2254C build/support thread

[syn]

WOW!!! Where did you get the knobs!!! It looks amazing!

 

[ultra-alex]

indeed a very nice one!!!

 

[kambo]

Yap. I used ST7 from Farnell, link:
http://il.farnell.com/anders-electronics/st7/vu-meter-rect-0-200ua/dp/7758200?_requestid=182388
and printed the scale by myself.

Meter connected this way:
200 Ohm 1/4W resistor connected in parallel (across the meter)
Plus of meter goes to 680 Ohm 1/4W resistor
Minus of meter goes to front pannel, to pad marked (-mtr1) (next to bypass switch)
Free leg of 680R resistor goes to front pannel, to pad marked (+mtr1) (next to bypass switch)

i am not sure if i understand this  ???

i have the same meter... fixed 200r in parallel... fine...but

where is this 690R come from... how exactly connected and, there is only one 680R and its on the main board  ???

thank you
kam


EDIT : ok miss understanding... its all clear now

 

[syn]

Yap. I used ST7 from Farnell, link:
http://il.farnell.com/anders-electronics/st7/vu-meter-rect-0-200ua/dp/7758200?_requestid=182388
and printed the scale by myself.

Meter connected this way:
200 Ohm 1/4W resistor connected in parallel (across the meter)
Plus of meter goes to 680 Ohm 1/4W resistor
Minus of meter goes to front pannel, to pad marked (-mtr1) (next to bypass switch)
Free leg of 680R resistor goes to front pannel, to pad marked (+mtr1) (next to bypass switch)

i am not sure if i understand this  ???

i have the same meter... fixed 200r in parallel... fine...but

where is this 690R come from... how exactly connected and, there is only one 680R and its on the main board  ???

thank you
kam

that is a series resistor from +meter pad on the FP board and goes to + on the VU. Now, I haven't started mine 2524c yet but I can't see what else can it be.
cheers

 

[kambo]

YUUUPPPIIIEEEE  ;D

my units are running beautifully on my first fire  
no hum, no noise, everything is working  
i was pretty scared to do this as a newbie, but it turned out OK
thank you Igor... and rest of you guys.
especially RuudNL who explained me the transformers in general concept.  

EDIT : i love the low end on this thing... such a monster  ;D

 

[TomWaterman]

i am using 100ua meters...

Hey Pete, looking great. Mine are 90% done but have had no time the last month.

Are those Sifam Edgewise DC meters? If so where'd you get them, direct?

About to ping them an email for some 1mA edgewise parts like those.

They look great!

-T

 

[kambo]

i cant calibrate with the 33609 calibration notes... its not exactly the same thing....
and i am newbie to follow 33609 circuit and adapt to 2254c

can somebody please send me the simplified calibration procedure.

thank you
kam

 

[user 10827]

Hi Tom,

yes those are vintage edgewise Sifam meters, cost me an arm and a leg, but i like them, in fact i have some more i might sell..they are 100ua..

Cheers,

Pete

 

[kambo]

Hi SIXTYNINER.
i have connected them like this, and its all working fine... experts please check for errors
rest is easy, just follow the connection names...

9046 line in
primary :
short pin 3-4
pri molex connect +2 -5

secondary :
short pin 8-9
sec molex connect +7 - 10, GRND 6


9045 interstage
primary :
short pin 3-4
pri molex connect +2 -5

secondary :
short pin 8-9
sec molex connect +7 - 10, GRND 6


VTB 4049 output :
primary :
short pin 2-4
pri molex connect +1 - 3

secondary :
short pin 6-7
sec molex connect +5- 8

 

[kambo]

What info did u use to callibrate the units ?

just look at the circuit diagram, I think its then pretty obvious, if you are not sure i can tell you when i get home at look at the diagrams no sweat..

Hi Pete, i will sure like to have this calibration info too. as newbie... thank you
kam

 

[kambo]

HEY
please vtb 4049 can be replaced by vtb 9046?
cheers

no, 4049 is an output transformer 200/600 +4
9046 is a line in transformer...

edit : typo

 

[user 10827]

Hi guys,

I know nothing of an official calibration proc, how ever points to think about, im at work so this is off the top of my head, don't hold me to any of this stuff, much better people will hopefully chime in, but this will get you started,

for start set up the voltages the same on both sides if you are making a stereo unit,

I found about a 1v for the CV, about 7v for the threshold, around a volt for the feedback although I have not played with this much to see if this changes any thing yet..leave the meters for now,

then line up for unity gain though the unit, make sure with no gain added with the unit engaged you get the same gain as when in bypass. of course use the gain trim for this..

feed a sine wave in to your 2254, and monitor the level out, maybe back into your DAW would be easy for you,
(this is of the top of my head so I could be wrong, im at work right now) but IIRC, set your threshold control to -20, feed a sine wave in at -20db, your output should read the same level, if not adjust the threshold until you have no compression, set it so its just off compression.

now push the level fader of the sine wave from -20 up to say 0db, watch for symmetry between left and right, both sides should compress the same is what you are looking for, if not quite moving together just play with the threshold until you do, once you are happy the unit is doing what is supposed to be doing then set up your meters..

got to dash, maybe Igor can give you some thing beter..

Cheers

Pete

 

[kambo]

Thanks Pete....

i think, Igor is busy, hopefully he will upload the full calibration procedure soon,

kam

 

[user 10827]

Try out the above, any questions just ask, if I can answer I will,

At the end of the day just play with it, see what affects what, you will soon get a feel for it im sure..

Pete

 

[kambo]

Hi Pete, thanks for the help

have you managed to adjust RV1 ?
if i go to much on CCV  - RV1, its burning my R7" 47ohm  ???


EDIT : never had the same problem on ba283am i have built ?

 

[user 10827]

No that should not be happening, mine do not do that, i wonder if you have some other component wrong around it?

in fact are you seeing any voltage change when you adjust it? if so what are you seeing there?

 

[kambo]

R7" trimmer's adjustment side ( facing the 9045-46) = 0 V
other end ( opposite to trimmer end)  , i am keeping it at around 1.5V, more CCV is giving more V,
and after certain point,
its going crazy... and BOOOOOM

lucky i have plenty of spares from BA283


EDIT : i have couple of built ba283's, i am gonna compare with them.. but the voltages seems ok for the BA part...
all the resistors are correct, transistors are all working with close enough V... i will get back...

EDIT 2 : R7" is starting to get really hot after around 4 V... is for equal clipping...  


EDIT 3: i have compared to my ba283's 183 part... its almost the same... i think i am on the safe side for the equal clipping adjustment...

 

[user 10827]

Hi Kambo,

its odd, im not seeing any thing like the range of voltages you are, cant see why r7" is burning out,  you have the trimmer in the right way?

i could be way off bur here is what i think..

with the trimmer in correctly you should have a constant 5k resistance across R7", then the tap of the trimmer feeds back to the input, so no mater how you set the trimmer R7" should not burn out.

what trimmers are you using, are you sure its has the same pin outs as indicated on the PCB?

cheers
pete

 

[kambo]

Hi Pete,

its Igor's kit... after the first burn... i have replaced it, just incase... fitting is the same... from my stock 1290 parts.
it only starts burning, i if go CCV too much... i have tried on my ba283 board (neve 1290) its almost the same problem...
on extreme CCV setting same resistor getting way too hot. check the other topics for it... there seem to be a burning problem,
on ba183, if the trim_pot is not set correctly... i think i am ok on that.... i am on the safe side for equal clipping adjustment.
good thing i made some 1290's

i have almost calibrated my units, with 33609 testProc.
but i have to set my make_up_gain i click CV, and use it as 0db gain. i click CCV is -db...
so my +2db is set to 0, 0 set to -2db on scale....

if i set full CCV to 0, as it suppose to be,  then i am having problem as -0.7db on the output, i can get 0 db, but then when i adjust RV2, i can only get -0.7db max...
with one extra click set to 0, everything seems to make more sense. i have plenty of room to calibrate...

with this adjustment i have finished section 3 and 4 on Igors Simplified version of testProc

sorry for the English

 

[kambo]

during the calibration,

where should i keep the attack, ratio, recovery, unless stated ?

even though threshold is set to 0, they are still interfering...