Agree that high frequency, in fact stability, is where the difficulty is...
For some reasons, i settle with manageable slew rates, no more than
60/80VuS for a 100W amp, and that is with mosfets power stage,
as it allow to have a totally device independant behaviour since
the caracteristics are defined by the compensation and feedback loops.
cheers
The Puppies are almost there (PS50 + PB60X2)
On another building "spree" , 2 of those (below) and I have a new 4.1 system (PB250H is the .1 😀) . On 1/1, the website will be back up with handy links (No more directory searching) and there will be so many amp projects .... All will be built and tested/ abused with pictures , Something for everyone.
Shown below (attachment 1/2) is the economical "mongrel" (under $60 power supply - trafo + 1 PB60X2 + 2 BX1.3's) , A full stereo 60w/ch BX and the small PS50 unregulated power supply is shown. I have just built my 23-24th amp in the last 6 weeks , so it is getting easy and better as I go along. Since I learned it on the forum , I might as well share it back. 🙂
I also must admit , watching MJL do his thing was both the example and inspiration for the 10-15 boards a night that I do sometimes (perfectly - no pits/undercut).
Edit : I must add ... below is my REAL simulator !!!
OS
On another building "spree" , 2 of those (below) and I have a new 4.1 system (PB250H is the .1 😀) . On 1/1, the website will be back up with handy links (No more directory searching) and there will be so many amp projects .... All will be built and tested/ abused with pictures , Something for everyone.
Shown below (attachment 1/2) is the economical "mongrel" (under $60 power supply - trafo + 1 PB60X2 + 2 BX1.3's) , A full stereo 60w/ch BX and the small PS50 unregulated power supply is shown. I have just built my 23-24th amp in the last 6 weeks , so it is getting easy and better as I go along. Since I learned it on the forum , I might as well share it back. 🙂
I also must admit , watching MJL do his thing was both the example and inspiration for the 10-15 boards a night that I do sometimes (perfectly - no pits/undercut).
Edit : I must add ... below is my REAL simulator !!!
OS
Attachments
Last edited:
Oz
Your new website layout is brilliant,
thanks,
Pete.
PS Cant wait for your new years surprises.
Your new website layout is brilliant,
thanks,
Pete.
PS Cant wait for your new years surprises.
Thanx...
Not brilliant , just simple. Yes, on 1/1, I will give everyone a BJT "overload".man... I have a ton of artwork (and amps). I just might create a "real" interactive website that comes off of the standard one .. the possibilities are endless , lots of bandwidth .... many terrabytes. 🙂
PS , I am almost out of solder , FR-4 , parts... whoahh ! But still , I have lots of amps (need more speakers)
OS
All done for today , both power supplies, Zappp ...
The PS50 and PS100 are finalized in sprint perfection. REAL circuits .. NO simulations (Below 1/2). In the mongrel root folder.
Tonight , maybe tomorrow .. the PB250H (mine) and the PB60X2 stereo board.. 🙂
OS
The PS50 and PS100 are finalized in sprint perfection. REAL circuits .. NO simulations (Below 1/2). In the mongrel root folder.
Tonight , maybe tomorrow .. the PB250H (mine) and the PB60X2 stereo board.. 🙂
OS
Attachments
A 1 inch wire is 25nH, so 100nH is just a 4 inch wire... Maybe 100uH was the goal...?
Yeah, new years and all that...
- keantoken
Yeah, new years and all that...
- keantoken
Nothing except reduce the G1 charging pulses to G2 by a factor of at least 4 , this was Andrew T's idea and it works (checked it with O scope). I should use a larger (longer ) piece of wire. This effect is seen at "nuclear volumes". If some one either does not like it or doesn't understand it , jumper the dang thing.. All I know I have 0 hum ,0 noise, and as much power as I would ever need. Here come the copz !! 😀
New year- old year- same year- one year older ... bahhhhh! 🙄
OS
If AndrewT suggested it, it must be true! 😀
Good luck with all your endeavors in the new year!
🙂
Good luck with all your endeavors in the new year!
🙂
Okay, but doesn't this also cause ground to "shudder" in relation to the rails? What was the problem? Also in your PS100 schematic, the resistors for the LEDs are unequal.
- keantoken
- keantoken
Thanks , john. I hope you understand I am NOT the GEB (golden ear brigade), and am even the sworn enemy of the "audiophool ripoff " . Better stuff can be had without silver wire and all that hoohaa. But some design decisions do pay off BIGTIME. I am playin' with my new years "present" (below 1 - that's my audio source)the kids never saw one of them (2 -listen to heart and trippin' on the graphics). 😀
OS
Attachments
LED resistors , Ha ha .. so the blue ones don't blind you. 😀 Keen ,you speculate on the grounding ... it is superior. You can see the charging pulses on G1 , you move the probe to G2 you see much smaller ones. That's why I did it. I left the board "open ended" to just take a jumper in case andrew's advice was lame.
I was trying to actually reduce the scope visible pulses even as I was hum free to start with. You don't see these effects on "iddy biddy amps" but at 10A short term demands, you do. I like it LOUD.
OS
Thanks for the credit, but as usual with my suggestions, it's not my idea. It is reported in the Forum and I just pass on what works for me.
I am not clever nor inventive enough to come up with "new" ways. I just learn to sift carefully and ask when I don't understand.
I am not clever nor inventive enough to come up with "new" ways. I just learn to sift carefully and ask when I don't understand.
PB60X2 survives NEW YEAR blowout.
Your the "ground man" andrew !! 😎
Our newest offering , the first one of 2011 .. is the "poor mans" output stage. Nothing fancy here , just a simple EF2 / Vbe multiplier and the "bare minimum" CRC to support any of the voltage modules. Ran the PB60X2 w/BX1.3 on the kitchen table (picture 1), clipping it and everything into a pair of 8" 2-way loudspeakers. A/B'ed it with a 80w/ch sherwood receiver ... NO contest. 30 visitors were in awe of the "poor man's DIY amp".
First time I tried the excellent Sanken 2SC3263 / 2SA1294 pair (picture 2) , they handled magnificently !! The "PB60X2 .zip" is a complete package (picture 3) with artwork/pictures/BOM , in the "mongrel Amplifier projects" folder (middle button) .
The PB250H, (my baby) is next to be released , it got the party test as well.
OS
Your the "ground man" andrew !! 😎
Our newest offering , the first one of 2011 .. is the "poor mans" output stage. Nothing fancy here , just a simple EF2 / Vbe multiplier and the "bare minimum" CRC to support any of the voltage modules. Ran the PB60X2 w/BX1.3 on the kitchen table (picture 1), clipping it and everything into a pair of 8" 2-way loudspeakers. A/B'ed it with a 80w/ch sherwood receiver ... NO contest. 30 visitors were in awe of the "poor man's DIY amp".
First time I tried the excellent Sanken 2SC3263 / 2SA1294 pair (picture 2) , they handled magnificently !! The "PB60X2 .zip" is a complete package (picture 3) with artwork/pictures/BOM , in the "mongrel Amplifier projects" folder (middle button) .
The PB250H, (my baby) is next to be released , it got the party test as well.
OS
Attachments
Hey OS, maybe you should experiment with the packaged Darlingtons from Sanken. That could be the ultimate "poor man's"... Plus no inductance between the driver and output, maybe more stable, maybe you can squeeze some extra speed...
BTW I've been looking at parasitics and thermal stuff, and I'm wondering about carbon composition resistors. At large voltage swings they distort, but they have no series inductance unlike film resistors. Is it possible that an inductive film resistor used as a gate stopper could be less effective than a carbon comp in the same position? Does this apply to degeneration resistors on an LTP? And in other places? I haven't been able to find any inductance measurements for film resistors though.
- keantoken
BTW I've been looking at parasitics and thermal stuff, and I'm wondering about carbon composition resistors. At large voltage swings they distort, but they have no series inductance unlike film resistors. Is it possible that an inductive film resistor used as a gate stopper could be less effective than a carbon comp in the same position? Does this apply to degeneration resistors on an LTP? And in other places? I haven't been able to find any inductance measurements for film resistors though.
- keantoken
Poor man ?.......
I would prefer Sanken s darlingtons than the usual Onsemi
MJE1503X/MJLXXXX double EF arrangement...
I had 5 pairs of sanken darlingtons. #1- they are 2X as expensive ( the SC/A's above are under 2$ apiece) ,# 2 - Darlingtons SUCK , I won't compromise like the cheap junk velleman kits... YUK! 🙁 # 3 STABILITY ... that EF2 above was being shorted out by drunks , had piezo tweeters hooked to it , 20 foot lampcord speaker cables .. ROCK SOLID ! Had a sony with darlingtons , probe in the wrong place , Zaaaap.
Carbon comp. resistors are good for base-stoppers and inside the OP inductor (I do this sometimes). For the voltage stage, thin film resistors are closer tolerance /better temp stability. This is best , especially for the IPS. Some OEM's do specify inductance as their products are used for high speed digital ... Ohmega News:😛ress Releases
For audio , I don't think we have much to worry about , the traces are a much larger factor here ... keep them short. 😀
OS
I think the factor is larger than you think. A wire alone has 25nH/inch. When you coil the wire, the inductance increases by the square of turns. So a single film resistor could effectively have more than an inch of trace inductance in it. What now about keeping short traces?
https://secure.wikimedia.org/wikipedia/en/wiki/Zobel_network#Zobel_networks_and_loudspeaker_drivers
- keantoken
https://secure.wikimedia.org/wikipedia/en/wiki/Zobel_network#Zobel_networks_and_loudspeaker_drivers
- keantoken