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Discrete Dynamics Amplifier:

Wharfedale EVO4.4

hydrovac

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I have encountered a massive breakdown on my power amplifier...

The story was like this, one day with the amp power on I tightened/snugged up the speaker binding post. There was a single frayed strand (unnoticed) that shorted. The amp proceeded to billow smoke. I looked inside to find power supply caps having oozed their electrolyte onto the circuit board.
A more likely scenario is that the short damaged the power transistors, and they in turn caused the capacitors to fail.

I am trying to rectify the amp, however I do not want to waste my time if there is likely to be damage to the circuits other than electrolytic capacitors.

I like an amp that is there to do it's job and do it's job well. To me that is something that acts as a conduit between cd/pre/dac etc., and the speakers.... something that can deliver grunt when required and also be delicate when needed. Something that can play quick dynamic music as well as it can laid back music.
In other words, I want my amp to sound like nothing.

In searching for an alternative DIY amp, contacted Aniket... he offered me this:
"We also have a more powerful version of Discrete Dynamics power amp. Transformer requirements 43-0-43, 600Va and 9-0-9, 5VA for protection. It will give you approx 200W/channel in 8 Ohms. The minimum driving load shouldn't be less than 4 Ohms."

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Rated power output and build quality looked impressive... so, ordered one stereo module.


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tuff

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Nice. Should gel well with the pre amplifier from them I assume. What power amplifier (brand) was the one that got fried?
 

yogibear

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A single freely hanging strand on any termination, speaker or pre or amp scares the hell out of me. Hence I have started paying a lot of attention to these details and insulate them carefully. These must be checked regularly else you would never know what’s wrong in the chain, effecting the sound.
 

Dr.Lakshay

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Wow! Never thought a single strand could do such big damage. I need to be more careful in future as sometimes I don't pay that much attention to strands coming out. Makes me want to get more banana plugs :oops:
Congrats on the new acquisition. That's a lot of power indeed.
 

MaSh

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In searching for an alternative DIY amp, contacted Aniket... he offered me this:
"We also have a more powerful version of Discrete Dynamics power amp. Transformer requirements 43-0-43, 600Va and 9-0-9, 5VA for protection. It will give you approx 200W/channel in 8 Ohms. The minimum driving load shouldn't be less than 4 Ohms."


Rated power output and build quality looked impressive... so, ordered one stereo module.


...
Oh cool. I am also sitting on the fence whether to upgrade from my 120w DD amp to the 200w or not. Its an awesome amp. Do let us know what the 200w beings in.

MaSh
 

SachinChavan

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Sad to hear about your loss. And hope you get your desired alternative soon. However, aren‘t amplifiers built with protections that can trip on such accidents to save itself and other components/speaker? This may be a silly question, but as a layman I’d like to know.
 

flat_listener

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A single freely hanging strand on any termination, speaker or pre or amp scares the hell out of me. Hence I have started paying a lot of attention to these details and insulate them carefully. These must be checked regularly else you would never know what’s wrong in the chain, effecting the sound.
Wow! Never thought a single strand could do such big damage. I need to be more careful in future as sometimes I don't pay that much attention to strands coming out. Makes me want to get more banana plugs :oops:
Congrats on the new acquisition. That's a lot of power indeed.
Yes it definitely can... it could be as simple as a stray strand of wire which has come loose from the binding post.
it will likely destroy the output stage unless there is "overload/short protection" in place.

The (very general) rule of thumb is: never open-circuit a tube amp and never short-circuit a solid state amp.
 

hydrovac

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Nice. Should gel well with the pre amplifier from them I assume. What power amplifier (brand) was the one that got fried?
Hopefully... presently using DD pre-amp.
Power amp is a DIY design.


Oh cool. I am also sitting on the fence whether to upgrade from my 120w DD amp to the 200w or not. Its an awesome amp. Do let us know what the 200w beings in.

MaSh
Oh! you have a DD amp already... did you built it yourself?
Using a DD pre-amp in the chain... haven't heard their power amp, though.


Yes it definitely can... it could be as simple as a stray strand of wire which has come loose from the binding post.
it will likely destroy the output stage unless there is "overload/short protection" in place.

The (very general) rule of thumb is: never open-circuit a tube amp and never short-circuit a solid state amp.
The corollary rule of thumb is: don't muck with the amplifier when it's running! :(


Add protection board!
Sad to hear about your loss. And hope you get your desired alternative soon. However, aren‘t amplifiers built with protections that can trip on such accidents to save itself and other components/speaker? This may be a silly question, but as a layman I’d like to know.
Over the years I have managed to short the output of transistor amp a few times. Definitely not a good idea. In most cases got away with it.
Probably, the protection circuit and fuses are not fast enough to save the outputs from an instantaneous overload caused by a momentary short.
on a lighter note - shorting the outputs is usually the easiest way to find out exactly how much smoke is packed in the amp... :)

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MaSh

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Oh! you have a DD amp already... did you built it yourself?
Using a DD pre-amp in the chain... haven't heard their power amp, though.












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Yes been using the 120w variant for a couple of months now with acoustic portrait tube preamp. I haven't heard the dd preamp. Needed a remote, hence got the AP. However i believe Aniket is working on adding a remote to the pre along with few other tweaks.

MaSh
 

hydrovac

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Recd the parcel, actually Aniket wanted to ship the module in separate packs, disassembled condition for safety reasons.
But later he realized that it would be too much hassle soldering the filter caps, tethering the output devices, fixing the heat sink and biasing, at my end.
The previous PCB pics i posted were designed to take screw on type capacitors... but, as i already had snap on type caps with me, requested Aniket to provide PCB to suit the same.

Thanks to India speed post, the module arrived in single piece.
The overall size is 12 x 9 x 5inches... have to figure out the layout and cabinet.
Here is how the amp looks:

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manniraj

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Because of the way the mosfets are mounted on the heat sink I think the internal spacing in the cabinet will become constraint right? I am not sure what is the exact size of this amp board but with all in one having speaker protection and psu less clutter of wiring :)
 

MaSh

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Oh wow this looks quite a bit different from mine. Heat sinks especially.

MaSh
 
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