If you have 100 ohm resistors, then a 100 ohm parallel with a 22 will
get you pretty close to 18 ohms.
Dennis
Are you saying parallel the 22 ohms with 10 ohms (gets you 16 ohms)? May be you mentioned 100 ohms as a typo.
My apologies for the brain freeze. Got it completely wrong. You are absolutely right.
Cheers.
Sorry it's taken so long to respond to this.
The 4U is totally fine for an F5, F6, F4, 24V BA-3, and AJ. In that chassis, the AJ will get the hottest, but that's just that the Aleph runs hot. The F6 (in a 4U) doesn't even get 'hot' in my experience so far.
But I stick to my original suggestion, the 4U is sufficient for any of the above amps.
I received my matched J-fets from the store today. Here is what I found.
LSK170 7.53
LSJ74 7.52
LSK170 7.63
LSJ74 7.57
Many thanks to Jim 6L6 for this service saving us a lot of money buying numerous quantities to get matches. I am sure he does this for the love of the hobby and not for monetary gain.
I would like to follow up on my review of the F6. The amplifier revealed a fault in my crossover network that I have never noticed before. I built another more simpler 1st order crossover and started using a B1 buffer and the touch of brightness I commented on previously is gone. This is a very revealing amplifier and I am enjoying it very much. Now there is an F7 coming out. I would love to hear a SIT 1 to see how much of an improvement it could be. My next project will have to be one of V-fet amplifiers. I believe I would be stepping back building anything else at this present time.
David
LSK170 7.53
LSJ74 7.52
LSK170 7.63
LSJ74 7.57
Many thanks to Jim 6L6 for this service saving us a lot of money buying numerous quantities to get matches. I am sure he does this for the love of the hobby and not for monetary gain.
I would like to follow up on my review of the F6. The amplifier revealed a fault in my crossover network that I have never noticed before. I built another more simpler 1st order crossover and started using a B1 buffer and the touch of brightness I commented on previously is gone. This is a very revealing amplifier and I am enjoying it very much. Now there is an F7 coming out. I would love to hear a SIT 1 to see how much of an improvement it could be. My next project will have to be one of V-fet amplifiers. I believe I would be stepping back building anything else at this present time.
David
F-6 Resistor Substitutions...close enough?
A couple of the resistor values not available from mouser in my preferred Vishay/dale RN pieces: R4 18 ohm is one, 18.2 ohm close enough? I bought a bunch figuring a couple would measure low, but low WAS 18.2 with a couple slightly higher! Is 18.2 close enough for R4, or should I get another type, or combine values to get 18 on the head?
R6: should be 47K, I have 47.5K on hand, close enough? or replace with exact value?
Finally, for R11 and R12, I have 47 ohm, but narrative says 110 ohm is needed here...I have 111 ohm RN 65 (would have to stand up soldier style) on hand, close enough? I know some values are not that critical and others are, need advice on which are and if these values are good to use.
Can anybody help out? I have other parts to order so its no big deal if something needs replaced, but on the other hand I'd like to use what I've got if it will not cause any degradation or problems.
Thanks for any advice here,
Russsellc
A couple of the resistor values not available from mouser in my preferred Vishay/dale RN pieces: R4 18 ohm is one, 18.2 ohm close enough? I bought a bunch figuring a couple would measure low, but low WAS 18.2 with a couple slightly higher! Is 18.2 close enough for R4, or should I get another type, or combine values to get 18 on the head?
R6: should be 47K, I have 47.5K on hand, close enough? or replace with exact value?
Finally, for R11 and R12, I have 47 ohm, but narrative says 110 ohm is needed here...I have 111 ohm RN 65 (would have to stand up soldier style) on hand, close enough? I know some values are not that critical and others are, need advice on which are and if these values are good to use.
Can anybody help out? I have other parts to order so its no big deal if something needs replaced, but on the other hand I'd like to use what I've got if it will not cause any degradation or problems.
Thanks for any advice here,
Russsellc
Hi Russellc,
I wouldn't worry too much about the resistors since what you have are pretty much
within 1% of the nominal value of the parts. Besides, did you subtract the lead's
resistance when you measured the 18.2 ohm resistor. 🙂 I'll use 150 ohm for R11/R12
since that's what I happen to have. (Pretty wide latitude on the gate stoppers.)
Cheers,
Dennis
I wouldn't worry too much about the resistors since what you have are pretty much
within 1% of the nominal value of the parts. Besides, did you subtract the lead's
resistance when you measured the 18.2 ohm resistor. 🙂 I'll use 150 ohm for R11/R12
since that's what I happen to have. (Pretty wide latitude on the gate stoppers.)
Cheers,
Dennis
That's usually the case, but you know what they say about a little bit of knowledge! With my luck I would alter something critical The one I really had no idea on was the 47k vs 47.5K....not much, but with my luck😱
Russellc
Hmmm...sometimes "revealing" can easily be mistaken as bright or harsh.
Are you saying the amplifier can accentuate the upper frequencies more than other amplifiers you've tried?
I can't imagine any amplifier sounding bright with a B1 in front of it. I've built several B1s, but have never warmed up to their sound...no pun intended.
For me, the BA-3 is in a whole different class with only a few more components, though I know it isn't a buffer.
Thanks...
I bought these and they not the typical shape with the "flat spot" and otherwise round body. These are more oval shaped...does the short leg or the long leg go closest to the "LED-Blue 1" or "LED-Blue 2" writing? Appears the short leg is the "Flat" side of the other shape LED, so does short leg go next to said writing on PCB?
Russellc
I didn't order those as they are odd-shaped LED's instead of the standard round.
The longer lead on the LED is the positive lead and should go in the pad that is connected to R13.
Looking at my F6 boards it isn't consistent with the writing on the board, so don't go by the silkscreen on the board.
If whoever designed the boards had just placed a "+" next to the pad going to R13, it would eliminate some confusion.
But it's difficult to think of everything when laying out a PCB.
I do that on any boards I design to eliminate any confusion as to which way the LED goes.
I've just finished my F6 clone and I also find it bright, or more revealing, if you like. I have a B1 in front and had been using my F3 clone and F5 clone just before the F6 so the comparison is fresh in my mind. I can tame the speakers with a resistor tweak but then they may then seem a bit flat with the other amps.
I now feel like the F6 is just more revealing with more detail. It is always the case when you put a better piece of equipment in your system it may show faults elsewhere that you did not hear before. To answer ammel68's question, I do not think it attenuates the upper frequencies just reveals more detail. I hear about people recapping their crossover networks and the sound is brighter to them until they realize that the old capacitors were making the sound duller. I have used a B1 before and did not care for it with the Aleph 30 or BA3 SE but with the F6 it sounds great to my ears. You may need gain with your speakers depending on what you are using for a source. 6L6 commented that when using a computer with just 1 volt output the B1 with the F6 may not be enough gain. With my very efficient speakers I have plenty of gain just using my computer with the B1 but I do have to use a preamp with gain for my turntable. I have been running the tube preamp through the B1 then the F6 for an experiment and I like the sound right now.
A comment for AUM911, I attenuated my speakers midrange to start with the F6 but after some more listening I went back to where it was before. Maybe you are like me and just have to get use to more detail. I catch myself listening when I should be doing something else now. I am retired and can listen for hours at a time.
David
In my expereince the F6 can sound bright or more warm, depending what k2 you have in the THD spectrum.
So I recommend to look for the k2 to k3 ratio.
So I recommend to look for the k2 to k3 ratio.
I played around with changing the values of R1 and R2 some but my ears are not trained enough to hear the difference. I do not have a distortion analyzer to set the F6 up with K2 to K3 ratio. My understanding is the B1 has a touch of K2 and it could be that is the reason I like the F6 with the B1. Interesting observation on your part. Thanks