The President of the NY St. Andrew's Society, why of course. I have never seen so much malt beverage consumed in my life, ever, than at their annual dinner.
Ay laddie, but how many can keep from spilling on their tartan ?
(at least the Irish are too skinflinty to waste some of the good stuff, and Norwegians generally tend to pass out before tossing breckie)
(at least the Irish are too skinflinty to waste some of the good stuff, and Norwegians generally tend to pass out before tossing breckie)
If you've had enough Scotch it doesn't matter. They do force you to eat the haggis -- an acquired taste if I must say so.
Some might think the US has a nationwide chain of Scot heritage force fed bagged intestine deli's.
preamp gain
Hi Thanks Andrew,
i will diy a simple pre with a gain of 1.5 to 2 to try out.
My dac output is 2 V .
kp93300
Hi Thanks Andrew,
i will diy a simple pre with a gain of 1.5 to 2 to try out.
My dac output is 2 V .
kp93300
I reckon on the pre-amp having 10dB to 20dB headroom above the maximum signal.
If the F5 needs 3.8Vpk and one allows 10dB headroom then the Pre must be capable of passing a 12Vpk signal.
The bf862 cannot do that. You will need at least +-13v supply rails to get that 10dB of headroom.
If the F5 needs 3.8Vpk and one allows 10dB headroom then the Pre must be capable of passing a 12Vpk signal.
The bf862 cannot do that. You will need at least +-13v supply rails to get that 10dB of headroom.
I reckon somebody is constantly trying to poison the subject
4KV might be even better
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Let us burn our loudspeakers yeah enjoyable
Calm down, gents.....
Juma is a nice and cute friend, as well as Andrew, who's often giving us valuable inputs and some food for thought. Sometime he might appear like a taleban, but he's always formally right. Someone might agree or not, but technically speaking it's hard to beat.
Juma is a nice and cute friend, as well as Andrew, who's often giving us valuable inputs and some food for thought. Sometime he might appear like a taleban, but he's always formally right. Someone might agree or not, but technically speaking it's hard to beat.
Bit of a noob question I would assume, but when adjusting the bias via P1/P2 am I also changing the overall gain of the circuit?
In reading the discussion of the simplified circuit in the article, it would seem that it would for the input JFETs at least. The reason for the question is now that I have my amp biased and stable (not running thermistors right now and it took forever to get consistent), the central image is far left. The bias of the left channel is slightly below that of the right channel (~ 25mV lower / 0.05A).
Thanks
In reading the discussion of the simplified circuit in the article, it would seem that it would for the input JFETs at least. The reason for the question is now that I have my amp biased and stable (not running thermistors right now and it took forever to get consistent), the central image is far left. The bias of the left channel is slightly below that of the right channel (~ 25mV lower / 0.05A).
Thanks
Thanks kind of what I figured when I was adjusting, thus was quite surprised when I hooked it up to the main system... I will measure the output into a resistor this evening to see if there is a voltage output difference.
I seriously doubt that this is what causes your image to shift left. I'm not sure the gain is that much influenced by this bias current. As long as it is in the same ballpark, the vgs will be nearly the same and thus also the gain.
I would advise you to switch around the channels to see if it not just a matter of room acoustics or your source. Your idea about measuring is also good, just make sure you use the same signal generator/preamp channel for both your channels to avoid false positives.
A question for you: Why was it impossible for you to adjust the values closer?
Another one, which amp did you use before? IMHO, the F5 has a very detailed image, so I wouldn't be surprised if you are just hearing things on your records which were smeared before.
I would advise you to switch around the channels to see if it not just a matter of room acoustics or your source. Your idea about measuring is also good, just make sure you use the same signal generator/preamp channel for both your channels to avoid false positives.
A question for you: Why was it impossible for you to adjust the values closer?
Another one, which amp did you use before? IMHO, the F5 has a very detailed image, so I wouldn't be surprised if you are just hearing things on your records which were smeared before.
I agree - not with the ear (at least not my 🙂) to hear the difference in volume between 0.55 to 0.6 V bias. There will be some other problem in your case.
Thanks Gents, I will continue my troubleshooting this weekend and see what I find.
Without the thermistors, I have been fighting the temperature impacts of from one channel heating up the other, putting the cover on the amp increasing the bias significantly, etc., etc.). I have found it VERY temperature sensitive. It ended up being stable at 0.575V on the left side and 0.600V on the right with minimal offset (<3mV) with the cover on so I went with it.
My current amp in the main system is a DIY F3 and have always found it to be a focused central image. My speakers are spread ~10 FT center to center, so I have found it easy to detect imaging shifts (and when its right, a really great soundstage).
Without the thermistors, I have been fighting the temperature impacts of from one channel heating up the other, putting the cover on the amp increasing the bias significantly, etc., etc.). I have found it VERY temperature sensitive. It ended up being stable at 0.575V on the left side and 0.600V on the right with minimal offset (<3mV) with the cover on so I went with it.
My current amp in the main system is a DIY F3 and have always found it to be a focused central image. My speakers are spread ~10 FT center to center, so I have found it easy to detect imaging shifts (and when its right, a really great soundstage).
umbillical
Does anyone have a part number on some 3 conductor (with shield) cable that I can use for an umbilical cord to connect an external power supply to the amp?
I will try a one box solution first. But, I will most probably remove the power supply after some time to see if there is a worthwhile difference. But, I'm having a little trouble sourcing 3 conductor shielded cable. I think 16 gauge should be sufficient.
Thanks,
Steve
Does anyone have a part number on some 3 conductor (with shield) cable that I can use for an umbilical cord to connect an external power supply to the amp?
I will try a one box solution first. But, I will most probably remove the power supply after some time to see if there is a worthwhile difference. But, I'm having a little trouble sourcing 3 conductor shielded cable. I think 16 gauge should be sufficient.
Thanks,
Steve