Banned
Joined 2002
choky said:
nope
I have same ,but my snakes are in different collours
sounds reasonable;
but-my choice will be Jfet front ;
ask Bill and boyz from shootout
Got a schematic i can sew with a jfet Front end ?
I was going to offer you a set for free
( the ones in pics are off ebay ) the other ones are ones i make.
Banned
Joined 2002
Banned
Joined 2002
Banned
Joined 2002
choky said:
Choky,
The only picture I have of my Aleph 3 that used to have the zvp3310a frontend is at this link:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=75685&perpage=10&highlight=&pagenumber=2
My jfet front end looks similar except for a 2.2 uF film capacitor in place of one of those yellow capacitors. It really is just a prototype, so is not very pretty. I plan on rebuilding it now that I have figured out what I like.
It is fan cooled in order to run it so hard. Next time I will use some other heatsinks that I recently purchased and build a wood chassis that is nicer.
This was from the previous pass shoot out part two. I guess I could add a photo of the board in my pdf as an example. Hopefully, you get some sleep though. 2AM?
Bill
Next round, May 28th
Well, here we go again.
We have two versions of the 12b4 linestage that we will be trying out, gas shunt regulator vs. a clean little solid state regulated power supply from Germany/Thel.
The amps will be a Pass Aleph 3 (mine), Pass Aleph 30 (using the new boards via Peter Daniel and Europe?), BillW's heavily modified Choky
Jfet Aleph 3, er 30, er what is it?, and to throw into the mix, Mark's Krell KSA 50 Klone, and trembling nervously in the corner, my newest orphan find, a stock Eico HF-81, with dripping wax electrolytics, a broken power switch, and used Heathkit tubes.
It should be fun. Mark will be posting pics later this evening, but I wish we could do an easy scope hookup, and that his Nikon would take a cleaner photo of the scope.
Lyndon
Well, here we go again.
We have two versions of the 12b4 linestage that we will be trying out, gas shunt regulator vs. a clean little solid state regulated power supply from Germany/Thel.
The amps will be a Pass Aleph 3 (mine), Pass Aleph 30 (using the new boards via Peter Daniel and Europe?), BillW's heavily modified Choky
Jfet Aleph 3, er 30, er what is it?, and to throw into the mix, Mark's Krell KSA 50 Klone, and trembling nervously in the corner, my newest orphan find, a stock Eico HF-81, with dripping wax electrolytics, a broken power switch, and used Heathkit tubes.
It should be fun. Mark will be posting pics later this evening, but I wish we could do an easy scope hookup, and that his Nikon would take a cleaner photo of the scope.
Lyndon
I think there is alot mroe work to be done. Billww made some minor adjustments and the sound improved dramatically over when we started out listening. At first the amp had VERY weak low end but a nice high end... very detailed. I think Bill is worried about running the fets at too high of corrent and blowing them however I would research it and see if there is a bit larger device that might safely work in there.
Re: The 12B4 line stage..... I like the gas regs way better over even using dual solid state power supply regs. To me the solid state boards definately added some grain and tizz to the top end. Last night I moved the gas regs to the line stage chassis and literally fastened them together.The sound improved very noticably with better macro details comming through and a far better sound stage, not even a hint of anr grain or tizz!.
Mark
Choky,
Not as clear this time around at all. I am still a bit mystified as how sensitive BillW's jfet Aleph 3 is to the smallest changes. And I don't blame him about being touchy and careful about blowing those jfets or anything else!
No general consensus. On the solid state, I liked the sound of my original Pass Aleph 3 (stock) best. It sounded better than the Aleph 30 (Peter Daniel boards)-though his had the best bottom end and BillW's jfet Aleph 3.
Mark's well burned in Krell Klone KSA-50 MkII sounded very good, but I am wondering if that amp emphasizes and brings out the upper mid-range, as well as the bass. My poor little Eico HF-81 came out at the bottom of the heap, but I give it credit for working! It probably had not been fired up in 15 to 20 years until yesterday! It is going to be my fall project, and if anybody can provide me with any links to someone's webpage (not Fiddler's) where someone has documented all the caps and electrolytics of a complete rebuild, I would greatly appreciate it!
Also, I wish we had had Dave (Amp Guy) present with his modified Aleph 30, and his little parafeed Magnavox 1515i, for the mix.
As to the 12b4 linestage, Choky is right, to each his own. Mark is convinced of the superior sound quality of the gas shunt regulator.
I am going ahead with that sweet little Thel board from Germany.
And the beauty of diy, if I don't like it down the road, I can rip it apart and go a different route.
Lyndon
Not as clear this time around at all. I am still a bit mystified as how sensitive BillW's jfet Aleph 3 is to the smallest changes. And I don't blame him about being touchy and careful about blowing those jfets or anything else!
No general consensus. On the solid state, I liked the sound of my original Pass Aleph 3 (stock) best. It sounded better than the Aleph 30 (Peter Daniel boards)-though his had the best bottom end and BillW's jfet Aleph 3.
Mark's well burned in Krell Klone KSA-50 MkII sounded very good, but I am wondering if that amp emphasizes and brings out the upper mid-range, as well as the bass. My poor little Eico HF-81 came out at the bottom of the heap, but I give it credit for working! It probably had not been fired up in 15 to 20 years until yesterday! It is going to be my fall project, and if anybody can provide me with any links to someone's webpage (not Fiddler's) where someone has documented all the caps and electrolytics of a complete rebuild, I would greatly appreciate it!
Also, I wish we had had Dave (Amp Guy) present with his modified Aleph 30, and his little parafeed Magnavox 1515i, for the mix.
As to the 12b4 linestage, Choky is right, to each his own. Mark is convinced of the superior sound quality of the gas shunt regulator.
I am going ahead with that sweet little Thel board from Germany.
And the beauty of diy, if I don't like it down the road, I can rip it apart and go a different route.
Lyndon
Lyndon,
I think you were lost in what amp sounds like what. It was hard for me to tell the difference between the regs until yesterday until last night whan I did aother listening test and then rewired the gas jobs back in(properly) and had another lsten..... all with the same amp. There is a definate improvement just like everyone else has been telling me all this time!!
Mark
I think you were lost in what amp sounds like what. It was hard for me to tell the difference between the regs until yesterday until last night whan I did aother listening test and then rewired the gas jobs back in(properly) and had another lsten..... all with the same amp. There is a definate improvement just like everyone else has been telling me all this time!!
Mark
Aleph 3 to jfet conversion
Well, I did not like the sound of my Aleph 3 jfet conversion with the current settings. I found it to be bright and lacking bass.
I found by running the stock 4.7 mA of current through the LED reference and giving 20 mA to the jfet current fet, the amp sounded very bright with no bass.
I later adjusted the voltage reference current to about 6.8 mA and the bass became much better and less bright in the highs. At that time, I did not adjust the AC current gain, but found adjustments on the Aleph jfet current reference alter the sound a great amount. I might try another irf9610 or zvp3310a in place with the higher current settings.
I am afraid with the j176, it would not be able to handle 26 mA of current where both Lyndon and Mark seemed to agree the amp sounded much better in the lower frequencies and with less brighter upper frequencies.
I noticed the previous time, I had no 10 pF compensation cap and the amp sounded much more detailed, but the square wave earlier in this thread had slight over shoot. To, me that sounded very nice back then compared to having this nice square wave and having the life sucked out of the music it seemed. While looking at Lyndon's Aleph 3, it looked like he had a .047 uF ceramic stabilization cap, but I did not see any 10 pF frequency compensation cap. This could be why his sounded very detailed. I would have liked to see his square waves. I bet that was why his sounded so detailed. The previous time I had no 10 pF cap, everyone seemed to like the jfet conversion the best, so this has led me to want to investigate Lyndon's boards for if he had compensation caps or not.
For those, who are asking which resister I am referring to, it is the 4.75K ohm below the zener voltage reference in the Nelson service manual of the Aleph 3. By lowering it to 3600 ohm, the aleph sounded much better in the bass with the j176. This in theory according to my calculation gave about 26 mA to the j176 current fet and must have been able to drive my heavily biased output mosfets stage better.
So, I may go back to the irf9610 to handle this higher current for the current source for the LTP. It seems by adjusting the current, I have found it affects the highs and lows, so I will investigate this further.
Everything is a learning experience with this project.
Regards, all
Well, I did not like the sound of my Aleph 3 jfet conversion with the current settings. I found it to be bright and lacking bass.
I found by running the stock 4.7 mA of current through the LED reference and giving 20 mA to the jfet current fet, the amp sounded very bright with no bass.
I later adjusted the voltage reference current to about 6.8 mA and the bass became much better and less bright in the highs. At that time, I did not adjust the AC current gain, but found adjustments on the Aleph jfet current reference alter the sound a great amount. I might try another irf9610 or zvp3310a in place with the higher current settings.
I am afraid with the j176, it would not be able to handle 26 mA of current where both Lyndon and Mark seemed to agree the amp sounded much better in the lower frequencies and with less brighter upper frequencies.
I noticed the previous time, I had no 10 pF compensation cap and the amp sounded much more detailed, but the square wave earlier in this thread had slight over shoot. To, me that sounded very nice back then compared to having this nice square wave and having the life sucked out of the music it seemed. While looking at Lyndon's Aleph 3, it looked like he had a .047 uF ceramic stabilization cap, but I did not see any 10 pF frequency compensation cap. This could be why his sounded very detailed. I would have liked to see his square waves. I bet that was why his sounded so detailed. The previous time I had no 10 pF cap, everyone seemed to like the jfet conversion the best, so this has led me to want to investigate Lyndon's boards for if he had compensation caps or not.
For those, who are asking which resister I am referring to, it is the 4.75K ohm below the zener voltage reference in the Nelson service manual of the Aleph 3. By lowering it to 3600 ohm, the aleph sounded much better in the bass with the j176. This in theory according to my calculation gave about 26 mA to the j176 current fet and must have been able to drive my heavily biased output mosfets stage better.
So, I may go back to the irf9610 to handle this higher current for the current source for the LTP. It seems by adjusting the current, I have found it affects the highs and lows, so I will investigate this further.
Everything is a learning experience with this project.
Regards, all
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