I was originally having problems because i did not pay attention to datasheet of lateral fets showing that the pinout was different than that of IRF fets. After fixing this, One channel fired up fine while the other was showing rail to rail voltage on N channel fets. I check all other active components with exception of the zener direction and all was OK. I assumed it was the output fets and checked each, one by one, by pulling Rs and Rg. Still could not find the culprit. I replaced one P fet and still had the problem. I was bout to quit when i noticed the Zener facing wrong direction on N-fet side. Viola. Problem solved. Now i need to figure out why having the zener backwards would cause full rail to show at positive side.
OK. I have two BA outputs built, one with IRF and one with Reenasas Laterals. Both are biased to .8A per fet, with 2 output pairs per channel. Offset less than 5mV per channel. On IRF version, I had to substitute 8K resistor for R9 to get appropriate bias to match lateral version. I also had to change R22 with 392R vs 750R resistor to achieve offset.
In the lateral version, I have 20K R for both R8 and R9 because the laterals have lower Vgs ratings for spec'ed current. I haven't listened a lot, but i can't tell a great deal of difference between the two. The IRF version seems a little more forward sounding. the Lateral version seems quieter with more detail, but also having everything set futher back in the soundstage. Oddly enough, It seems as though the IRF version using 3 pairs had more presence at the cost of less background detail. More bias definitely brought down the distortion and provided ability to listen deeper into the recording. If i had to pick right now, I would have a hard time. I need more listening time. I can't decide whether or not to get another set of boards to try Fairchild version. I don't like comparing amps unless all are present. I may build another with Fairchild along with ABS switcher from ESP and give it a go. Nothing will change with the outputs for a while. Just listening. I will now move on to FE's, which will include BA-2, BA-3, OPA1632 and maybe Magma,M2 type FE. The balanced versions will have to wait on output decision, although I could probably give a listen using different output version. Perhaps this would reveal differences better. I have 4 R085 fets that I may try in power B1 setup. Been in the back of my head ever since hearing this buffer. MOre to come.
In the lateral version, I have 20K R for both R8 and R9 because the laterals have lower Vgs ratings for spec'ed current. I haven't listened a lot, but i can't tell a great deal of difference between the two. The IRF version seems a little more forward sounding. the Lateral version seems quieter with more detail, but also having everything set futher back in the soundstage. Oddly enough, It seems as though the IRF version using 3 pairs had more presence at the cost of less background detail. More bias definitely brought down the distortion and provided ability to listen deeper into the recording. If i had to pick right now, I would have a hard time. I need more listening time. I can't decide whether or not to get another set of boards to try Fairchild version. I don't like comparing amps unless all are present. I may build another with Fairchild along with ABS switcher from ESP and give it a go. Nothing will change with the outputs for a while. Just listening. I will now move on to FE's, which will include BA-2, BA-3, OPA1632 and maybe Magma,M2 type FE. The balanced versions will have to wait on output decision, although I could probably give a listen using different output version. Perhaps this would reveal differences better. I have 4 R085 fets that I may try in power B1 setup. Been in the back of my head ever since hearing this buffer. MOre to come.
you are deep ln the affair......
good coming in and out of the different possibilities....
I just had a shortcut because I have in one case two amp halves one with +-24V and one with +48V ( to compare sound) and two different earth points and one cinch mass had contact with the case, not allowed.......
some sparkles, fun in the moment ....repentence tomorrow!
good coming in and out of the different possibilities....
I just had a shortcut because I have in one case two amp halves one with +-24V and one with +48V ( to compare sound) and two different earth points and one cinch mass had contact with the case, not allowed.......
some sparkles, fun in the moment ....repentence tomorrow!
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Hi Zen Mod,
I suppose you had already more fun.......
I had good luck, nothing else happened, both amp halves work still fine!
Ufff a stone rolling from .........whatever!
I really must create me an experimental set separate from my working amp......I will buy another set of heatsinks, all the other parts I have already....
I suppose you had already more fun.......
I had good luck, nothing else happened, both amp halves work still fine!
Ufff a stone rolling from .........whatever!
I really must create me an experimental set separate from my working amp......I will buy another set of heatsinks, all the other parts I have already....
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you are deep ln the affair......
good coming in and out of the different possibilities....
I just had a shortcut because I have in one case two amp halves one with +-24V and one with +48V ( to compare sound) and two different earth points and one cinch mass had contact with the case, not allowed.......
some sparkles, fun in the moment ....repentence tomorrow!
It seems we both have affairs to attend to. I am inspired by your daring and willingness to try crazy ideas. I heard a song that made me think of you. "Why Aye Man" by Dire Straits. It speaks of German beer and other such wonderful German things.
From what I have heard, I think I will try to reduce the distortion level as much sa possible in the output stage. If nothing else, the fets that do this the best will probably be used, assuming they don't have some other undesirable trait. I was listening to the two output stages with my all J-fet preamp by Borberly and really enjoyed it, but this evening I put on the BA-3 FE and just was astonished at the difference. Two things that stood out were, how the lower distortion of the higher biased amps allowed even more of the character of the BA3 to show through, and how the BA-3 added so much body to the music vs ,y other pre-amp. It accomplished this without losing detail or clarity. It maintained the excellent imaging that seemed to come from more bias at the output, but kept the expansive and very present sound-stage. Even my wife commented on it and you know she is tired of all this Hopefully I will be getting a sound-card for distortion measurement soon and will be able to put numbers on my findings.
Hopefully I will be getting a sound-card for distortion measurement soon and will be able to put numbers on my findings.I ordered and have recieved probes listed on ebay for $9.79 plus $2.99 for total $12.78 from danteegoods. Have checked them out on 1KH square wave calabration on scope (tektronix 2245A 100mhz) and they are a super buy for the price. Are they as good as tektronix probes no but at 1/10 the price, order some for spares. Highly reccomended
ok i had to go to ebay.com not ebay.de
sorry....
http://www.ebay.com/itm/New-Two-100...ultDomain_0&hash=item256a3aa84b#ht_4779wt_907
sorry....
http://www.ebay.com/itm/New-Two-100...ultDomain_0&hash=item256a3aa84b#ht_4779wt_907
my two affairs, very different, still sleep and work in the same case...
and as I told they are very different beasts, one crippled F4 and one try to build a kind of F2J with other voltages.....
but this try has so much gain, that BBA-3 and modified F2J combined are too loud at the lowest position of my pot.....
all tries to tame BBA-3 to a gain of, lets say, 6 did not really succeed, I increased the output source resistors even to 88 Ohm, and loose 4V per side in the resistor, but still to much gain for this lady.....
But I do not give up.....
of course I could try to make a feedback loop in BBA-3 like in the UGS, but I like the sound of no feedback, but why should I not try...?
and as I told they are very different beasts, one crippled F4 and one try to build a kind of F2J with other voltages.....
but this try has so much gain, that BBA-3 and modified F2J combined are too loud at the lowest position of my pot.....
all tries to tame BBA-3 to a gain of, lets say, 6 did not really succeed, I increased the output source resistors even to 88 Ohm, and loose 4V per side in the resistor, but still to much gain for this lady.....
But I do not give up.....
of course I could try to make a feedback loop in BBA-3 like in the UGS, but I like the sound of no feedback, but why should I not try...?
HI Zen Mod, you mean the output stage of BA-3? isn't it the same effect increasing source resistor or putting in a drain resistor and not changing the source resistor.....? I am bit ashamed not to know this....
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