mpmarino said:
As long as you bury them for 3, or 7, or 12 days, you'll be fine.😉 Kentucky-bluegrass is the best lawn to use. Time it so that you unearth the FETs on a full moon.😀 They'll run cooler that way.
Another transformer question ... sorry!
Hello Folks,
I can purchase 18Volt Dual secondary 300Va transformers at half price on a "run-out" special.
My plan was to build my channels of Aleph-X simple and small for a set of active speakers, so the 15V rail, 4 mosfets per channel version would suit my purposes fine. Unfortunately, the rail voltage on the above transformers will be approximately 24 to 25 volts, which normally would translate to a humungous Aleph-X amp with lots of mosfets per channel.
Two kind contributors have suggested that nearly all the Aleph variations (both normal and X-ed) can be built using 18V secondaries, and the lower power versions can be done by reducing bias ... I presume by recalculating the mosfet Source resistors and fiddling with the "fine adjustment" bias pot.
A couple of things pop into mind, however:
1) "More bias sounds better" is a strong message I get from these threads (but I presume that the output mosfets can still be chewing up a fair amount of electricity) - but will I lose out on sound quality overall?
2) That I might be trying to dissipate a lot of energy/voltage without increasing the number of mosfets - and that the energy must go somewhere, so:
a) Would I have to increase the power rating of the Source resistors, and/or
b) Do I stand a chance of stewing the Constant Current control circuit, or
c) Is this all just a bad idea and I should just get some 12 V secondary transformers and be done with it?
Another reason I wanted to keep the number of mosfets low, is that I was going to have a go at a 2SJ109BL front end, and those little critters apparently cannot drive too many big Mosfets. If I were to go with more mosfets, it appears to me that I would be one of the first going the way of parallelling 2SJ109's or putting in a cascoded front end ... and I don't really want to be the first or second doing anything at all! (I only put in Windows XP a year ago
I know there have been lots of transformer discussions, but I can find none which appear to actually cover this problem.
With thanks,
George.
Hello Folks,
I can purchase 18Volt Dual secondary 300Va transformers at half price on a "run-out" special.
My plan was to build my channels of Aleph-X simple and small for a set of active speakers, so the 15V rail, 4 mosfets per channel version would suit my purposes fine. Unfortunately, the rail voltage on the above transformers will be approximately 24 to 25 volts, which normally would translate to a humungous Aleph-X amp with lots of mosfets per channel.
Two kind contributors have suggested that nearly all the Aleph variations (both normal and X-ed) can be built using 18V secondaries, and the lower power versions can be done by reducing bias ... I presume by recalculating the mosfet Source resistors and fiddling with the "fine adjustment" bias pot.
A couple of things pop into mind, however:
1) "More bias sounds better" is a strong message I get from these threads (but I presume that the output mosfets can still be chewing up a fair amount of electricity) - but will I lose out on sound quality overall?
2) That I might be trying to dissipate a lot of energy/voltage without increasing the number of mosfets - and that the energy must go somewhere, so:
a) Would I have to increase the power rating of the Source resistors, and/or
b) Do I stand a chance of stewing the Constant Current control circuit, or
c) Is this all just a bad idea and I should just get some 12 V secondary transformers and be done with it?
Another reason I wanted to keep the number of mosfets low, is that I was going to have a go at a 2SJ109BL front end, and those little critters apparently cannot drive too many big Mosfets. If I were to go with more mosfets, it appears to me that I would be one of the first going the way of parallelling 2SJ109's or putting in a cascoded front end ... and I don't really want to be the first or second doing anything at all! (I only put in Windows XP a year ago
I know there have been lots of transformer discussions, but I can find none which appear to actually cover this problem.
With thanks,
George.
you can have some voltage regolator ic like 7815 or 7818 follow by a big transisor put one capasitor in front of it and then put the rest in the buck of it that we you don't loss the sound quality there 2n3055 will work
Pass DIY Addict
Joined 2000
Paid Member
Another idea for your 18v transformers is to use a choke input power supply. After rectification, send the power directly into a choke and then to the caps. This will reduce the 18v secondary to about 16v, thus eliminating the need to change anything in Grey's original design.
Just trying to point out another solution for you.
Eric
Just trying to point out another solution for you.
Eric
Re: Another transformer question ... sorry!
Ah, the perennial problem: How to flog a given transformer (feel free to substitute "heatsink") into doing what you want it to do. And, yep, it's been covered pretty thoroughly, but here goes...
--Reducing bias. Coarse bias adjustment is handled by choice of Source resistor value. Fine adjustment via the pots. You can either raise or lower bias according to your needs. Quiescent power dissipation calculation is trivial: Count on about .5V across the Source resistor. .5V/R gives you the quiescent bias current. That current times .5V gives you the power dissipated in the resistor. For any rational design the 3W Panasonic "blue" resistors will do just fine.
--Will it change the sound quality? Obviously. If we could get class A sound with less bias, then full class A would be just a laboratory curiosity. Whether this is a deal killer is up to the individual. I have noted in the past some bias experiments I did on the Alephs. Lean out the bias and it starts sounding thin and "hi-fi," or perhaps I should say "mid-fi." More bias rounds out the sound and makes things better...and better...and better...but keep an eye on the SOA for the output devices.
--Higher voltage rails also help. That's been covered too. The more voltage, the better. The 15V rails I specified for the initial project were just for example. Will the Aleph-X work with 15V rails? Of course. But there are improvements to be had by increasing the rails to higher voltages. It's pretty clear from the data sheets that the MOSFET capacitances decrease with increasing voltage. This is good. There are other benefits, too.
--The Aleph current source will not spontaneously explode at higher voltages. Note that the Aleph 1 ran 60V rails--considerably higher than you're talking about. It's not topologies that die...it's parts.
--Asking me about how much current it takes to drive a MOSFET is like asking Half-Ton Man what constitutes a square meal. I want lots of drive. Lots. I have my reasons, but freely admit that I'm verging on being considered a member of the lunatic fringe. Ask others how many MOSFETs you can drive with a single JFET and you'll get entirely different answers from the ones I'd give. Nelson, I think, would say that a single '109BL could drive at least two or three devices comfortably. Possibly four. Me? One. Two at most. (Yes, it depends on the MOSFET, but that's yet another can of worms and Logan isn't cooperative this morning.)
Grey
GeorgeBoles said:
1) "More bias sounds better" is a strong message I get from these threads (but I presume that the output mosfets can still be chewing up a fair amount of electricity) - but will I lose out on sound quality overall?
2) That I might be trying to dissipate a lot of energy/voltage without increasing the number of mosfets - and that the energy must go somewhere, so:
a) Would I have to increase the power rating of the Source resistors, and/or
b) Do I stand a chance of stewing the Constant Current control circuit, or
c) Is this all just a bad idea and I should just get some 12 V secondary transformers and be done with it?
Another reason I wanted to keep the number of mosfets low, is that I was going to have a go at a 2SJ109BL front end, and those little critters apparently cannot drive too many big Mosfets. If I were to go with more mosfets, it appears to me that I would be one of the first going the way of parallelling 2SJ109's or putting in a cascoded front end ... and I don't really want to be the first or second doing anything at all! (I only put in Windows XP a year ago
Ah, the perennial problem: How to flog a given transformer (feel free to substitute "heatsink") into doing what you want it to do. And, yep, it's been covered pretty thoroughly, but here goes...
--Reducing bias. Coarse bias adjustment is handled by choice of Source resistor value. Fine adjustment via the pots. You can either raise or lower bias according to your needs. Quiescent power dissipation calculation is trivial: Count on about .5V across the Source resistor. .5V/R gives you the quiescent bias current. That current times .5V gives you the power dissipated in the resistor. For any rational design the 3W Panasonic "blue" resistors will do just fine.
--Will it change the sound quality? Obviously. If we could get class A sound with less bias, then full class A would be just a laboratory curiosity. Whether this is a deal killer is up to the individual. I have noted in the past some bias experiments I did on the Alephs. Lean out the bias and it starts sounding thin and "hi-fi," or perhaps I should say "mid-fi." More bias rounds out the sound and makes things better...and better...and better...but keep an eye on the SOA for the output devices.
--Higher voltage rails also help. That's been covered too. The more voltage, the better. The 15V rails I specified for the initial project were just for example. Will the Aleph-X work with 15V rails? Of course. But there are improvements to be had by increasing the rails to higher voltages. It's pretty clear from the data sheets that the MOSFET capacitances decrease with increasing voltage. This is good. There are other benefits, too.
--The Aleph current source will not spontaneously explode at higher voltages. Note that the Aleph 1 ran 60V rails--considerably higher than you're talking about. It's not topologies that die...it's parts.
--Asking me about how much current it takes to drive a MOSFET is like asking Half-Ton Man what constitutes a square meal. I want lots of drive. Lots. I have my reasons, but freely admit that I'm verging on being considered a member of the lunatic fringe. Ask others how many MOSFETs you can drive with a single JFET and you'll get entirely different answers from the ones I'd give. Nelson, I think, would say that a single '109BL could drive at least two or three devices comfortably. Possibly four. Me? One. Two at most. (Yes, it depends on the MOSFET, but that's yet another can of worms and Logan isn't cooperative this morning.)
Grey
any bords left
Hi, Is there anyone that has 2 or 4 bords left they will sell or maby a pdf file of the bord layout so i can make my one
Hi, Is there anyone that has 2 or 4 bords left they will sell or maby a pdf file of the bord layout so i can make my one
Re: any bords left
Theoretically there are hundreds of un-used boards laying around, but I guess a search for boards with the add on of that you will put up with that they have been soldered some, would help your situation....and you would get a lot more response if you also post in the trading post forum...
Cheers
Magura 🙂
skjold said:
Theoretically there are hundreds of un-used boards laying around, but I guess a search for boards with the add on of that you will put up with that they have been soldered some, would help your situation....and you would get a lot more response if you also post in the trading post forum...
Cheers
Magura 🙂
....but do yourself a favour and stay clear of Kristians boards (his site is called something like KK-pcb design) as I am yet to see one that actually have made an ax that works based on those boards.
Magura 🙂
Magura 🙂
Transformers
Hi folks,
Thanks for the replies to my transformer question on the Aleph-X:
I have buckets of heat-sink capacity ... perhaps dangerous to say, but it feels like it anyway.
I have purchased a "lifetime's supply" of the 18V secondary transformers. Using the information on this thread, it appears I can run 24V rails and run a lot of bias through the power mosfets and still have about 32watts dissipation per mosfet (using 4 mosfets per channel) - which should not be too bad, I imagine.
If I smoke my output mosfets, I will parallel them up and abandon the Jfet long-tailed pair input stage for the time being for mid-range and/or the tweeter, or perhaps just make an Aleph-J type amplifier for the tweeters. (Once I have a working Aleph-X and I have enjoyed the results for a while, then I will re-consider the possiblities of parallelling the input jfets or cascoding them.)
(From what I can see, the "Safe Operating Area" graphs on the IRF datasheets appear to only have a microsecond to millisecond "on" phase, which is not what we are doing. I am using the 30 watt guideline from this and other threads, and the "dreaded" spreadsheets.)
Thanks,
George.
Hi folks,
Thanks for the replies to my transformer question on the Aleph-X:
I have buckets of heat-sink capacity ... perhaps dangerous to say, but it feels like it anyway.
I have purchased a "lifetime's supply" of the 18V secondary transformers. Using the information on this thread, it appears I can run 24V rails and run a lot of bias through the power mosfets and still have about 32watts dissipation per mosfet (using 4 mosfets per channel) - which should not be too bad, I imagine.
If I smoke my output mosfets, I will parallel them up and abandon the Jfet long-tailed pair input stage for the time being for mid-range and/or the tweeter, or perhaps just make an Aleph-J type amplifier for the tweeters. (Once I have a working Aleph-X and I have enjoyed the results for a while, then I will re-consider the possiblities of parallelling the input jfets or cascoding them.)
(From what I can see, the "Safe Operating Area" graphs on the IRF datasheets appear to only have a microsecond to millisecond "on" phase, which is not what we are doing. I am using the 30 watt guideline from this and other threads, and the "dreaded" spreadsheets.)
Thanks,
George.
Transformers
Hi folks,
Thanks for the replies to my transformer question on the Aleph-X:
I have buckets of heat-sink capacity ... perhaps naive to say, but it feels like it anyway.
I have purchased a "lifetime's supply" of the 18V secondary transformers. Using the information on this thread, it appears I can run approximately 24V rails (or a little less with CRC or highish resistance "L" CLC power supply), run the "correct amount" of bias for 6 and 8 ohm speakers, and still have a bit less than 32 watts dissipation per mosfet (using 4 mosfets per channel) - which should not be too bad, I imagine and hope. (Blimey, I really hope I got that calculation right🙂)
If I smoke my output mosfets, I will parallel them up and abandon the Jfet long-tailed pair input stage for the time and make "normal" Aleph-X versions for mid-range and/or the tweeter; or perhaps make an Aleph-J type amplifier for the tweeters. (Once I have a working Aleph-X and I have enjoyed the results for a while, then I will re-consider the possiblities of parallelling the input jfets or cascoding them.)
(From what I can see, the "Safe Operating Area" graphs on the IRF datasheets appear to only have a microsecond to millisecond "on" phase, which is not what we are doing. I am using the 20 - 30 watt guideline from this and other threads, and the "dreaded" spreadsheets.)
Thanks,
George.
Hi folks,
Thanks for the replies to my transformer question on the Aleph-X:
I have buckets of heat-sink capacity ... perhaps naive to say, but it feels like it anyway.
I have purchased a "lifetime's supply" of the 18V secondary transformers. Using the information on this thread, it appears I can run approximately 24V rails (or a little less with CRC or highish resistance "L" CLC power supply), run the "correct amount" of bias for 6 and 8 ohm speakers, and still have a bit less than 32 watts dissipation per mosfet (using 4 mosfets per channel) - which should not be too bad, I imagine and hope. (Blimey, I really hope I got that calculation right🙂)
If I smoke my output mosfets, I will parallel them up and abandon the Jfet long-tailed pair input stage for the time and make "normal" Aleph-X versions for mid-range and/or the tweeter; or perhaps make an Aleph-J type amplifier for the tweeters. (Once I have a working Aleph-X and I have enjoyed the results for a while, then I will re-consider the possiblities of parallelling the input jfets or cascoding them.)
(From what I can see, the "Safe Operating Area" graphs on the IRF datasheets appear to only have a microsecond to millisecond "on" phase, which is not what we are doing. I am using the 20 - 30 watt guideline from this and other threads, and the "dreaded" spreadsheets.)
Thanks,
George.
PCB Boards Aleph-X-V2.2
Ian if you are able to could you guide me to other people who are working on the Aleph-X-V2.2 along with yourself so I can find their postings.
Ian if you are able to could you guide me to other people who are working on the Aleph-X-V2.2 along with yourself so I can find their postings.
Aleph-X-V2.2
I am looking for some information from anyone because I have only just found out about the Aleph-X Projects. The most interesting one(s) I have found are the "Grey Rollins Aleph-X because it is well documented, however it is not as interesting as the Ballanced-PP-AlephCS(big values) ,but I have not come accross usefull documentation for it, and my favorate Aleph-X that I intend on working through is by Ian calledAleph-X-V2.2 posted from 24June07 , I have found some documentation on this prototype(s) schematic but I am still not very close to understanding all of the components relative significance to the entire circuit.
I know that i am not very experianced but I believe that Aleph-X-2.2 has a ballanced Cascode Differential Input using JFET(s), but I dont know where the current source is for it, and what are Q12 & Q17 & Q18 & Q9 purposes, I think they might have a similar purpose, and I think that Q15 & Q16 &Q14 & Q22 are a pushpull output stage of the Aleph-X-V2.2, and are Q13 & Q20 part of the variable resisters VR1 & VR4 that set the AC to 50% ????
Please can someone contact me and give me some help finding the information i am looking for because this is the most interesting project I have come accross lately and am dying to build a Prototype Aleph-X-2.2series amplifier mono blocks at 100watts each
Thank You for your help
scatterbrain001
I am looking for some information from anyone because I have only just found out about the Aleph-X Projects. The most interesting one(s) I have found are the "Grey Rollins Aleph-X because it is well documented, however it is not as interesting as the Ballanced-PP-AlephCS(big values) ,but I have not come accross usefull documentation for it, and my favorate Aleph-X that I intend on working through is by Ian calledAleph-X-V2.2 posted from 24June07 , I have found some documentation on this prototype(s) schematic but I am still not very close to understanding all of the components relative significance to the entire circuit.
I know that i am not very experianced but I believe that Aleph-X-2.2 has a ballanced Cascode Differential Input using JFET(s), but I dont know where the current source is for it, and what are Q12 & Q17 & Q18 & Q9 purposes, I think they might have a similar purpose, and I think that Q15 & Q16 &Q14 & Q22 are a pushpull output stage of the Aleph-X-V2.2, and are Q13 & Q20 part of the variable resisters VR1 & VR4 that set the AC to 50% ????
Please can someone contact me and give me some help finding the information i am looking for because this is the most interesting project I have come accross lately and am dying to build a Prototype Aleph-X-2.2series amplifier mono blocks at 100watts each
Thank You for your help
scatterbrain001
Hi,
The forum is quiet this summer; I suggest you continue reading and experimenting. Get your project underway and start a thread showing your progress. People in the "know" are more inclined to get on-board if they see active participation--not to mention, your efforts to generate excitement.
Ian has offered an excellent start. The Aleph-X is in several power stages. Follow those threads.
I'm busy finishing my house in order to get my "final" inspection and have drifted away from DIY Audio and am up to my neck in DIY Home-building!🙂 I love it as much as I love building my amplifiers.
Best of luck,
John
The forum is quiet this summer; I suggest you continue reading and experimenting. Get your project underway and start a thread showing your progress. People in the "know" are more inclined to get on-board if they see active participation--not to mention, your efforts to generate excitement.
Ian has offered an excellent start. The Aleph-X is in several power stages. Follow those threads.
I'm busy finishing my house in order to get my "final" inspection and have drifted away from DIY Audio and am up to my neck in DIY Home-building!🙂 I love it as much as I love building my amplifiers.
Best of luck,
John
scatterbrain001 said:
I'm working on this but I've been on holiday for the last two weeks so haven't made much recent progress. I will post as soon as I am able.
Ian.
