Hi Madhu,
I have already posted copper and component side PDFs for the version I prototyped. Will very likely post eagle files for this design at some point probably after the group buy, as I need to get some money for parts!
And more importantly to pay for my eagle license. Anything I make above the cost of the boards will go toward paying for my eagle license. Once that is done the files are my gift to you all.
Cheers!
Russ
I have already posted copper and component side PDFs for the version I prototyped. Will very likely post eagle files for this design at some point probably after the group buy, as I need to get some money for parts!
And more importantly to pay for my eagle license. Anything I make above the cost of the boards will go toward paying for my eagle license. Once that is done the files are my gift to you all.Cheers!
Russ
I know that this is stoopid question to ask after reading all the 480 posts, but im actually planning to make a 7.1Ch amp; 7 channels at about say, 40W into 8Ohms, and the sub at 200W into 4 Ohm.
can i stack up your boards for that?
and how do i order the boards? do you have a website?
tia,
Madhu.
P.S. I could not download your post with the attachment, as the server said something about it not being found...
saltnpeppah said:
Sorry about the bad link, I will post some fresh PDFs tomorrow of the single sided version.
There will be a group buy soon, with a kit. Brian Donegan (who did a rocking job on the last GB) will be doing the kits. Stay tuned as there will be more posts about the GB as things progress.
I would not literally "stack" these board in a single case as they get a little warm.
But you could easily put 6 or so in a case, just side by side 3 per side of the case.
Cheers!
Russ
I am a three
Put my 2 cents in for option 3. I like the idea of using the backside to run the lines that are jumpered now.
Far as the relays, I need to see one and then go hunt them up locally. Guess they are 24 volt dc, 10 amp single pole with five pins.
Just for grins, what are the present dimensions of the mono boards? I need to see what cast aluminum box with be needed to house a pair. When I printed the picture it was huge, would not fit on a 8 1/2 x 11.
George
Put my 2 cents in for option 3. I like the idea of using the backside to run the lines that are jumpered now.
Far as the relays, I need to see one and then go hunt them up locally. Guess they are 24 volt dc, 10 amp single pole with five pins.
Just for grins, what are the present dimensions of the mono boards? I need to see what cast aluminum box with be needed to house a pair. When I printed the picture it was huge, would not fit on a 8 1/2 x 11.
George
The size right now is roughly 4.2" x 3.3".
The relays I use are here:
http://www.futurlec.com/Relays/JQC-21FF-24.shtml
But honestly its a standard size, so lot of options there.
Cheers!
Russ
The relays I use are here:
http://www.futurlec.com/Relays/JQC-21FF-24.shtml
But honestly its a standard size, so lot of options there.
Cheers!
Russ
Meddling again
With the dual sided board you now have the opportunity to address the issue I raised about the loop area of the output. The problem at the moment is that the positive output exits just after R3, but the negative return is way over the other side of the board by the relay. If you think about the currents there is a rather large loop running around the board with the full output current in it.
I would be inclined to see if you can't get the two outputs close to one another, in particular by looking at relocating the relay. (If there was no relay it would be an easy route of a track in parallel with the current ground track for the 3883 power de-coupling.)
No doubt it is a nuisance to move the relay, but I feel it would be worth trying to eliminate this large loop. It may be that the P/S caps can be shifted up to the current space the the relay occupies, and then there is enough room to place the relay at the bottom of the board, and run the ground return track in parallel with the power runs.
Nit picking, one could also subtly re-route the output track and location of R3 so the tracks further close the loop area.
With the dual sided board you now have the opportunity to address the issue I raised about the loop area of the output. The problem at the moment is that the positive output exits just after R3, but the negative return is way over the other side of the board by the relay. If you think about the currents there is a rather large loop running around the board with the full output current in it.
I would be inclined to see if you can't get the two outputs close to one another, in particular by looking at relocating the relay. (If there was no relay it would be an easy route of a track in parallel with the current ground track for the 3883 power de-coupling.)
No doubt it is a nuisance to move the relay, but I feel it would be worth trying to eliminate this large loop. It may be that the P/S caps can be shifted up to the current space the the relay occupies, and then there is enough room to place the relay at the bottom of the board, and run the ground return track in parallel with the power runs.
Nit picking, one could also subtly re-route the output track and location of R3 so the tracks further close the loop area.
Francis_Vaughan said:Meddling again
No doubt it is a nuisance to move the relay....
It's no problem. The issue of the relay has been addressed before. The relay is back away from the ICs on purpose, to minimize EMI and noise. I have experimented with this, and it does make a difference. The relay needs to away from the LM3886 and epecially the LM318.BTW you absolutely cannot omit the relay, you will get horrible DC and clipping on startup until the amp settles, your speakers will not last long that way.
It is something I have already addressed with Mauro in the past(long ago). As it is I percieve no problems in practice, as we talking a space of about 1.5". I will see what I can do to move the output side up a little, but the relay needs to stay where it is for shielding purposes.
I wish you could hear my prototype.
You would have no doubts. Though I understand there is always room for tweaking, but hey there has to be a point where this thing is finished, and I can tell you that right now as it is I have never heard anything better, nothing.I feel like as long as the design is at least as good as the REV A boards were I should go forward. I believe it is.
Cheers!
Russ
This sort of reinforces my concern about stray magnetic fields. Clearly despite the low pass R/C filter the residual AC on the current feeding the relay still enough to create a field that can affect the sound. Maybe upping the 220uF capacitor to say 1000uF or more might help, but nothing beats a bit of r cubed
Playing with the dressing of the output lead will have exactly the same effect as my suggestion about tracks anyway, just dress the output lead so it lays over the ground track from the 3883 back between the P/S caps, between them so it overlays the star ground, and then continue to follow the output ground return track to the relay, run the cable around the outside edge of the relay and then twist it together with the output ground lead and take the pair off. Easy
Again, an easy thing to try.Yeah, would be good. I don't have too many doubts now - but one never knows how much better still something can be. It is a constant journey, and one filled with some delightful surprises.
I am a three
Well, I know I'm kind of paranoid, but having a relay contact in series with the signal path is maybe the only thing I don't like about this circuit.
So I was wondering... Mauro, wouldn't it be possible to arrange the protection circuit differently so that it will not be in the way during normal working?
I mean, for instance, wouldn't it be possible to connect the relay contact in parallel with the output, so that the output is shorted while the circuit settle down and/or in case of DC present at the output, while being completely out of the way during normal operation?
Other question: Russ, are your new PCB suited for building either one of Rev A,B,C (I would like that) or are they suitable for RevC only?
As for the PCB design, I would prefer "the third option" (double-sided, tested).
Russ White said:
Well, I know I'm kind of paranoid, but having a relay contact in series with the signal path is maybe the only thing I don't like about this circuit.
So I was wondering... Mauro, wouldn't it be possible to arrange the protection circuit differently so that it will not be in the way during normal working?
I mean, for instance, wouldn't it be possible to connect the relay contact in parallel with the output, so that the output is shorted while the circuit settle down and/or in case of DC present at the output, while being completely out of the way during normal operation?
Other question: Russ, are your new PCB suited for building either one of Rev A,B,C (I would like that) or are they suitable for RevC only?
As for the PCB design, I would prefer "the third option" (double-sided, tested).
Re: I am a three
Yes, you can easily do all three (A,B,C) on this PCB.
I am for the third option too. Though I really like the SS version too. It is the exact same size.
Is anyone interested in particpating with me in a beta test? This would help me defray the cost. I will contact my PCB manufacturer today about a prototype to see excactly what we are looking at. I would like to get 10 boards, for 5 pairs, so 4 other besides me, probably around $20 per person to cover the cost.
If anyone is interested in the beta test please indicate so here or by email.
Cheers!
Russ
UnixMan said:
Yes, you can easily do all three (A,B,C) on this PCB.
I am for the third option too. Though I really like the SS version too. It is the exact same size.
Is anyone interested in particpating with me in a beta test? This would help me defray the cost. I will contact my PCB manufacturer today about a prototype to see excactly what we are looking at. I would like to get 10 boards, for 5 pairs, so 4 other besides me, probably around $20 per person to cover the cost.
If anyone is interested in the beta test please indicate so here or by email.
Cheers!
Russ
I just want to chime in about noise concerns. The single sided RevA (Russ tells me he has the same result with his RevC) is the ONLY amp I have built where, even with my ear next to my horn tweeter and midrange, I hear no hiss (until I turn on my CD player ). This is with open or shorted input, full volume.
). This is with open or shorted input, full volume.
BrianDonegan said:I just want to chime in about noise concerns. The single sided RevA (Russ tells me he has the same result with his RevC) is the ONLY amp I have built where, even with my ear next to my horn tweeter and midrange, I hear no hiss (until I turn on my CD player
Yes, It is true, the amp is dead silent noise floor non-existant both my monoblocs and my REV-A Mauro layout.
My thoughts exactly. Maybe i've only used very poor relays but including them in series with the speakers has always brought unacceptable degradation. And what's the point of using high quality binding posts if there is a relay?
Probably not possible. The 3886 won't mind a shorted output as it's got a good protection but the circuit won't reallly 'settle' as the 318 will be deprived of feedback. The thump may be reduced but not eliminated.
Re: Re: I am a three
Count me in. It would make it easier/quicker if I could get the PS caps and rectfiers along with the boards (will pay of course) I can get 85 degree caps in that size locally, but haven't found 105 degree yet. Rectifiers in 6 amp, but not 8amp in the catalog here. Is a 1N4742 suitable as zener? (1 watt, 12v)
Have got some 3886TF's and 318's, and also a bunch of resistors and stuff left over from the first Mauro...
Michael
Russ White said:
Count me in. It would make it easier/quicker if I could get the PS caps and rectfiers along with the boards (will pay of course) I can get 85 degree caps in that size locally, but haven't found 105 degree yet. Rectifiers in 6 amp, but not 8amp in the catalog here. Is a 1N4742 suitable as zener? (1 watt, 12v)
Have got some 3886TF's and 318's, and also a bunch of resistors and stuff left over from the first Mauro...
Michael
Ok so far the beta testers are:
Myself
Brian Donegan
Michael
Craig
smellofpoo
If anyone else wants to be a beta tester let my know in the next 6 hours.
Thx to all who volunteered so far. I will send payment and PCB details as soon as I get a price from the manufacturer.
I will also post my final tweaks here before I order the boards.
Cheers!
Russ
Myself
Brian Donegan
Michael
Craig
smellofpoo
If anyone else wants to be a beta tester let my know in the next 6 hours.
Thx to all who volunteered so far. I will send payment and PCB details as soon as I get a price from the manufacturer.
I will also post my final tweaks here before I order the boards.
Cheers!
Russ