2254C build/support thread

[haima]

EDIT : Yep, was 100 ohm I got the neve sound now

glad to hear you got to the bottom of it! looking good 

 

[jandoste]

EDIT : Yep, was 100 ohm I got the neve sound now

glad to hear you got to the bottom of it! looking good 

Thanks Haima
The calibration is so hard how did you get the right sound?
Cheers,

 

[haima]

haha. i haven't finished mine yet - i've been too busy in the studio....

 

[kambo]

you get use to it after some 6 units  ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


if you read the calib_pro carefully; its actually easy. patient

 

[jandoste]

you get use to it after some 6 units  ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


if you read the calib_pro carefully; its actually easy. patient

Hey Kambo,

I can't have this?
- Adjust Pot on PSU for -20db at output  !!

may I'm wrong but tried two sides(left and right

 

[kambo]

there is a 8pin IC and a trip pot on your PSU PCB.... sort of separated from main PSU... there is a trimpot too... use that trimpot...
inject 0.775V 0db to input.... start measuring output.... turn that trimpot until you read -20db at output....

EDIT: connect + of that PSU output to your CV link point.... make sure link is off ( mono operation )... MAKE SURE YOU DONT CONNECT 24V OUTPUT TO CV LINK  

EDIT 2: measure that PSU output... and play with the trimpot... you should have variable output there... you had a major problem with your PSU. hope you didnt fry your chip

 

[Igor]

For those who PM'd me regarding 2254C cal proc, write here or clean your PM boxes!!!!

 

[pacemaker]

Hi Igor,
i' m preparing my order at mouser for this build,
and The LOW ESR caps are expensive,
Aren't the usual suspects, panasonic FC , Nichicon KW can fit ?

I saw you used a few styroflex for your build,
and if i' remember correctly, 2254 compressor had a lot of these caps in his guts
So for a more "nevey" build, would it be better to use styro's for all small values ( 100 pF to 10nF)
than WIMA's etc... ?
Regards,
Francois

 

[Igor]

For audio path, these are rated as "audio" and cheap,
I had very good experience using them in MixBuzz1, MixBuzz500, F76, etc etc:
http://il.farnell.com/jsp/level5/module.jsp?moduleId=en/388706.xml

For power supply bypassing, Panasonic FC can be good choice.

Suspects??? Dunno, this is not capacitor...anyway....
Mouser have big range of cheap Xicon IIRC styro'

Nevish sound like all we "used" is in the original iron+old tantallums.
Idea for startup: aged blue tantallums to keep your Neve sound always Nevish

Electrochronic supposed to have old Motorola 2n3055,
when I see'em, everything starts to sound better

 

[pacemaker]

ok so no need to spend a lot of $$$ in the low ESR caps,
better to use the BC axial AML 138 caps for audio path,
and good to use polystyrene caps for small values ?

Francois

 

[pacemaker]

Hey Igor,
i was looking at the pics of your unit,
what did you use for non audio caps ?
regards,
francois

 

[jandoste]

Hey Igor,
i was looking at the pics of your unit,
what did you use for non audio caps ?
regards,
francois

Yep, I would like to know it !! good question.
cheers,

 

[muffy1975]

Team 2254C,

I have run into some problems with sourcing parts.

Can anyone sell me some 1n4153 diodes ( matched would be uber nice of you ).??? These are no longer stocked by Farnell or Mouser.

Can anyone tell me the part code from Farnell for the relays??? Not sure what to buy here exactly.

Any help here would be fantastic. I want to get this compressor right!!!

Michael
Oxford
England

 

[daggertX]

relays:  single side stable non latching 2 form C I believe; in the specified voltage 24v?

 

[pacemaker]

mouser is listing this diode
http://fr.mouser.com/Search/ProductDetail.aspx?R=512-1N483B&bdprt=1&cartid=18735959
as a replacement for 1N4153,
seems pretty close no ?

 

[Igor]

has anyone got some spare 1n4153 diodes they could sell me?

I ordered 100 of 4153 some time ago, can send 8 diodes, as one-time action,
just pay for shipping. PM.

I don't want to use the mouser replacement option unless IGOR says they are cool!

Haven't tried, however, there are people who already assembled some 2254C's, and maybe
they can try this substitute?

Is this the relay for the 2254c

http://uk.farnell.com/tyco-electronics/fx2-d3226/relay-pcb-dpco-12vdc/dp/9913920

NO!!!!! This package has 2.54mm spacing.

Use something like:
http://uk.farnell.com/tyco-electronics/mt2-c93402/relay-pcb-dpco-12vdc/dp/9913653

It is standard DPDT, DIP-16 relay. Just be sure it is non-latching type.

are the switches DPDT on/on types?

Yep.

 

[pacemaker]

Igor if you really have several 1N4153,
i would be really happy to get some for my 2254C too,
You can even ship them with my mixbuzz1 and Bypass PCB order,
and i can give you a few bucks for them,
Regards,
Francois

 

[Igor]

I trying to buy some thousands of 1N4153 and supply PCB's with these diodes.
If someone have an idea where to find them for reasonable cost, please PM.

 

[jandoste]

hello All,
I have almost finished the n2254 but  two/three bug is discoverable for me.
1 -Gain is not function properly: I have no signal change with 1 +2 +3 +4 +5 + switch and when I switch to 6th I have a level too high!!!
I tried what Igor says ;
"before clipping.
Check the reistors on gain switch; if all is fine according to schematic:
feed +10 db signal to input, crank the makeup switch till output starts to clip,
no compression (put comp threshold to +10); take a scope and check the output of
2254C
with 1k load in parallel, it should have about +26..28 DBU max undistorted
signal at its output.
Adjust second half of BA283 (output section) for minimum distortion @+27dbU,
by turning 5k trimpot located near the 2N3055.
For more info about quiescent current for Neve class A check the web."

2 nd: threshold!
when I turned to -12 dB I think it does not work! I have no compression with the threshold when I switch to -20 it works !

Maybe I got some problem with cables (grounds)?
Any idea ?
Thanks

 

[Igor]

hello All,
I have almost finished the n2254 but  two/three bug is discoverable for me.
1 -Gain is not function properly: I have no signal change with 1 +2 +3 +4 +5 + switch and when I switch to 6th I have a level too high!!!
I tried what Igor says ;
"before clipping.
Check the reistors on gain switch; if all is fine according to schematic:
feed +10 db signal to input, crank the makeup switch till output starts to clip,
no compression (put comp threshold to +10); take a scope and check the output of
2254C
with 1k load in parallel, it should have about +26..28 DBU max undistorted
signal at its output.
Adjust second half of BA283 (output section) for minimum distortion @+27dbU,
by turning 5k trimpot located near the 2N3055.
For more info about quiescent current for Neve class A check the web."

2 nd: threshold!
when I turned to -12 dB I think it does not work! I have no compression with the threshold when I switch to -20 it works !

Maybe I got some problem with cables (grounds)?
Any idea ?
Thanks

OK... it looks like wrong resistor.
Disconnect the cable going from makeup switch to main pcb, and measure
the resistance at every step. Compare with schematic.

Do same for threshold switch.

Regarding the threshold, what is the input level?

BTW, to be clear, you told about low clipping point as well and posted my answer related to this,
please don't mix different things