Unexpected simulation problems
I have encountered some unexpected simulation problems when running circuitmaker 2000 for this project. The problem manifests itself as instability, strange waveforms and gain issues after replacing current sources with real devices.
After taking a very long and hard look at it, I am suspecting that the circuit is a little hard for CM to analyze, and very susceptible to exact levels of bias (which cannot be accurately known at design time anyway due to device variation in all current sources). I am tempted to use active sense devices to control the current sources.
I guess it is time to stop playing and start building. The proof is in the pudding.
I am considering putting dual JFET's instead of IRF610's at the input -- this will definitely require cascoding and probably Zener crowbar protection. I an also toying with the idea of a tubed input which would be nice since tubes don't mind getting hot -- unlike JFET's. Both these approaches would likely yield better linearity.
I am also considering cascoding of the IRF610 input devices based on comments by Nelson Pass. However I don't really see the need for it as I am not expecting much variability in voltage across the 610 (it is already cascoded you might say) and power dissipation does not seem to be an issue either (unless you want to keep it cool with minimal heatsinking to reduce variability due to temperature variations). In fact, I would expect it to perform better with a higher voltage across it. Please comment if you have input.
Petter
I have encountered some unexpected simulation problems when running circuitmaker 2000 for this project. The problem manifests itself as instability, strange waveforms and gain issues after replacing current sources with real devices.
After taking a very long and hard look at it, I am suspecting that the circuit is a little hard for CM to analyze, and very susceptible to exact levels of bias (which cannot be accurately known at design time anyway due to device variation in all current sources). I am tempted to use active sense devices to control the current sources.
I guess it is time to stop playing and start building. The proof is in the pudding.
I am considering putting dual JFET's instead of IRF610's at the input -- this will definitely require cascoding and probably Zener crowbar protection. I an also toying with the idea of a tubed input which would be nice since tubes don't mind getting hot -- unlike JFET's. Both these approaches would likely yield better linearity.
I am also considering cascoding of the IRF610 input devices based on comments by Nelson Pass. However I don't really see the need for it as I am not expecting much variability in voltage across the 610 (it is already cascoded you might say) and power dissipation does not seem to be an issue either (unless you want to keep it cool with minimal heatsinking to reduce variability due to temperature variations). In fact, I would expect it to perform better with a higher voltage across it. Please comment if you have input.
Petter
Petter,
My sympathy on simulation problems. I've run into problems in the past, myself, which is why I tend to build rather than model.
I have in mind a possible alternate front end for the Aleph I'm building using 6DJ8s, although I'm going through with the stock version first (IRF9610s in the front end differential). What tubes were you thinking of using?
Grey
My sympathy on simulation problems. I've run into problems in the past, myself, which is why I tend to build rather than model.
I have in mind a possible alternate front end for the Aleph I'm building using 6DJ8s, although I'm going through with the stock version first (IRF9610s in the front end differential). What tubes were you thinking of using?
Grey
Types of tubes
I was thinking about using 6H30P dual russion military radar units -- basically 12AX7's on steroids.
They would require about 100V and 30mA. Perhaps your choice is a little more convenient. I am using these tubes in my X-Stax OTL electrostatic headphone design.
The nice thing about tubes is that they are more linear and are usually much closer in device matching than are semiconductors (not to mention FET's)
Petter
I was thinking about using 6H30P dual russion military radar units -- basically 12AX7's on steroids.
They would require about 100V and 30mA. Perhaps your choice is a little more convenient. I am using these tubes in my X-Stax OTL electrostatic headphone design.
The nice thing about tubes is that they are more linear and are usually much closer in device matching than are semiconductors (not to mention FET's)
Petter
For the record, I'd like to correct an apparent error in my earlier (4/2) post regarding makers of MOSFET "circlotron" amplifiers. I've just learned that Lamm uses complementary MOSFETs in the output stage of at least one model, which suggests that they don't use the circlotron after all. I'm still sure that BAT does, however, as I was told as much by VK himself a few years ago.
So Petter how is it going ?
Anything new with the X100 ?
Things have calmed down here for a while.
Is everybody busy with projects or everybody busy at work...
hmm hope I a not the only one not having much time lately for projects. If anything new please post.
Greetings to Petter and the rest of the guys here.
Anything new with the X100 ?
Things have calmed down here for a while.
Is everybody busy with projects or everybody busy at work...
hmm hope I a not the only one not having much time lately for projects. If anything new please post.
Greetings to Petter and the rest of the guys here.
promitheus,
I reported not long ago on water-cooled heat sinking for my Aleph 2 project(and a review of the sound thereof). At the moment I'm diverting to pick up on a project I left unfinished last fall, to wit, a tube phono stage w/passive RIAA. I was nearly done when I was waylaid by a few mundane problems around the house. Once I place an order in the next day or two, I should get in enough parts to finish the phono and build another Aleph, just for the heck of it. Then, more along the lines of the thread here, I'm still interested in the idea of melding an X front end to an Aleph rear as I mentioned above. Once I've got a spare Aleph to play with I can contrast and compare betwixt and between. Then a combination line stage/crossover. And in spare moments here and there, I'm going to make decent cabinetry for my mid/tweeter array (bought the MDF Friday). Then there's the oddball idea I've got for diddling a SOZ circuit, the hybrid amp I want to try (6922s or 6SN7s for the front, MOSFET rear--maybe push-pull, maybe Aleph-style), etc. etc. And while I'm ejoying Alephs so much, why not build a 1.2 to go along with my 2s? But, of course, I'd like to run the current up from .33A/device to .5A/device like the 2--that raises the possibility of cutting back on the output pairs from 12 to 8 for the same output capability, which would reduce the cumulative gate capacitance load seen by the front end.
Ahem.
Oh, and it's been busy at work, too...
Grey
P.S.: What's up with you? Anything interesting to report?
P.P.S.: Yo, Vince! Wake up, fella! How's the SOZ going? Say something once in a while.
I reported not long ago on water-cooled heat sinking for my Aleph 2 project(and a review of the sound thereof). At the moment I'm diverting to pick up on a project I left unfinished last fall, to wit, a tube phono stage w/passive RIAA. I was nearly done when I was waylaid by a few mundane problems around the house. Once I place an order in the next day or two, I should get in enough parts to finish the phono and build another Aleph, just for the heck of it. Then, more along the lines of the thread here, I'm still interested in the idea of melding an X front end to an Aleph rear as I mentioned above. Once I've got a spare Aleph to play with I can contrast and compare betwixt and between. Then a combination line stage/crossover. And in spare moments here and there, I'm going to make decent cabinetry for my mid/tweeter array (bought the MDF Friday). Then there's the oddball idea I've got for diddling a SOZ circuit, the hybrid amp I want to try (6922s or 6SN7s for the front, MOSFET rear--maybe push-pull, maybe Aleph-style), etc. etc. And while I'm ejoying Alephs so much, why not build a 1.2 to go along with my 2s? But, of course, I'd like to run the current up from .33A/device to .5A/device like the 2--that raises the possibility of cutting back on the output pairs from 12 to 8 for the same output capability, which would reduce the cumulative gate capacitance load seen by the front end.
Ahem.
Oh, and it's been busy at work, too...
Grey
P.S.: What's up with you? Anything interesting to report?
P.P.S.: Yo, Vince! Wake up, fella! How's the SOZ going? Say something once in a while.
I'm projecting a bit...
Well, I hate to say it, but I put it on a back-burner again! I've been thinking about another project for the past week or longer. I've been tossing it around as a possibility even longer, but gave up on it. What is it? I'm working on a DIY video projector. Crazy? Maybe. Impossible? No Way! The parts are out there, but few examples. It has been done. I'm putting it together sort of like a PC- in chunks. Lens here, light source there, LCD module here, ect...
There are some neat part available to regular people. I found a site that will sell a driver board for a LCD module that has a built-in line doubler, just like off the shelf projectors.
Granted, it won't look like a $20,000 Runco, but it will be fun to see what I can get for a few hundred bucks, and maybe learn a thing or two along the way.
Someone once told me it is the equivalent of building a car. After seeing what some of you guys did w/ the Aleph, anything is possible. Funny thing is, once again, heat removal is a problem.
It's one of those projects that keeps me up nights...you know the feeling. I have to try this.
Sorry to write in w/ something irrelavent. I'll be sure to let you all know if I succeed or not...and maybe post the plans!
See you!
Vince
Well, I hate to say it, but I put it on a back-burner again! I've been thinking about another project for the past week or longer. I've been tossing it around as a possibility even longer, but gave up on it. What is it? I'm working on a DIY video projector. Crazy? Maybe. Impossible? No Way! The parts are out there, but few examples. It has been done. I'm putting it together sort of like a PC- in chunks. Lens here, light source there, LCD module here, ect...
There are some neat part available to regular people. I found a site that will sell a driver board for a LCD module that has a built-in line doubler, just like off the shelf projectors.
Granted, it won't look like a $20,000 Runco, but it will be fun to see what I can get for a few hundred bucks, and maybe learn a thing or two along the way.
Someone once told me it is the equivalent of building a car. After seeing what some of you guys did w/ the Aleph, anything is possible. Funny thing is, once again, heat removal is a problem.
It's one of those projects that keeps me up nights...you know the feeling. I have to try this.
Sorry to write in w/ something irrelavent. I'll be sure to let you all know if I succeed or not...and maybe post the plans!
See you!
Vince
nearing completed design
Things have been crazy for me the last few months.
Nevertheless, I am posting this status message. I am nearing completion of the design and will have PCB's made up and (hopefully) professionally laid out -- that is if it is not too costly. Hopefully I will get this done in not too many weeks ...
I am getting some assistance from a pro designer handling grounding.
I do not plan to offer PCB's, nor making money out of this effort.
Keep up the good work, guys!
Petter
Things have been crazy for me the last few months.
Nevertheless, I am posting this status message. I am nearing completion of the design and will have PCB's made up and (hopefully) professionally laid out -- that is if it is not too costly. Hopefully I will get this done in not too many weeks ...
I am getting some assistance from a pro designer handling grounding.
I do not plan to offer PCB's, nor making money out of this effort.
Keep up the good work, guys!
Petter
That´s cool Peter. Good luck in completing your design. If you don´t sell the PCB´s, do you concider giving maybe the layout? It would be cool for the rest of us who don´t have the means to get a profesional designed PCB at least to make them ourselves with some help from you.
I am lately reading and searching around for cables. I have found some info abaout making the famous by now Cat5 speaker cables. I want to make some and try them.
I will probably post in the speaker forum about them.
Greetings to all.
Ilias Kamouzis
I am lately reading and searching around for cables. I have found some info abaout making the famous by now Cat5 speaker cables. I want to make some and try them.
I will probably post in the speaker forum about them.
Greetings to all.
Ilias Kamouzis
Near completion (yes, really)!
I have completed the circuit (long time ago).
I have been fighting with Circuitmaker (Traxmaker Demo version) which bombs out when you have too many devices, and spent a good few hours making the PCB.
It turned out as a single sided board with only 1 jumber -- yu-hu!
Now, I need to match devices, build the input stage and test. The circuit is in principle exactly the same as the "inner circuit" of what I presented on page 1 in this thread.
If the test is good, I will match output devices and build + post pictures and possibly even measurements. This will be extremely interesting (for me at least!)
Anybody else out there contemplating the same DIY project?
Petter
I have completed the circuit (long time ago).
I have been fighting with Circuitmaker (Traxmaker Demo version) which bombs out when you have too many devices, and spent a good few hours making the PCB.
It turned out as a single sided board with only 1 jumber -- yu-hu!
Now, I need to match devices, build the input stage and test. The circuit is in principle exactly the same as the "inner circuit" of what I presented on page 1 in this thread.
If the test is good, I will match output devices and build + post pictures and possibly even measurements. This will be extremely interesting (for me at least!)
Anybody else out there contemplating the same DIY project?
Petter
Yes, I'm thinking of building this amp cause i'm so tired of my Class A amp which draws 400W and heats up my small (9 squaremeter) listening room too much. Nice when its cold though
It would also be very fun building something like this!!
Please post the schematic and PCB for the amp, or mail it to me!
Thanks
fty@spray.se
It would also be very fun building something like this!!
Please post the schematic and PCB for the amp, or mail it to me!
Thanks
fty@spray.se
x series amplifier
Greetings Petter
I have been looking into the x series design as well and have a working design on the Electronics Workbench.
But I to had a lot for trouble getting it to work, going from ideal current sources to discrete current sources.
Anyway I look forward to hearing more from you once you have the amplifier built and running OK.
I would expect it will sound absolutely wonderfull.
Warm regards
Anthony Holton
http://www.aussieamplifiers.com
Greetings Petter
I have been looking into the x series design as well and have a working design on the Electronics Workbench.
But I to had a lot for trouble getting it to work, going from ideal current sources to discrete current sources.
Anyway I look forward to hearing more from you once you have the amplifier built and running OK.
I would expect it will sound absolutely wonderfull.
Warm regards
Anthony Holton
http://www.aussieamplifiers.com
Hi Anthony,
I've also encountered problems with EWB along the way, though fewer with later versions. Even at the V5.12 level (the last revision prior to to MultiSim, I believe), some of their P-channel MOSFET models just don't seem to work.
I've found the IRF9120 and 9520 models least troublesome among those I've tried in these types of circuits. I've also found that the IRF130/9130 complementary pair gives fewer problems in some cases than the alternatives.
Don't know if this addresses your present difficulties, but thought I should mention it as it has made the simulation phase of my investigations less frustrating.
BTW, I enjoy visiting your web site!
I've also encountered problems with EWB along the way, though fewer with later versions. Even at the V5.12 level (the last revision prior to to MultiSim, I believe), some of their P-channel MOSFET models just don't seem to work.
I've found the IRF9120 and 9520 models least troublesome among those I've tried in these types of circuits. I've also found that the IRF130/9130 complementary pair gives fewer problems in some cases than the alternatives.
Don't know if this addresses your present difficulties, but thought I should mention it as it has made the simulation phase of my investigations less frustrating.
BTW, I enjoy visiting your web site!
Howdy, folks...
"Rediscovered" this forum just a few days ago..
Have been reading the posts in this thread with the utmost of interest.
I too downloaded the supersymmetry patent some time ago, and have been scratching my head over it, the Aleph's, A-75 and the likes for some time now. I seriously concider to go along with an X clone.....IF I can find the X-files......
To Petter...
tried to download the files from your "file cabinet" ( MSN link)- but with no luck.....
Something tells me that we possibly live and work in the same region ( well- everything is relative..??) .........if you are interested...drop me an E-mail...
"Rediscovered" this forum just a few days ago..
Have been reading the posts in this thread with the utmost of interest.
I too downloaded the supersymmetry patent some time ago, and have been scratching my head over it, the Aleph's, A-75 and the likes for some time now. I seriously concider to go along with an X clone.....IF I can find the X-files......
To Petter...
tried to download the files from your "file cabinet" ( MSN link)- but with no luck.....
Something tells me that we possibly live and work in the same region ( well- everything is relative..??) .........if you are interested...drop me an E-mail...
PSPICE data
Petter,
On your recommendation I’m trying Circuitmaker and am impressed with the results, based on my very brief experience, so far. I’m used to the “suck it and see” method of circuit design so this is my first exposure to this type of simulator. Unfortunately I cannot seem to email you, so post this message hoping you could advise where you source your PSPICE data for the MOSFETs?
Please feel free to email me if you prefer, however I will be in Frankfurt for a few days so will reply when able.
Cheers,
Pete Fleming
Petter,
On your recommendation I’m trying Circuitmaker and am impressed with the results, based on my very brief experience, so far. I’m used to the “suck it and see” method of circuit design so this is my first exposure to this type of simulator. Unfortunately I cannot seem to email you, so post this message hoping you could advise where you source your PSPICE data for the MOSFETs?
Please feel free to email me if you prefer, however I will be in Frankfurt for a few days so will reply when able.
Cheers,
Pete Fleming