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Old 16th October 2013, 01:31 PM   #11
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DOXA 40 is a class A/B amp. and 40W class A. it might be this one he got.

Last edited by AudioSan; 16th October 2013 at 01:33 PM.
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Old 16th October 2013, 01:34 PM   #12
tinitus is offline tinitus  Europe
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(that would be very cool running 40watt classA)

but his is clearly dual mono ?
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Old 16th October 2013, 01:40 PM   #13
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as i understand it. it is a dual mono with dual 500VA 2*31V transformers. wish also backs up the 40W class A power. and the chassis is huge.
so this can be used for class A amp. or bridged/X'ed class A/B amp
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Old 16th October 2013, 01:43 PM   #14
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Quote:
Originally Posted by AudioSan View Post
as i understand it. it is a dual mono with dual 500VA 2*31V transformers. wish also backs up the 40W class A power. and the chassis is huge.
so this can be used for class A amp. or bridged/X'ed class A/B amp
Hi guys,
It's a Doxa 70 from (I think) 1979 or thereabouts. It's dual mono, with two toroids and a big chassis with heat-sinks serving as the side members of the enclosure.

Thanks!
Henrik
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Old 16th October 2013, 02:10 PM   #15
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It's amazing what you find if you go looking hard enough.
Attached Images
File Type: jpg DOXA 70.JPG (282.0 KB, 158 views)
Attached Files
File Type: pdf Doxa-70Signature pwramp[1].pdf (361.0 KB, 22 views)

Last edited by KatieandDad; 16th October 2013 at 02:13 PM.
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Old 16th October 2013, 02:40 PM   #16
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Henrik. i think you have to post some pics
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Old 16th October 2013, 03:00 PM   #17
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Henrik76 View Post
Hi guys,
It's a Doxa 70 from (I think) 1979 or thereabouts. It's dual mono, with two toroids and a big chassis with heat-sinks serving as the side members of the enclosure.

Thanks!
Henrik


heatsinks appear like real heavy duty
but keep in mind that finning is rather short
lowers effiency more than you might think

but big enough to keep a classAB safe into low 2ohm load
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Old 16th October 2013, 03:17 PM   #18
AndrewT is offline AndrewT  Scotland
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40W of ClassA into 8ohms requires a peak ClassA output current of 3.2Apk

The quiescent current of the output stage would need to be set to ~1.6A to achieve that 40W, i.e. 320mA through each of those ten 0r56 emitter resistors. That is 179mVre

Could the bias be set that high?
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Old 16th October 2013, 03:31 PM   #19
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there is atleast 4 Versions of this amp. SE mkI, SE mkII, signature mkI and signature mkII.
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Old 16th October 2013, 03:55 PM   #20
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Those heatsinks would work far better if the fins were vertical.
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