Uh, look how far it went...
As for me, who I started this thread, I've been forced out of business in the last few months (terribly busy with job and various stuff). Now that it looks like I came back, I also find that I changed my mind, and preferred not to find a suitable preamp, but instead... Try a different "F", for the sake of entertainment.
I find my speakers to be potentially OK with an intriguing F1J, and it looks cheap enough because I can keep my power supply and cabinet/heatsinks etc.
The idea of the transconductance amp fires me up high enough to try this, as soon as I find someone with parts.
I don't mean to drive this thread away from its rails, so I resurrected the latest F1J-based one that I could find.
I'm still thankful for all the replies here, even if things evolved like this.
Giacomo
As for me, who I started this thread, I've been forced out of business in the last few months (terribly busy with job and various stuff). Now that it looks like I came back, I also find that I changed my mind, and preferred not to find a suitable preamp, but instead... Try a different "F", for the sake of entertainment.
I find my speakers to be potentially OK with an intriguing F1J, and it looks cheap enough because I can keep my power supply and cabinet/heatsinks etc.
The idea of the transconductance amp fires me up high enough to try this, as soon as I find someone with parts.
I don't mean to drive this thread away from its rails, so I resurrected the latest F1J-based one that I could find.
I'm still thankful for all the replies here, even if things evolved like this.
Giacomo
considering that MotoGP season is here ..... we have busy period in front of us
Vale + Ducati, huh?
Giacomo
SET as a preamp for F4
Hi all,
Not sure if this is the right spot but in the F4 manual and the 6 Moons review it is suggested that a small power amp makes a good preamp for the F4.
I have a nice little 45 based tube amp I'd like to try...but...I'm shakey on how to hook my 45 to the F4.
It looks like one just cuts off one of the RCAs on a given interconnect, puts an 8 Ohm/2W resistor across the resulting bare wires and then connects bare wires to little (45) amp's speaker terminals - remaining RCA to F4. (respecting polarity)
Is it that basic?
Hi all,
Not sure if this is the right spot but in the F4 manual and the 6 Moons review it is suggested that a small power amp makes a good preamp for the F4.
I have a nice little 45 based tube amp I'd like to try...but...I'm shakey on how to hook my 45 to the F4.
It looks like one just cuts off one of the RCAs on a given interconnect, puts an 8 Ohm/2W resistor across the resulting bare wires and then connects bare wires to little (45) amp's speaker terminals - remaining RCA to F4. (respecting polarity)
Is it that basic?
using SET as a preamp
Well so much for my beliefs; the speaker terminal (-) does have a lead back to signal ground. The transformer has a lead marked "0" going to the speaker terminal (-) so it is grounded through it's connection to the speaker terminal.
But...
This lead from speaker terminal (-) to signal ground is connected at signal ground with a spade and screw. I could disconnect it and thus float the transformer but I don't know if that is wise.
Well so much for my beliefs; the speaker terminal (-) does have a lead back to signal ground. The transformer has a lead marked "0" going to the speaker terminal (-) so it is grounded through it's connection to the speaker terminal.But...
This lead from speaker terminal (-) to signal ground is connected at signal ground with a spade and screw. I could disconnect it and thus float the transformer but I don't know if that is wise.
something strange
OK, I made interconnects with 10R/2W resistors across the the + and - , checked continuity and R and connected these across my speaker terminals (on my 45 SETs monoblocks). These interconnects then fed the F4.
The SETs were fed by a B1 which in turn was fed by a CD player. This is my normal set up for playback with the SETs. All units/connections are unbalanced.
Turn on CDP, turn on B1, turn on first 45 SET, turn on F4, all's quiet...turn on second 45 SET...Bias shoots up on both 45 SETS. I have to turn it all the way down to get it just over safe levels. What I get from the speakers is low level signal, distorted.
I went back and checked all my connections, checked the 10R resistors (not warm). Made sure all the connections made sense made sure I had the source correct. It just doesn't work
OK, I made interconnects with 10R/2W resistors across the the + and - , checked continuity and R and connected these across my speaker terminals (on my 45 SETs monoblocks). These interconnects then fed the F4.The SETs were fed by a B1 which in turn was fed by a CD player. This is my normal set up for playback with the SETs. All units/connections are unbalanced.
Turn on CDP, turn on B1, turn on first 45 SET, turn on F4, all's quiet...turn on second 45 SET...Bias shoots up on both 45 SETS. I have to turn it all the way down to get it just over safe levels. What I get from the speakers is low level signal, distorted.
I went back and checked all my connections, checked the 10R resistors (not warm). Made sure all the connections made sense made sure I had the source correct. It just doesn't work
The SETs were fed by a B1 which in turn was fed by a CD player. This is my normal set up for playback with the SETs. All units/connections are unbalanced.
Turn on CDP, turn on B1, turn on first 45 SET, turn on F4, all's quiet...turn on second 45 SET...Bias shoots up on both 45 SETS. I have to turn it all the way down to get it just over safe levels. What I get from the speakers is low level signal, distorted.
I went back and checked all my connections, checked the 10R resistors (not warm). Made sure all the connections made sense made sure I had the source correct. It just doesn't work
Whats the gain of your 45 SET? Your output transformer assuming is a 25:1 ?
results...
'Floated the secodary, checked for playback and wired up the SET for feeding the F4. (16 Ohm 2W across the + and -, No problem.
I'm a little underwhelmed though. I can't say anything against the combo; it's competent...like a Toyota Camry. But who gets excited by a Camry?
I really like the SET as an amp, driving the very same speakers! I really like the F4 (fed by the BA3 FE as preamp) driving these same speakers (Klipsch La scala). I just can't get excited by the SET driving the F4 But hey, it works! Maybe your little amp is the little amp that could
'Floated the secodary, checked for playback and wired up the SET for feeding the F4. (16 Ohm 2W across the + and -, No problem.
I'm a little underwhelmed though. I can't say anything against the combo; it's competent...like a Toyota Camry. But who gets excited by a Camry?
I really like the SET as an amp, driving the very same speakers! I really like the F4 (fed by the BA3 FE as preamp) driving these same speakers (Klipsch La scala). I just can't get excited by the SET driving the F4
But hey, it works! Maybe your little amp is the little amp that could 
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Joined 2009
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Perhaps you discovered one of the 'truths' about hybrid amplifiers? I've read comments that it's not the tube by itself that has the 'magic' but the interaction of tube with OPT and speaker. When you isolate the tube from the speaker (with the F4) it's just another voltage gain stage. I would like to hear it for myself one of these days.