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A little Audio project I have virtually completed
spuddevans:
--- Quote from: Imagineering on April 14, 2011, 07:30:16 AM ---Good that the CNC Conversion worked then, isn't it.
Murray.
--- End quote ---
You better believe it!!! I wouldn't have even dreamt about doing this without cnc.
As it was it took about 3.5 hours to drill it (split up into 5 little sessions) after I modded my mill slightly to get the ability to drill into the center of the lid.
I'm toying with the thought of putting in a few LED's to backlight the holes, might look cool?
Tim
spuddevans:
Well, one step forward, and a whole leap back.
I just finished the lid off and carefully reassembled the amp, then took it to my listening room along with my cd player and a couple of my fave cd's, plugged in the speakers and cd player, turned the power on and then after waiting a couple of mins to let the valve heaters warm up, hit the power switch to apply the power to the 4780's and the HT supply, and there was a sickening "CRACK!!" :zap:
I immediately turned the power off, and smelt the familiar scent of exploded silicon. :( :(
I took the lid off and couldnt see exactly where the problem was, so I turned the power back on very briefly to identify the exact whereabouts of the problem, I immediately saw that the RH amp module emitted a flash and another crack from the 4780 chip.
A little further testing revealed that there is a 16ohm short from the faulty chip's heatsink and ground (the heatsink should be at -VE as it wasnt electrically isolated from the chip, but I had kept the heatsink clear of touching any ground's (or at least I thought I had!! ) ) This short is steady at 16ohms to ground, even when applying pressure in all directions to the heatsink.
So I have to order a spare 4780, I guess I'll order a couple to be sure, and then I'll take it to bits and replace the faulty chip and make sure that everything else is ok. I'm also going to get a couple of isolating washers for both amp modules.
So, I'm sorry to report that the audio test will have to wait for a week or so for me to get the replacement and then fit them.
Tim
Chazz:
Beautiful work! :thumbup: What is the Wattage rating of your amp?
Cheers,
Chazz
spuddevans:
--- Quote from: Chazz on April 21, 2011, 03:28:12 PM ---Beautiful work! :thumbup: What is the Wattage rating of your amp?
Cheers,
Chazz
--- End quote ---
Thanks mate :thumbup:
The wattage is 2x 30watts per side, it is configured as biamp so there is one 60 watt stereo amp for each speaker.
So I guess the total max wattage would be 120watts, I say the max wattage as I am not running it at full gain, I have modified the amp circuit to reduce the gain somewhat so I would guess that I have it running at 60watts rms max, my speakers are around the 89dB sensitivity mark so that is plenty loud enough for me.
Although at the moment one amp chip has had the blue smoke let out of it, so the amp is currently rated at 0 watts rms :D
Tim
Jonny:
Missed this one, nice work there Spuddy love the case and knobs but not keen in brass.
Next step to alter the sound 6N copper purity, silver plated wire throughout.
Separate ground outside, dont use the supplied earth, will be able to tell if its raining!
Junk them cheap 1/2p resistors, go for Holco or Vishay on input stages, got mine from Croft amps down the road- wow.
Another biggy is the change of the cheap diodes to something like Schotky, work tremendous with rectifiers.
For about £150 you may well have a better performer than a multi £k amp and pre amp setup!
To alter the actual sound play around with cabling if load tolerant, i used anything and everything i could get hold of in a tri wired setup, even tv coax steel core for Dynaudio base drivers. Interconnects same thing, most are not neutral except the dry Roksan and liquid Audionote tonearm silver stuff.
Caps will change the sound too, forget what i ended up with.
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