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
Go back with your settings untill the bulb slight glows.
Take out the bulb and start again your settings..
Take out the bulb and start again your settings..
I got it to dim lightly by setting the pots to a minimum, so I can now plug it into the power strip, and then adjust bias?
Can I adjust one side at a time, or do I have to go back and forth between channels?
Can I adjust one side at a time, or do I have to go back and forth between channels?
Last edited:
It is ok too.
The bulb allows to check there is no big issue at first powering on but must be out when setting.
The bulb allows to check there is no big issue at first powering on but must be out when setting.
Last edited:
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...
pots read 0.3R, the fuse is fine, and my 0.47R resistor reads 0.5R. not sure why my other resistors are all now out of wack though...
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.
Last edited: