it seems that you made everything properly ;
so - I really can't see need for any answer - you already know
btw . stock F5 is biased at ~ 1A3 , meaning ~610mV across source resistors
your's is biased to ~500mV , meaning ~1A06
considering equal PSU voltage ( comparing to origigi) that difference isn't worth to call it "Mini"
btw. if your spks aren't of hungry breed , do not worry about klank!!
http://www.firstwatt.com/pdf/art_leave_classa.pdf
so - I really can't see need for any answer - you already know
btw . stock F5 is biased at ~ 1A3 , meaning ~610mV across source resistors
your's is biased to ~500mV , meaning ~1A06
considering equal PSU voltage ( comparing to origigi) that difference isn't worth to call it "Mini"
btw. if your spks aren't of hungry breed , do not worry about klank!!
http://www.firstwatt.com/pdf/art_leave_classa.pdf
Thanks ZM. Will call it regular F5 and not 'mini'.
I am very happy I could make use of some 15 year old transformers lying in my store room and save buying a expensive toroid again. I also used a quite fan and saved big on heatsinks.
Cheers.
first class 250VA toroid , with static shield , made for constant 100VA load ( meaning core double baked and over-sized ) cost me here ( in funny Serbia ) around 35E
when using one per channel , 70E is bargain , when one is making amp in 3K $ league .
considering that Papa's 3K$ amp is in league of moreK$ other amps , you must green even more when you save those 70E for xformers
now you must go out and buy some muzak for that money
when using one per channel , 70E is bargain , when one is making amp in 3K $ league .
considering that Papa's 3K$ amp is in league of moreK$ other amps , you must green even more when you save those 70E for xformers
now you must go out and buy some muzak for that money
first class 250VA toroid , with static shield , made for constant 100VA load ( meaning core double baked and over-sized ) cost me here ( in funny Serbia ) around 35E
when using one per channel , 70E is bargain , when one is making amp in 3K $ league .
considering that Papa's 3K$ amp is in league of moreK$ other amps , you must green even more when you save those 70E for xformers
now you must go out and buy some muzak for that money
You bet. That is exactly what I am doing this evening. Hunting around for some great recordings. I have become very demanding in my sources, after I got myself F5s... 😀
Maybe this has been discussed before. Anyone know what would be a good value for an attenuator or pot on the F5 input?
that's more matter of nature of source ( output impedance )
F5 doesn't know what's impedance feeding it ....... considering that input impedance of it (F5 itself) is pretty high
in other words - use whatever you like
F5 doesn't know what's impedance feeding it ....... considering that input impedance of it (F5 itself) is pretty high
in other words - use whatever you like
Using a pot directly at amp's input will raise the impedance of the source.
10k pot, in worst case scenario (at 50% position), will add 2k5 to it. Combined with parasitic capacitances of JFETs it will make effective LP filter.
Maybe you could get away with 10k pot but it will leave its sonic imprint.
You can avoid that by using a buffer.
nice to see two well respected and very knowledgeable Members disagreeing on what seems a very simple question requiring a simple solution.
Just to compound it I shall add a third opinion.
Do not try to convert a Power Amplifier into a reduced feature Integrated Amplifier by sticking an unbuffered attenuator up it's input.
The Power Amps belong beside the Speakers. The Attenuator belongs beside the Listener or at least accessible to the Operator.
Just to compound it I shall add a third opinion.
Do not try to convert a Power Amplifier into a reduced feature Integrated Amplifier by sticking an unbuffered attenuator up it's input.
The Power Amps belong beside the Speakers. The Attenuator belongs beside the Listener or at least accessible to the Operator.
naah ..... I'm dumb as usual , so nothing serious to be respected here 
mea culpa that I didn't mention well known fact for solid state - use more than 10K pot - with caution .....
mea culpa that I didn't mention well known fact for solid state - use more than 10K pot - with caution .....
How do you do that without sitting on top of the system?
I agree though. If it ain't broken, don't fix it😎
Ideally I would like the attenuator beside me while I am listening.
That is part of the reason technology has been brought to bare and given us remote control.
Next best to save the long cables between the sources and the attenuator is to locate the attenuator beside the sources thus allowing short cables to the attenuator.
We do not put the attenuators beside or inside the various Monoblocks feeding their nearby speakers which will be at least 1.5m apart and for 5.1 could be 6m apart, or even much longer if the cable runs do not run straight across the listening room.
That is part of the reason technology has been brought to bare and given us remote control.
Next best to save the long cables between the sources and the attenuator is to locate the attenuator beside the sources thus allowing short cables to the attenuator.
We do not put the attenuators beside or inside the various Monoblocks feeding their nearby speakers which will be at least 1.5m apart and for 5.1 could be 6m apart, or even much longer if the cable runs do not run straight across the listening room.
Not really - as I understood that, in his casual way, ZM is saying: "use what you want, but you'll pay the price anyway..."
And that's not much different from my post, I just explained a bit more ...
Normally the attenuator is a part of the preamplifier ( or in the input of preamplifier) and the output of the preamplifier remains low out put impedance enabling long cabling without affecting the signal.
If you are planning on using an attenuator before the Power amp , best option is to add a buffer before the attenuator something like B1 which will not alter the quality of F5.
Andrew is expecting that the control to be near the listener away from the speakers if F5 is kept near the speakers (and control preamp is in near the listener).
in effect do not connect an attenuator ( without buffer) to F5 if you want to retain the F5 sound quality!
That is why I said Attenuator before the buffer - like a CD Player with Volume pot provided the volume pot is before the buffer. Since most of the sources do not have any volume /Attenuator control, preamps are used before the Power amp seperates like F5. Still if you have no options, use an attenuators having lower than 10K Ohm or 5K Ohm to minimize the effects particularly for K170/J74 Fet inputs as in F5.