Misc. Regarding F5

[MagnumOpus]

Hello, I am recking my brain these days trying to decide what to build. I have ordered parts for a B1, and I think I'll get a Lighter Note to go with that. Either that or a Lightspeed. Any thoughts on which?

But to the point. I am opting for either a SKA or a chipamp from AudioSector. But these are really just second options. I want the F5, but it's really big. Another thing is the speakers I want to build. The Swans M1, with a 86db sensitivity. Will the F5 be good enough?

But my main question: Could I reduce the size of the F5's enclosure, and use the MF30 or 35 heatsinks from conrad if I use a fan? I have seen some builds using a fan, but I can't seem to find much more about it.

Does anyone have some thoughts on where to get a dead quiet fan, how to power it and incorporate it in the build?

Any thoughts on this are most welcome

[Marra]

Regarding the Lighternote/Lightspeed if you want to cook your own I can certainly recommend the pcb's from dvbprojekt. I built one using these boards powered by a Salas + 5 volt shunt regulator. Pcb again from dvbprojekt with LDR's from udailey although I have yet to try it with my DCB1.

[MagnumOpus]

Originally Posted by Marra

Regarding the Lighternote/Lightspeed if you want to cook your own I can certainly recommend the pcb's from dvbprojekt. I built one using these boards powered by a Salas + 5 volt shunt regulator. Pcb again from dvbprojekt with LDR's from udailey although I have yet to try it with my DCB1.

Yes I have seen the stuff from dvbprojekt. udailey also has psb with parts

[6L6]

Originally Posted by MagnumOpus

But my main question: Could I reduce the size of the F5's enclosure, and use the MF30 or 35 heatsinks from conrad if I use a fan?

A MF35 at 75mm tall will be enough for a single channel F5. Make two monoblocks with the heatsink on the back or the front.

Or, think about an Aleph 30 style case, where the heatsink is on all 4 sides of the box. You could do that with Peter Daniel's boards, whereby you have an output transistor on each face.

I have seen some builds using a fan, but I can't seem to find much more about it. Does anyone have some thoughts on where to get a dead quiet fan, how to power it and incorporate it in the build?

Get a DC fan and run it a few volts lower than it's rating. Slower = quieter. Power it with a simple DC supply that has variable output voltage. The Velleman you are using for your B1 would be great.

[MagnumOpus]

Looks great. But if the MF35 at 75mm height is good for one channel, makes me wonder why everybody is building this into a box twice the size...

So, in conclution..if I get 1 pice of Conrad MF35 @75mm per channel, it's ok?
I reckon that would make it ok with an MF30 aswell, only at 151.5mm then?

That would take it back into the game. I have looked at some Audio Nirvana speakers to go with it, allthough I have allready bought some xover caps for the Swans M1....

[MagnumOpus]

"Heat Sinking
At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the
temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want
a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a
chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will
need two per channel."

Would this mean that even the MF20-75 with 0.55 C/Watt is enough?

If so the box would have to be musch bigger than 200-300mm deep and 300mm wide and 75mm tall...

How much space does the stock components require? From the different pics I have seen, about 350-400mm wide should do then....

So it would be plenty cool enough with a modu 3U cabinet. (size-wize that is, in case I decide to buy instead of making the plans for it myself...

[6L6]

Originally Posted by MagnumOpus

...you will want a heat sink rated at about .6 deg C./watt for each transistor.

I.E., about .3 or so per channel.

The general consensus is that the Modu 3U is a bit small (heatsink, not physical size) and the 4U is enough.

As for the size required for the 'guts' of the f5, the amp circuit adds about 1/2 - 1" (13-26 mm) to the thickness of the heatsink, and the PSU requires a 400va (stereo) transformer, 120,000uf of capacitance, a pair of rectifier blocks and (generally) a barrier strip with 4 or 6 terminals. It could be built very compactly if you wanted to. Monoblocks could make your individual cases/chassis smaller, but you would obviously need two...

[MagnumOpus]

Your assistance is priceless 6L6

So I'll go for the MF35-100 or the MF 30-151.5.

Now I'll just have to find a way to design an enclosure around them...

In either case, the external width would be 400-450mm, and depth according to heatsink. I won't be building mono's this time around.

I think I have the design for the B1 cabinet figured..sort of a Tent Labs look...

[MagnumOpus]

Ok. Trying to source some capacitaors for the psu. Are these ok: VISHAY BC COMPONENTS|MAL205656153E3|CAPACITOR, 15000UF, 25V | Farnell United Kingdom

If not, does anyone have any suggestion? I can get RIFA locally though, but waaay expensive...

What about rectefiers?

[Marra]

I used these from Farnell:- PANASONIC|ECOS1VP333EA|CAPACITOR, 33000UF, 35V | Farnell United Kingdom

VISHAY FORMERLY I.R.|VS-30CPQ150PBF|DIODE, SCHOTTKY, 2X15A, 150V | Farnell United Kingdom

I would definately recommend using 35V caps as with 18V secondaries you will be running very close to +- 25V dc.

I've enjoyed the amps performance with these in the power supply and the more I listen to it the better it seems to get.