F4 power amplifier

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#1,582
with all my respect to Mr. Broskie for all his work ,sharing and ingeniosity - I can't see how double Aikido ( and you need stereo one , or double for balanced channel) can be better than Sy's dreky preamp ....... intentionally made for F4 ;

as I wrote to :captain: in PM , I personally tend more to either brutally simpler , or brutally more complex designs than Aikido .

basic virtue ( and that virtue isn't in any case for underestimation ) of Aikido is versatility - use your fave ( or only kind you have ) tube and build gin block with it .

it's certainly honest preamp in most iterations but - for best results I think that amount of compromises implemented primary because of versatility is more than nuisance .

skygood stage must be good in every aspect , and that can be more than big snack for ordinary DiyA fellow , not just to construct , but even just to build .

I have no doubts that Mr. Broskie is more than capable to make (not just ) one ......... but - it's certain that that sort of quality have much less possible buyers than Aikido does .

conclusion - make humpty dumpty WOT preamp , maybe even with WE tricks , or made sort of humpty dumpty LTP stage with medium mu/low Rp triodes , possibly loaded with CCS-es ......... with already inherent balancing........ and even Wright - like SLCF stages on outputs.......or use Aikidos as base and tweak it to something completely different .........

and call that preamp simple - Larch ..........

:rofl:
 
#1,583
Does anyone have any potential comments about break in with an F4. I fired mine up last night and got everything to behave as far as bias and offset is concerned and then wired them into my mains.😎 This amp seems to do some things incredibly well, but it has a thickness in the lower mids that just isn't quite right. Some tones in the lower male voice range seem to jump out where they never did before, and they seem to be a bit sluggish. I used Black Gate caps and have heard they take forever (100+ hours) to break in. Might that do what I am hearing? I am using a J-BOZ pre that sounds great driving my gainclone.

Hmmmm... I was just wondering if anyone else had a similar experience.


P.S. I did end up sitting and listening to about 12:30. I couldn't break away. It may have the one range that isn't perfect, but I was hearing things I could not hear with other gear. And effortless...Very nice. I will post some pictures when it is a little more presentable. It is a real Frankenstein right now.
 
#1,585
DaveM said:
Does anyone have any potential comments about break in with an F4. I fired mine up last night and got everything to behave as far as bias and offset is concerned and then wired them into my mains.😎 This amp seems to do some things incredibly well, but it has a thickness in the lower mids that just isn't quite right. Some tones in the lower male voice range seem to jump out where they never did before, and they seem to be a bit sluggish. I used Black Gate caps and have heard they take forever (100+ hours) to break in. Might that do what I am hearing? I am using a J-BOZ pre that sounds great driving my gainclone.

Hmmmm... I was just wondering if anyone else had a similar experience.


P.S. I did end up sitting and listening to about 12:30. I couldn't break away. It may have the one range that isn't perfect, but I was hearing things I could not hear with other gear. And effortless...Very nice. I will post some pictures when it is a little more presentable. It is a real Frankenstein right now.
Click to expand...

Pictures yessss gimme more !
About the sound, what source are you playing with ? and what kind of speakers have you tide up to your F4 ?
 
#1,586
Dave,
Relax and just leave it running for about 2 weeks and it'll come good - the BG's are worth the trouble. Is so transparent that you may want to revisit your Preamp for adjustment,changeout some components, etc and then you'll be doing the same with your speakers, room position, etc.
 
#1,589
Maybe the only recommendation I can make is...leave it for a few weeks and see. Mine changed.

Choky is right about personal preference. Also, I am saddled with a small room at the moment(4mx4m) and The F2 may have more dynamic at low volume levels. I do know that when I turn the F4 volume up it does sing with more authority...but I fear the wrath of the neighbours......

as an aside, I have discovered that my Squeezebox has a pre-amp capability whereby I can change the gain of the output. So far I have been running at 0db(line level) but I may set it to max and try the F4 with my electrostats....just in the interest of science you understand.
 
#1,590
Well, I fired the amp up when I got home last night and played a few cds through while I was having dinner and putting my daughter to bed. Then I went into my "man cave" - my wifes name for my basement listening room - and did a bit of serious listening.

WOW! :bigeyes: This thing is amazing. The thickness and bloom that I asked about yesterday is gone. Completely gone. What is left is magic. It's funny - I have a NAD silver line integrated amp. It was $2700 new and was considered a giant killer. The amp is very, very well built - 3 torriodal transformers, dual mono, balanced circuit etc. Well I swapped that out for a J-BOZ and a gainclone several months ago and found that the new DIY setup was more involving. When I did a back to back, there was no night and day difference other than a slight bit of increased resolution that made the DIY gear more interesting to listen to. So, last night I sat and played my standard audio-fool evaluation recordings. I was able to tell the size and type of room the recording was done in. I felt like I could reach out and touch the walls of the room. If there was a mouse farting in the recording studio, I think I would have heard it. It's as close I've heard to live music at home as I have ever heard. This thing is worlds better than anything I have heard before. I'm sorry if I am gushing and spilling the beans, but this is my first Pass amp and I love it. To think that it is going to get better as the Black Gates break in is inconceivable. I guess I wont cry if it gets better though.😉


The system as it sits now is NAD S-500 silver line CD player, Tara labs RSC Prime interconnects, J-BOZ, F-4, Tara Labs Prime 1800 speaker wire and DIY MTM speakers with PHL 1240's and a Raven R2 tweeter. My analogue source is a Music Hall MMF-7 through a Pass Pearl which I haven't put through the F-4 yet. Maybe this weekend.
 
#1,593
I have a X-BOSOZ from the Kari GB that is near completion. I need to wire the power supply and deal with source selection and volume. I don't know if that will have enough guts to drive the F-4. I guess there is one way to find out. The efficiency of my speakers is certainly a plus as they are 94 db efficient.

I could also modify the pre before it is even finished. :devilr:
 
#1,594
DaveM said:
I have a X-BOSOZ from the Kari GB that is near completion. I need to wire the power supply and deal with source selection and volume. I don't know if that will have enough guts to drive the F-4. I guess there is one way to find out. The efficiency of my speakers is certainly a plus as they are 94 db efficient.

I could also modify the pre before it is even finished. :devilr:
Click to expand...


try like this ....... just place NPN bjts in place of IRFs

http://www.diyaudio.com/forums/showthread.php?postid=1362196#post1362196

http://www.diyaudio.com/forums/attachment.php?s=&postid=1362196&stamp=1196241299


or even better - look at pic
 

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