My first GainClone is up and running...

timbarnes · 9th January 2005, 12:42 AM

Pictures here: Tim's GainClone

Built with briangt's kit and standard parts. I had a bit of a problem with DC offset at first, but fixed (below 1.5mV) with an electrolytic in the feedback circuit as suggested in the app. note.

I was hoping the three cases would give good hum isolation, but there is some hum (only audible with my ear to the speaker), and some pickup of clicks from other appliances in the room - I probably didn't take enough trouble to twist power wires and I didn't use shielded signal cables. I also didn't ground the outer cases (they only receive DC from the power supply - this may be unwise and I'll probably change it as I suppose there's a remote possibility that AC could short to a DC wire...

But the sound - now that the DC offset is fixed - is superb. Very accurate, very listenable, no complaints.

tim.

Vuamp2 · 9th January 2005, 01:34 AM

Look great. I realy like the way you isolate the transformer. It is some what similar to what I am trying to build now.... your look better than my, however .

troystg · 9th January 2005, 01:54 AM

Hey Tim-

Really good idea. I like the visual effect and the pwr supply isolation.

May I suggest grommets around the holes between enclosures? I would hate to see such a great project go up in smoke due to skinned wire.

Look for "caterpillar grommet" at your local electronic store. I oversize mine a tad bit to keep outward pressure on it and I usually put a dab of silicone or hot glue to hold it in place.

timbarnes · 9th January 2005, 07:37 AM

Thanks for your comments. You're right about the grommets - I couldn't find the right size at Maplins, so I used heatshrink to add a layer of protection over the power supply wiring. I did work quite hard to d-burr the holes, but you can't be too careful with power wiring.

Regards,
tim.

jaudio · 9th January 2005, 01:21 PM

Excellent work.

Upupa Epops · 9th January 2005, 02:01 PM

Nice work, but isolation of transformer's hum by aluminium have low efficiency.

timbarnes · 9th January 2005, 11:05 PM

Quote:

Originally posted by Upupa Epops
Nice work, but isolation of transformer's hum by aluminium have low efficiency.

Any good ideas about how to simply improve the hum isolation? I thought I might put a steel mesh cage around the transformer (mesh is cheapish at the local DIY store). I could also twist the power wiring that passes across the top of the transformer...

tim.

Vuamp2 · 10th January 2005, 11:32 PM

Tim,

Have you try to run DC power conductors to your amp around the transformer instead of accross it? Center of the transformer has the strongest electromagnetic field and should be avoid to have any cables run accross it. You can easily check this out.

timbarnes · 11th January 2005, 05:44 PM

I'll try re-routing the power wiring. I'm also going to do some RFI work

- the amp picks up cell phones from quite a distance.

tim.

Vuamp2 · 11th January 2005, 11:29 PM

Quote:

Originally posted by timbarnes
the amp picks up cell phones from quite a distance.

tim.

Look like you may be able to patent this

9th January 2005, 12:42 AM	#1
timbarnes diyAudio Member Join Date: Dec 2004 Location: Los Gatos	My first GainClone is up and running... Pictures here: Tim's GainClone Built with briangt's kit and standard parts. I had a bit of a problem with DC offset at first, but fixed (below 1.5mV) with an electrolytic in the feedback circuit as suggested in the app. note. I was hoping the three cases would give good hum isolation, but there is some hum (only audible with my ear to the speaker), and some pickup of clicks from other appliances in the room - I probably didn't take enough trouble to twist power wires and I didn't use shielded signal cables. I also didn't ground the outer cases (they only receive DC from the power supply - this may be unwise and I'll probably change it as I suppose there's a remote possibility that AC could short to a DC wire... But the sound - now that the DC offset is fixed - is superb. Very accurate, very listenable, no complaints. tim.

9th January 2005, 01:34 AM	#2
Vuamp2 diyAudio Member Join Date: Dec 2001 Location: Texas	Look great. I realy like the way you isolate the transformer. It is some what similar to what I am trying to build now.... your look better than my, however . __________________ VuAmp2 http://community.webshots.com/user/vuamp2

9th January 2005, 01:54 AM	#3
troystg diyAudio Member Join Date: Apr 2004 Location: Lousy Anna	Hey Tim- Really good idea. I like the visual effect and the pwr supply isolation. May I suggest grommets around the holes between enclosures? I would hate to see such a great project go up in smoke due to skinned wire. Look for "caterpillar grommet" at your local electronic store. I oversize mine a tad bit to keep outward pressure on it and I usually put a dab of silicone or hot glue to hold it in place. __________________ Troy Thinking positive doesn't make things better, it makes you a better person.

10th January 2005, 11:32 PM	#8
Vuamp2 diyAudio Member Join Date: Dec 2001 Location: Texas	Tim, Have you try to run DC power conductors to your amp around the transformer instead of accross it? Center of the transformer has the strongest electromagnetic field and should be avoid to have any cables run accross it. You can easily check this out. __________________ VuAmp2 http://community.webshots.com/user/vuamp2

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9th January 2005, 07:37 AM	#4
timbarnes diyAudio Member Join Date: Dec 2004 Location: Los Gatos	Thanks for your comments. You're right about the grommets - I couldn't find the right size at Maplins, so I used heatshrink to add a layer of protection over the power supply wiring. I did work quite hard to d-burr the holes, but you can't be too careful with power wiring. Regards, tim.

9th January 2005, 01:21 PM	#5
jaudio diyAudio Member Join Date: Oct 2004	Excellent work.

9th January 2005, 02:01 PM	#6
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	Nice work, but isolation of transformer's hum by aluminium have low efficiency.

11th January 2005, 05:44 PM	#9
timbarnes diyAudio Member Join Date: Dec 2004 Location: Los Gatos	I'll try re-routing the power wiring. I'm also going to do some RFI work - the amp picks up cell phones from quite a distance. tim.

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