I received the last shipment of parts for the LM4780 kits. I also managed to get one channel working tonight. It seems to work rather well. I haven't done any extended testing, as I only have one channel finished. I will take some pictures once I can find my digital camera charger.
The kits should start shipping out this weekend. I will be putting together the shipment of parts for Peter tomorrow morning to mail up to him. (already mailed him some board for his testing).
--
Brian
The kits should start shipping out this weekend. I will be putting together the shipment of parts for Peter tomorrow morning to mail up to him. (already mailed him some board for his testing).
--
Brian
Was any thought given to using a differential input instead of single ended? That would open up the board to balanced inputs along with possibly an cleaner input.
I had lots of trouble getting a LM3886 quiet but it was much, much easier with a differential input.
I had lots of trouble getting a LM3886 quiet but it was much, much easier with a differential input.
Hi Evan-
Did you use a differential buffer for the LM3886?
If not, can you post your circuit layout?
Did you use a differential buffer for the LM3886?
If not, can you post your circuit layout?
So here it is, first two boards assembled ( as I believe Brian assembled only one so far 😉).
I got a bit sidetracked with my recent experiments with TDA1541 DAC, but yesterday I finally managed to put together those boards and today I hope to put it into a chassis and compare with 3875 chip (that's why I used similar components). It seems like leaving rectifier board connected is a good idea and I will feed two double bridges from common secondaries.
I must say that this board came up pretty nice actually and there is not a single thing yet I would like to change here.😉
It seems like double aluminum oxide insulators might work here, as they provide more than enough spacing on mounting holes. In that case a push bar would have to be used.
I will be experimenting with bridged configuration soon.
I got a bit sidetracked with my recent experiments with TDA1541 DAC, but yesterday I finally managed to put together those boards and today I hope to put it into a chassis and compare with 3875 chip (that's why I used similar components). It seems like leaving rectifier board connected is a good idea and I will feed two double bridges from common secondaries.
I must say that this board came up pretty nice actually and there is not a single thing yet I would like to change here.😉
It seems like double aluminum oxide insulators might work here, as they provide more than enough spacing on mounting holes. In that case a push bar would have to be used.
I will be experimenting with bridged configuration soon.
Attachments
They have a very professional good look. I like it. 
Just wondering, what is the obvious advantage to your design compared to using only one LM3886 (I know that LM4780 contains two LM3886 dices)?
Just wondering, what is the obvious advantage to your design compared to using only one LM3886 (I know that LM4780 contains two LM3886 dices)?
paging brian...
Tried to email some pictures but my mail to you has bounced. Please feel free to contact me at cmanning(at)metalworkingsystems.com.
Tried to email some pictures but my mail to you has bounced. Please feel free to contact me at cmanning(at)metalworkingsystems.com.
Peter:
From your pictures it appears that you've used larger capacitors (physically) on one of your LM4780 amps than the other. Are the larger capacitors (physically) black gate? Are they higher capacitance? Why did you choose to use different capacitors on each of the LM4780 amps?
From your pictures it appears that you've used larger capacitors (physically) on one of your LM4780 amps than the other. Are the larger capacitors (physically) black gate? Are they higher capacitance? Why did you choose to use different capacitors on each of the LM4780 amps?
Peter Daniel said:
I don't think it's a good idea at all, Peter...
PSU diodes near the signal inputs?
carlosfm said:
I don't think it's a good idea at all, Peter...
PSU diodes near the signal inputs?
If I didn't try it I wouldn't say so. I'm using this arrangement in my monoblocks and I don't see any problems whatsoever. I was kinda surprised myself, but I usually try things before making any comments😉
m0tion said:
On one board are 1500u Panasonics. I tried them already in a protoype and they work fine. On the other board are 1000u BG STD, to show that they also fit the board.
1 1300 W halogen with an umbrella
2 A good tripod, very stable
3 White, silver and grey cardboards
4 Minolta F100 4MPx (an "old" camera now, 2 years old)
5 Remote control (in order to avoid vibrations)
6 Manual exposure
7 Manual focusing
8 Manual white balance
9 5 different exposures for each picture
That's it!
Hints: Don't mix different light sources => bad colours
Calibrate the white balance before each session.
Your latest picures weren't too bad. You only have to get a bigger white cardboard plus an additional to get more controlled relections.
2 A good tripod, very stable
3 White, silver and grey cardboards
4 Minolta F100 4MPx (an "old" camera now, 2 years old)
5 Remote control (in order to avoid vibrations)
6 Manual exposure
7 Manual focusing
8 Manual white balance
9 5 different exposures for each picture
That's it!
Hints: Don't mix different light sources => bad colours
Calibrate the white balance before each session.
Your latest picures weren't too bad. You only have to get a bigger white cardboard plus an additional to get more controlled relections.
And what for background?
If I have enough time, I also use tripod, remote and no flash, natural light, but never tried those additional diffusors with a lamp.
If I have enough time, I also use tripod, remote and no flash, natural light, but never tried those additional diffusors with a lamp.
I have never used a background. If you have a cardboard size 0,7 x 1 m (2.5' x 3.5') or so you won't need a background.
... ooh, I forgot... Photoshop of course.
1 Unsharp mask (a must!), Unsharp maks is like waxing your car. It simply gets better, a win-win situation
2 Make sharper (occationally)
3 Levels, sometimes
4 Contrast, brightness often
5 Colour balance, not often
I have not practiced so much using "curves" but this makes wonders also... but... nothing can be as good as a good taken picuture to begin with. Put most of your efforrts there and try also to handle those cardboards carefully so you don't get scracthes becuase this creates much work in Photoshop to remove.
... ooh, I forgot... Photoshop of course.
1 Unsharp mask (a must!), Unsharp maks is like waxing your car. It simply gets better, a win-win situation
2 Make sharper (occationally)
3 Levels, sometimes
4 Contrast, brightness often
5 Colour balance, not often
I have not practiced so much using "curves" but this makes wonders also... but... nothing can be as good as a good taken picuture to begin with. Put most of your efforrts there and try also to handle those cardboards carefully so you don't get scracthes becuase this creates much work in Photoshop to remove.
peranders said:
Aaahhhh... I see you know what you're doing!😎
I can't leave my trusty Canon T90 because there has to be invented a digital (or whatever) SLR as good as this, and such a pleasure to use.
Probably the best manual-focus SLR ever made.
Peter Daniel said:
At least I listened to my one channel, instead of spending a bunch of time taking pictures of it 😉
--
Brian
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