Just finish my Aleph J. I was able to do it from beginning to end without asking a single stupid question so that’s an accomplishment
Bravo! each and every clone I've built here is full of dumb questions....
Revealing my ignorance on the world wide interweb low these many years,
Russellc
Better late than never
I am finally getting around to building this. I ordered the boards in 2013, I already have a good number of the components as I have been building/repairing audio items for 40 years...but just a few questions before I start stuffing boards.
In my collection of semis, I have several choices for Q1A and Q1B. I missed out on the 2SJ74s when they were cheap $.75 (back when I bought a mess of other semis for various projects) and I refuse to spend $10+ per item for them today. I have 2SJ109, which are V gain code, probably too high although I don't know enough about them to know if they will work in this application, and they will need to do some yoga moves to fit the PCB layout. My other option which is the one I am leaning towards assuming somebody could confirm this is true, is I have some 2SJ75, which I think are a matched pair of 2SJ74s in a metal container, and they are the BL code, and I think they will drop right into the board layout without any yoga moves. For some reason back in the 90's I didn't buy the complimentary 2SK240s so I have these 2SJ75s to use up.
Second Q is re: the Zetex parts, I assume there is nothing special about these and any old 1A 1W 50V TO-92 part should work? I have many different types to choose from, just need to find a suitable sub. If not Digikey still has the Zetex xstrs.
The 2 electrolytic caps C3, 4, can these be standard electrolytics or is there a reason Elna and Panasonic are spec'd? Again, I have tons of new caps in stock maybe so are low ESR but if there is nothing special about them....
I think that is it. Thank you in advance for any help forthcoming, I'm looking forward to building this.
I can't believe how this thread has grown in 7 years, there are SO many pages to read thru.
Cheers
I am finally getting around to building this. I ordered the boards in 2013, I already have a good number of the components as I have been building/repairing audio items for 40 years...but just a few questions before I start stuffing boards.
In my collection of semis, I have several choices for Q1A and Q1B. I missed out on the 2SJ74s when they were cheap $.75 (back when I bought a mess of other semis for various projects) and I refuse to spend $10+ per item for them today. I have 2SJ109, which are V gain code, probably too high although I don't know enough about them to know if they will work in this application, and they will need to do some yoga moves to fit the PCB layout. My other option which is the one I am leaning towards assuming somebody could confirm this is true, is I have some 2SJ75, which I think are a matched pair of 2SJ74s in a metal container, and they are the BL code, and I think they will drop right into the board layout without any yoga moves. For some reason back in the 90's I didn't buy the complimentary 2SK240s so I have these 2SJ75s to use up.
Second Q is re: the Zetex parts, I assume there is nothing special about these and any old 1A 1W 50V TO-92 part should work? I have many different types to choose from, just need to find a suitable sub. If not Digikey still has the Zetex xstrs.
The 2 electrolytic caps C3, 4, can these be standard electrolytics or is there a reason Elna and Panasonic are spec'd? Again, I have tons of new caps in stock maybe so are low ESR but if there is nothing special about them....
I think that is it. Thank you in advance for any help forthcoming, I'm looking forward to building this.
I can't believe how this thread has grown in 7 years, there are SO many pages to read thru.
Cheers
you can use 2SJ109V , in J they're biased with CCS so no problem with higher Idss
or , simply use 2SJ75BL , perfect ; that's practically older brother of 2SJ109
second question - these bjts are practically universal type , so any decent general purpose types will work with no prob
caps - use decent ones and chill ; what's spec'd is quality , not brand
or , simply use 2SJ75BL , perfect ; that's practically older brother of 2SJ109
second question - these bjts are practically universal type , so any decent general purpose types will work with no prob
caps - use decent ones and chill ; what's spec'd is quality , not brand
Thanks ZM, appreciate the quick reply. I am currently cleaning off 8 years of repair crap from the workbench, old parts, screws, clipped leads, loose wires...you know the mess that can gather.
Okay, that's great, I'll use the 2SJ75BL as I assume Toshiba would have matched them before embedding in the little aluminum case so I also assume I don't need to do any further with these. And, I just discovered that I DO have 2SK240 matching BL codes to the 2SJ75s, but I have many more of the 2SJ109/K389 pairs, so I may use the 109s and save the J75/K240 for other projects.
I know I started reading the Babelfish design a few years ago, but I think since I already have the original boards, I will just build it stock. I may have to modify a torroid transformer as most of mine are 22-24VAC and may be too high for the 2SJ75s, or I could regulate the voltage going to the input stage, or ?? I'll figure it out.
Thanks again!
Okay, that's great, I'll use the 2SJ75BL as I assume Toshiba would have matched them before embedding in the little aluminum case so I also assume I don't need to do any further with these. And, I just discovered that I DO have 2SK240 matching BL codes to the 2SJ75s, but I have many more of the 2SJ109/K389 pairs, so I may use the 109s and save the J75/K240 for other projects.
I know I started reading the Babelfish design a few years ago, but I think since I already have the original boards, I will just build it stock. I may have to modify a torroid transformer as most of mine are 22-24VAC and may be too high for the 2SJ75s, or I could regulate the voltage going to the input stage, or ?? I'll figure it out.
Thanks again!
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Another good option, which I will investigate, there is enough room on the boards to add more devices. Thx for the reminder of cascodes.
Cheers
if you need a hand with that,just buzz
if you don't need , even better
Thanks ZM, IIRC you detailed it on your Babelfish version so I will read that first, should be pretty straightforward.
Thank you for the offer.
Cheers
It is worth the read for sure. Pretty much any question a new builder may have will be in there, and known values for parts (like R8) will have been explained. Plus, you get to learn about the circuit operation and get ideas for your build. It’s a win-win.
I'd love to read all 466 pages, and someday probably will, but as it took me an hour to get to page 26, I'll continue to ask a few questions as I would like to get this built before I retire.
I have found my transformers, perfect units I think 2x20VAC @ 5A, so I could use one for each channel. I also have 2X20VAC @ 8 amps, so could use one of those for both channels. I found these Talema xfmrs years ago and have been saving them for the right project.
Now just a couple of questions re: the resistors. Are any of them critical of absolute value? I have boxes of RN60D resistors but not many of the exact value specified. I have the right values in other 1% R's but not the same quality as the Dales and are physically smaller.
I don't have .47R for the output stage and power supply, could I use .27R or .68R in those places as I have many of either? Pros-Cons?
Think that's it for now. Still lots to do but the bulk of materials are on hand already including chassis, heat sinks, PS caps etc. Still need to match the IRFP240s.
Thanks!
I have found my transformers, perfect units I think 2x20VAC @ 5A, so I could use one for each channel. I also have 2X20VAC @ 8 amps, so could use one of those for both channels. I found these Talema xfmrs years ago and have been saving them for the right project.
Now just a couple of questions re: the resistors. Are any of them critical of absolute value? I have boxes of RN60D resistors but not many of the exact value specified. I have the right values in other 1% R's but not the same quality as the Dales and are physically smaller.
I don't have .47R for the output stage and power supply, could I use .27R or .68R in those places as I have many of either? Pros-Cons?
Think that's it for now. Still lots to do but the bulk of materials are on hand already including chassis, heat sinks, PS caps etc. Still need to match the IRFP240s.
Thanks!
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most resistor positions aren't critical , +/-10% is OK
only that 1K resistor for Aleph CCS modulation ( in series with big elco going from output node) , keep it tight
source resistors - better lower than higher
I did use 0R25 with IRF150 , but I also had doubled Iq
put two 0R68 , ending with 0R34
only that 1K resistor for Aleph CCS modulation ( in series with big elco going from output node) , keep it tight
source resistors - better lower than higher
I did use 0R25 with IRF150 , but I also had doubled Iq
put two 0R68 , ending with 0R34
Thanks ZM.....you reminded me...I have several rails of IRFP150 as well that I had forgot about, just found them. Would I be better off using a single IRFP150 and an 0R27, thus saving me matching IRFP240s and paralleling resistors or are the IRFP240s preferred for this original version of J?
Cheers
PS now working my way thru Babelfish J thread as well...so much catching up to do.
Moving forward today which is good, gathering all the bits. My heatsinks are Aavid extrusion 65340, 6" high x 11" front to back, 2" fins on .25" base. Thermal data .44*C/W for the 6" piece and .55*C/W @ 40*C rise in ambient.
My question is (and I looked all over the DIY store and couldn't find it) is what is the thermal data for the 4U chassis Jim spec'd in the first page of this thread? My entire chassis is machined and milled aluminum, 3/8" front panel, 1/4" rear panel and 3/16" top and bottom, all black anodized. Chassis width is 13.5" between heatsink bases.
Going to do some reading, and hoping I'll be able to keep the heat sink around 50*C or so.
Cheers
My question is (and I looked all over the DIY store and couldn't find it) is what is the thermal data for the 4U chassis Jim spec'd in the first page of this thread? My entire chassis is machined and milled aluminum, 3/8" front panel, 1/4" rear panel and 3/16" top and bottom, all black anodized. Chassis width is 13.5" between heatsink bases.
Going to do some reading, and hoping I'll be able to keep the heat sink around 50*C or so.
Cheers
From the DIYAudio Store:
40mm Heatsinks – diyAudio Store
The "base" of the heatsink has a minimum thickness of 8mm
Please see our UMS heatsink page if you would like pre-drilled and pre-tapped UMS versions of these heatsinks.
Dissipation Ratings
Dimensions C/W
200 x 40 x 80 0.67
200 x 40 x 120 0.5
200 x 40 x 165 0.38
200 x 40 x 210 0.28
250 x 40 x 210 0.19
300 x 40 x 80 0.45
300 x 40 x 120 0.40
300 x 40 x 165 0.31
300 x 40 x 210 0.18
The 4U is 165mm high, with the choice of 300mm or 400mm deep.
40mm Heatsinks – diyAudio Store
The "base" of the heatsink has a minimum thickness of 8mm
Please see our UMS heatsink page if you would like pre-drilled and pre-tapped UMS versions of these heatsinks.
Dissipation Ratings
Dimensions C/W
200 x 40 x 80 0.67
200 x 40 x 120 0.5
200 x 40 x 165 0.38
200 x 40 x 210 0.28
250 x 40 x 210 0.19
300 x 40 x 80 0.45
300 x 40 x 120 0.40
300 x 40 x 165 0.31
300 x 40 x 210 0.18
The 4U is 165mm high, with the choice of 300mm or 400mm deep.
Well don't I feel dumb.I was looking at the complete chassis descriptions which don't give any thermal detail on the heatsinks.
Thanks Ben.
I am up to page 82 of the thread now....
You’re doing great! Ask questions, don’t feel shy to ask because you’re not sure, there’s plenty of help from great members of this forum! I’ll help you out with the R8 thing I’d mentioned you’ll inevitably come to on page 132, post 1311.
Aleph J illustrated build guide
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Thank you, very much appreciate the encouragement, it sure is relaxing getting all this together and getting in touch with my audio roots again. A nice project such as this is a good thing.
Today I started playing around with the 2SJ109s and tested them, just to learn how to check for matching, and was amazed at how much variation there is in their Idss, but also amazed at how closely matched each pair were. It only took 6 units to find a pair that measured 12.45mA each section, so those are set aside for this amp. Highest I measured was 18mA, these are the V(iolet) gain code devices.
Tomorrow, the search continues for more metal film Rs.
I had to laugh, in my search for heat sink data, I found several boxes of my old audio notes, data books and such from the early 90's, when I was VERY MUCH into building, and found a quote for RN60 Dale resistors, boxes of 100, $.04 each...ah how times have changed. Digikey wants $2.60 each in small numbers today which is why I am trying to use what I have.
Now reading about dual versus single bridge rectifiers, with dual winding xfmrs, something that caught my attention on the first page of this thread when I looked at the PS schematic.
More later, I'm sure.
Cheers
Today I started playing around with the 2SJ109s and tested them, just to learn how to check for matching, and was amazed at how much variation there is in their Idss, but also amazed at how closely matched each pair were. It only took 6 units to find a pair that measured 12.45mA each section, so those are set aside for this amp. Highest I measured was 18mA, these are the V(iolet) gain code devices.
Tomorrow, the search continues for more metal film Rs.
I had to laugh, in my search for heat sink data, I found several boxes of my old audio notes, data books and such from the early 90's, when I was VERY MUCH into building, and found a quote for RN60 Dale resistors, boxes of 100, $.04 each...ah how times have changed. Digikey wants $2.60 each in small numbers today
which is why I am trying to use what I have. Now reading about dual versus single bridge rectifiers, with dual winding xfmrs, something that caught my attention on the first page of this thread when I looked at the PS schematic.
More later, I'm sure.
Cheers
Thank you, very much appreciate the encouragement, it sure is relaxing getting all this together and getting in touch with my audio roots again. A nice project such as this is a good thing.
Today I started playing around with the 2SJ109s and tested them, just to learn how to check for matching, and was amazed at how much variation there is in their Idss, but also amazed at how closely matched each pair were. It only took 6 units to find a pair that measured 12.45mA each section, so those are set aside for this amp. Highest I measured was 18mA, these are the V(iolet) gain code devices.
Tomorrow, the search continues for more metal film Rs.
I had to laugh, in my search for heat sink data, I found several boxes of my old audio notes, data books and such from the early 90's, when I was VERY MUCH into building, and found a quote for RN60 Dale resistors, boxes of 100, $.04 each...ah how times have changed. Digikey wants $2.60 each in small numbers today
Now reading about dual versus single bridge rectifiers, with dual winding xfmrs, something that caught my attention on the first page of this thread when I looked at the PS schematic.
More later, I'm sure.
Cheers
You can skim it pretty quickly, a lot is just banter that isn't relative to your build. Note interesting questions and answers by post number, or questions/problems you don't understand.
You will also learn as time goes by that if certain people elaborate on a topic, it is worth noting.
Go through your notes, ask questions you develop....then review 6l6's build guides for more clarity.
In time, you may dethrone me as king of dumb questions! But I doubt it. LOL
Russellc