F5 power amplifier

[Babowana]

Bob Dylan has been long staying with me . . .
From "A Hard Rain's A-gonna Fall"

Not through flying-fighters . . .

"Together Through Life" flowing through B1/F5,
melting into my mind . . . Hmm . . .

Nice music . . .
Long live, Zimmerman . . .
And, more please . . .

[Melon Head]

If I buy a new cd player I am thinking of buying a SACD player. My choice is between spending as little as possible on something that has potential for modding or just spending a couple of grand and get something decent out of the box.

So I have narrowed it down to:
Sony SCD-CE595 SACD/CD Changer - cheap but good
Marantz SA-11S2 - I am really not sure I can afford this but it is ready to go out of the box.

If I buy second hand then it could be something like:
Arcam Alpha that can be modded.
or other (eg Philips CD630)

It doesn't surprise me that you like the Philips CD630. I checked out the specs, it looks like it has the TDA1541 DA converter in it which quite a few peope like.

If anyone can give me a few more suggestions that would be appreciated.

[Babowana]

I have Marantz SA-14 SACD/CD player, quite expensive.
But, I don't have any SACD . . .
The life of the pick-up was very short.
I had to buy a new pick-up, heck . . . sky expensive.

I have also a cheap CD player as a transport . . .
And, a cheap DAC, class-A descrete output . . .
Now I use these. Total price was much cheaper
than Marantz SA-14.
Nevertheless, Sonic quality puts Marantz aside . . .

Hope you will choose good value . . .

[woodturner-fran]

You could look at the shigaclone thread......

Fran

[Melon Head]

What about this: http://us.hifidiy.net/Article.asp?articleid=207

Has anyone bought one of these?
What do you think?

I am also potentially interested in buying or building a hard drive player.

[tinitus]

I want to read about building Pass F5, not CD drives

Besides, why not just buy a cheap DVD with hard disc drive, ups

[Melon Head]

Ok, Thanks and Sorry to everyone.
I didn't want to start a new thread, because my question specifically relates to the the F5 amp.
A few people have not been entirely happy with the sound of their F5. So rather than mess around with the amp I thought it made more sense to look at the source.

[tinitus]

Sure
On firstwatt site about F5 I believe it says that what comes in comes out, sort of
It may sound like its exstremely sensible to any changes

Why not make a dedicated thread about how people do it, I mean about complete setup

[jackinnj]

Originally posted by tinitus
Sure
On firstwatt site about F5 I believe it says that what comes in comes out, sort of
It may sound like its exstremely sensible to any changes

Why not make a dedicated thread about how people do it, I mean about complete setup

Setup is very easy --- probably easier than any amp you want to build. Even just getting the bias correct yields a good (great) sounding amp with remarkably low THD.

If you want to get more complicated, the source resistors on the JFETs and (according to NP) the 0.47 resistors can be tweaked to just about null out any distortion. But you need a good distortion analyzer, a very good signal generator, and a spectrum analyzer (or good sound card analyzer) to look at the distortion artifacts.

I've twiddled with other components and looked at the results -- probably out of some obsessiveness --but as I've said, out of the box this is a wonderful amp. If you just get the bias correct you're going to have a killer amplifier.

[steveleen]

Thanks for the previous posts on measuring heatsink and device temperatures.

I have decided to add fans to my F5 to just slightly reduce the heat levels. I have two Papst 3414 NGL fans (EC, 24vdc, 1.5W), one for each channel. I want to keep this simple: no heat-sensing auto-on/off circuits; no separate power supply for the fans. I want to be able to turn them on or off using a switch on the back of the amp case.

I have constructed the F5 power supply exactly as specified in Nelson’s F5 user manual. My first tests used the 24v + and – rails directly and the fans ran too fast and loud. Inserting a 680 ohm resistor in series slows things down nicely and they are very quiet. When the amp is turned on, the fans twitch a bit, then start turning. The heatsink touch test after one hour gives me a good 5 to 10 seconds.

My concern is how to best wire the fans to the power supply for lowest electrical interference into the F5 signal stages. So far I am thinking:
- attach the fans negative leads directly to star ground
- tap into the DC on the power supply board, directly off the V+ and V- that the F5 circuits are using, or should I tap into the supply further back, or even directly off of the diode packages?
- attaching small caps across the fan leads (47uF – 220uF), or do I really need these given the filtering on the power supply itself?
- ensuring that the fan wires are separated from any signal wires

Any advice would be appreciated.

Steve