My monoblock Gainclone LM3886 (photos link)

steeve · 10th March 2005, 09:08 PM

My amps built a year ago:

http://briefcase.pathfinder.gr/contents/stry/25160

Any comments welcome

WARNING: large pics !

jaudio · 10th March 2005, 09:40 PM

Are you going to put them in cases? Perhaps plexiglass.

rodolfo · 11th March 2005, 06:41 AM

very nice work

stry · 11th March 2005, 09:15 AM

jaudio,

this is my final assembly (acc to my tastes).

Characteristics:

No hum, no strange offsets (< 20 mV), no heating (when driving 84dB 4-ohm speakers), after 1 year.

Includes zobel and coil at the output.

The building platform is solid copper 10 mm!

Includes thermometer on top (at the first days, oscillation was a frequent phenomenon, and this was VERY useful !).

Cap bank is ELNA cerafine (before, i included 10.000 uF bank in parallel, but something bad happended with the bass. ... you know)

Trafos are 300 VA (custom order)

No FUSES (direct connection to mains)!

Not MUR 860 diodes (!)

Special internally hardwired ac outlets, only for two GCs

... and sound? Very very good, but ... remember: my speakers (Audio Phycic Step SLE) are not an optimum match.

PS. A lesson for me: NEVER use cap in the feedback loop of such an amplifier !!!

jaudio · 11th March 2005, 10:13 AM

"Includes thermometer on top (at the first days, oscillation was a frequent phenomenon, and this was VERY useful !)."

How was the thermometer used?

How was the oscillation problem fixed?

stry · 11th March 2005, 01:11 PM

Simply,

the thermometer exceeded 49oC reading during oscillation

Now, never exceeds 30oC.

Problems fixed by removing the cap from the feedback loop and by setting a 47 k resistor input (-) to ground.

DC Dave · 11th March 2005, 06:41 PM

Quote:

No FUSES (direct connection to mains)!

Sounds like a fire hazard to me. You shouldn't get in the habit of building anything mains powered without using fuses, IMHO.

steeve · 11th March 2005, 08:37 PM

DC dave,

this will terrify you:

My other amp, McCormack DNA 0.5, with upgraded power supply (2 x 600 VA + 1 x 300 VA, 100.000uF total) is also direclty connected to mains (direct run to the power switchboard).

Also all four fuses at the output stages have been removed.

Of course, operation is always supervised.

But, all good (sound) things have a cost: A fatal short circuit (during the mis-insertion of a plug) burnt a handful of fets and transistors.

Anyway, i must say that i trust GC as it is. One year now and is very stable.

10th March 2005, 09:08 PM	#1
steeve diyAudio Member Join Date: Nov 2004 Location: athens	My monoblock Gainclone LM3886 (photos link) My amps built a year ago: http://briefcase.pathfinder.gr/contents/stry/25160 Any comments welcome WARNING: large pics ! __________________ Better is the enemy of good!

11th March 2005, 06:41 AM	#3
rodolfo diyAudio Member Join Date: Jan 2005 Location: tamaulipas	nicee very nice work

11th March 2005, 08:37 PM	#8
steeve diyAudio Member Join Date: Nov 2004 Location: athens	DC dave, this will terrify you: My other amp, McCormack DNA 0.5, with upgraded power supply (2 x 600 VA + 1 x 300 VA, 100.000uF total) is also direclty connected to mains (direct run to the power switchboard). Also all four fuses at the output stages have been removed. Of course, operation is always supervised. But, all good (sound) things have a cost: A fatal short circuit (during the mis-insertion of a plug) burnt a handful of fets and transistors. Anyway, i must say that i trust GC as it is. One year now and is very stable. __________________ Better is the enemy of good!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FS LM3886 Triple monoblock amp	chevy2410	Swap Meet	7	8th February 2009 06:08 PM
Lm3886 Gainclone Help	barry.childs	Chip Amps	10	6th September 2008 03:02 AM
Toroid question and LM3886 photos	slomatt	Chip Amps	21	26th February 2008 11:22 AM
photos new gainclone	serosmaness	Chip Amps	5	25th December 2004 10:43 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

10th March 2005, 09:40 PM	#2
jaudio diyAudio Member Join Date: Oct 2004	Are you going to put them in cases? Perhaps plexiglass.

11th March 2005, 09:15 AM	#4
stry diyAudio Member Join Date: Jun 2004 Location: athens	jaudio, this is my final assembly (acc to my tastes). Characteristics: No hum, no strange offsets (< 20 mV), no heating (when driving 84dB 4-ohm speakers), after 1 year. Includes zobel and coil at the output. The building platform is solid copper 10 mm! Includes thermometer on top (at the first days, oscillation was a frequent phenomenon, and this was VERY useful !). Cap bank is ELNA cerafine (before, i included 10.000 uF bank in parallel, but something bad happended with the bass. ... you know) Trafos are 300 VA (custom order) No FUSES (direct connection to mains)! Not MUR 860 diodes (!) Special internally hardwired ac outlets, only for two GCs ... and sound? Very very good, but ... remember: my speakers (Audio Phycic Step SLE) are not an optimum match. PS. A lesson for me: NEVER use cap in the feedback loop of such an amplifier !!!

11th March 2005, 10:13 AM	#5
jaudio diyAudio Member Join Date: Oct 2004	"Includes thermometer on top (at the first days, oscillation was a frequent phenomenon, and this was VERY useful !)." How was the thermometer used? How was the oscillation problem fixed?

11th March 2005, 01:11 PM	#6
stry diyAudio Member Join Date: Jun 2004 Location: athens	Simply, the thermometer exceeded 49oC reading during oscillation Now, never exceeds 30oC. Problems fixed by removing the cap from the feedback loop and by setting a 47 k resistor input (-) to ground.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read