A guide to building the Pass F4 amplifier

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#481
Thank you 6L6! If you look at it, it really reflects your example on the guide. I could follow it even if I did not read English, it is so... step by step. It's a good map, and I like to explore.

ZenMod,
you are right, Sit was my admission fee to this world... It's always good to present offerings at the start of the way.
I have tried different speakers with the Sit, currently they are paired to the best I have, a pair of Zu Omen. I also tried them with AL VOTT, it's sweet but too big of a combo to have in the living room.
These two guys, Sit and F4, are getting tubes all right. My next step is increasing the gain of a Grounded Grid Pre to 30dB to see how they like it. For now the F4 sings really sweet paired to the Bottlehead.
I appreciate this forums very much, and you guys... One craves good company on the way.

An externally hosted image should be here but it was not working when we last tested it.
 
#483
mcandmar said:
How usable is the volume pot on the S.E.X, hair trigger or in the middle of the usable range?
Click to expand...

When driving an F4, nothing has a hair trigger - very few preamp can sing the voltage necessary to run an F4 to full output, so you will have plenty of fine tuning.

The S.E.X. is perfect for the F4 - the F4 was designed to be driven by flea-power power amps. Those that have used it as such have reported fantastic results.
 
#484
mcandmar said:
I cant wait to try this too as i recently built an F4 and also own a Bottlehead S.E.X. 🙂

How usable is the volume pot on the S.E.X, hair trigger or in the middle of the usable range?
Click to expand...

Hi,
it depends on the preamp also. I had an Emotiva Stealth DC1 first as a source, the sound was good but thin. Then I switched to a Maverick D1 dac and with it the sound became fuller. With that I turn the know on the Bottlehead to 7 o'clock and it is not too loud but loud anyway. I can listen to it turned to 8 o'clock, but my wife will be complaining. I have turned it up to 4 o'clock and the windows rattle, the sound at this level is astonishing, it is even richer than at lower levels, it sounds clean and clear but I have to turn it down or leave the room because the sound pressure is too high.
The F4 delivers, but we have to match it weel to the rest of the chain.
Enjoy!
 
#486
Same question about availability : i bought some kits that where not assembled by previous owner (2 stereo sets), bought the diyaudio 4U chassis and Universal psu and damn : the amp PCB is not the standard 25 cm Diyaudio PCB but some 32.8 cm version that does NOT fit in the 4u chassis.

Is there an alternate source or some one has one or two sets unused or a gerber file available so that I may have some manufactured as i know shortage on diyaudio store may be long ?
BR
Jean-Louis
 
#491
I see the boards are up for pre-order now. Nifty. I placed my order but for some reason the Quantity of each piece in my order got screwed up and I only noticed after I placed the order. Bloody late night shopping... Still waiting to hear back from the Helpdesk, or is there a better way to contact someone to get my order fixed? Cheers.
 
#492
Excuse the 3 posts in a row... In the BOM on the store page I noticed some differences with the latest PDF found on firstwatt.com (Clicky!)...

I'm betting this has been posted somewhere before but I'm at a loss here.

R10-15 are 150R in the original circuit, but 100R in the diyAudio Store BOM.

R8 was 27.4K originally, but 22.1K in the BOM

R3-R4 was 10R originally, but 22.1R in the BOM.

Also having trouble finding the proper variable resistors... Does anyone have a part number they can share with me? I'd really appreciate it. Still trying to decide where to get the MOSFETs as well as the input JFETs.

Store says end of March is the expected date the boards will be in, I can't wait!
 
#493
#497
Spent about two hours so far trying to find a part found in this picture.

DSCF0098.jpg


I'm looking for the washer(?) that is able to be screwed down to the terminal with the tab on the end which you can solder a wire to, just as 6L6 was doing here... I am completely stumped, and I had Mouser nightmares last night...
 
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