2254C build/support thread

[substitute]

Does anyone have anything useful to add that might address my other questions having nothing to do with my eyesight?  Are these solder pads supposed to touch, and what are the extra little holes for?

Quote
- On the switch boards there are a few extra holes: Makeup next to the 27 Ohm; threshold next to the 680 Ohm; attack next to the 5K6 Ohm.  Anyone know what these are for?  Since the boards are black, it's hard to trace where these go.

- Makeup gain resistors 51 & 33 Ohm seem to touch (solder bridge) as well as 310 Ohm & 180 Ohm.  Is this intentional?

- Also R'11 & R'12 seem to connect also, as does R'12 & R'13 - is this right?  They don't seem to share a pad, but they're REALLY close.

Thanks

I don't know what the deal is with those little extra holes, I ignored them and all is well. 

 

[juniorhifikit]

yes they share pads, if you look at the other side of the pcb you will see...

if you send a jpeg etc with marks, where 5k6 etc wholes are, then i can help,
my eye sight is worst than urs  ;D

Thanks.  Here's a markup of what I was referring to - the extra holes are in red, and the pads that look like they're touching are in blue:

 

[kambo]

nothing to worry about them....
wholes are just extras from copy/paste on pcb design,
solder pads are shared,  look at the other side of the pcb...

 

[user 10827]

Hey guys,

Just to say, you may all have worked this out, and i built 4 working units already and this still almost got me, and there is probably good reason, but ive forgotten..

if you are using carnhill 9045(inter)/9046(input)

the PCB says for the input tx labelled 1, PRI & SEC, well these are the wrong way round relative to the connection next to it labelled INTR1. the SEC is wired to the PRI of the INTR1 connector.

make sense? as i say maybe there is a reason that i've now forgotten, but thought it was worth mentioning just in case that catches people out..

Pete

 

[Carlos Lima]

One question:

Anyone got a substitute to the defunct (obsolete) BC-214C ?

Thanks

Carlos Lima

 

[Igor]

BC107 or 109 for 184;
BC177 or 179 for 214
Beta (h21e):
A ~100
B~200
C >400
C will fit. B-marginally OK.
http://il.farnell.com/semelab/bc179/transistor-pnp-to-18/dp/1208594
http://il.farnell.com/multicomp/bc109c/transistor-npn-to-18/dp/9206809

 

[Carlos Lima]

Thanks

 

[Carlos Lima]

Still having problems to find BC179 "C". After a search into Fairchild database, found this:

BC559B / BC559C

http://www.fairchildsemi.com/ds/BC/BC560.pdf

Looks good. It will take some time for me, but I will try it...

Best,

Carlos Lima

 

[substitute]

Two quick calibration questions...

Kam says...

feed 1khz 0.775v 0dbu

adjust gain trimpot until you read 0.775 v 0dbu at output

Igor says...

Feed 0dbV or 1V RMS 1 kHz measured between pins 2 and 3 on input XLR with AC voltmeter

should we be using the dbu or dbv calculator?

Also, there's been a couple posts saying to set the ratio to 1:2 while calibrating.  This doesn't seem to be an available setting based on the silkscreen on igor/puruscha/dan's cases.  What am I missing here?

Thanks!

 

[kambo]

Igor says...

Feed 0dbV or 1V RMS 1 kHz measured between pins 2 and 3 on input XLR with AC voltmeter

where did you read this  ???
i remember reading something like this, but direct link would be great....

on 33609 calibration page its all dbu 0.775V....

 

[substitute]

page 14 (this thread), kind of near the bottom.

 

[kambo]

got it...
its ~2 dbu difference

as for standard calibrating procedure 0.775V is 0 dbu... as in 33609 and others....
and Igor, never said otherwise...

 

[matta]

That has been the rub I think, not knowing how to convert dBu to Volts AC RMS, the calculator that Kambo posted a few posts back is invaluable! I have 3 of the units I built calibrated and the 'ideal' is to to get 0.123 I think, in the 'matched' pair I did I got 0.116 on one and 0.114 on the other... not bad, and they sound great!

Thanks again for the help Kambo, added some much needed clarity to the build!

Cheers

Matt

 

[substitute]

got it...
its ~2 dbu difference

as for standard calibrating procedure 0.775V is 0 dbu... as in 33609 and others....
and Igor, never said otherwise...

yeah, I didn't think it was a real make or brake point. 

Any one have any insights into the ratio question?

That has been the rub I think, not knowing how to convert dBu to Volts AC RMS, the calculator that Kambo posted a few posts back is invaluable! I have 3 of the units I built calibrated and the 'ideal' is to to get 0.123 I think, in the 'matched' pair I did I got 0.116 on one and 0.114 on the other... not bad, and they sound great!

Thanks again for the help Kambo, added some much needed clarity to the build!

Cheers

I seem to remember you doing a lot of leg work on the s800 project, so cheers all around!

 

[kambo]

ratio CCV is fine,

 

[ultra-alex]

finished! ;D

a big THANK YOU to igor, dan (ddt) and frank (frontpanels.de)! and of course to all the other polite and helpful gentlemen in this forum...
cheers, alex

 

[kambo]

holly **** 
fantastic build, cheers 

 

[substitute]

No kidding Looks great!  Do you have igor's meter scale?

 

[haima]

beautiful! how does it sound? i'd love to hear some clips (dry / compressed)... thinking about making one of these (even though i have a igor 33609 on the go too... haha)

 

[ultra-alex]

beautiful! how does it sound? i'd love to hear some clips (dry / compressed)... thinking about making one of these (even though i have a igor 33609 on the go too... haha)

you shure have to build one. it´s an amazing comp! the hpf is veryvery useful (although i didn´t see the advantage at first). the 2254 seems to react a little smoother (in a good meaning) compared to the 33609. but if you like you can squeeze tracks anyway. different! i love both!
sorry for my poor english/description and thanks for the nice comments. cheers, alex