Re: Re: Re: Loud hum with open inputs
Well, that (nearly) did it. All what´s left with open inputs is a little, but clearly aubible hum. With CDP connected I got to put my ear at the speaker to hear it. I´ll try conventionally shielded input cables and shielding the wires from trafo too. Tinker, tinker ...
Russ White said:
Well, that (nearly) did it. All what´s left with open inputs is a little, but clearly aubible hum. With CDP connected I got to put my ear at the speaker to hear it. I´ll try conventionally shielded input cables and shielding the wires from trafo too. Tinker, tinker ...
Beleive it or not, you can connect the pwr grnd from the AC to the chassis, and NOT connect the secondary cntr tap ground to it. Then there will not be a grnd loop between earth and pwr.
As long as the input AC grd is tied to the chassis the cahssis can't become "live", and any pwr issues in the chassis will be grnded out to the AC input grnd.
The cntr tap grnd should remain "floating" from the chassis and AC input grd. As should the signal ground from the RCA's.
If that is done, I would then tie the signal sheild you have to the chassis again. But only once the AC grd and the secondary grd are seperated.
As long as the input AC grd is tied to the chassis the cahssis can't become "live", and any pwr issues in the chassis will be grnded out to the AC input grnd.
The cntr tap grnd should remain "floating" from the chassis and AC input grd. As should the signal ground from the RCA's.
If that is done, I would then tie the signal sheild you have to the chassis again. But only once the AC grd and the secondary grd are seperated.
rabstg said:
By "floating" you mean the center tap ground isn´t connected neither to chassis nor to AC ground. That´s what I did before. RCA jacks are fully insulated. HUMMMM !!!
Please ave a look at the two last pics: http://www.diyaudio.com/forums/showthread.php?postid=744874#post744874 If I understand you right I did anything as you described ...
SmellOfPoo said:
Oh... what a download...
Smell, if you want help, you need to post smaller pics.
That page takes almost 3Mb to load, most people will quit. I almost did.
Regarding you amp, it looks like you are using the shield of the signal cable to connect to the chassis, and at two different points. (!)
Am I right?
Disconnect those wires from the chassis.
I mean these two wires I'm pointing out on your pic.
PS: with a technical miracle, your 1Mb pic was cropped and compressed to 98.5Kb.
Attachments
SOP-
I see a dual secondary trafo... I can only ASSUME you are using 1 bridge rectifier and are paralleling the pwr leads from the supply to the two broards.
I ASSUME the first configuration correct?
EDIT:
I just assumed he had 2 wires inside the shield, and the shield was only connected to the chassis.
SOP- Can you say if there is 1 or 2 wires in the shield, and is the shield tied to the grnd signal wire under the red heat shrink?
By the way, I still think it is a great execution of an amp, I'm just trying to help make it quiet.
I see a dual secondary trafo... I can only ASSUME you are using 1 bridge rectifier and are paralleling the pwr leads from the supply to the two broards.
I ASSUME the first configuration correct?
EDIT:
I just assumed he had 2 wires inside the shield, and the shield was only connected to the chassis.
SOP- Can you say if there is 1 or 2 wires in the shield, and is the shield tied to the grnd signal wire under the red heat shrink?
By the way, I still think it is a great execution of an amp, I'm just trying to help make it quiet.
Attachments
It's alive!!
Well I left work early today to come home and tinker.
I pulled the relay / pot brd off the chassis and looked on the bottom.
What to my wondering eyes did appear, but I reversed the coil polarity to each relay. DC coils, 50-50 chance. Go figure. Once I swapped the polarity so + went to +12VDC and the switch controlled the grnds as planned, everything worked great.
I fired it up and listened to a cd (Sony walkman portable) on my test speakers. ( I measured voltage offset the other day, 0.03 for the left, 0.00 for the right. Those "be" Milli volts from my Fluke 87!)
After listening on the old test speakers with my wife we closed each others jaw and I went set it up in my living room.
I connected my Sony DVD player via copper interconnects with WBT midline RCA's to the int. amp then out via Canare quad spkr cable to my "refurbished" with Hi-Vi drivers B&W Matrix 805's.
I listened to Lyle Lovett’s "I love Everybody" CD and sat in amazement.
It was equal to my Sony DVD transport via Co-ax to Proceed AVP via balanced Kimber ? ( the shielded PBJ, KC-1 maybe?) with Nuetrik XLR's to my Jeff Rowland Model 2.
And I can say that after 2 cd's! The tone, pitch and pace were dead on. It was smooth and DETAILED!
I will be bringing it to a friend’s house shortly to listen on his Madisound Thor kit. I happen to be "between" speakers at the moment. My new ones are not here yet.
Thus far I am absolutely amazed at what is coming out of this inexpensive amp!
Fabuluos job Mauro, and thanks for doing the boards / kits Russ and Brian! Now anyone can aford top notch audio.
Well I left work early today to come home and tinker.
I pulled the relay / pot brd off the chassis and looked on the bottom.
What to my wondering eyes did appear, but I reversed the coil polarity to each relay. DC coils, 50-50 chance. Go figure. Once I swapped the polarity so + went to +12VDC and the switch controlled the grnds as planned, everything worked great.
I fired it up and listened to a cd (Sony walkman portable) on my test speakers. ( I measured voltage offset the other day, 0.03 for the left, 0.00 for the right. Those "be" Milli volts from my Fluke 87!)
After listening on the old test speakers with my wife we closed each others jaw and I went set it up in my living room.
I connected my Sony DVD player via copper interconnects with WBT midline RCA's to the int. amp then out via Canare quad spkr cable to my "refurbished" with Hi-Vi drivers B&W Matrix 805's.
I listened to Lyle Lovett’s "I love Everybody" CD and sat in amazement.
It was equal to my Sony DVD transport via Co-ax to Proceed AVP via balanced Kimber ? ( the shielded PBJ, KC-1 maybe?) with Nuetrik XLR's to my Jeff Rowland Model 2.
And I can say that after 2 cd's! The tone, pitch and pace were dead on. It was smooth and DETAILED!
I will be bringing it to a friend’s house shortly to listen on his Madisound Thor kit. I happen to be "between" speakers at the moment. My new ones are not here yet.
Thus far I am absolutely amazed at what is coming out of this inexpensive amp!
Fabuluos job Mauro, and thanks for doing the boards / kits Russ and Brian! Now anyone can aford top notch audio.
carlosfm said:Oh... what a download...
Sorry for that, I have a SDSL connection and didn´t mention that others might go to the www with less bandwith. Next time I´ll use smaller and compressed pics.
carlosfm said:
I tried that before. No cure. Btw it is not a coaxial cable; it is a twisted pair. So signal ground is not connected to the chassis.
carlosfm said:PS: with a technical miracle, your 1Mb pic was cropped and compressed to 98.5Kb.
I know that kind of miracle, next time I´ll make use of it.
rabstg said:
Nope. Any board has it´s own rectifier. Power grounds are not tied to the chassis.
rabstg said:
I can say that there are 2 wires in the shield and signal ground is NOT tied to the shield or chassis.
rabstg said:
Thank you !
Re: It's alive!!
Troy,
I know the feeling! I had been biased for a long time that nothing could approach the quality of big dollar big current (but not necessarily big output lol!) Class A amps. Well this amp clearly blows that myth away. After months of critical listening I would choose "My Ref" over my KSA-50 or my Aleph 30SE.
You did an awesome build. Thanks for being a beta tester.
It is guys like you who make this fun for me, and thats the whole point really.
Cheers!
Russ
rabstg said:
Troy,
I know the feeling!
I had been biased for a long time that nothing could approach the quality of big dollar big current (but not necessarily big output lol!) Class A amps. Well this amp clearly blows that myth away. After months of critical listening I would choose "My Ref" over my KSA-50 or my Aleph 30SE.You did an awesome build. Thanks for being a beta tester.
It is guys like you who make this fun for me, and thats the whole point really.Cheers!
Russ
Re: Re: It's alive!!
I will be cleaning up the wiring and layout shortly to make it much "prettier" inside.
Please hurry on the source selector and Kookaburra so I can put those in!
EDIT:
By the way, I can solder pretty well, but for fun and an even better job I had Repute assemble the boards... He did a fabulous job, and I was very happy with the outcome.
If anyone wants a kit built and can't do the soldering required, they can Email Repute and maybe work something out... I am NOT advocating Repute for anything, he is just a long time friend that did PCB rework in a prior lifetime. I would just hate to see someone miss out on this GREAT amp because they can't solder.
Russ White said:
I will be cleaning up the wiring and layout shortly to make it much "prettier" inside.
Please hurry on the source selector and Kookaburra so I can put those in!
EDIT:
By the way, I can solder pretty well, but for fun and an even better job I had Repute assemble the boards... He did a fabulous job, and I was very happy with the outcome.
If anyone wants a kit built and can't do the soldering required, they can Email Repute and maybe work something out... I am NOT advocating Repute for anything, he is just a long time friend that did PCB rework in a prior lifetime. I would just hate to see someone miss out on this GREAT amp because they can't solder.
Well, I can't resist any more.....
This little hussy has been tempting me for a while; I thought I'd probably try a Ucd400 instead but with funds being shorter than ambitions .....
Question to the Pear chaps- can I still get in on the first delivery run of the kit (oct 24th?)
Weeks to make my mind up and now I WANT IT NOW!!
This little hussy has been tempting me for a while; I thought I'd probably try a Ucd400 instead but with funds being shorter than ambitions
.....Question to the Pear chaps- can I still get in on the first delivery run of the kit (oct 24th?)
Weeks to make my mind up and now I WANT IT NOW!!
float said:
Question to the Pear chaps- can I still get in on the first delivery run of the kit (oct 24th?)
Weeks to make my mind up and now I WANT IT NOW!!
Absolutely, we have plenty of PCBs which are in stock right now, and can ship now, and kits which should ship by Monday.
Enjoy!
Cheers!
Russ
Finished my first Gainclone Rev_A
Pictures ( warning, each one, full size - about 800k !!!) at :
ftp://ftp.dallnet.ro/public/hi-fi&stuff/Gainclone/
DIY case, black painted - one 400 VA @ 2x22V toroidal transformer
2x15000 microFarads on each rail - I'm not sure if they're really Rubycon
The list of components sticked to Mauro recomandations.
PCB's made at scale after Mauro's PDF at a local manufacturer.
Speakers are 4 ohms ones. T+A .
First impressions : detailed, powerfull, with a LOT of bass . I mean a LOT !
Maybe that's why a have the impression that, somewhow, highs are little bit less present than with my Yamaha , for instance.
One strange issue - one of the chips is getting a litlle bit warmer than the other one .Sensible warm ! Also the chips are warm if the amp is left alone with the power on but with no input at all.
Otherwise - is extremely quiet . No hum at all, even at maximum.
Mr.Penasa , could you be so kind to advise if and how is possible to connect the actual module in paralell mode. Would they be any implications regarding your concept ?
Regarding the high frequencies .Have I done something wrong or is just my ear ?
Could it be a high frequency oscilattion heating my chips differentelly and also heating the chips even with no signal ? Should I move to Rev_C ?
Thanks for your nice threads, everybody.
Best Regards
Pictures ( warning, each one, full size - about 800k !!!) at :
ftp://ftp.dallnet.ro/public/hi-fi&stuff/Gainclone/
DIY case, black painted - one 400 VA @ 2x22V toroidal transformer
2x15000 microFarads on each rail - I'm not sure if they're really Rubycon
The list of components sticked to Mauro recomandations.
PCB's made at scale after Mauro's PDF at a local manufacturer.
Speakers are 4 ohms ones. T+A .
First impressions : detailed, powerfull, with a LOT of bass . I mean a LOT !
Maybe that's why a have the impression that, somewhow, highs are little bit less present than with my Yamaha , for instance.
One strange issue - one of the chips is getting a litlle bit warmer than the other one .Sensible warm ! Also the chips are warm if the amp is left alone with the power on but with no input at all.
Otherwise - is extremely quiet . No hum at all, even at maximum.
Mr.Penasa , could you be so kind to advise if and how is possible to connect the actual module in paralell mode. Would they be any implications regarding your concept ?
Regarding the high frequencies .Have I done something wrong or is just my ear ?
Could it be a high frequency oscilattion heating my chips differentelly and also heating the chips even with no signal ? Should I move to Rev_C ?
Thanks for your nice threads, everybody.
Best Regards
Carlos-
I will try two 2 tweaks to my amp:
1. Op-amp zener change to 18volts from 12
2. your snubbers
The zener is a no brainer, but may I ask you what values to try for the snubber?
I have the stock rev c kit using dedicated 25-0-25 volt transformers.
I can't wait to go home and set up the amp down stairs to listen to over the weekend as I very seldom get to listen upstairs in the tv room.
I will try two 2 tweaks to my amp:
1. Op-amp zener change to 18volts from 12
2. your snubbers
The zener is a no brainer, but may I ask you what values to try for the snubber?
I have the stock rev c kit using dedicated 25-0-25 volt transformers.
I can't wait to go home and set up the amp down stairs to listen to over the weekend as I very seldom get to listen upstairs in the tv room.