2254C build/support thread

[ptron]

Ah sorry again! I didnt know how to type it

It is prim. 115 - 0. / 115 - 0
    sec. 15-0 / 15-0

I thought would work like this..

 

[duantro]

Ah sorry again! I didnt know how to type it

It is prim. 115 - 0. / 115 - 0
    sec. 15-0 / 15-0

I thought would work like this..

Ok, If it is dual secondaries, I'd try it in series. take a look at this linked image. I'm not sure about the adjustment and being able to knock the 30v down to the needed 24v though.
http://www.delabs-circuits.com/cirdir/electric/tables/transformer_types.png

 

[ptron]

Woah well i measured and consulted my uncle (which happens to be an electric engineer eheh (good luck for me!) he confirmed it and yeah i got about 38v between the 2 wires.. A bit over but i think is fine. PS, doing 24.1V ... now im still happy that it doesnt smoke.. But i want to calibrate the mofo... First channel is attatched and still nothin smokes..
Im really confused with the calibration tho... How do i measure unity on output? Dmm on ac voltage i guess? But im finding out how much of a noob i am day by day with this project ehehh

 

[ptron]

Ah nothing is burning! It sounds great!... Just its compressing from very low levels with no threshold or anything.. I need the +10 switched on to get the unit not compressing very low level.. Eheheh i think i need to understand the test and calibration proc...

Ill be back with more, but... Any pointers? The dc bias i dont understand where i need to measure, i read from matt 4.7VDC across 47 r but where do i attach the DMM wires? To the reaistor and ground?
EDIT: multiturn.. Took a while eheheh

Wohoo! It works! thanks a lot igor for this killer project!

 

[ptron]

Is it normal PS heatsink gets very very hot in like 1 hour of messing around.. (i mean really really hot...)  it sounds killer, it just is bit louder on one channel, not sure how to work out the calibration from this point...

Quoted from matt:
With the compressor switched in adjust GAIN trimmer to get unity gain. (trimmer doesnt do anything to output xlr.. )

Then croc clip the +3VDC C+V voltage from PSU to the LINK on Main Board (this probably i can do..)

Adjust RV2 to get -8db (0.308VAC RMS) at output XLR
Adjust the +CV trimmer on PSU for -20db / (0.0775VAC RMS) at output XLR ( when saying at output xlr, do i measure between gnd and + OR +and -)

Adjust RV3 to reflect 0db on Meter (DMM or compression meter?) i guess DMM .775VAC?
REMOVE the croc clip to the main board and PSU
Set the Threshold to -2db (1st click on the Threshold switch)
Adjust RV5 for -1db / 0.690 at output
Set the Ratio to 6:1
Set the Threshold to -20db and measure -16db / (0.123VAC RMS) ( my DMM is really bad maybe i need another better one, mine only has 200 and 750 on the V~ (i think this is VAC)

Adjust RV3 to reflect this accordingly

If all goes well your unit should be fully calibrated!

Happy compressing 

....

my unit actually is  lower on left channel by 0.3 db (on level meter) even on bypass and off! ehm.. weird i think i got something wrong with a cable there...



Thanks a lot!

 

[ptron]

aaah well... few turns on them and they started doing some damage heheh i think its calibrated!! not quite unity gain as i would like ( im measuring about -1.1db on the output....
but its pretty darn accurate with compression ... and needless to say ... damn sounds so nice!!!!

i still dunno about PS heatsink.. im not sure if it should get this hot! its very very hot. gets really warm from fireup, and keeps gettin bit by bit warmer and warmer... is it normal?

anyways.. damn fine machine this is.

Reading -90 db noise floor.. Bit of dc (i think) low end spiking.. Maybe to do with calibration and the 47/1w resistor?
ill post pics very soon

thanks a lot igor!! and all the kind people replying to my (and other) messages in this thread lot of help !!

 

[Nobru]

Hi everybody; it seems there is a mis print on the 2254 pcb regarding the audio transfo is there anybody that did a version where the tranies are soldered to the pcb and could confirm the misprint on the tranie slot of the 9046. To me it looks backward but i'm not so sure... thx; B

 

[duantro]

AAhh, I've been swamped at work.

Ptron- good work! How are your voltages? I can possibly try to put my meter on my heat sink sometime this week to check temperature.
Nobru- I recommend using the molex connections for the transformers. I have Carnhills in mine and the molex's are labeled correct. Zip tie the input trannies on their sides with the spacer bords underneath them to keep them from shorting. Look back in this thread. I never understood the transformer pcb mount cutouts. I assumed they were for different transformers.

 

[ptron]

Yeah i think tthose cutouts are for marinairs, belclare and somethin else...  Def not for carnies (at least the ones i got!

Duantro, thanks a lot man! Would be great help to know is normal this thing is so dam hot ..(even from startup..). I tried it on for an hour or two after the calibration, had too many things to actually get to it properly.. One thing is certain, i need a new dmm.. Other thing tho.. On my level meter, the noise floor is about -90 in general, but i got this low end spike kinda messin with it, and i think mainly comin from the left

(spikes to -80 or something.. Not a big spike but bothers me like u probably understand

Thanks a lot!

 

[Nobru]

Molex it is molex I go...  I've seen grand master doing the pcb and trannies soldering but as you guys I'm not about to try to  see the smoke... Thx Duantro

 

[duantro]

Hey Ptron,
Maybe a connection issue? Have you checked your molex connections? I had a loose connection at the molex of an input tranny, that was doing some weird things.
I'll try to pull my stereo unit out of the rack and measure the temp in the near future. It is living on my drum buss, feasting on all of the drums that I can send it!

 

[duantro]

Hey Ptron, I've finished my single channel unit and it fired up successfully! It's working great.
I haven't calibrated it yet, but I did do some temperature measurements of the PSU heat sink for you. I hope this helps!
Turn on temp 72 degrees F
1 minute      101F
2 Minutes    106.3F
3 Minutes    111.1F
4 Minutes    112.9F
5 Minutes    114.9F
6 Minutes    115.6F It leveled off here and was pretty stable.

 

[ptron]

agh! sorry doomed with tons of work.. been completely out of my bench for a week or so

no my unit is way hotter than that.. i cant put a finger on it for over 2 seconds or it burns... still havent fumed, but im a bit concerned about this...
altho it calibrated and all, left side still has about 2Db rms more noise.. im beggining to think maybe when i put the lid on it will all go away heh i still havent i got to mount the LED`s first...
(left is top channel so maybe some interference or stuff from somewhere gettin in there... )

Q-  can i hook up the power LED onto one channel`s VU LED? is it ok to have 2LEDs on one channel and 3 on the other?



anyways. it sounds fabulous.. i hope i got the time to check more of it.. where is your noise floor? with gain makeup on 0. mine about -85db on the rme digicheck totalizer.. (i found to be somewhat accurate with measuring this stuff)

Thanks a lot Duantro. u have been so much support for me (and future builders) on this project. i appreciate it a lot
got 4 channels of sontec waiting for the DOA`s ... damn too much to do too few hours in the day.

best!

 

[king-rb]

is there a formula for the makeup gain resistors? i want to change the steps to 0,3 db and the first step should be 0 db.

 

[ptron]

one question to anyone that has measured (i guess yall have..) 

what is the noise floor on your units?? mine is awkwardly loud.. (on around -85 rms / -75 peak).. is about 30 db or more over the gssl noise floor.. is this normal??
-when i turn the speakers up all the way i can really hear the hiss.. very present. i bypass so only gssl comes in, no hiss even on extreme makeup gain.. im sure i did something wrong?!

-big PS capacitor has 46V -47V thru it...bit hi ..  i guess this is why the heatsink is goin so hot!!

-other funny thing.. when i place my finger over the 9046 the noise goes up ! makes me think the problem is near these transformers their grounding or something. (it is when i fiddle with the ground cable going into the molex terminal that the noise also spikes up. )

just wonderin.. the compressor sounds awsome, but with this much noise is not suitable for mastering at least for the style of music i do mastering for!! would very much like to lower that floor by a bit..

thanks yall!!

 

[Sylvain D.]

I am following this with interst.

Mine is also hot like ptron's. "Can't keep my finger on the heatsink more than two seconds"...
and one chanel higher output than the other... ???

 

[ptron]

(not because i like your misery), but im glad im not the only one with this problem! What voltage are you measuring across the big PS cap?
Igor asked me to measure current on output stage of 183 and 1n3055 ... Im not entirely sure where is this measuring point..

Anyways.. Got a week here at home to sort this out, if not, ill come back a month later from few gigs and try again.. But ill keep u posted about my progress.
Cheers!

 

[Igor]

Overheating problem - check the voltage on power supply capacitor right after rectifier; should be 29...38V DC.
Power trafo should be 24V AC 1A secondary.

 

[ptron]

My traffo suposedly is 15V 1A secondaries.. Why is it givin out 46 - 47V?

Im away now but id love to tackle this as soon as im back!

Thanks a lot to yall for the help

 

[Sylvain D.]

Hey Ptron,

I have 37v at ps cap.
And temperature at ps regulator "heat sink" seems to stabilise at about 49c (after about 7 or 8 minutes)
Is this normal temperature Igor?