I was referring to MOSFET nonlinear capacitance. JFET, never gave it much thought.
Do both types share in this same capacitive misbehavior? I don't know...
I notice how you got the JFET depletion drop oriented to help with Q7,8 VBE up front.
Actually had to look at that twice. I almost complained on it, thinking the opposite.
Do both types share in this same capacitive misbehavior? I don't know...
I notice how you got the JFET depletion drop oriented to help with Q7,8 VBE up front.
Actually had to look at that twice. I almost complained on it, thinking the opposite.
Actually, I just assumed Jfets had the same capacitance distortions just like BJTs or Varactors. Maybe I'm wrong?
- keantoken
In addition to many assorted junker caps, some really good Panasonic stacked films.
Twenty of the 1uF, 10 of the 1nF ECQ-V series. For small comp caps, threw in 10
yellow Murata tweakers 6.8pF - 48pF I think roughly the covered adjustment range?
I got TO3 heatsinks drillel to fit. And in the process abandoned the notion of direct
collector to sink suicide. Micad them properly, slathered with generic thermoglorp.
Less hazard to wandering screwdrivers... Though exposed TO3 cans will still be hot,
at least its not the whole sink(s) riding the rails...
Twenty of the 1uF, 10 of the 1nF ECQ-V series. For small comp caps, threw in 10
yellow Murata tweakers 6.8pF - 48pF I think roughly the covered adjustment range?
I got TO3 heatsinks drillel to fit. And in the process abandoned the notion of direct
collector to sink suicide. Micad them properly, slathered with generic thermoglorp.
Less hazard to wandering screwdrivers... Though exposed TO3 cans will still be hot,
at least its not the whole sink(s) riding the rails...
I should find that address soon, before he adds anything else to the box! 
Today was a holiday so I didn't have to go to school. I will ask my debate teacher tomorrow, with special attention paid to my choice of words...
Good news: A teacher at school suddenly values my opinions after I told him my story. He says he can get me a nice cabinet to put it in once it's built.
Eventually I want to add the usual features such as preamp, maybe even RIAA thing and, my personal requirement, input taken from multiple sources switched and/or mixed together so that I don't have to swap cables. Also, a headphone output. I want to design it all myself (If it all goes smoothly it'll be a like a dream...).
Now to begin investing a a pair of fostex or whatever speakers...
- keantoken
Today was a holiday so I didn't have to go to school. I will ask my debate teacher tomorrow, with special attention paid to my choice of words...
Good news: A teacher at school suddenly values my opinions after I told him my story. He says he can get me a nice cabinet to put it in once it's built.
Eventually I want to add the usual features such as preamp, maybe even RIAA thing and, my personal requirement, input taken from multiple sources switched and/or mixed together so that I don't have to swap cables. Also, a headphone output. I want to design it all myself (If it all goes smoothly it'll be a like a dream...).
Now to begin investing a a pair of fostex or whatever speakers...
- keantoken
I kinda doubt my parts are the best match for your boards...
But he should be able to fake something, and have enough
parts left over to make an amp of his own design too.
I've tried medium flat rate box, but slightly too much bulk.
The large what I need, but the post office temporarily out.
But he should be able to fake something, and have enough
parts left over to make an amp of his own design too.
I've tried medium flat rate box, but slightly too much bulk.
The large what I need, but the post office temporarily out.
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Sorry about the address, I'm still working on it...
Just to be clear, the only speakers I can currently make use of are 6.5" types. I'm currently using Boston Acoustics BA40 bookshelf boxes, and they're the only thing I would trust mildly with good speakers. That aside, I will accept them no matter the size, and thanks!
It appears that the 2sk164/2sJ1104 are the best HF Jfets suited for the Allison circuit. Problem is they have much lower gain so I actually end up with lower bandwidth than if I used the 2sk170/j74. My emphasis is on Cob for this application because if we overwork one half of the circuit we end up having unequal BW between the top and bottom halves, making for weird output characteristics.
- keantoken
Just to be clear, the only speakers I can currently make use of are 6.5" types. I'm currently using Boston Acoustics BA40 bookshelf boxes, and they're the only thing I would trust mildly with good speakers. That aside, I will accept them no matter the size, and thanks!
It appears that the 2sk164/2sJ1104 are the best HF Jfets suited for the Allison circuit. Problem is they have much lower gain so I actually end up with lower bandwidth than if I used the 2sk170/j74. My emphasis is on Cob for this application because if we overwork one half of the circuit we end up having unequal BW between the top and bottom halves, making for weird output characteristics.
- keantoken
They are 6 inch I think... I accidently tore a whizzer Friday while removing one of
the grill, but fixed right quick with diluted white fabric glue. Still sound plenty good.
Podging, like one of those "extra value" mods for Fostex style whizzer anyway...
My WT3 (tester) is across town, but I'll plot you Theile Smalls if I get a chance.
I got a vague feeling these may be 94dB or better.
More parts, somebody stop me, please!!! MJE270 and MJE271 (real Motorola with
gold plated leads) complimentary 15W Darlingtons... You might find the spice model
at OnSemi, inside the big Discrete Models zipfile. Or I can post extracted as text.
Anyways, its a subcircuit, but a real simple one. You won't have trouble breaking
each down to two discrete .model transistors and two resistors. If LTSpice won't
cooperate with the OnSemi subcircuit in its original format.
Also some Intersil matched pair NPNs in TO5 cans w. heatsinks. I forget the part#?.
I still can't find you matched pairs of PNP, P-JFET, nor P-Anything in matchpairs...
Except for the Germaniums I had already matched by hand, but they don't share
the same thermal package unless you were to glue em together or whatnot...
the grill, but fixed right quick with diluted white fabric glue. Still sound plenty good.
Podging, like one of those "extra value" mods for Fostex style whizzer anyway...
My WT3 (tester) is across town, but I'll plot you Theile Smalls if I get a chance.
I got a vague feeling these may be 94dB or better.
More parts, somebody stop me, please!!! MJE270 and MJE271 (real Motorola with
gold plated leads) complimentary 15W Darlingtons... You might find the spice model
at OnSemi, inside the big Discrete Models zipfile. Or I can post extracted as text.
Anyways, its a subcircuit, but a real simple one. You won't have trouble breaking
each down to two discrete .model transistors and two resistors. If LTSpice won't
cooperate with the OnSemi subcircuit in its original format.
Also some Intersil matched pair NPNs in TO5 cans w. heatsinks. I forget the part#?.
I still can't find you matched pairs of PNP, P-JFET, nor P-Anything in matchpairs...
Except for the Germaniums I had already matched by hand, but they don't share
the same thermal package unless you were to glue em together or whatnot...
Thanks Ken... That is a LOT of stuff.
If you feel you should stop, by all means do. I was quite happy with just the caps and PSU items.
I had a strange dream last night. The context of the dream was that I had ordered some amp boards online. I was inspecting on of them and my subconscious mind was apparently only powerful enough to cover it with multiple dipped blue/green caps marked "arco". I love my dreams. They feel sooooooo real until I wake up. It's like I'm in a parallel reality, unaware.
I have been researching dual transistors, and I've found some that are good candidates for my HF allison buffer: the LS3250/3550. These have an Ft of 600MHz. Cob is typically 2pF, slightly less than my current 5769/5771 combo. Hfe is also larger. They are also 40V as opposed to 15.
EDIT: Okay, I finally got an address! Whew... A PM is heading your way.
- keantoken
If you feel you should stop, by all means do. I was quite happy with just the caps and PSU items.
I had a strange dream last night. The context of the dream was that I had ordered some amp boards online. I was inspecting on of them and my subconscious mind was apparently only powerful enough to cover it with multiple dipped blue/green caps marked "arco". I love my dreams. They feel sooooooo real until I wake up. It's like I'm in a parallel reality, unaware.
I have been researching dual transistors, and I've found some that are good candidates for my HF allison buffer: the LS3250/3550. These have an Ft of 600MHz. Cob is typically 2pF, slightly less than my current 5769/5771 combo. Hfe is also larger. They are also 40V as opposed to 15.
EDIT: Okay, I finally got an address! Whew... A PM is heading your way.
- keantoken
Thats what drills and/or JBWeld are for. But you should have plenty medium and
small sinks soon, clip on types or with screws included... For larger sinks, old PC
processors, you only need to scavenge the local dumpster.
You will learn a great deal from the challenge of using lesser grade parts to best.
Its not all about finding the coolest new spec that cost overruns a million bucks.
Everything you need is here, including parts that probably did cost a wad when
they were new, 20 or more years ago....
small sinks soon, clip on types or with screws included... For larger sinks, old PC
processors, you only need to scavenge the local dumpster.
You will learn a great deal from the challenge of using lesser grade parts to best.
Its not all about finding the coolest new spec that cost overruns a million bucks.
Everything you need is here, including parts that probably did cost a wad when
they were new, 20 or more years ago....
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A PC cooler might look quite elegant, but I'm not that adventurous yet.
There is a drill press at a certain pawn shop I have been eying for some time. What I need is to throw together one of my own designs and sell a few. Get the process started, then I'll have a source of income.
I still have some tricks up my sleeve (JBWelding OPs to heatsink!?).
- keantoken
There is a drill press at a certain pawn shop I have been eying for some time. What I need is to throw together one of my own designs and sell a few. Get the process started, then I'll have a source of income.
I still have some tricks up my sleeve (JBWelding OPs to heatsink!?).
- keantoken
Okay everyone, I've done something I know many people might regret... Except me.
I finally got fed up with procrastinating and tore apart the nice amplifier described here. I had vague fantasies of fixing it and selling it, but I finally realized that the world is just cruel, and that I have to be cruel too in order to thrive.
http://www.diyaudio.com/forums/showthread.php?t=145918
I disassembled it piece by piece, very slowly, very painfully. I then took a butane torch to the back as per Kenpeter's advice (yes, he and I are in it together) and pulled out the output transistors, rectifiers, and caps. I tried not to make smoke but there were a few times I just couldn't hold it in.
I was having so much fun I even burnt my foot several times.
Please don't judge me.
Okay, here is the lineup:
5x 2SA1940 (one or two of these may be blown)
5x 2SC5197
10x 2SC4370
5x 2SA1659
2x high current rectifier
1x low current rectifier
1x huge power trafo (+ AC power board, complete with fuses and switched outlets)
1x large heatsink originally included left, right, and center channel amplifiers.
1x smaller heatsink, originally included left and right surround channels.
5x Absolutely useless peripheral boards.
1x Treble, bass, and midrange equalizer.
2x 6800uF, 50WV caps.
5x Small and medium 78XX heatsinks.
5x dual-pack 5W 0.22 ohm resistors.
1x gold-plated switching headphone jack.
Several small orange caps marked MKT
The heatsinks from this one aren't the showy type I would put on the outside of an amp as I intend... So I will probably use the sink from the Onkyo. The C4370/A1659 look like good candidates to replace the C4793/A1837 recommended by Hugh (these could also be more linear due to the higher Icmax). The datasheet doesn't provide much data though. If H/K used them, they can't be bad.
http://pdf1.alldatasheet.com/datasheet-pdf/view/270215/SAVANTIC/2SA1659.html
- keantoken
I finally got fed up with procrastinating and tore apart the nice amplifier described here. I had vague fantasies of fixing it and selling it, but I finally realized that the world is just cruel, and that I have to be cruel too in order to thrive.
http://www.diyaudio.com/forums/showthread.php?t=145918
I disassembled it piece by piece, very slowly, very painfully. I then took a butane torch to the back as per Kenpeter's advice (yes, he and I are in it together) and pulled out the output transistors, rectifiers, and caps. I tried not to make smoke but there were a few times I just couldn't hold it in.
I was having so much fun I even burnt my foot several times.
Please don't judge me.
Okay, here is the lineup:
5x 2SA1940 (one or two of these may be blown)
5x 2SC5197
10x 2SC4370
5x 2SA1659
2x high current rectifier
1x low current rectifier
1x huge power trafo (+ AC power board, complete with fuses and switched outlets)
1x large heatsink originally included left, right, and center channel amplifiers.
1x smaller heatsink, originally included left and right surround channels.
5x Absolutely useless peripheral boards.
1x Treble, bass, and midrange equalizer.
2x 6800uF, 50WV caps.
5x Small and medium 78XX heatsinks.
5x dual-pack 5W 0.22 ohm resistors.
1x gold-plated switching headphone jack.
Several small orange caps marked MKT
The heatsinks from this one aren't the showy type I would put on the outside of an amp as I intend... So I will probably use the sink from the Onkyo. The C4370/A1659 look like good candidates to replace the C4793/A1837 recommended by Hugh (these could also be more linear due to the higher Icmax). The datasheet doesn't provide much data though. If H/K used them, they can't be bad.
http://pdf1.alldatasheet.com/datasheet-pdf/view/270215/SAVANTIC/2SA1659.html
- keantoken
Sorry. I don't get out enough to really know the value of anything.
I only need one amp. This one would have sat around for several years until I parted it out anyways. It was just one half of the commercial product, as well as missing the remote. Besides, everyone was encouraging me to rip apart heavy amps! Where did all that bloodlust go?
Can't look back now.
- keantoken
I only need one amp. This one would have sat around for several years until I parted it out anyways. It was just one half of the commercial product, as well as missing the remote. Besides, everyone was encouraging me to rip apart heavy amps! Where did all that bloodlust go?
Can't look back now.
- keantoken
You need at least one famous reference amp that others would recognize,
as a baseline for comparison sake. How else you gonna brag on your stuff?
That HK contained no special parts according to your list. But the design...
Besides, in less than a week you will have more semi-pro junk parts than
you can shake a stick at.
Did I mention the Clarostat pots? 5 each of 500K, 100K, 20K, 1K, 200R
and one other value I forget... These are the 20turn linear variety, 1W.
Figure that covers for any fixed resistors not immediately available.
A dozen 1N4005 silicon diodes. Qty10 1000uF 50V electrolytics, 105C...
Do you have a use for any relays?
as a baseline for comparison sake. How else you gonna brag on your stuff?
That HK contained no special parts according to your list. But the design...
Besides, in less than a week you will have more semi-pro junk parts than
you can shake a stick at.
Did I mention the Clarostat pots? 5 each of 500K, 100K, 20K, 1K, 200R
and one other value I forget... These are the 20turn linear variety, 1W.
Figure that covers for any fixed resistors not immediately available.
A dozen 1N4005 silicon diodes. Qty10 1000uF 50V electrolytics, 105C...
Do you have a use for any relays?
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