I would always go with the bigger transformer, unless the bigger transformer is absolute rubbish, which does not seem to be the case here.
So my vote is with 400VA.
Personally I would use 600VA as a minimum.
So my vote is with 400VA.
Personally I would use 600VA as a minimum.
I have both the 300VA Plitrons and the 400VA Anteks in my other Fx clones and they seem to work out fine for those. The J idles a bit higher so I went with a bigger Antek AN-6218 600VA 18-0-18.
Would 2 of Ross's newer heatsinks in the full 12" length be good for an Aleph J-X with the full 12 output devices per channel? One sink per 6 devices. So each channel would have 2 12" sinks in a monoblock configuration.
pmchoong,
I bought 20 of the 2sk109 jfets from the ebay seller. I had very good delivery time and everything worked out o.k. I can not at this time attest to the quality of the devices because they are not installed yet.
I feel like this is a reputable source. I believe he just got lucky and stumbled on to a stash leftover from some large companies inventory. If we are lucky we will see other situations like this in the future.
Tad
I bought 20 of the 2sk109 jfets from the ebay seller. I had very good delivery time and everything worked out o.k. I can not at this time attest to the quality of the devices because they are not installed yet.
I feel like this is a reputable source. I believe he just got lucky and stumbled on to a stash leftover from some large companies inventory. If we are lucky we will see other situations like this in the future.
Tad
I purchased 5 from that seller as well and had a good experience. The devices seem to be legit and as stated I believe that he had a reputable NOS source.
However, I also can not attest to the quality as I just received mine yesterday and am still collecting parts to build my five J-X's.
James
However, I also can not attest to the quality as I just received mine yesterday and am still collecting parts to build my five J-X's.
James
So is it not super important to match the devices as close as possible? It seems you guys are ordering small batches and not matching them? Or am I wrong here? Or are the ones this guy is selling pretty well matched as is?
Yes,That is correct.
You only need to match if using 2x 2SJ74's in place of the 2SJ109. Only one 2SJ109 is required for the board. 2SJ109 is becoming harder to source and you can use the matched 2SJ74's as an alternative.
You only need to match if using 2x 2SJ74's in place of the 2SJ109. Only one 2SJ109 is required for the board. 2SJ109 is becoming harder to source and you can use the matched 2SJ74's as an alternative.
I noticed there's another 2sj109 on the daughter board if you want to build the AJ-X, which mean 3 x 2sj109 for the 'X' version?
Ok now I understand. Might have to hurry and order some from this guy. I think I'm going to build the Aleph J-X as 2 mono blocks for my 2 channel system that I'm working on that will be used with John Marshes new Ardent speakers that are based on Scan Speak tweeter, Accuton mids, and seas woofers. I know it doesn't matter much but how much power do you think should be expected from 12 total output devices per channel? Also does anyone have a BOM put together for the J-X?
No, when you use the daughter board for J-X it is just a single 2SJ109 (or matched pair of 2SJ74's). The 2 output boards themselves do not have those input section components populated, so 1 is all that is required per channel.
Tom
The BOM is basically the exact same except some of the components are moved from the main board to the daughter board. Check back a few pages and there is one there.
James
So I think I'll use 2 of these
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170386010164&ssPageName=STRK:MEWAX:IT
One on each side of the chassis with one half of each channel mounted to each heat sink. They will be mono blocks and 12" tall 8.5" deep or so. I'm wondering if I do it like this and then use some extended wires so that the X board is bridged across between the 2 heatsinks will this hinder the sound quality or create any problems at all? If this is hard to understand I can probably do a sketchup.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170386010164&ssPageName=STRK:MEWAX:IT
One on each side of the chassis with one half of each channel mounted to each heat sink. They will be mono blocks and 12" tall 8.5" deep or so. I'm wondering if I do it like this and then use some extended wires so that the X board is bridged across between the 2 heatsinks will this hinder the sound quality or create any problems at all? If this is hard to understand I can probably do a sketchup.
Everything inside the input section box (J109, R1,R2,R3,R4,R5,R8,Q2,C1,C4,C5,Z1) is left out/moved to daughter board. Then choose either the ZTX550 (Q2) or 2SJ74 (single) for the current source on the daughter board with appropriate values for Rp and P1. ZTX is helped by some R in parallel with R8 for trimming to 8.3v across R8-Rp/P1 combo (8.3ma) or use similar series Rp/P1 combo on the source of J74 to V+. Not both.
Wow, this is difficult to digest. Which means, if you want to build a monoblock, you use 2 x main board plus 1 x daughter board, and only populate the daughter board with the 2sj109. And everything else inside the 'input section box' of the main boards are left untouched. For the Q2, if we use ZTX550 (which is easier to find than the 2sj74), the pins are the same direction as the marking on the board?
Everything in the white box that is outlined gets left out on the main board. There is a white square everything in it you don't put in. They go on the daughter board for the X'd version.
There are actually 2 transistor locations (marked Q2 and J74) and 2 Rp and P1 locations on the daughter board. Pick one or they other and Peter's markings should be correct as far as I know.
I am not that far along yet as I wanted to build up the standard J first to learn a little more about it before tackling the J-X.