No need. I mount them onto the heatsink :
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-30.html#post1538826
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-30.html#post1538826
Yes Patrick, but you designed a specific board. Not everybody can mount them on the heatsink.
I've got mine from THL Audio, Taiwan. They are available also in Germany AFAIK. Try eBay too.
Metal Plate Cement Resistors
There are diffent kind/size, the most common are: 2W and 5W, standard and "low distortion". Range from 0.1 ohm to 1 ohm E12
MPC70 = 2W std
MPC78 = 2W low distortion
MPC71 = 5W std
MPC74 = 5W low distortion
I cannot attach the complete data sheet. PM if you need it.
I've got mine from THL Audio, Taiwan. They are available also in Germany AFAIK. Try eBay too.
Metal Plate Cement Resistors
There are diffent kind/size, the most common are: 2W and 5W, standard and "low distortion". Range from 0.1 ohm to 1 ohm E12
MPC70 = 2W std
MPC78 = 2W low distortion
MPC71 = 5W std
MPC74 = 5W low distortion
I cannot attach the complete data sheet. PM if you need it.
You can get MPC71 at :
5W Metallband 10% MPC71
Hardly any difference to MPC74 that you can hear.
Patrick
5W Metallband 10% MPC71
Hardly any difference to MPC74 that you can hear.
Patrick
Or maybe this is better?
Ohmite Audio Gold non-magnetic, non-inductive 5W axial
AG5NGR47E 0,47R/5W 2% (VE=1Stück)
AG5NGR47E 0,47R/5W 2% (VE=1Stück)
An externally hosted image should be here but it was not working when we last tested it.
I bought mine from this ebay seller, quite reliable and very communicative.
They're are not listed now though. But you can ask.
Negozio eBay - Albert's Audio Store: AUDIO WIRE CABLES, Electrostatic Speaker, 802.11N WIFI 3G 3.5G
couple noob biasing questions:
1. do I bias one side at a time or do I have to bring up both sides together?
2. I hooked up a 25w lightbulb in series with the mains and it glowed dimly after settling. After bringing up the bias on the right side, the bulb started glowing brighter and brighter. This sounds normal (since its drawing more current), but want to check. I then put a 75W bulb in when the 25W got to "normal" brightness. The 75W was alot brighter. This is normal as well, right?
Am I safe to wire the amp to my power strip without the lightbulb limiter?
thanks,
kevin
1. do I bias one side at a time or do I have to bring up both sides together?
2. I hooked up a 25w lightbulb in series with the mains and it glowed dimly after settling. After bringing up the bias on the right side, the bulb started glowing brighter and brighter. This sounds normal (since its drawing more current), but want to check. I then put a 75W bulb in when the 25W got to "normal" brightness. The 75W was alot brighter. This is normal as well, right?
Am I safe to wire the amp to my power strip without the lightbulb limiter?
thanks,
kevin
Ummmm connected it to the power strip and I got some smoke?! I checked the obvious, there are no shorts, I had proper voltage at the boards with the bulb in series, and my pots were at a minimum. The only things it COULD be are bad capacitors or rectifiers. The only reason I say that is because the PSU is recycled from my previous attempt that had the V- and gnd reversed at one rectifier.
I always start with the bulb with series, and if everything is ok I put the pots again to zero (by measuring the R3 and next R4 across their legs, the voltometer shows zero ohm).
If the fuse blowed after sometime, then you burnt the 0.47R resistor together with some of your mosfets...
Disconnect one channel from the PSU.
Check the pots are at min. measuring almost 0 ohm across R3 and R4.
Short circuit the input.
No speaker wired.
Insert the bulb again.
If OK, the bulb glows while the caps are charging and then stops glowing.
Check and set one channel at a time.
Check the pots are at min. measuring almost 0 ohm across R3 and R4.
Short circuit the input.
No speaker wired.
Insert the bulb again.
If OK, the bulb glows while the caps are charging and then stops glowing.
Check and set one channel at a time.
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