013 2:15:59 GMT -6
...On the pics ...I've done test with 5814a tube instead of 6189 at first...
I've got great result now...BUT I've passed time as I said before in changing components....soldering and of course de-soldering..
Cutting trace on my pcb to do mods too....
Adjusting the psu voltage ....that's interact with all of course...
I find ...that's adjusting the caps (the both that's feed the sidechain)...from 22nf/400v to 47nf/400v interact nicely on the frequencie response in GR mode...it's fix a kind of high pass filter in the low end...)
The calibration of the ecc189 plate voltage close as possible is one of the best things...(I understand now more...) by adjusting the 10 pot turn.
The same for the ecc189 100 Ohm cathode pot...inside the rack..
Of course....after and when I have much more cash...I will upgrade the input transformer with a sowter 3575 .
Cheers ,Bruno.
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Post by b2 on Sept 18, 2013 2:30:10 GMT -6
And more...
I want to say to Fellow who want to diy ,build gears....The Edcor transformers are great for starting project..at first don't spend cash in "expensives" transformers..
Just at first,wired correctly your build....take care of the ground loop...do star ground...used twist pair..etc...and run your project Fire up!
When you 've done measurement and all is ok ...voltage, calibration,etc...
Test it with audio...if it work correctly and do the job.....OK upgrade it with great caps....and EXPENSIVES transformers!
...The job is done ...by upgrading with great caps ,transformers and the most famous tube brand of the world...For sure you will have great results!!
Cheers.
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Post by svart on Sept 18, 2013 6:55:58 GMT -6
Bruno, dude, that looks great!
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Post by b2 on Sept 18, 2013 7:38:46 GMT -6
Thank's a lot Svart ! You see ...It's an old project from 6..8 months ago..From the design to now.. I've passed time in trying to understand schematic ..of some nice varimu comp as 436c ,levelines, ..CCA la1-d...collins ba6....etc to know how to build a gain stage reduction . I design the gain stage reduction around e ecc189..(6es8) cause I've got some very nice from years.. I know great people do it on commercial unit...some other fine design run with 6bc8 or the famous 6386..to and some other with pentode 12sk7 etc.. But I've got nice ecc189 so ....go on . As I said I didn't passed audio inside for this time......so I hope the sound and the reduction job will be great.....  So waiting for my friends!!! BUT I was really impressed by the value of the GR ....(control voltage)...this pretty tube ecc189 seems to work great!! |
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Post by tonycamphd on Sept 18, 2013 16:37:47 GMT -6
impressive Bruno!
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Post by b2 on Sept 19, 2013 1:00:00 GMT -6
Thank's Tony! ...As I said...now I want to "see" the sound of this baby ! I've done plot of the frequency response with no compression just the unit use as a preamp (gain=33dB) and I was very surprise of the good job do by the edcor transformers . and so I've done plot with the compression from minus to full ...and the reponse was great too , there's a kind of high pass filter in the low end under 20Hz to 60Hz. The value still -2..-3dB from 20Hz to 60Hz and after 0dB to 10Khz...and from 10Khz to 20Khz a gentle low pass at -3..-4dB . I've put a square wave at 1Khz at full compression ...and this one still very nice!!Same with no compression. BUT it still with no sound inside....with a bass or vocal ..... want to see... The thing which is interesting is ...as the 436c schematic...or others "simple"compressor design , the schematic is "simple"...the audio path still humble...and so you can play with and do mods to see what go on may be if it sound great....I will do a dual version for bus ....BUT I will change the rack for a 3U...  cause not enough space inside.. cheers ,Bruno. |
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Post by gar381 on Dec 31, 2013 1:27:32 GMT -6
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Post by jsteiger on Dec 31, 2013 11:53:23 GMT -6
Johnkenn did you see what my buddy Gary has been up to?
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Post by Johnkenn on Dec 31, 2013 13:40:09 GMT -6
Johnkenn did you see what my buddy Gary has been up to? Nice! That is officially above my pay scale. |
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But I was on holidays !
)
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!
cause not enough space inside..
