Build This MoFo!

PRR

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> 24V 2.5A MOFO? 50mH?

50mH will support 8 Ohms down to 26Hz. It is plenty big for any system of this power level.

The choke is not a "low pass", it is not choking your highs.

It has capacitance but at 8 Ohms even 1uFd is barely tolerable and even a physically huge choke won't be 2,000p[/u]Fd, 500 times higher. (MOSFET Gate capacitance is more likely than choke capacitance.)

Source impedance driving the Gate should be under a few K Ohms. 4K makes a 20KHz low-pass. Most solid-state preamps are much-much lower than this, though few have the Volts to drive a 24V Mofo to full output. A low-current 6B4 may be a few K Ohms.
 
Hi guys,

I did some test yesterday. Surprise surprise...

I tested it from from 10Hz till 200kHz sine wave and sees NO drop in output - no attenuation even at near 200kHz. 1kHz square wave looked perfect from 2Vpp to 20Vpp.

Still, I did some further listening test and still preferred the 6B4G tube SET - it has more transparency, more forward image, and more air on the high frequencies.

Now I gotta see if the output coupling caps (Nichicon KG Super Through) are to be replaced with something brighter/airier sounding. Any recommendations for e-caps with better highs? Gaborbela mentioned SEWA - can't find it here. I'll try a smaller cap too, perhaps 10,000UF is too much.

The other option i see is to just eliminate the output-coupling altogether - by custom making a 1:1, 2.5A air-gap output transformer. About U$490/pc I checked. Not too bad and I get to eliminate the caps. Only down side is the waiting time. May be long.

Will post some pics when I get them.

Rgds.
 
1khz%2Bsqwave.jpeg


50khz.jpeg


Only 0.2V attenuation at 50kHz!

20khz.jpeg


20Vpp flat from 10Hz to 20kHz.
 
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You should try other types of caps on the output.
To me, this type was far the best with SEWA, I tested several audiophile caps. Need a week or so to burn in and please pull off the plastic from the cap. :violin:
Not much change in my health, at least I attend a therapy group (7 weeks more) where they try their usual treatment. Until now I just took medication for sleep, not to feel dizzy all day, faint or avoid blackout & collapse (maintain the symptoms) In case if I could not sleep for a couple of days I start blackouts, etc. :eek:
 

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MoFo vs VTL ST-80

try listening with switched polarity of speakers , maybe you'll like it more

That's very interesting. Going to try flipping at speaker.

The VTL ST-80 (push-pull) has the ability to extend or reveal the harmonics in say a piano chord. There's better sustain and the harmonics are more apparent. The same goes for reverb. Changes the performance space.

Another nice thing VTL does is magnify the size of instruments and vocals. Depth is nice too, although the MoFo can do depth well.

Aside from these traits, the MoFo and VTL are very much the same, although they are important differences in my opinion.
 
"Sold out"??
Dang. I was really looking forward to my first attempt at an amplifier.
Apparently, I'm not so smart, and already ordered components, not thinking that I should have checked for the BOARD FIRST.
#facepalm
I guess I can spend the next week reading the other 208 pages of comments.
Many thanks to Mr. Rothacher and all those who chime in here to help.

Kind regards,
Drew