F5 power amplifier

[EUVL]

I have recently measured 500x 2SK170BL and 500x 2SK74BL.
None of these 1000 FETs were outside the range of 6-12mA.

Just for your reference.

http://www.diyaudio.com/forums/showthread.php?postid=1730586#post1730586


Patrick

 

[sheim]

JL Audio 300/2

I have a need to know some componet locations for this Amp. Please Help

Steve

 

[increek22]

Hum on F5

Just finished my F5 DIY clone and it sounds fantastic. Small problem though as I hear a low level 60hz hum when both right and left audio cables are plugged in. no hum if only one side plugged in, either side.

The power supply is built to the schematic on PassDIY/Firstwatt site (F5 OM manual), and I am using a CViller cap board (very nice board by the way), and my own one-sided amp pc boards (artwork posted on earlier thread).

I tried multiple combinations of preamps, battery operated diskman, different cables, etc. but can't seem to lose the hum when both right and left input cables are attached.

Has anyone had a similar problem or could suggest where to look to get rid of this hum? Thanks, Joe

 

[woodturner-fran]

Most likely its grounding..... time to go look over all that again I would say.



Fran

EDIT: Some pics might help a bit here...

 

[elecres]

power supply capacitor recommendations

Hello ,I am looking for recommendations on power supply capacitor brand and sources 22,000 uf for aleph 3 and 15,000 uf for F5 and also transformer recommendations [anteks any good?]or stick with piltron?.thanks for any input,peter

 

[dcbingaman]

F5 PSU Filter Caps

The cogniscenti are gaa-gaa over Blackgates, (see Micheal Percy's site), but they are VERY expensive.....Panasonic TSHA series caps are available for Digi-Key for ~1/4 the price, work quite well, and are good enough for Mr. Pass.

 

[slr 5000]

hi all
a quik suggestion for all you guys needing powersupplys for your pass amps

i just use either the aussie amplifiers or greg ball ska kits for all my amp projects which are pre built and can be fitted with up to 60,000 mf per rail ,these work great and best of all come assembled so you just plug them in

with the aussie dollar the way it is at the moment over seas buyers will get a great price

regards sheafer

 

[khundude]

heatsink question

I have found a few heatsinks in this profile from Aavid.

http://www.aavidthermalloy.com/cgi-...M&CType=Natural&ExLength=6.000&LengthUnits=in

If I were to use two, one for each board, would they dissipate enough heat for a F5 with 20C ambient room temp? As far as I can tell, it should give me around 50C heatsink temp.

 

[JimT]

An F5 dissipates 180 Watts, 90 per side. You would need 2 of these per board. You would have to be careful to make sure that the fins are outside of the amp or they will not be effective.

Jim

 

[Zen Mod]

An F5 dissipates 180 Watts, 90 per side. You would need 2 of these per board. You would have to be careful to make sure that the fins are outside of the amp or they will not be effective.

Jim

more like 65W per side , if stock bias

 

[JimT]

I think thats just the mosfets and the rest of the parts produce an additional 25 watts for each side. He should consider that extra heat when working out his heatsink requirements. They will have to help dissipate some of that heat and the heatsinks will not work with perfect efficiency as one side will be in the hot box. Perhaps he could get away with 2 of those heatsinks and a fan for the inside.

Jim

 

[juluska]

Re: Hum on F5

Just finished my F5 DIY clone and it sounds fantastic. Small problem though as I hear a low level 60hz hum when both right and left audio cables are plugged in. no hum if only one side plugged in, either side.

The power supply is built to the schematic on PassDIY/Firstwatt site (F5 OM manual), and I am using a CViller cap board (very nice board by the way), and my own one-sided amp pc boards (artwork posted on earlier thread).

I tried multiple combinations of preamps, battery operated diskman, different cables, etc. but can't seem to lose the hum when both right and left input cables are attached.

Has anyone had a similar problem or could suggest where to look to get rid of this hum? Thanks, Joe

Is the loudspeakers ground connected to star ground in the power supply board? is the input cable shielded? Can you post photos?

 

[bobodioulasso]

This hum is typical from a ground loop. Mr leach explains this very well.
Google "the leach amp".

 

[bubba177]

i have 2 F5's ---one with plitron transformer and 15,000uf xicon caps---second with antek transformer and 22,000 uf panasonic caps, ever thing else equal....second is marginally better

 

[labjr]

i have 2 F5's ---one with plitron transformer and 15,000uf xicon caps---second with antek transformer and 22,000 uf panasonic caps, ever thing else equal....second is marginally better

Interesting. I wonder what makes the difference? The Panasonic caps, the extra capacitance or the transformer itself?

 

[AndrewT]

Re: heatsink question

would they dissipate enough heat for a F5 with 20C ambient room temp? As far as I can tell, it should give me around 50C heatsink temp.

make sure you fit a latching temperature sensor that cuts the mains supply if it runs hotter in the warmer weather.
A 70degC switch located near one of the devices would probably do.

 

[AndrewT]

i have 2 F5's ---one with plitron transformer and 15,000uf xicon caps---second with antek transformer and 22,000 uf panasonic caps

Hi,
an F5 running on just 15mF or 22mF seems very light.
How many caps are on each channel?

 

[bubba177]

andrew sorry for the brief answer-both have 8 caps in the PS one has 15,000uf caps and the other 22,000uf caps ---60,000uf and 88,000uf per rail respectively

 

[labjr]

andrew sorry for the brief answer-both have 8 caps in the PS one has 15,000uf caps and the other 22,000uf caps ---60,000uf and 88,000uf per rail respectively

I suspect a difference in sound would be from the quality of the caps.

 

[bubba177]

that would be my thought- but this shows that the antek is a good transformer and for the money a good value