Commercial Gainclone kit- building instructions

[Peter Daniel]

I tried EI transformers only once with the amps and good quality toroids worked better.

 

[dannycelluk]

thanks again.

sorry to be a pain. I need to get a few other bits from RS which is a local shop. does this transformer from RS look ok?

 

[Peter Daniel]

That one is fine too, although 25V may be a bit high with 6ohm speakers.

 

[dannycelluk]

cool cheers for the help. off to RS for me tommorrow to get a decent soldering iron and a few bits

 

[samsagaz]

Dear Peter, im planning to mount and test the LM4780 or LM3875 kits that I purchased in an MonoBlock design, I was thinking abt use aluminium instead an heatsink, want to know if you test it. I see that you use no heatsinks in some of your amps using copper/aluminium.

I want to know if you measure the volume of the aluminium to see how is the minimum to get an optimal chip temperature.

I was thinking about use an aluminium of like 10cm x 15cm x 1cm You think that this will work? I really want an small piece, but don’t want to get it too hot!

Btw have you some LM4780 pic of Bottom and top with components on it? I don’t finish it because really don’t know wich are the pcs that I really needs!

Thanks in advance.

 

[Peter Daniel]

It all depends how loud you play, what type of music and with what kind of speakers. Usually the amps run cool, but when pushed extensively things can get hot pretty quickly.

Try whatever seems right to you and adjust when needed.

You will find pics of LM4780 here: http://www.diyaudio.com/forums/showthread.php?postid=636565#post636565

 

[samsagaz]

Ok, thanks too much, will see that pics

 

[samsagaz]

Peter Under CZ dont need to use any res?

i populated the board in the wrong way, i set the big resistors under these Cap

 

[Peter Daniel]

All the parts should be installed according to schematic supplied with a kit: http://audiosector.com/lm4780 amp.pdf

Rz and Cz are optional Zobel parts.

PS schematic, including optional snubber parts: http://audiosector.com/lm4780 psu.pdf

 

[samsagaz]

Peter on this thread http://www.diyaudio.com/forums/showthread.php?postid=636570#post636570

i see that you are using the Cz but not the Rz, i already cut the legs of the Rz what about the Cz? i need to remove it too?

 

[Peter Daniel]

That was for demonstration purpose only. Rz and Cz are connected in series: one will not work without the other.

 

[markblun]

slight buzz

Peter, I completed one of your 3875 kits last weekend and it sounds great . Only issue I have is an audible buzz that is noticeable when you are very close to either loudspeaker. The level of buzz is not affected by volume - still there with volume control at minimum. Doesn't affect music listening but I'm curious what is causing it and how I might resolve it. Note - no hum at all - followed your earthing advice! This forum provided excellent build support - thanks!! Mark

 

[kele1975]

Hello
I'm planing to install led's on the front panel of amp chassis.
Can someone tell me which type,size,volts or candela rating is preferred?

 

[AndrewT]

type: LED.
size: try 3mm or 5mm diameter.
colour: select which you like and/or can afford.
current: 2mA to 5mA for brightness of choice.

Voltage: irrelevant, colour determines the voltage.
Candela: irrelevant, current determines brightness.

 

[VictoriaGuy]

There are also 'diffuse' LEDs available which reduce the 'headlight effect' of some of the brighter/clearer (esp blue) LEDs.

John

 

[dannycelluk]

Recieved my Gainclone kit today, Thanks PD.

Just gotta try and assemble it now hmmm better read through this thread one more time

 

[markdonnaharris]

Which Schematic

Peter...

Which schematic are you using for the amp portion (LM3875)?

I have at least 6 versions... is it the "minimal" with only 4 resistors & no capacitors?

2nd question... How does one order the Black gate caps with the kit? It looks like even the premium kit does not include these?

3rd question... Can one use a CD player w/ volume control drive the Gainclone when not using a pot, IE using the CD player volume control?

Thanks in advance.

MDH

 

[Peter Daniel]

With kits I use schematic posted here: http://www.diyaudio.com/forums/showthread.php?postid=1508778#post1508778

The Integrated amp uses Premium kit components, including Panasonic FC caps, with exception of 220R Caddocks which are simply omitted.

With Patek, I'm using parts as in attachment.

I'm not selling Black Gates, as they are discontinued. AFAIK, BG STD 1000/50 are still available, BG N 100/50 not any more.

A volume control in CD player will work fine, although the sound quality may not be exactly the same as using quality pot directly at amp's input.

 

[markdonnaharris]

Capacitors ?

Peter...

Thank you for the information.

Two further questions... I'm ready to build using the Patec schematic.

1) Since the BG's are not available what brand / value are needed for the PS caps and the AMP caps?

2) If I use no pot, is a series resistor needed at the signal input? Say 200R.

Best regards,

MDH

 

[Peter Daniel]

Besides the BGs, I always liked Panasonic FCs the most in this amp.

You can try FC 100/50 on amps board and BG STD (which are still available from Percy) in PS.

Even without the pot, I'm not using 220R resistor in my amps.