F5 power amplifier

[Zen Mod]

first try Quad's original

then play with it

 

[bobodioulasso]

I have been playing with the quad circuit in an single ended F5. It worked fine.
Though, through this forum, i found this:
http://www.diyaudio.com/forums/power-supplies/174791-virtual-ground-power-amp-applications-4.html

 

[mrivera982]

So I am new, This is my first Post, My knowledge level is painfully low compared to the rest here.... I am amazed as for how many pages I was able to read without having my wife thinkin I as upto no good here!!! Wow 909 pages! I will be learning from you guys as much as I can and ... would love to build and amplifier as my very first project.

wish me luck and I am happy to have such knowledable company.

See you soon guys.

Marvin

 

[fustyfish]

Hello,

I am hoping to build the Toshiba 2SJ201 / 2SK1530 (Non-balanced) version of the F5, using the 2SK170 / 2SJ47 input FET’s which are BL type (I have a few pairs I need to use). Would this circuit, with these values work? Or will I have to buy GR or V type JFET’s?

Hope you can help

(Circuit taken from earlier post)

 

[Chad]

Marvin,

Your wife just hasn't figure out that your reading and looking at audio porn.

Chad

 

[Zen Mod]

Hello,

I am hoping to build the Toshiba 2SJ201 / 2SK1530 (Non-balanced) .......

(Circuit taken from earlier post)

BL's are fine , and exactly what majority use

circuit is probably fine , too

 

[flg]

I plan on puting together a Tosh output version also 2 parallel pairs in the output though. Have you seen Euvl's/Tino's values for the F5 Toshiba Balanced version. Diferent MOSFET Rs values and Different JFET Rs values?

 

[fustyfish]

Thank you Zen for your advice, I’ll build it and see how it sounds.

I’ve seen Euvl's balanced version, but I believe he’s running at a different voltage. I’d love to be more ambitious like some of the other guys and build a Tosh balanced version, looks awesome, but I don’t have the gear to match MOSFET’s or a distortion analyser. This truly is a cave man attempt at building an F5, with my trusty MM in one hand and a club in the other, I am sure that how we all started . .

 

[labjr]

Seems to me it would be easier to use headers with screw terminals on Cviller's PSU boards to prevent breaking wires while installing the boards. Is there any disadvantage doing this?

 

[Zen Mod]

probably just matter of preference

I'm not braking my wires while installing the boards - maybe because I'm always using fine speaker cable , with isolation ends conditioned with heatshrinks .

that's overkill , but I like it that way

 

[Bksabath]

Quote:
From Papa this tread page 48/49
There will be a short piece on tweaking F5's, and then the next major
article is about buffers.

I have found this comment By Nelson Pass and I am looking at this tread but just got to page 160 any kindered spirit willing to tel me where to look preaty please

Tanks

 

[Zen Mod]

it's pretty useless to mark place in thread as # of page , just because everyone can use different number of posts on page , or is it simply dependable of browser used .
it's convenient to left-click on No. of post and copy link of it . that's right upper angle of each post


considering Papa's buffers - dunno .......

 

[udailey]

B1?

 

[Melon Head]

There will be a short piece on tweaking F5's, and then the next major
article is about buffers.

Is this the quote you are referring to?

Gee you guys are task masters. Doesn't Nelson do enough. If you read all of Nelson's comments in this thread and actually apply the ideas you will find Nelson has given us quite a bit of information.
Sorry Nelson.

On the other hand, it would be nice to see an article about it.

 

[bobodioulasso]

it's convenient to left-click on No. of post and copy link of it

Or right click?

 

[Zen Mod]

Or right click?

 

[andRookie]

Too high Vac

I have almost everything I need for an F5 amp now. Boards + parts, heatsinks, casing, connectors, caps and a nice pair of filterchokes.

My problem is that the trafo has 2 x 25Vac (off-load) secondaries. I tried to figure out if a choke - input filter is a possibility, a that might be a solution. I wired the psu - parts up as a choke input filter and used light bulbs as a load. Drawing 2,8A I got 40Vdc (secondaries i series) and that is a bit low I guess. NP says 23-24V in the F5 article.

Could winding down my trafo and make a CLC filter be a solution? It is the one in the picture and it is potted with something in a plastic bucket, so winding it down seems a bit troublesome. Is it possible to heat the thing up and get the potting substance of?

 

[Zen Mod]

nope

make cap multiplier in both legs

it will shave ~ 4Vdc

 

[andRookie]

nope

make cap multiplier in both legs

it will shave ~ 4Vdc

Tried reading up just quick. Could it be something like this:

What voltage would come out?

 

[Zen Mod]

nope - use mosfet instead of bjt ;
as I said - you'll loose 4V