2254C build/support thread

[kambo]

what exactly is the +10 switch ?

 

[kambo]

i think i have sorted out everything and calibrated the unit with in +/- 0.3 db. i cant get any better...

 

[user 10827]

Woo hoo well done!

The +10 just pushes the range of the threshold up, if you have really hot signal going in you'll need it.
On the original 2254 the threshold control was 30db, but they were not using lorins 12 way switches, so it's Igors way of utilising much cheaper switches, works well I think.

 

[kambo]

thank you,

L and R are exact same calibration, -/+ 0db
vu meter responds the same

-/+ 0.3 db stuff, is on some in/out, on/off etc calibration stuff... but exact same values on both channels.
its all good...
i havent checked with scope for all that graph etc yet... but, it sounds ;D
i need to sleep its 9:00 am

 

[audiovisceral]

So if I understand this project, it's a 2254 amp combined with a 33609 compression section (with added HPF and attack controls).

I like these controls, but would prefer the crispness of the 33609's BA440 class AB amp. Is it possible to modify for this?

Also, how are the noise levels on the finished units? What are you guys finding it useful on besides drum bus? Is it fast enough for kick/snare/toms?

Anyone got audio clips - anything at all?

Thanks  

 

[SIXTYNINER]

Hi SIXTYNINER.
................

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

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

HEY kambo
In original i see vtb1148 at output
is  it the same of........?

cheers

 

[kambo]

yes, as far as i know its the same connection....

ps: corrected typo re:  out db values on 9049 on earlier post....

 

[user 10827]

Hi Igor,

not sure if you'd seen this yet...

http://www.groupdiy.com/index.php?topic=34563.0

thanks Igor

 

[substitute]

Hey all, I can't find R34 on the BOM, on the PCB it's 47k, I assume the pcb is correct but just wanted to confirm.

THANKS! 

 

[Igor]

Nope, I've just found the notification turned off.
R34 is 47k.
@audiovisceral : yes, you absolutely right,
" it's a 2254 amp combined with a 33609 compression section (with added HPF and attack controls)".
BA440 or  BA183, all this is matter of taste, I choosed 183, however, it is easy to use BA440 instead of BA183,
just a matter of wires and reading the schem thoroughtly.
2254C is fast as 33609, not audio-wise, (it has some darkness of 2254 if Neve trafos or subs used),
but time-response is same as 33609.
I think people who finnished the project can post some audio files.
@kam: I got your mail with "fixed, OK", but please explain (just curious) what was the problem with smoking resistors???


BTW, test procedure from 33609 build thread is OK for 2254C,
same part numbers for sidechain and 33609-related components.

http://www.groupdiy.com/index.php?topic=26218.0
Have to find some time for updating this thread.

And yes, big thanx to sinestaraudio for the help!!!!

 

[RightOnMusic]

also, igor, r"19 is 820 on the pcb, but 1k on the BOM.  which is right?

 

[Igor]

No matter, it can be in range of 680R...1k, it connected in series with trimpot.

 

[RightOnMusic]

ok... please bear with me since i'm a major newbie...  (this is my first DIY project...)

i've gotten almost all the resistors onto the first channel except for the 27 and 33 on the mkup switch and the 130 on the attack switch.  from the kit (which i'd already split up for each channel), i'm left with 2 resistors labeled 27R4, and 2 resistors labeled 33R2...  how do i read those values?  not sure what the R means, and i thought the last digit was the multiplier, but that would mean i've got 3k3 and 270k and no 130...  *confused*

also, i'm a bit confused about what to put in the following spots on the PCB: J', R7, and R10...  any help for the new guy?

 

[Igor]

J: jumper (piece of wire)
R7: 0R i.e. piece of wire
R10 N/A i.e. not available (do not install nothing)

27R4=27.4 Ohm
33R2=33.2 Ohm

All resistors in kit are in +/-2% range, because sometimes I have in stock,
for example, 46.4 Kohm 1% instead of 47 kOhm 5%.

2254 is not very good for first diy project.

 

[RightOnMusic]

2254 is not very good for first diy project.

i see that now.  but i am learning a heck of a lot, and enjoying the crap out of myself, so it's all good.

thanks igor!

 

[Igor]

Yap. Little by little. Will go fine with some patience.
Every day take some time for good porn reading, like Horovitz And Hill, Art Of Electronics.

 

[kambo]

@kam: I got your mail with "fixed, OK", but please explain (just curious) what was the problem with smoking resistors???

nice to see you back Igor

i am just back from my short holiday.
resistor was the one in the amp BA section (R7" 1/2w 47ohm) ... i did some research over it... and its normal to burn that
resistor if you go too much CCV on equal clipping setting...
my cases arrived today too... as soon as i finish my casing, i will send some sound samples...

best
kam

 

[RightOnMusic]

i will send some sound samples...

please do!

j

 

[user 10827]

That's odd, my resistors do not burn up or even get hot....

 

[kambo]

That's odd, my resistors do not burn up or even get hot....

when the units are calibrated and running, R7" doesnt get hot at all.... not even worm...
have you tried all the way CCV on your RV1 trim_pot while calibrating ?

EDIT : if you did extreme CCV, and they didnt get hot, then there is something seriously odd....
i have some BA283 line in modules  they behave the same... may be then we compare some Volt reading...
have you calibrated your RV1 using a scope ?