| rampage101 |
After my first humble attempt, I decided it was time for a clean up and rewire, also to try and get rid of ground hum.
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| wintermute |
looking good rampage :) have you suceeded in fixing the hum problem??
Tony. |
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| Crazy-Stereo |
| :cool: Can you tell us your result after clean up? and more pics. |
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| rampage101 |
Well, the pictures above are actually of my latest incarnation. From my little tests it appears the hum is gone, but I can't be certain until I completly wire it all.
My last approach used a piece of laminated masonite as a pcb, and just drilled holes and did p2p type joining on the back of the board. My grounds all went to the one location and was quite possibly the reason for hum and noise.
Now, I decided on a 3mm Angle alloy strip, drill some holes, mount all components and then wire p2p. I wired all signal grounds to input ground, then joined that to power ground point. I've only tested 1 channel so far, as I don't have a working mult-meter at home I'll take both my old amp (integrated with ESP HiFi diy preamp kit, 300va (18-0-18-0) toroid, which gives me 25v-26v rails.
So as yet, I have no idea on dc-offset or anything else, just that from preliminary testing on 1 channel before completion it seemed better;)
I had to use the paper on the banana posts as I didn't have any insulation washers or anything, so I used some clear tape to insulate some of the shaft and then paper for washers. I need to check for continuity though before further testing.:bigeyes: |
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| wintermute |
Hi Rampage,
I'm using these http://www.jaycar.com.au/productVie...eMax=&SUBCATID= from jaycar. they come with insulation washers. Make sure if you get washers you get ones that go inside the hole as well (sort of stepped) so that they stop the bolt from touching if you don't center it properly :)
edit: notice you use insulation tape on the shaft, I guess a bit of heat shrink would work too :)
Tony. |
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| rampage101 |
Hey Tony,
Thanks for the link. The ones I'm using must be for wooden speaker boxes or something. I was going to just use heatshrink for insulation around the shaft, but the only stuff I had handy was a tiny bit too small to get over the shaft. :(
Anyways, I'll get this thing checked with a multimeter. |
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| rampage101 |
Problems, the amp is working, but I'm getting very uneven volume level from each chip. I can't see anything wrong, all resistors seem to be in the correct place.
Ideas? |
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| Upupa Epops |
| ... looking good.... realy ? :D |
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| wintermute |
Had you finished soldering in the pics you posted rampage?? the connection on the right channel rca doesn't appear to be soldered ;)
Tony. |
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| wintermute |
| quote: | Originally posted by Upupa Epops
... looking good.... realy ? :D |
compared to some of the stuff I posted in the ugly amp and ugly prototype threads definitely :D
Tony. |
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| Greg Erskine |
Hi Rampage,
Sounds and looks like you are on the right track. I have attached my last and neatest p2p gainclone and you should recognise all the bits (all Jaycar except the main caps). Mine looks like a close cousin of yours. ;)
I'd have a look at the wire size you are using. Generally, cat 5 is OK for signal in, but beefier wire for output. Think about the voltage and/or current flowing in each wire and size accordingly.
The only time I have a problem with volume is when I got the feedback resistors reversed. :o
The toriod you are using should be OK.
Regards |
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| Upupa Epops |
| All is relative... but you have thruth, ugly women give you at the last the same enjoy as pretty one... :D |
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| rampage101 |
| The wiring in the photo's was not finished, I finished the rest off today. But, I can't find out where I went wrong. Both channels use the same wiring, so I can't figure out why its not working. |
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| rampage101 |
| Might be gone now, seems to be working fine. Will let you guys know:xeye: |
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| wintermute |
good to hear it is working now :) you might have an intermittent connection somewhere, probably be a good idea just to check all your joints (preferably with a magnifying glass) and also the the tightness of your rca connections.
so now you have both channels up and running, have you beaten the hum?
Tony. |
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| rampage101 |
Yes, there is no noise. I think I have a problem with my pre, I had it connected before (albeit really ghetto:D) and only 1 channel was working properly, so I'll finish getting cases made up for each (I'm seperating the pre and pwr amp's) and test with some proper interconnects. Gotta do a parts order though, 1/2 the ghetto'ness is because I have no other rca sockets :rolleyes:
But otherwise I'm really happy with the amp, the only noise is coming from my source (pc). Perhaps I should try building one of those spdif dac's to try. |
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| wintermute |
| quote: | Originally posted by Greg Erskine
I have attached my last and neatest p2p gainclone and you should recognise all the bits (all Jaycar except the main caps). Mine looks like a close cousin of yours. ;)
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Very nice Greg, and very ZEN :) but I think there was one other bit that wasn't jaycar, ie the feedback resistors ;) I thought about using those welwyns, but in the end I just went with some of RS's 7c jobs.... (partly because I already had them left over from a different project, and partly because I was trying to keep the cost down!).
Tony. |
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| wintermute |
| quote: | Originally posted by rampage101
But otherwise I'm really happy with the amp, the only noise is coming from my source (pc). Perhaps I should try building one of those spdif dac's to try. |
ecellent :) what sound card are you using?? also what sort of noise are you getting from the pc? I have an Audigy II ZS and it is very quiet indeed, and seems to have very good sound quality too.
I had some hum problems with my pc and old amp, mostly due I think to the fact that both have chassis connected to the mains earth, and I think I was getting a ground loop back through the mains.
Tony. |
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| rampage101 |
| Soundstorm audio, Abit NF7-S mobo. It just really low level fuzzy sort of noise. I assume its that because if I mute the audio though the soundstorm software I don't get any noise. |
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| wintermute |
yeah I have found that the sound cards built onto mother boards don't tend to be very good. I guess when the whole motherboard costs maybe between $90 and $200 you can't really expect it to keep up with a dedicated sound card in the same price range ;)
Dac could be the way to go, it will no doubt be better than almost any sound cards built in dac (regardless of the claims) and since it will be external it removes the risk of anything else in the pc causing noise. My audigy is really quiet, but that doesn't mean that it will necessarily be quiet in every pc :)
Tony. |
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| Greg Erskine |
| quote: | Originally posted by wintermute
but I think there was one other bit that wasn't jaycar, ie the feedback resistors ;) |
oooops! Caught out! :o
I should have read the label. :D |
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| rampage101 |
| Well, I've just rebuilt the amp using a new piece of angle alloy, this time I did all the holes all nice and neat first, then pieced the amp together. Now, everything seems fine (although no dc-offset values yet, no mm) except with the volume on my pre all the way down I get sound coming through, it never used to on my old amp. Any ideas? |
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| wintermute |
Hi Rampage,
I assume when you say you have sound comming through you mean the source signal isn't completely muted with the volume right down (ie you can still hear music or whatever).
how have you wired up your volume pot in the pre?? you should have one side connected to the input signal, the middle going to output and the other side connected to earth.... (at least that is how I always do them....)
Tony. |
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| jacco vermeulen |
| quote: | Originally posted by Upupa Epops
All is relative... but you have thruth, ugly women give you at the last the same enjoy as pretty one... :D |
A big ugly one is even better.
Make that two !
Ever heard of anyone integrating a DAC with a chip amp before ?
Just figured that something like that could be interesting in a car, to improove regular car CD/amplifier combo's.
(Yeah,Yeah: Sheila has been breaking my B's about her poor quality car gear) |
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| rampage101 |
| quote: | Originally posted by wintermute
Hi Rampage,
I assume when you say you have sound comming through you mean the source signal isn't completely muted with the volume right down (ie you can still hear music or whatever). |
Well, the pre in this case is Project 97 from ESP.
http://sound.westhost.com/project97.htm
It was working fine on my old amp, I had problems with hooking it up to the amp at the start of this thread, but I put that down to bad wires and ghetto wiring. Now I've hooked it all up correctly, so I have nfi. |
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| wintermute |
Hi rampage,
I would say this would have to be a problem with the pre not the power amp. if the pre is working properly then there will be no signal reaching the amp, for it to amplify :) again I'm assuming it is music and not noise you are hearing on the amp with the volume turned right down.
Since the pre is on a pcb (I'm assuming you used Rod's PCB) wiring problems seem unlikely, I'd check the solder joints on the earth side of the volume pot :) and also on the earth connection to the preamps pcb. I suppose another possibility is that you have a faulty pot.
One thing you can do to check is put the multimeter on low ohms (or continuity) and put it across the center pot pin, and the earthed pot pin. with the volume in the fully down position, it should be a short circuit. if not then the pot is probably a dud. also check from center pin to earth in this position to test the solder joint (should also be a short).
Tony. |
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| Evilsizer |
| was wonder what type of ALU. did you use and what thickness... looking to make a 60/40 wood covers front, sides and top. The ALU for bottom and back... |
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| rampage101 |
| its 50mm , 3mm Angle Aluminium Bar. |
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