SI,
I'm already a writer. Been one for fifteen years or so. If you read science fiction, I'll have a Victor & Martin story in the June (I think) issue of Analog...and a story which uses electronics as a plot device, no less. www.analogsf.com
Books require a tremendous commitment of time. No gots. I've been trying to pull together a fixup of my Darwin's Children series for several years now, but it's a battle to get large blocks of uninterrupted time. Incidentally, do not confuse my title Darwin's Children with a recent book by an author whom I shall not name. I asked him not to use that title, but was basically told to take a hike. As far as I can tell I originated the phrase. Since then, it's been used for at least one song, one poem, and the aforementioned book. No, I don't have any legal way to stop them from doing that.
arold19,
The 3W blue Panasonic metal film resistors are ideal for the job. Get 'em at Digikey. As SI says, the rest can be 1/4 or 1/2W, whatever makes you happy.
Oh, and uli...you get bonus points for taking out the entire block...
Grey
I'm already a writer. Been one for fifteen years or so. If you read science fiction, I'll have a Victor & Martin story in the June (I think) issue of Analog...and a story which uses electronics as a plot device, no less. www.analogsf.com
Books require a tremendous commitment of time. No gots. I've been trying to pull together a fixup of my Darwin's Children series for several years now, but it's a battle to get large blocks of uninterrupted time. Incidentally, do not confuse my title Darwin's Children with a recent book by an author whom I shall not name. I asked him not to use that title, but was basically told to take a hike. As far as I can tell I originated the phrase. Since then, it's been used for at least one song, one poem, and the aforementioned book. No, I don't have any legal way to stop them from doing that.
arold19,
The 3W blue Panasonic metal film resistors are ideal for the job. Get 'em at Digikey. As SI says, the rest can be 1/4 or 1/2W, whatever makes you happy.
Oh, and uli...you get bonus points for taking out the entire block...
Grey
Like the most commoners I never cared much for reading of any kind, even a machine manual puts me to deep coma. These even has pictures. Since I started the DIY amp project I did a book worth of reading and I like it.
Even when pictures are as rare as me reading.
Ironically, In your case "The survival of the fittest" comes to mind or is it "The survival of the one with most expensive lawyers", I don't know. Good luck with the book and keep us informed. For all it's worth, I think you are an asset to this forum.
Thanks,
SAAD//
Even when pictures are as rare as me reading.Ironically, In your case "The survival of the fittest" comes to mind or is it "The survival of the one with most expensive lawyers", I don't know. Good luck with the book and keep us informed. For all it's worth, I think you are an asset to this forum.
Thanks,
SAAD//
SI,
Its sad that you hate reading. while I'm not a really good reader...some comprenhension problems and such so I sometimes need to re-read things over a couple of times... I still view reading as a learning experience for the most part. Manuals are a great learning tool and I read and study many...pictures or not.
Mark
Its sad that you hate reading. while I'm not a really good reader...some comprenhension problems and such so I sometimes need to re-read things over a couple of times... I still view reading as a learning experience for the most part. Manuals are a great learning tool and I read and study many...pictures or not.
Mark
SI,
You're probably pulling my leg, but I had a story called Survival of the Fittest back about ten years ago.
Manuals are good, too. Textbooks. Mysteries. Spy novels. Oddly, I don't read much science fiction any more. I don't care for the way the field is going. Strange, but there it is.
Reading is good in a number of ways. I think I heard recently that they've completed a study that indicates that reading (hence keeping your mind active) can reduce your chances of getting Alzheimers (that's probably not how it's spelled, but I'm too tired to look it up). Who knows what the mechanism is. Kinda like audio...there are things that you can observe, but you can't see why they work. Someone will figure it out one of these days.
Grey
You're probably pulling my leg, but I had a story called Survival of the Fittest back about ten years ago.
Manuals are good, too. Textbooks. Mysteries. Spy novels. Oddly, I don't read much science fiction any more. I don't care for the way the field is going. Strange, but there it is.
Reading is good in a number of ways. I think I heard recently that they've completed a study that indicates that reading (hence keeping your mind active) can reduce your chances of getting Alzheimers (that's probably not how it's spelled, but I'm too tired to look it up). Who knows what the mechanism is. Kinda like audio...there are things that you can observe, but you can't see why they work. Someone will figure it out one of these days.
Grey
The Panasonic resistors are not true non-ferrous metal leads or they have some steel or iron in them. These types of resistors should be avoided for audio as the lead came become magnetized, inductive and harder to solder. You can tell if a resistor or capacitor has these types of leads with a magnet, if it attracts then you should not use them.
My recommendation is to use Dales-Vishay resistors use RN55 or RN60. I refer the RN60 and feel they sound just a little better. You can get these resistor at www.mouser.com or from www.newark.com.
My recommendation is to use Dales-Vishay resistors use RN55 or RN60. I refer the RN60 and feel they sound just a little better. You can get these resistor at www.mouser.com or from www.newark.com.
SI
I changed the source resistors to .68 ohm and added 2 more fets per side. I also put pots in for R 19 and R 21 so I could vary the Bias and AC current gain. The rest is stock Aleph 2. My goal was 200 W into 4 ohms without running out of current. And by god, they'll heat up a room.
I'm gettin ready to move into my new house with a listening room upstairs. I had the electrician add a 220V 20A circuit for these babys.
I changed the source resistors to .68 ohm and added 2 more fets per side. I also put pots in for R 19 and R 21 so I could vary the Bias and AC current gain. The rest is stock Aleph 2. My goal was 200 W into 4 ohms without running out of current. And by god, they'll heat up a room.
I'm gettin ready to move into my new house with a listening room upstairs. I had the electrician add a 220V 20A circuit for these babys.
Bias is set by the source resistors on the current source (positive half) and adjusted by r 19. lowering resistance lowers bias. Nelson suggested (and I followed) using a pot and listen and measure. If you like, replace with a resistor after you find what you like.
I think the current gain is set by the bank of resistor between the speaker and the output rails. It is adjused buy r21. I don't recall what the relation is. But again, put in a pot and a resistor so you can vary from around 30% to 300% of original value and play with it.
I dropped the source resistors from 6 @ 1 ohm to 8 @ .68 ohm to roughly half the impeadance. So my bias should be double the stock amp (everything else being equal) I also almost halfed the output sense resistance, so the AC gain would remain the same at 4ohms as the stock amp at 8ohm load. I also marked my pots so I knew where the stock resisance was so I could start there and return there if I had doubts or problems.
The pots also serve another purpose. You can see how hot you feel comfortable running the amps and dial in the minimum A/C gain you need to not be current starved.
I think the current gain is set by the bank of resistor between the speaker and the output rails. It is adjused buy r21. I don't recall what the relation is. But again, put in a pot and a resistor so you can vary from around 30% to 300% of original value and play with it.
I dropped the source resistors from 6 @ 1 ohm to 8 @ .68 ohm to roughly half the impeadance. So my bias should be double the stock amp (everything else being equal) I also almost halfed the output sense resistance, so the AC gain would remain the same at 4ohms as the stock amp at 8ohm load. I also marked my pots so I knew where the stock resisance was so I could start there and return there if I had doubts or problems.
The pots also serve another purpose. You can see how hot you feel comfortable running the amps and dial in the minimum A/C gain you need to not be current starved.
Actually, the Aleph CCS seems to have 2 senses. The 220 uf off the output rails that connects between 4.75K and 1.5K between +rail and bjt modulates based on voltage, and 220 uf through 681 ohm to base of bjt modulates based on current load. Am I understanding this correctly? A while back when I was working on the mods, I thought I understood it, but now I'm unsure. I'll have to study this some more.
Ok, Aleph 2 parts questions. I'm planning on using 16 fets total per channel, 1 ohm mills MRA-5's on each FET, and i was thinking of using for outputs ...instead of 8 of the .47 ohms in parallel for the output, how about 3 of the .33 ohm MRA-12's. I'm trying to save a few bucks and just wondering if doing this would be ok. Later!
-Matthew K. Olson
-Matthew K. Olson
anyone have any idea on how to use fewer higher power resistor on aleph 2 outputs rather than like 7 or 8 .47 ohm 3 watts?
since i'm using 16 FETs per channel, could I drop the emmitter resistors to .75 ohm mills mra-5's and use perhaps 3 of the .22ohm mra-12's as output resistors? thanks guys!
other options? i'm ordering from percyaudio.com soon i hope
-Matthew K. Olson
since i'm using 16 FETs per channel, could I drop the emmitter resistors to .75 ohm mills mra-5's and use perhaps 3 of the .22ohm mra-12's as output resistors? thanks guys!
other options? i'm ordering from percyaudio.com soon i hope
-Matthew K. Olson
Using the 3 .33 ohm output resistors (I think) will increase AC current gain by almost 2X. 3 .22 ohms will increas by +- 1.5X
Decreasing source resistors from 1 ohm to .75 will up bias as will adding 2 fets per rail. Doing both will increase idle current around 2X. Should make a really spunky Aleph, with enough heatsinks. Almost able to push 2ohm loads to 400 W (these are all best case guesses of course)
Decreasing source resistors from 1 ohm to .75 will up bias as will adding 2 fets per rail. Doing both will increase idle current around 2X. Should make a really spunky Aleph, with enough heatsinks. Almost able to push 2ohm loads to 400 W (these are all best case guesses of course)
Ok, lets assume I don't want to change ac current gain or bias, i'll stick w/ 1 ohm resistors for source resistors, for all 16 devices, now, since I don't want to use 8 resistors for output resistors, how many mills MRA-12 and what value should I use (to save $$). I'll have a variable resistor for the bias setting (i've actually got a pot in mind and possibly a lighted meter for the back panel to indicate bias :-D). I've got some big sinks, no doubt, but i don't know if it'll be that spunky an aleph
-Matthew K. Olson
-Matthew K. Olson
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