Giovanni,
Moving to a lower power amp can be problematic and in an earlier post (#2690 : https://www.diyaudio.com/community/...eamp-build-guide.258022/page-135#post-7047392 ) a test was suggested to see if the F4's +/-20V voltage swing range is enough for you and your speakers. This will let you decide if a single F4 is enough (perhaps with a different gain stage) or if you will need something more.
Moving to a lower power amp can be problematic and in an earlier post (#2690 : https://www.diyaudio.com/community/...eamp-build-guide.258022/page-135#post-7047392 ) a test was suggested to see if the F4's +/-20V voltage swing range is enough for you and your speakers. This will let you decide if a single F4 is enough (perhaps with a different gain stage) or if you will need something more.
I have a lightly used 4U aluminum faceplate with two holes for LEDs and 1 19MM hole for an MFR# MC010920 push button on/off. Ideal when used with Mark's soft start CB.
I offer this for shipping costs, which have been $22.00 for the other ones I have shipped.
Send me a VM if interested.
I offer this for shipping costs, which have been $22.00 for the other ones I have shipped.
Send me a VM if interested.
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Funny your F4 is just warm, probably not biased high enough. I can hold my hand on mine for 5 seconds. I am running one off a ASKA lender preamp to a pair of frugal horns and it swings about 40V. When I ran both stereo amps together balanced I used Sy’s Impass and it was plenty loud.
Even after building a Sony V-Fet amp, I still love my F4. Unfortunately, we're down to one set of speakers at the moment so I can only use one or the other - but I plan to fix that soon by building a new pair. This made me wonder about the ways an F4 can be used with a flea watt integrated, as outlined in the manual, but I don't fully understand the limitations of those options. They are unusual ways of connecting amplifiers that I don't think many people do, and I don't want to break an amp I greatly enjoy.
Could an Elekit TU-8200R be used to drive the F4? Directly? Meaning, basically as a preamp? At what point would the flea watt amp be too big?
Or, could a TU-8200R be used to drive the mid/high part of a speaker - with the F4 after driving the woofer, but still running off the output from the TU unit? Would that change the point at which a flea watt amp is considere too big?
I don't understand these things but love tubes, and my F4 - and want to use them together. I'm very sure the results will be awesome but I want to make sure I do it right.
Any thoughts/feedback will be appreciated!
🙂
Could an Elekit TU-8200R be used to drive the F4? Directly? Meaning, basically as a preamp? At what point would the flea watt amp be too big?
Or, could a TU-8200R be used to drive the mid/high part of a speaker - with the F4 after driving the woofer, but still running off the output from the TU unit? Would that change the point at which a flea watt amp is considere too big?
I don't understand these things but love tubes, and my F4 - and want to use them together. I'm very sure the results will be awesome but I want to make sure I do it right.
Any thoughts/feedback will be appreciated!
🙂
practically, yes to both questions
of course - source amp (especially if tube one) always need to have load, be it dummy (nominal or twice that, if you need some more swing) or mid/high section of speaker
of course - source amp (especially if tube one) always need to have load, be it dummy (nominal or twice that, if you need some more swing) or mid/high section of speaker
You won’t break anything.
The people who I’ve talked to that have used a flea watt amp to drive F4 have found that a 20ohm 3W resistor loading the tube amp output works the best. Then you attach to the F4 input with RCA.
The people who I’ve talked to that have used a flea watt amp to drive F4 have found that a 20ohm 3W resistor loading the tube amp output works the best. Then you attach to the F4 input with RCA.
I used a wavelength 45 to drive lowthers and also drive a f4 driving 15 inch woofers. No problems
Awesome, thank you guys!
The F4 still puts a smile on my face every time it gets a turn in the living room. Looking forward to trying something different.
The F4 still puts a smile on my face every time it gets a turn in the living room. Looking forward to trying something different.
I drove mine with a 45 or a 2A3 amp with great results using 16 ohm load to a 8-ohm drivers (Fostex). I also found the F4 exceptionally sounding with the BA3 preamp in front and can recommend type 26, 26, or a 01A tube preamps as well.
To me, the F4 sounds great when the equipment in front of it sounds great! It is really transparent to what’s ahead making tube preamps a great match to it as it will retain the tube preamp sound.
+1 on the BA3 front end as pre. Simple and easy to build, sounds excellent with F4.
I did build a BA3-FE preamp, and definitely loved the combo. Even without a distortion analyzer to dial it in better....still very good. My speakers are definitely at least 93db efficient, as the combo was more than enough to fill the whole house, to irresponsible levels, without getting too far past noon on the volume knob. That was a nice surprise.
I also happen to have a smattering of very nice NOS American and European 12au7 variants from a preamplifier I sold years ago, so began to wonder how some of those could sound in an elekit product in front of the F4.
The glowing bottles please my ears and eyes...
🙂
I also happen to have a smattering of very nice NOS American and European 12au7 variants from a preamplifier I sold years ago, so began to wonder how some of those could sound in an elekit product in front of the F4.
The glowing bottles please my ears and eyes...
🙂
My F4 has already gone pufff, switch one, fuse breaks, change fuse, it breaks again, my very skilled friend came to check it out and the rectifiers on a channel broke, he says not enough cooling, they were installed underneath a thick aluminum plate but, eventually, not enough to cool it all down...
I'll have to wait to first carry it at my friend's workshop then to hear from him, at first sight he thinks not enough cooling on the rectifiers
It seems odd for the rectifier to break if it's in good contact with a thick aluminum plate. Is it possible that it was not tightened down properly had worked itself loose from the thermal cycles?
So far it seems there are well screwed to the thick aluminum plate, my guy says there could even be some issue with the relais which serves to power the whole thing up, it is all about to take it to him (no joke since this thing is about 20Kg and here it is all pedestrian and a good 15 min walk uphill to get there) and figure rectifiers, relais and bias, the good news is that the MOSFETs are safe and sound (sound...)