needlz said:The hum when source is connected has now magically gone (for peace of mind I will pretend the problem never happened) but all 3 sets of inputs hum badly without an input. Is there a trick for killing this hum while the inputs are disconnected? Sorry for the newbiesque questions. I am very close to replacing my gainclone with this amp (the nervous looking little amp in the background of the other photo)... the Rev A sounds amazing. I'll have to wait for another paycheck to fund a Rev C but if it indeed sounds better, I'll have to check it out.
How much are these typ. costing to build.. if it hasnt already been asked.
This is one long mofo of a post.
Look at previos page
They estimate the boards and components to stuff at 100.00. You still need a chassis, power transformer, binding posts, RCA's, IEC connector, switch, and fuse.
This will most likely come out at around 250.00 - 300.00. Unless you use the 7.00 power transformer from Parts Express and already have a power amp chassis to strip and use. Then it should run less than 200.00.
While they still have them, the 48 volt center tapped transformer from Parts Express works great. At 7.00, it saves maybe 60.00 compared to buying a 24 volt dual secondary transformer from Pliton or another source. Some feel an EI transformer is better anyway.
If you plan on ordering a set of boards and parts from Russ and Brian, you might want to get a power transformer now.
George
seahag said:
They estimate the boards and components to stuff at 100.00. You still need a chassis, power transformer, binding posts, RCA's, IEC connector, switch, and fuse.
This will most likely come out at around 250.00 - 300.00. Unless you use the 7.00 power transformer from Parts Express and already have a power amp chassis to strip and use. Then it should run less than 200.00.
While they still have them, the 48 volt center tapped transformer from Parts Express works great. At 7.00, it saves maybe 60.00 compared to buying a 24 volt dual secondary transformer from Pliton or another source. Some feel an EI transformer is better anyway.
If you plan on ordering a set of boards and parts from Russ and Brian, you might want to get a power transformer now.
George
Re: Look at previos page
I can tell you those $7.00 PE buyout trafos work great. They just run a bit warm all the time(even with no load at all, not very effecient) so build a case with plenty of ventilation. My protos are using those trafos (one per channel for true monobloc operation).
My guess is they are somewhere between 125-175VA. The are heavy! But that is just a guess. Definitely beats $40-60 each for two trafos.
BTW the parts kit is a very good deal, Brian is pulling together some very good parts for the price. If you get a kit, you will have a nice amp, just as with the REV A kits which turned out incredibly well.
Cheers!
Russ
Panelhead said:
I can tell you those $7.00 PE buyout trafos work great. They just run a bit warm all the time(even with no load at all, not very effecient) so build a case with plenty of ventilation. My protos are using those trafos (one per channel for true monobloc operation).
My guess is they are somewhere between 125-175VA. The are heavy! But that is just a guess. Definitely beats $40-60 each for two trafos.
BTW the parts kit is a very good deal, Brian is pulling together some very good parts for the price. If you get a kit, you will have a nice amp, just as with the REV A kits which turned out incredibly well.
Cheers!
Russ
Heat from 7.00 transformer
I have only used one of my three so far, but it does not get warm even playing. But playing in my case is close to idling, 1 watt = 100dB, so it runs in the milliwatt range of output normally.
If they are herating up with no load, either the capacitance leakage is huge, or there is an insulation breakdown.
Even after three -four hours of playing, my sealed, shoehorned cast aluminum box holding the trafo is room temp. The box holding the Rev A is a different thing. It is about 120 -130F all over.
George
I have only used one of my three so far, but it does not get warm even playing. But playing in my case is close to idling, 1 watt = 100dB, so it runs in the milliwatt range of output normally.
If they are herating up with no load, either the capacitance leakage is huge, or there is an insulation breakdown.
Even after three -four hours of playing, my sealed, shoehorned cast aluminum box holding the trafo is room temp. The box holding the Rev A is a different thing. It is about 120 -130F all over.
George
Re: Heat from 7.00 transformer
Hmmm.. interesting. Well I have 8 of them, and I have tested them all on the bench. They all get warm, but it does not happen quickly, it takes couple of hours at least. they all draw the same idle current too. About 300ma. Which is a lot for a trafo. But like I said, its warm, not hot. They are pefectly fine. A metal case probably helps to sink the heat. What should I expect for $7.00? All in all I am happy with them. As long as they last a few years without burning up.
Cheers!
Russ
Panelhead said:
Hmmm.. interesting. Well I have 8 of them, and I have tested them all on the bench. They all get warm, but it does not happen quickly, it takes couple of hours at least. they all draw the same idle current too. About 300ma. Which is a lot for a trafo.
But like I said, its warm, not hot. They are pefectly fine. A metal case probably helps to sink the heat. What should I expect for $7.00? All in all I am happy with them. As long as they last a few years without burning up. Cheers!
Russ
Well I guess a good thing like that can't last forever. 
seahag said:
Well, for monobloc I would use 2 x ~200VA 24V dual secondary trafos or 2 x ~200Va 48VCT trafos.
For stereo(shared trafo between two channels) I would use use 1 x ~300-400 VA 24V dual secondary or 1 x ~300-400VA 48VCT trafo.
You can get a really good dual 24V torroid from Avel for about $50. Get it from them directly, its cheaper.
Cheers!
Russ
Beta Update
OK, the Elnas fit fine today. I couldn't have been the German beer last night.
Pads on R19 and R20 are a bit close. Had to fix a solder bridge. Other than that, all parts are mounted and soldered except the 3886. Will hopefully power up tomorrow.
Russ, you were right about those clips being tight.
Craig
OK, the Elnas fit fine today. I couldn't have been the German beer last night.
Pads on R19 and R20 are a bit close. Had to fix a solder bridge. Other than that, all parts are mounted and soldered except the 3886. Will hopefully power up tomorrow.
Russ, you were right about those clips being tight.
Craig
Checked 7.00 trafo
Russ,
I should not not doubted your observation about the transformers. After playing for three hours I opened up the case and checked. The transformer was fairly warm, 125 degrees or so.
Guess the box needs ventilation holes like the box that holds the amp. I did not check the current draw, but if they pull 300 ma with the secoundaries open these are only worth 7.00. I know you will get some current flow, but 40 watts is a bunch. That is all heat.
Mine never gets pushed, but if you run one hard, the single 7.00 trafo may not be up to the job. I felt as big and heavy as they are that they could do it easily. Wrong again.
George
Russ,
I should not not doubted your observation about the transformers. After playing for three hours I opened up the case and checked. The transformer was fairly warm, 125 degrees or so.
Guess the box needs ventilation holes like the box that holds the amp. I did not check the current draw, but if they pull 300 ma with the secoundaries open these are only worth 7.00. I know you will get some current flow, but 40 watts is a bunch. That is all heat.
Mine never gets pushed, but if you run one hard, the single 7.00 trafo may not be up to the job. I felt as big and heavy as they are that they could do it easily. Wrong again.
George
Re: Checked 7.00 trafo
Hi George,
All is forgiven.
I have come to the conclusion that I would not use those trafos in my main system, but I have them in my garage amp, and in my test boxes, as I do not ever leave those on all the time. But I don't think they are too bad. I am going to run a pair on my PC amp for a while and see how they hold up.
Cheers!
Russ
Hi George,
All is forgiven.
I have come to the conclusion that I would not use those trafos in my main system, but I have them in my garage amp, and in my test boxes, as I do not ever leave those on all the time.
But I don't think they are too bad. I am going to run a pair on my PC amp for a while and see how they hold up. Cheers!
Russ
I will add my 2.5 cents worth on the transformers. I agree with Russ. Great for testing and checkout. Will use one one each mono for the the betas, but the final amp I built uses an Avel toroid. Just less heat.
Only problem with soldering with beer is remember where to put each one. Haven't burned my lips yet and beer is not a good flux remover.
C
Only problem with soldering with beer is remember where to put each one. Haven't burned my lips yet and beer is not a good flux remover.
C
5 channel amp layout
Hi.
I'm beginning to think about my 5 channel power amp layout, and need some feedback.
What I'm thinking is to have a pair of Mauro monoblocks each with their own toroid for the front stereo channels, and 3 Mauros as surround channels fed from a single toroid.
This should give the best of both worlds if I do it right. I'm thinking of having 2 powerswitches - 1 for the stereo amp, and one for surround, so that I can eliminate current draw and heat from the surround amps when listening to 2 channel material.
Layout attached, feedback welcome...
Hi.
I'm beginning to think about my 5 channel power amp layout, and need some feedback.
What I'm thinking is to have a pair of Mauro monoblocks each with their own toroid for the front stereo channels, and 3 Mauros as surround channels fed from a single toroid.
This should give the best of both worlds if I do it right. I'm thinking of having 2 powerswitches - 1 for the stereo amp, and one for surround, so that I can eliminate current draw and heat from the surround amps when listening to 2 channel material.
Layout attached, feedback welcome...
Attachments
Just to be controversial, I would question whether you really need the metal between the transformers and the PC boards. I have my toroid on the Ref_A about a half inch (~10mm) from the edge of the board and the amp is still dead quiet. I like that the layout that uses the capacitors as a shield between the power section and the signal section and it seems to be quite effective. And I won't even start on my leanings towards symmetry that would put the center channel amp in the center. Only opinions, so no offense intended.
hayenc,
No offense taken
I'm sure the layout will get pushed around quite a bit, it's probably a couple of months away. I could run the toroids down the centre of the case, and I had drawn that at one stage, maybe that's a better idea, it would certainly make it more balanced to pick up and carry. Of course your symmetry instinct is important, it should sound and look good. I'll keep tinkering with the layout, I need to do it to scale.
Michael
No offense taken
I'm sure the layout will get pushed around quite a bit, it's probably a couple of months away. I could run the toroids down the centre of the case, and I had drawn that at one stage, maybe that's a better idea, it would certainly make it more balanced to pick up and carry. Of course your symmetry instinct is important, it should sound and look good. I'll keep tinkering with the layout, I need to do it to scale.
Michael
bg40403 said:
We also have the option of orienting the boards vertically rather than horizontally as is typical....or anything in between....
Barredboss will cut heatsinks to your specified lengths. This will promote a taller case if you wish.
Interesting, I hadn't considered that. So, if I were to pinch the spacing down to 60mm per board (I think the 10,000uf elcaps are the highest component at 50mm), I could fit 5 channels in 300mm... Boards down one side, trafo's down the other. Would probably need a ventilated case to go that dense unless the revC doesn't heat those resistors like the revA...
Would packing them in like that impact the sound at all?
Michael
Hi Michael,
What difference is ? you speak of the 2W res. in place of 1W (more warm) ?
I suggestion to use always chassis with ventilation holes (on 2 sides, top and bottom), to have a good air exchange. The heat goes always toward on top, and everything that is over to the heat sources ( power res, LM3886, zener ) suffers the heating.
The components the more sensible to the heat is the ELcap...
Ciao
Mauro