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Old 26th February 2013, 11:21 PM   #1051
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For those 3 watters many will use the Panasonic ERG series metal oxide film resistors, also commonly used as source resistors in the output stage. For the rest of those small resistors I like to use the Vishay/Dale CMF55 series (1/4 watt). Capacitor voltage rating should be higher than whatever rail voltage you are feeding the stage with. 24V rails as shown, 25V caps are OK. Case - look in the diyaudio store to see if something there could be an option for you. Transformer - jump in on that SumR group buy, but it's closing real soon so hurry.
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Old 27th February 2013, 05:01 AM   #1052
oiphy is offline oiphy  Norway
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depends on your railvoltage. eg. if rail=25v caps need to be >25v.
case is in the store in top of page.
power supply boards also in store.
transformer depends on witch part of the world you live in.... post is expensive, but in Europe maybe this?? : 58-0300-018-S TALEMA - Transformator: toroidformad | Transfer Multisort Elektronik
or bigger trafos in VA.
I belive there is some GB too. just search in the GB forum .

Stig
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Old 27th February 2013, 05:20 PM   #1053
WalterW is offline WalterW  Netherlands
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That transformer is only 1 x 18v, so I would not advice it.... you need 2 x 18V.
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Old 27th February 2013, 05:36 PM   #1054
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It's 800 ba right
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Old 27th February 2013, 07:34 PM   #1055
oiphy is offline oiphy  Norway
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Chassis mounting toroidal transformers
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Old 28th February 2013, 09:58 PM   #1056
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Default Ordered wrong Boards

I thought I ordered ba2 i ordered ba1 Can ba1 boards set up as 9240 and 240 as well for more power or will I have to order the other boards or what combo for 100 watts a channel? Sorry I am new to all this bare with me lol
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Old 28th February 2013, 11:54 PM   #1057
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You won't have the correct bias boards if you want a BA-2. This is just me, but if I wanted 100W I guess I would build 2 F4's and run them "balanced mono". Read the F4 service manual at firstwatt.com to understand how to set them up as such (and drive requirements, etc.). People have scaled up the BA-2 but you really need to understand what you're doing if going that route. I think Teabag is one of those folks. Might be easier just to get more efficient speakers that work well with 20~30 watts.
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Old 14th March 2013, 07:05 PM   #1058
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Default problems with my BA-2 monoblock build

Wondering if anyone can steer me in direction to look for my problems.

I am building BA-2 monoblocks. 300va transformers 20-0-20v using Cviller PS boards, and am using the diyAudio circuit boards. Built up one monoblock, and did the powerup as recommended in the BA-2 article. I am using 2 output boards with 6 matched 240s and 6 matched 9240s. Easily able to get DC offset to 0mv on the gain board and outputs. Voltages all are very close to published values in the article for the gain board. Only parts substitutions are increasing the voltages on the caps to handle the 25 or 26vdc rail voltages I have.

I can easily bias the output transistors to around 250mv, with about 0.5Amp total current draw, with no input signal. Heat levels are about 15 degrees above ambient on the heatsinks.

My problem is that when I put a test signal (1 khz from a Leader signal generator) into the unit, I do not get any gain, perhaps a loss of 15% when checked at the output of the gain board, or at the speaker outs. Even worse is that as I increase the input signal voltage, I get an increase in the current draw of the unit, such that 1 volt input takes me from 0.5A to about 2.0A current draw.

Built up the other mono and it does the same thing!

I obviously must have some wiring wrong, but cannot understand where or how….

Any suggestions on what I screwed up?

Thanks, Matt

Last edited by mattattnet; 14th March 2013 at 07:08 PM.
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Old 14th March 2013, 07:20 PM   #1059
Zen Mod is offline Zen Mod  Serbia
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please be patient ;

my crystal ball is in service , and they're saying it will be repaired in a month or so

in a meantime , if you get your camera from (probably same ) service , try to use it

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Old 14th March 2013, 07:38 PM   #1060
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Default Sorry...

Meant to say photos on the way...
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