Re: Re: Re: Re: Re: Zen version 9
In Nelson's Zen 9 article,
R4 thru R6 are 1 ohm source resisters that set the bias to the irfp240 at 2.0 Amps. Could I add 1 more 1 ohm resister in parallel to these 3 1 ohm resisters, which would increase the current to the irfp240 current source?
I think the lovotech jfet could handle more current since it was only running 1.8 volts in my setup.
This would be .25 ohms instead of the higher .33 ohm 2.0 amp bias setting?
Or will this throw the whole circuit out of balance or spec?
Thanks Bill
PS, I upped my fan speed to my heat tunnel, so it could handle the new higher bias setting if this would work.
Zen Mod said:
In Nelson's Zen 9 article,
R4 thru R6 are 1 ohm source resisters that set the bias to the irfp240 at 2.0 Amps. Could I add 1 more 1 ohm resister in parallel to these 3 1 ohm resisters, which would increase the current to the irfp240 current source?
I think the lovotech jfet could handle more current since it was only running 1.8 volts in my setup.
This would be .25 ohms instead of the higher .33 ohm 2.0 amp bias setting?
Or will this throw the whole circuit out of balance or spec?
Thanks Bill
PS, I upped my fan speed to my heat tunnel, so it could handle the new higher bias setting if this would work.
Re: Re: Re: Re: Re: Re: Zen version 9
dunno right now;look in LU datasheets
I'll look tomorrow..........doing some stupid house works now
BillWW said:
dunno right now;look in LU datasheets
I'll look tomorrow..........doing some stupid house works now
Re: Re: Re: Re: Re: Re: Zen version 9
Yes, but you may need to adjust R13, R18, and R19 too to readjust the ac current gain.
BillWW said:
Yes, but you may need to adjust R13, R18, and R19 too to readjust the ac current gain.
Zen version 9
Thanks for the replies.
If I add 1 more 1 ohm resister, the bias would be about 2.6 amps. I think that would be safe. I have seen Nelson in his Return of Zen suggest as high as 3.0 amps of bias, so I would be fine with 2.6 amps.
I guess I could adjust the AC current gain like I did on my Alephs.
So, this should bring it one step closer to my Aleph 3 in spaciousness with higher biasing. Who knows, since I found I liked 1.8 volts across the Vds of the jfet, maybe the higher bias will work out to roughly 2.5 volts like Nelson has said the Lovotechs have the optimum distortion reduction around that voltage.
I guess in the next day or so I will try this out.
Bill
Thanks for the replies.
If I add 1 more 1 ohm resister, the bias would be about 2.6 amps. I think that would be safe. I have seen Nelson in his Return of Zen suggest as high as 3.0 amps of bias, so I would be fine with 2.6 amps.
I guess I could adjust the AC current gain like I did on my Alephs.
So, this should bring it one step closer to my Aleph 3 in spaciousness with higher biasing. Who knows, since I found I liked 1.8 volts across the Vds of the jfet, maybe the higher bias will work out to roughly 2.5 volts like Nelson has said the Lovotechs have the optimum distortion reduction around that voltage.
I guess in the next day or so I will try this out.
Bill
After checking the Zv9 pdf,
R19 3.31K seems to be the same position as the Alephs, so I will put in a 5K ohm pot and check the AC current gain with that R19 resister.
I hope Zen mod, you do not mind me discussing this zv9 here, since it is a jfet amp. If need by I could move this to some other Zv9 project thread, but I kind of like having all of the jfet comparisons here, unless others object. 🙂
Bill
R19 3.31K seems to be the same position as the Alephs, so I will put in a 5K ohm pot and check the AC current gain with that R19 resister.
I hope Zen mod, you do not mind me discussing this zv9 here, since it is a jfet amp.
If need by I could move this to some other Zv9 project thread, but I kind of like having all of the jfet comparisons here, unless others object. 🙂 Bill
BillWW said:After checking the Zv9 pdf,
R19 3.31K seems to be the same position as the Alephs, so I will put in a 5K ohm pot and check the AC current gain with that R19 resister.
I hope Zen mod, you do not mind me discussing this zv9 here, since it is a jfet amp.
Bill
this time I'll not moderate you
this is not just mine thread -write poetry here if you wish, I'm not "keep it on topic" sort of puritan
Zen Version 9
I got the Zen version 9 sounding very good now. I decided the higher bias was very helpful. It made the amp sound cleaner into my 2 ohm load.
I noticed the compensation cap does vary on the value now with this higher bias. It needs less capacitance now.
I think it sounds very close to my over biased Aleph 3 j176 amp now, although the bass is still not very strong due to a fraction of the dampening factor of my Aleph.
I think it would make a wonderful midrange/tweeter amp now. I like the higher bias too, because my Apex jr capacitors were 50 volts 12,000 uF caps and with the stock bias, my capacitors were seeing 50.4 to 50.6 volts. Now they are a lot less than this now and no need to worry about that any longer. The toroid was a 400Va 20 Volt with dual secondaries that I wired in series at 40 volts AC unloaded. Loaded it was just at 50.4 volts after an hour with my cl-60 inrush limiters.
This 10 watt amp seems to go plenty loud on my corner horn, but the bass is missing compared to what I am used to.
I think this amp would be absolutely perfect for a Lowther or Fostex full range speaker project.
I got rid of the annoying midrange scratchiness that it had initially and now it seems just as refined as my Aleph 3 jfet except for the bass now. 😀
So, I guess I lied saying I would take another year tweaking it. It only took 3 days with a year's prior experience to get it sounding almost the exact same as my previous Aleph 3 jfet project.
Bill
I got the Zen version 9 sounding very good now. I decided the higher bias was very helpful. It made the amp sound cleaner into my 2 ohm load.
I noticed the compensation cap does vary on the value now with this higher bias. It needs less capacitance now.
I think it sounds very close to my over biased Aleph 3 j176 amp now, although the bass is still not very strong due to a fraction of the dampening factor of my Aleph.
I think it would make a wonderful midrange/tweeter amp now. I like the higher bias too, because my Apex jr capacitors were 50 volts 12,000 uF caps and with the stock bias, my capacitors were seeing 50.4 to 50.6 volts. Now they are a lot less than this now and no need to worry about that any longer. The toroid was a 400Va 20 Volt with dual secondaries that I wired in series at 40 volts AC unloaded. Loaded it was just at 50.4 volts after an hour with my cl-60 inrush limiters.
This 10 watt amp seems to go plenty loud on my corner horn, but the bass is missing compared to what I am used to.
I think this amp would be absolutely perfect for a Lowther or Fostex full range speaker project.
I got rid of the annoying midrange scratchiness that it had initially and now it seems just as refined as my Aleph 3 jfet except for the bass now. 😀
So, I guess I lied saying I would take another year tweaking it. It only took 3 days with a year's prior experience to get it sounding almost the exact same as my previous Aleph 3 jfet project.
Bill
Zen version 9
After trying various music, I think my Zen version 9 with my mods sounds nicer in the highs than my former tweaked Aleph 3 jfet amp. It is an amazing amp now. I did not expect it would sound as nice as I got it now.
Bill
After trying various music, I think my Zen version 9 with my mods sounds nicer in the highs than my former tweaked Aleph 3 jfet amp. It is an amazing amp now. I did not expect it would sound as nice as I got it now.
Bill
Re: Zen version 9
Impressions after a week of listening have changed somewhat.
I notice my over-biased Aleph 3 still had a more romanticed sound that seemed more tube like than the Zen. Piano was very relaxing and very enjoyable. In the over biased Zen 9 it seems to sound dry and not as enjoyable. It seems more neutral or less romantic in the music.
I specificially increased the bias with 1 extra 1 ohm resister in parallel with those other 3 one ohm resisters and adjusted the AC current gain to the new 50 percent setting 3.5K ohm instead of the original 3.1K ohm and tried various voltage ranges for the jfet on the drain to source voltages.
I noticed the Zen 9 amp sounded more dry with more bias and not as rich as the original stock settings from Nelson Pass.
So, I am back to the stock settings from Nelson's schematic.
Why would the amp sound dry with more bias?
It did not increase the spaciousness like with my Aleph projects. Why would that be?
So, it seems the stock settings that Nelson gave in the schematic seem to be as best sounding as I can get this amp. It still does not sound as spacious as my over biased Aleph 3.
It sounds very nice for the stock setting, but I have after about a week or so of listening decided the Aleph 3 with more bias sounds more spacious and romantic with music. I can listen to it much longer with far less fatigue than the Zen 9.
There is somewhat of a difference with the two amps, I have noticed now. It seems like the Zen 9 stresses the midrange more than the Aleph 3 does. I find now the tweeter resolution is about the same compared to each.
I would like to comlete my Aleph mini before the weekend to compare directly to the zen 9, since it would only use 1 irfp240 like the Zen 9 does. That would be a more fair comparison.
So, far for my low impedence horn, I am starting to prefer the Aleph more so. It seems to me the capacitor coupling of the Zen also reduces some of the resolving power compared to direct coupling without a capacitor.
This saturday, I will have Mark Gulbrandsen, and Lucky Lyndon listen and see what they think.
The Zen 9 is still a nice sounding amp, especially for the small 2.25 amps at 117 AC it draws. It still sounds better than most amps that I have compared it too.
It does need a preamp even with my 104db/W horn to drive the Zen compared to my Alephs that were fine with just a passive volume pot off of the CD player.
Bill
BillWW said:After trying various music, I think my Zen version 9 with my mods sounds nicer in the highs than my former tweaked Aleph 3 jfet amp. It is an amazing amp now. I did not expect it would sound as nice as I got it now.
Bill
Impressions after a week of listening have changed somewhat.
I notice my over-biased Aleph 3 still had a more romanticed sound that seemed more tube like than the Zen. Piano was very relaxing and very enjoyable. In the over biased Zen 9 it seems to sound dry and not as enjoyable. It seems more neutral or less romantic in the music.
I specificially increased the bias with 1 extra 1 ohm resister in parallel with those other 3 one ohm resisters and adjusted the AC current gain to the new 50 percent setting 3.5K ohm instead of the original 3.1K ohm and tried various voltage ranges for the jfet on the drain to source voltages.
I noticed the Zen 9 amp sounded more dry with more bias and not as rich as the original stock settings from Nelson Pass.
So, I am back to the stock settings from Nelson's schematic.
Why would the amp sound dry with more bias?
It did not increase the spaciousness like with my Aleph projects. Why would that be?
So, it seems the stock settings that Nelson gave in the schematic seem to be as best sounding as I can get this amp. It still does not sound as spacious as my over biased Aleph 3.
It sounds very nice for the stock setting, but I have after about a week or so of listening decided the Aleph 3 with more bias sounds more spacious and romantic with music. I can listen to it much longer with far less fatigue than the Zen 9.
There is somewhat of a difference with the two amps, I have noticed now. It seems like the Zen 9 stresses the midrange more than the Aleph 3 does. I find now the tweeter resolution is about the same compared to each.
I would like to comlete my Aleph mini before the weekend to compare directly to the zen 9, since it would only use 1 irfp240 like the Zen 9 does. That would be a more fair comparison.
So, far for my low impedence horn, I am starting to prefer the Aleph more so. It seems to me the capacitor coupling of the Zen also reduces some of the resolving power compared to direct coupling without a capacitor.
This saturday, I will have Mark Gulbrandsen, and Lucky Lyndon listen and see what they think.
The Zen 9 is still a nice sounding amp, especially for the small 2.25 amps at 117 AC it draws. It still sounds better than most amps that I have compared it too.
It does need a preamp even with my 104db/W horn to drive the Zen compared to my Alephs that were fine with just a passive volume pot off of the CD player.
Bill
Re: Re: Zen version 9
hehe-now you shake some trees........contrary to local folks habit that every new Pass's baby is somewhat better than previous one.......
but who knows......maybe others will have different opinions........
maybe?
sure!
me?
probably not in near future......ZV9 is pretty low on my priority list.
BillWW said:
hehe-now you shake some trees........contrary to local folks habit that every new Pass's baby is somewhat better than previous one.......
but who knows......maybe others will have different opinions........
maybe?
sure!
me?
probably not in near future......ZV9 is pretty low on my priority list.
Re: Re: Re: Zen version 9
Well, I will have to see what Mark and Lyndon think when we compare them this Saturday hopefully, when Mark gets back from another business trip.
More opinions, make things more fair or less biased I think.
I should get working on the mini aleph jfet j176 chassis. Perhaps to get it going faster, I will just bolt everything to a wood board so that I can have it for Mark and Lyndon to compare on a more equal power rating.
I do not want to get people upset over a project. The more comparisons, the better.
I would say it sounded similar to my stock bias setting with my Aleph 3 jfet conversion, but once I bias the Aleph 3 jfet setup, it seems that amp is difficult to excel above that amp.
I only hoped to do the same with the Zen version 9, but it seemed to not work the way my Aleph did on the biasing. The more with the Zen, the more dry it sounded.
So, stock it sounds the best that I could get it to sound--still a nice sounding amp compared to many out there. Much better than the return of Zen amp that I built from Nelson.
It seems to me his commercial products are nicer still in my mind.
I'm glad I have my Alephs, because they seem to be the best sounding with my tweaks than other amps that I have tried or heard. I will have to stick with the Aleph 3, mini and 30 for the next couple of years though, because I will be going back to school full time and will not have time to build or spend on projects for the next couple of years.
I still have an Aleph Xa board BrianGT board using my j176 fets, I would like to try, but realistically it will be down a couple of years, unless I get some more funding I do not foresee for future projects on the side.
The Zen is still nice for protecting speakers from no DC worries with the capacitor coupling. It was the most quiet amp I have heard on turn on and turn off thump. If I had to agree with the reviewer between my Aleph 3 jfet and the Zen version 9, it would be like the 6moons review between French Vanilla and plain Vanilla. They are both great amps, but there is a difference between these flavors.
Bill
Bill
Zen Mod said:
Well, I will have to see what Mark and Lyndon think when we compare them this Saturday hopefully, when Mark gets back from another business trip.
More opinions, make things more fair or less biased I think.
I should get working on the mini aleph jfet j176 chassis. Perhaps to get it going faster, I will just bolt everything to a wood board so that I can have it for Mark and Lyndon to compare on a more equal power rating.
I do not want to get people upset over a project. The more comparisons, the better.
I would say it sounded similar to my stock bias setting with my Aleph 3 jfet conversion, but once I bias the Aleph 3 jfet setup, it seems that amp is difficult to excel above that amp.
I only hoped to do the same with the Zen version 9, but it seemed to not work the way my Aleph did on the biasing. The more with the Zen, the more dry it sounded.
So, stock it sounds the best that I could get it to sound--still a nice sounding amp compared to many out there. Much better than the return of Zen amp that I built from Nelson.
It seems to me his commercial products are nicer still in my mind.
I'm glad I have my Alephs, because they seem to be the best sounding with my tweaks than other amps that I have tried or heard. I will have to stick with the Aleph 3, mini and 30 for the next couple of years though, because I will be going back to school full time and will not have time to build or spend on projects for the next couple of years.
I still have an Aleph Xa board BrianGT board using my j176 fets, I would like to try, but realistically it will be down a couple of years, unless I get some more funding I do not foresee for future projects on the side.
The Zen is still nice for protecting speakers from no DC worries with the capacitor coupling. It was the most quiet amp I have heard on turn on and turn off thump. If I had to agree with the reviewer between my Aleph 3 jfet and the Zen version 9, it would be like the 6moons review between French Vanilla and plain Vanilla. They are both great amps, but there is a difference between these flavors.
Bill
Bill
Re: Re: Re: Re: Zen version 9
Wish your successful school project.
I have F1 here, and X-ZV2 at home with different CD players and
speakers. Whenever I have chances, I listen to the different sounds.
Sometimes I feel this better or another better. . . Always confused. . .
But, whatever. . . I forget such things after one or two days
because there are always nice music. This could mean that both
systems are good. Maybe very good. 🙂
BillWW said:
Wish your successful school project.
I have F1 here, and X-ZV2 at home with different CD players and
speakers. Whenever I have chances, I listen to the different sounds.
Sometimes I feel this better or another better. . . Always confused. . .
But, whatever. . . I forget such things after one or two days
because there are always nice music. This could mean that both
systems are good. Maybe very good. 🙂
mini Aleph j
I have a mini aleph zvp3310a version, but just want to convert that one to the j176 jfet differential. Those j176 are turning into very good sounding jfets even compared to those Lovotech in the Zen version 9.
I will have to buy the 22K ohm and 220K ohm resisters for the j176 jfet conversion tomorrow. I will have to work late on that project Thursday and Friday and hopefully have everything mounted for Saturday's GTG.
The heatsink was already done for this previous version, but I never built a chassis for it. So, for fast action, I think I will just bolt the power supply to a wood board and mount the speaker and input terminals some how. This would be about the same power level to be more fair comparing to the Zen version 9.
I should further explain the french Vanillia versus plain was referring to the F3 review from 6moons versus some 2a3 tube amp that the reviewer liked a lot. The 6moons review of the F3 on tonal quality seemed to agree with my feelings of the Zen version 9. This review was highly favorable still of this F3, so do not be discouraged by my comparison of my tweaked Alephs.
They both have advantages such as speaker protection from the Zen version 9, versus direct coupling--very dangerous to a speaker when things go wrong that I have experienced.
The Alephs seem to have far less capacitors, which I favor. The Alephs seem to have a lot more dampening, which I favor for my cornerhorn 15" woofer. It seems to need more control than the Zen version 9.
When I looked at the square wave of the Zen version 9, it was having a lot of problems driving my 2 ohm load, so perhaps that was why it did not sound as nice as the Aleph, which is designed to handle as low as 2 ohms.
Maybe on a 8 or 16 ohm speaker the Zen version 9 would sound better than it did on my 2 ohm load.
So, do not give up on the Zen yet. It may be speaker dependant or designed better for high quality full range speakers. Mine are not the right ones for it. 🙂
Bill
winslow said:
I have a mini aleph zvp3310a version, but just want to convert that one to the j176 jfet differential. Those j176 are turning into very good sounding jfets even compared to those Lovotech in the Zen version 9.
I will have to buy the 22K ohm and 220K ohm resisters for the j176 jfet conversion tomorrow. I will have to work late on that project Thursday and Friday and hopefully have everything mounted for Saturday's GTG.
The heatsink was already done for this previous version, but I never built a chassis for it. So, for fast action, I think I will just bolt the power supply to a wood board and mount the speaker and input terminals some how. This would be about the same power level to be more fair comparing to the Zen version 9.
I should further explain the french Vanillia versus plain was referring to the F3 review from 6moons versus some 2a3 tube amp that the reviewer liked a lot. The 6moons review of the F3 on tonal quality seemed to agree with my feelings of the Zen version 9. This review was highly favorable still of this F3, so do not be discouraged by my comparison of my tweaked Alephs.
They both have advantages such as speaker protection from the Zen version 9, versus direct coupling--very dangerous to a speaker when things go wrong that I have experienced.
The Alephs seem to have far less capacitors, which I favor. The Alephs seem to have a lot more dampening, which I favor for my cornerhorn 15" woofer. It seems to need more control than the Zen version 9.
When I looked at the square wave of the Zen version 9, it was having a lot of problems driving my 2 ohm load, so perhaps that was why it did not sound as nice as the Aleph, which is designed to handle as low as 2 ohms.
Maybe on a 8 or 16 ohm speaker the Zen version 9 would sound better than it did on my 2 ohm load.
So, do not give up on the Zen yet. It may be speaker dependant or designed better for high quality full range speakers. Mine are not the right ones for it. 🙂
Bill
Very interesting reading. 🙂
BTW, wondering why the sound of ZV9 is getting dry with more current. . .
Probably, the Lovoltech JFET has an allergy to too much current. . . ?
BTW, wondering why the sound of ZV9 is getting dry with more current. . .
Probably, the Lovoltech JFET has an allergy to too much current. . . ?
I have been waiting on someone to do a jfet miniA, especially one based on BrianGT's boards. I have an extra set of amp and PS boards that I have the itch to build, and wanted to do a JFET version...but I'm not inclined enough to know what needs to be changed to what to make it work.
Bill, you mind if I pick your brain to get the skinny on your JFET version? Sounds fun for a new project.
Bill, you mind if I pick your brain to get the skinny on your JFET version? Sounds fun for a new project.
Re: mini Aleph j
Some thoughts on the ZV9 from my experience with other Zen’s
I guess you are right with the comment on 2 ohm load; you might also be clipping the amp. A more objective sound description could be made under 8 Ohms load.
Regarding the dry sound, besides the load issue, could be the type of cap at the output, I have noticed quite different sound signatures fooling around with this cap and a good 10uf MKP parallel to this cap does wonders.
Now on cap voltage rating is not enough to have a similar voltage as at idle since you are not considering the AC portion which is significant at this position.
I would also test a 4 Ohms –or higher- series resistor with the speaker even if this will also decrease the actual power to the speaker (which I assume is quite efficient). The amp will see a higher load and might behave different.
I have only read the last 2 pages of this thread so I might be wrong with some of my comments. Only my 2c
BTW where can I read more on your high bias Aleph?
BillWW said:
Some thoughts on the ZV9 from my experience with other Zen’s
I guess you are right with the comment on 2 ohm load; you might also be clipping the amp. A more objective sound description could be made under 8 Ohms load.
Regarding the dry sound, besides the load issue, could be the type of cap at the output, I have noticed quite different sound signatures fooling around with this cap and a good 10uf MKP parallel to this cap does wonders.
Now on cap voltage rating is not enough to have a similar voltage as at idle since you are not considering the AC portion which is significant at this position.
I would also test a 4 Ohms –or higher- series resistor with the speaker even if this will also decrease the actual power to the speaker (which I assume is quite efficient). The amp will see a higher load and might behave different.
I have only read the last 2 pages of this thread so I might be wrong with some of my comments. Only my 2c
BTW where can I read more on your high bias Aleph?
winslow said:
use same schmtc as for your mini,but with jfet front stage-meaning on CCS for input diff pair and dedicated resistors.....look here for Bill's pdf about conversion;if you have further qstns,just ask
- Status
- Not open for further replies.