It would be a self judged challenge to battle heat, if you actually felt enough subjective gains with 1R VS 2.7R. The question is, did you?
Cheers Andrew & Salas,
I did not really spend any time listening to the 1ohm setting.
It was hot here in the UK yesterday and the amp case got quite hot to the touch. Think I need to get an IR temperature probe
I also have a wood fired pizza over and have planned to get a IR temperature probe, so it will get well used.
Brad
I did not really spend any time listening to the 1ohm setting.
It was hot here in the UK yesterday and the amp case got quite hot to the touch. Think I need to get an IR temperature probe
I also have a wood fired pizza over and have planned to get a IR temperature probe, so it will get well used.
Brad
Brad,
May I ask what is your heatsinking method?
I ask because I would like a reference for my set-up, planning 600mA (3.3ohm) stage.
I’m building a balanced version DCB1, 2 boards in the one chassis, each board sits on it’s own 111mm x 222mm 10mm thick anodised al blocks, the mosfets and diodes will be bolted to these, the blocks with then be bolted to a 453mm x 353mm 3mm thick anodised al panel, I’ll be putting thermal grease in between and ensuring I’ll have good thermal contact. Aiming for 600mA.
Hot Australian summers days can top 40° 😱
May I ask what is your heatsinking method?
I ask because I would like a reference for my set-up, planning 600mA (3.3ohm) stage.
I’m building a balanced version DCB1, 2 boards in the one chassis, each board sits on it’s own 111mm x 222mm 10mm thick anodised al blocks, the mosfets and diodes will be bolted to these, the blocks with then be bolted to a 453mm x 353mm 3mm thick anodised al panel, I’ll be putting thermal grease in between and ensuring I’ll have good thermal contact. Aiming for 600mA.
Hot Australian summers days can top 40° 😱
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Hi John,
I have bolted the MOSFETS directly to my casework - sounds similar to yours - 12mm thick alu on the side and 3mm on the base. I am using silicone TO220 insulating washers which seem to do a pretty good job transferring the heat from the ICs.
I am thinking about dropping back to 5 Ohm current setting resistors as the casework has got pretty hot over the last few days - its been hot here in SE England for a change!
As its easy to change those resistors you can experiment and see how your build works during the hot Australian summer. The ambient temps really do dictate the efficiency of your heatsinking. i thought I was good to go for 1ohm resistors when I first fired up my B1 when the temps were in the 60s, but have had a rethink over the last few days.
I may add some switches that add additional parallel resistances to the 5 ohm resistor, so that I can run the super hot-rod version when I am critically listening, and then switch back for normal day-time entertainment, no point burning rubber when you don't need to, or cannot afford the fuel bills LOL.
Brad
I have bolted the MOSFETS directly to my casework - sounds similar to yours - 12mm thick alu on the side and 3mm on the base. I am using silicone TO220 insulating washers which seem to do a pretty good job transferring the heat from the ICs.
I am thinking about dropping back to 5 Ohm current setting resistors as the casework has got pretty hot over the last few days - its been hot here in SE England for a change!
As its easy to change those resistors you can experiment and see how your build works during the hot Australian summer. The ambient temps really do dictate the efficiency of your heatsinking. i thought I was good to go for 1ohm resistors when I first fired up my B1 when the temps were in the 60s, but have had a rethink over the last few days.
I may add some switches that add additional parallel resistances to the 5 ohm resistor, so that I can run the super hot-rod version when I am critically listening, and then switch back for normal day-time entertainment, no point burning rubber when you don't need to, or cannot afford the fuel bills LOL.
Brad
Brad,
That’s a great help thank you, to clarify, have you bolted the IC’s to the 3mm base or 12mm sides?
BTW your the first person I’ve come across that’s had a stab at 1ohm circa, hat’s off to you sir!
John
That’s a great help thank you, to clarify, have you bolted the IC’s to the 3mm base or 12mm sides?
BTW your the first person I’ve come across that’s had a stab at 1ohm circa, hat’s off to you sir!
John
Man they must run hellish hot! I went as far as 5R but did'nt like the sound it seemed to harden up somehow so went back to 10R. Maybe I did;nt give it long enough. I'll follow your posts with interest; as you say its easy enough to change the resistors.
John,
the negative MOSFETS are bolted to the 3mm thick base plate and the + ones are ob the 12mm side, they seem to heat up to similar temps, although my hand is not a very accurate or scientific way of measuring this.
I thought that everyone tried 1ohm - mine was 0.909 ohms as I had a 10 and 1ohm in parallel. it did get quite hot, but at least I know it could work.
I like my idea of switched "boost"
Brad
the negative MOSFETS are bolted to the 3mm thick base plate and the + ones are ob the 12mm side, they seem to heat up to similar temps, although my hand is not a very accurate or scientific way of measuring this.
I thought that everyone tried 1ohm - mine was 0.909 ohms as I had a 10 and 1ohm in parallel. it did get quite hot, but at least I know it could work.
I like my idea of switched "boost"
Brad
Marra,
once I hit 2.7 ohms and below everything was hot. from what I remember how the case felt at 0.909 ohms, I think that I am now feeling similar temps with 2.7ohms, although the ambient temps are some 10 degrees C hotter - I know that at 5ohms there was a very slight warm feeling around the MOSFET positions.
As Salas mentioned a couple of pages back, your subjective experience with the higher current versions may not even make this worth it, as you may have found.
once I hit 2.7 ohms and below everything was hot. from what I remember how the case felt at 0.909 ohms, I think that I am now feeling similar temps with 2.7ohms, although the ambient temps are some 10 degrees C hotter - I know that at 5ohms there was a very slight warm feeling around the MOSFET positions.
As Salas mentioned a couple of pages back, your subjective experience with the higher current versions may not even make this worth it, as you may have found.
Brad;
Yes I found that at 5R the temperature differance was minimal both on the resistors and mosfets which at the time were fastened to a piece of 10mm alluminium 300mmx135mm; no case. Its now cased up with the fets bolted to the base and the temp is just warm.
Marra
Yes I found that at 5R the temperature differance was minimal both on the resistors and mosfets which at the time were fastened to a piece of 10mm alluminium 300mmx135mm; no case. Its now cased up with the fets bolted to the base and the temp is just warm.
Marra
I am building a second DCB1 and fired it up for the first time and have +9.63 and -9.65 volts after the regs with -2.1mv and -4.5mv. Is the -4.5mv 0k or do I need to swap over the 170's on that channel?
Yeah my first build had around 1mv offset. Because my Aleph 5 clone and F5 build don't have caps on their inputs I will be using capacitors on the output of the DCB1 so will the -4.5mv not really matter?
If you will use output coupling capacitors there's no point, do it only if you plan a DC parallel output also. If you don't have very good matches its 50-50 it will do better by swapping, but it may.
Hi,
I bought a bunch of 3mm red LED. There are well matched ... but all around 2.0V.
Is that a problem (I guess yes) ?
Would you know a source of 1.8Vf LED in France ?
Thanks
I bought a bunch of 3mm red LED. There are well matched ... but all around 2.0V.
Is that a problem (I guess yes) ?
Would you know a source of 1.8Vf LED in France ?
Thanks
Not a real problem, its just I prefer it around +/-10V subjectively. Keep those for the strings of 3, they are beneficial with average VGS of Mosfets in reaching 200mA CCS. Mix a couple of generic red ones which are usually less Vf in the strings of 5. Or use 4 and a 220R instead of a fifth LED. Your targets are about 200mA current per side and about 10V PSUs. The means are relative. Good luck.
I googled and searched through most of the dcb1 posts, but couldn't seem to find a conclusive answer. For the 10r/5w hotrod option, do the mur840 diodes need to have their own heatsinks, assuming i do not bolt them down to chassis?