F5 power amplifier

[tinitus]

Just got a price on the Fisher SK157 heatsink
Absolutely horrendous

[AndrewT]

ClassA is expensive.
That expense is due to PSU and heatsink.
The amplifier, the chassis and the hardware cost much the same.

[Russellc]

Originally Posted by Beftus

Measure resistance between the right and left leg (ignore middle leg) with a DMM. See how resistance changes when you rotate the screw.

Thanks, I didnt know if it would measure properly in circuit. I'll try it as soon as I get home.

Russellc

[cviller]

Originally Posted by Russellc

Thanks, I didnt know if it would measure properly in circuit. I'll try it as soon as I get home.

Russellc

If your board is already mounted, you can measure across R3 and R4 instead - their legs are tied to P1 and P2 respectively.

[tinitus]

Originally Posted by AndrewT

ClassA is expensive.

Hmm, its was more my ambitions
I have asked fore their best, and wanted 4 of them
Price of those is not far from a pair of italian Modu enclosures

[CBRworm]

Originally Posted by tinitus

Hmm, its was more my ambitions
I have asked fore their best, and wanted 4 of them
Price of those is not far from a pair of italian Modu enclosures

I worked my way down to E-bay (barred boss) heatsinks. Spending hundreds of dollars on heatsinks just does not seem appropriate for something that will inevitably end up sitting in my closet once it is perfected. My advice (which could be wrong) is that if you are going to spend a ton on heatsinks, go overboard and get enough heatsink so that in the future if you want to add more devices and/or more bias; you won't run into a wall. I am also thinking ahead to maybe X-ing 4 F5's into a stereo set - needs lots of cooling ability.

I bought all my components seperately - I think next time I may buy a premade chassis with full length heatsinks included. I saw a chassis I liked that even had an IEC connector and holes for speaker binding posts and RCA's, but it was going to be an additional $200 for shipping which made the total just too much.

[massimo]

Originally Posted by tinitus

Hmm, its was more my ambitions
I have asked fore their best, and wanted 4 of them
Price of those is not far from a pair of italian Modu enclosures

BTW, two days ago I went to the hifi2000/modu factory to collect some enclosures and I discovered that they are going to introduce a new "all aluminum" version of their Pesante Dissipante model.
Now you can ask for top, bottom and rear panels made out of 3mm thick aluminum, brushed and black anodized.
I've been told the enclosures will be aprox. 30 € more expensive, but they now look really gorgeous.

[tinitus]

Originally Posted by massimo

they are going to introduce a new "all aluminum" version of their Pesante Dissipante model.

THAT is really very good news

If they would offer more width options too it would be perfect

Anyway, Im probly just being stupid
I have TWO heatsinks, each measure 300 wide and 400 long(high), with thick base
They should give plenty cooling, tho I dont know excact cooling specs
I still regret having cut 100mm off each of them

QUESTION?
If I cut each of them in half, so that I have 4x 300x200
That way I can have 2 heatsinks pr mono
Would that give more effective cooling, over using ONE sink twice as big pr mono
I know this is more of a luxury problem, and may sound pretty daft

btw, only reason I was looking at Fissher SK157 is that it has long 80mm finning, and very effective
But I certainly wont pay 600 EUR to 1meter raw heatsink
US heatsinks on Ebay? Its heavy and shipping is a problem

dammit, I had promissed myself I would lay off this kind of hysteria

[jacco vermeulen]

take a wild guess =>

[Blues]

Originally Posted by alazira

Hi,

Looking at the picture of Cviller's board for P2 I can see that if you use the 3266W (offset legs) ...

On Peter Daniel's board he has a little symbol on the board ...

When I design a pcb layout that mounts on the heatsink vertically (ie parallel to the heatsink flat back), I make it a point to orient the pads to mount a trimmer that has its adjustment screw facing and close to the top of the amp case. Bourns has a type with this screw. Much easier to adjust when the case is all built up. Think of servicing accessability and ease in the future. Also connect pins such that CW is less resistance and CCW more...much like adjusting a volume control.