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Old 15th April 2012, 12:52 AM   #1
quan is offline quan  Australia
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Default aleph X monoblocks

Hi guys , my first post on this section of diy. I have never build an amp before. I bought off a diy fellow aleph X monoblocks few years ago but got sidetrack until now . The problem i have with it is that it won't work with the pre-amps that i have at home which includes heron VTSP3 and Parasound HP850. But if i take the output from my headphone amp then it would work but the relays from protection circuit constantly kicking in. My speaker is typical bookshelf 6-8ohm load. I am not sure where to start to trouble shoot a problem. I suspect it could be impedance mismatching? . Please advise where should i start . I have been having problem with posting attachments for pictures.
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Old 15th April 2012, 12:11 PM   #2
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Hi,

does your Aleph X have input caps? This could be a cause. Impedance mismatching wonīt cause things like that. Did you measure the dc offset (absolute and relative)?

William
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Old 15th April 2012, 09:08 PM   #3
quan is offline quan  Australia
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Hi William, i am not sure but will check.
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Old 16th April 2012, 06:03 AM   #4
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Quote:
Did you measure the dc offset (absolute and relative)?
That's the very first thing to check!

Different impedances at the inputs do cause dc-offset variations, but typically not something to worry about. However, if the protection kicks in, that usually means at least 1V offset.

Hannes
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Old 16th April 2012, 10:20 AM   #5
quan is offline quan  Australia
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Default aleph x monoblocks

Hi guys, i measured the monoblocks and get zero DC output at speakers terminals. I measured it by turning the amp on with no speaker load and waiting for about 10mins. The heatsink does get really hot but i gather it is class A thus putting out a lot of heat. The protection circuit from what i can see is a DC offset protection circuit board designed bu Daniel Purvis. What should i do next ?
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Old 16th April 2012, 10:28 AM   #6
quan is offline quan  Australia
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Originally Posted by wuffwaff View Post
Hi,

does your Aleph X have input caps? This could be a cause. Impedance mismatching wonīt cause things like that. Did you measure the dc offset (absolute and relative)?

William
Hi William ,i could not see any assoc input cap
Quan
Sorry guys , i am having problem with posting pic-

Last edited by quan; 16th April 2012 at 10:38 AM.
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Old 16th April 2012, 03:12 PM   #7
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Hi,

normally the heatsink canīt get really hot after 10minutes unless something is wrong or it is way too small.
Zero DC output? Normally you should measure some mV of DC offset (absolute) and a lot more (relative). Are you sure the relay switched through?

William
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Old 16th April 2012, 09:08 PM   #8
quan is offline quan  Australia
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Originally Posted by wuffwaff View Post
Hi,

normally the heatsink canīt get really hot after 10minutes unless something is wrong or it is way too small.
Zero DC output? Normally you should measure some mV of DC offset (absolute) and a lot more (relative). Are you sure the relay switched through?

William
Sorry , do i have to play some signal thru the amp before i measure the dc offset? I find before that the relays keep on kicking in when playing the music .
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Old 17th April 2012, 05:20 AM   #9
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No you donīt. Set the Meter to DC mV and have a look.

I think it would be a good idea to find someone in your neigbourhood who can take a closer look at your amp.

William
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Old 17th April 2012, 07:10 AM   #10
quan is offline quan  Australia
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Originally Posted by wuffwaff View Post
No you donīt. Set the Meter to DC mV and have a look.

I think it would be a good idea to find someone in your neigbourhood who can take a closer look at your amp.

William
Yes, i did exactly just that and measures zero DC offset.
Quan
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