F5 power amplifier

[Zen Mod]

every output xistor must have own gate and source resistor

feel free to do anything you like with feedback net ...... at least as long you know what are you doing , and you don't have oscillations in amp .

'scope is your friend here .....

[alazira]

Hi,
I was wondering what scopes/distortion analyzers people here use to find the sweetspot. I don't have any experience with these devices so I don't know what features to look for. Some of the USB devices I've seen on eBay look interesting like the following:
New PC-USB DSO-2090 USB PC-Based Digital Oscilloscope - eBay (item 110459178938 end time Dec-18-09 05:34:45 PST)
VT 100MHz PC USB Oscilloscope, Spectrum Analyzer, Meter - eBay (item 110458713563 end time Nov-26-09 23:40:54 PST)
Any advice or recommendations appreciated.
Thanks

[alazira]

Originally Posted by Zen Mod

every output xistor must have own gate and source resistor

feel free to do anything you like with feedback net ...... at least as long you know what are you doing , and you don't have oscillations in amp .

'scope is your friend here .....

Thanks ZM,
If I try the lateral pair I'll be sure each has their own resistors.

[tinitus]

I hope its ok

[Tea-Bag]

alazira, you going for less gain with the feedback resistors?

[ichiban]

One channel of the Hitachi/F5 has been up and running since this afternoon.
Circuit same as F5 only with 2sk134 & 2sj49.
Biased up very easily to 1.24amps and >1mv offset which has not varied over a four hour period.

Taking this short break before heading back to wire in the +-G to the second channel.

Playing a Philips CD80 single crown dac w/ mod'd op amp outputs. BUF03 for the output buffer, I think the I/V is done with an AD797 if I recall. Running directly into the F5/H as the CD80 has variable outputs. Playing thru an old Maggie II.

I've got the mosfets on the paddle-wheel heatsink from the Old Colony Borbely B60 kit. I'm surprised it's running as cool as it is!

If this sounds good and behaves I'll switch the outputs over to the DC100's
which has three pair 2sj56/2sk176 per channel.

[tinitus]

btw, its easy to do a thermal heatsink "coupling" of Jfets

[gaborbela]

To those guys who want to use laterals instead the orig designed vertical I would think about to use lateral mosfet from Class D .
ACD101NDD Lateral Mosfets - Class-D Design Ltd.
These are nice 24A lateral .About the sound of these device I didn't heard them yet .
I have 8 pair at home , I did match them and thy are pretty close to each-other .
One think to be clear I do no want to advertise these mosfet , I do not get nothing for them .
I just put them up probably many people doesn't know these laterals .
May be I will test them in a regular (not X-ed) multiple power power mosfet version amplifier .
Yesterday I did modified my layout so I can use laterals to in case that would be better sound wise than my Toshiba devices .
Probably not , at last hard to believe it .
But who knows .
I think is better device than the 7A Renesans . You can read about the quality Renesans in the ESP site if you look up the project 101.
I built amplifier with the newly produced (by Renesans) mosfet I wasn't happy at all especially when I com paired them with the similar Exicon or with the orig Hitachi device .
Please do not ask me what was the differences . I woud not comment due to those people who already own some Rensans laterals .
Still can be better or much better than the IR device .
So I went to a local store in Toronto and I bought some (10 pair ,all what they had in the store ) orig Hitachi laterals . It was pricey butt hard to find orig Hitachi mosfet.

Greets

[EUVL]

> btw, its easy to do a thermal heatsink "coupling" of Jfets

For the balanced version at least, I have a better (looking) solution.


Patrick

[BrianGT]

That is a pretty cool looking heatsink for the Jfets. Any idea of where to get a few of those?

--
Brian