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In Reply to: RE: First Watt J2 single-ended, Class-A, all-J-FET amps posted by jeffreybehr on December 23, 2014 at 16:58:25
I see you have removed the bolt from the transformer. This is good. If the screws holding down the diode bridges are magnetic then change them to brass hardware for better sound as well. Same with the washers and screws holding down the big transistors. Remove the indicator LEDs if you have not done so. They really mess up the sound. Remove all AC filters (thermistors, etc.)....they veil the sound. Put a top of the line Audio Magic fuse in it, bypass the binding posts, use better input wire, output wire, input jacks, power supply wire, better solder, resistors, smaller faster bypass caps (my modded Wimas for instance), damp the heatsinks, twist tightly the AC wires to and from the transformer.....plenty more to do after this too!
One does not need anyones approval to mod a piece of equipment. Once you own it you can do what you want. Obviously, mods can effect resale value.
Follow Ups:
... about some of your ideas. I would imagine that he's aware of what some hobbyists are doing with his stuff. I would also imagine that he is a pretty liberal or open-minded guy when it comes to new ideas, so long as they rest upon a firm scientific and audible basis.
To your knowledge, has Pass ever personally chimed in to approve or disapprove of anything proposed by various tweakers on audio boards?
"While I don't pursue the same methods, you are correct that playing with the circuit while listening yields a lot of benefits. I like to concentrate my efforts in my particular style - I leave others to pursue it in their own way.
You are of course free to play with my designs as you like."
The above is the exact email Nelson sent me when I informed him of my intentions to offer mods on the First Watt amps. Basically, what he is saying is that he is not interested in parts and execution.....only circuit design. Once he said that people would send him different caps and resistors to play with and his comment was "why don't they send me better transistors?". He has the world's only stash of power Jfets and had his SITs made custom for him. He likes devices and circuits. Not interested in wires, caps, damping, solder, sound of LEDs, etc. His products sound great because they are made well and the circuits are fantastic and simple and pure......but circuits are only 50%. The other 50% comes from execution. You would die and go to heaven if you heard one of his circuits (or any great circuit) executed to the max.
I have had zero people send me First Watt amps to mod....a couple of people said they would but never did. I mean, you spend $3000 on a low power amp that you may sell shortly (you know, you are looking at less sensitive speakers, whatever) so why invest in an amp that will lose resale value because some "tweaker" made it sound better?
Back in 98 I was going to produce an all out class A amp but could not find the means to get heatsinks and chassis in small quantity with large enough heatsinks......now there are chassis from Italy and China that are made for Class A circuits. So, I have decided to make my own Class A amps now....now finally, people can hear a great class A amp done with great execution. Should be fun.
Sounds good, I'm sure you'll find many here who will be interested in your products.
"[Nelson's] Not interested in wires, caps, damping, solder, sound of LEDs, etc."
I'm not a Pass devotee*, but I do admire the respect he garners among those who truly know amplifier circuits. I will take a slight exception to the above statement, only because I read a post somewhere of Pass recommending Elna Silmic electrolytic capacitors for their sonic quality. It's a minor quibble though, and in general, your point is well taken.
"why invest in an amp that will lose resale value because some "tweaker" made it sound better?"
I'm not an equipment flipper, so I ask myself, "Why not get all I can out of my F1?" (upgraded to F1J by Pass). But, even though I have little doubt that it could be sonically improved, I baulk because of the resale value. If I'm going to keep the amp, it makes little sense, I know. Maybe if there were 1001 or even better, 10,001 of them made, I might be more willing. But with only 101 of them out there, I'm far more cautious of doing something I'll regret.
*Some of his followers call him "Papa", which kinda gives me the creeps.
http://www.diyaudio.com/forums/pass-labs/Since I can't get a schematic for this amp, I've e-mailed him several times to discuss the functions of various devices in these amps. He's been informative, helpful, and, if not exactly encouraging, at least not discouraging at my intentions.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Edits: 01/04/15
NP,Is one of the great guys in audio, not only exceptionally talented as a designer , but well respected and respectful as well , I'm a big fan and always have a few of his offerings at one time or the other on hand...
NP telling you to give it a go is not unexpected , he welcomes your discovery ..:)
Regards
Edits: 12/26/14
WHat? No bashing of his horribly underpowered clip machines?!?!? Aren't you going to tell him how his 25 watt distortion generators will be clipping continuously and that he must love the sound of distortion?? No...hypocrisy is a word I guess you are familiar with.
And if your note is what passes as a helpful comment from you, then I agree with Mr. Wayne--you better adjust your meds.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Morri,
Err, Hmmm, Please ask your helper to read the OP, they are bridged , lot more than 25 watts and look at that, 97db sensitive speakers to boot, get a hold of yourself man.
When paralleled, two channels double current compared with one channel. When bridged, they double Voltage.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Congrats Jeff with all of your audibly successful mods on the J2 amps. I also have a J2 amp and will use it to drive clones I'm building of a very successful two-way hybrid horn system. Designed by Gary Dahl and Lynn Olson, the mains are Radian 745 Neo/Be drivers in Azura 425 horns. They are passively crossed to a pair of GPA Altec 416-B midwoofers. The sealed cabinets cut the midwoofers off at just below 70Hz, where my pair of Rythmik 12" sealed servo subs take over. System sensitivity is 97db and impedance is between 8 and 7 ohms. My room is only 14 ft x 19 and my average listening levels will probably be between 68 and 75db @ 70Hz at 11 feet, before my subs kick in. https://en.wikipedia.org/wiki/Fletcher%E2%80%93Munson_curves So the J2 would hardly break a sweat pushing these speakers.Two questions.
1.) Sadly, things have changed and after completing these speakers I won't be doing much more DIYing. But as you are clearly thrilled with the increased sound quality from your modded J2, might you or someone you know do these J2 mods to order? I'd want the mods that would most contribute to the improved sound.
2.) Have you ever heard the Pass XA30.5? If yes, how would you compare its sound to that of a stock J2 amp? More precisely, how would compare their sound when the XA30.5 is under load such that the needle of its front panel ammeter is very close to its center position-that is, where the amp is operating within its Class A bias region?**
Bigger soundstage in all dimensions? Deeper more robust midbass and low bass? More 3D imaging. More lifelike midrange? More extended and sweeter sounding highs? Better micro and macrodynamic detail? Better overall tonality?
Also, perhaps a rather silly question, but I am curious about which amp makes a better space heater.
** The Pass XA30.5 does 30 wpc and can handle 60 watt peaks, all in Class A. Beyond this output level it moves into Class AB where it does > 100 wpc.
Edits: 09/27/16
Most-probably, Jeffrey Glowacki of Sonic Craft could and would perform the upgrades that I did on mine.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Are you out there?
Good to see you- Jeffrey
please post some current pics of your system! Any new gear arriving to you this Fall?
Yes , correct , i had missed you saying parallel as opposed to bridge ....
Regards ...
...some of them. :-)I removed that power-transformer screw because in this later-of-the-two amps the PT is silicon-sealed to the floor of the amp. In the earlier amp, the PT is not glued in and I'll be replacing the screw/nut/washers with brass stuff.
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Edits: 01/04/15
Agreed- RS.
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