Correct.
Bridging helps if you want more voltage swing, and (much) less 2nd harmonics.
Parallelling gets you more output current and lower output impedance.
You can also play with the resistor values R11~14 at the upper half to change the current ratio between the modulated current source and the Semisouth.
But that will also change your distortion spectrum.
There is a schematics of a parallel version at the UDNeSS thread which will give you some ideas.
Patrick
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NO need to trade sweeter 2nd harmonic for cruder 3rd harmonic just to get more wpc Instead, get more efficient speakers!! That's what Nelson Pass typically uses. You can choose the Lowther or similar drivers he often uses, or something very different; though its usually best to settle on some kind of horn design as many will easily pressurize most rooms with as little as 10 wpc or less. PLENTY of driver options for building horn or "quasi" horn speakers that do NOT sound like the honking metallic pro audio crap people point to when those like Lynn Olson, PierreQuiRoule or Troy Crowe discuss those that sound better than probably anything you've heard.
Example driver/horn combos: Pierre's perfectly passively EQed Radian745neoBE/Athos TH4001 ; Troy Crowe B&C DCM50/ES450 ; Gary Dahl's Azurahorn JMLC AH425/Yamaha JA6681B ; Lynn Olson's Azurahorn AH340/B&C DCM50.
Note: Pierre's combo are atop his sealed TAD woofers. See them here; posts 15,266, 15, 276.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764
Gary's are atop his 3 cu ft sealed GPA Altec 416-8B midwoofers. Lynn's will be atop his sealed ~ 4 cu ft Altec 416-8B woofers. My midwoofers are clones of Gary's, though I wish I would have gone with bigger boxes like Lynn's, whose go down to 40Hz. See Lynn's cabinet plans here.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-767
Like Gary;s mine will do down to 70Hz, below which are my Rythmik F12 sealed subs. Though I know the midwoofers will deliver extremely low IM distortion this way, I'm hoping that the bass crossing from the Altecs to the subs from
~ 65Hz to 40Hz won't sound colored. Thus, I'd go with Lynn's bigger sealed boxes, especially if you're going for
$$$$ bass drivers like the GPA 416-8B 16ohm. Troy and I still have to decide on a driver/horn combo.
As you probably know, among other things, what's important is to select drivers for the speakers and design the crossover so that the speakers are at least 93db/w/m and that system impedance is well above 4 ohms. Do this an according to John Atkinson's measurements "the J2 will sing!" https://www.stereophile.com/content/first-watt-j2-power-amplifier-measurements
I have a stock J2 and F4 driven by my Don Sachs preamp. Exciting!
Check out these plans. https://josephcrowe.com/collections/speaker-plans 🙂
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That’s cool, does @Nelson Pass like the mid-bass punch a McIntosh ML1C produces in the opening of the song Ziggy Stardust? If he does we could be twiners.
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Doubt it. At 89db, sensitivity's on the low side, https://www.hifiengine.com/manual_library/mcintosh/ml-1c.shtml
And if impedance drops to 4 ohms for too long along the audio band the J2 will distort a lot more.
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I’m not saying those are the speakers I use now…that’s what I grew up on 40+ years ago and the sound I’ve been chasing since.
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Point is we’re all chasing a different “sound”. Kind of like Eddie VanHalen wouldn’t use the same rig as Al DiMeola.
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Point is we’re all chasing a different “sound”. Kind of like Eddie VanHalen wouldn’t use the same rig as Al DiMeola.
As much as I’d like to hear the J2 I think I’m better off building a different amp in the queue first. I have one complete set of F4 boards that could use a companion, Aleph 60 kit (from Randy), Stasis front end and output, and others. Hi, my name is Kevin and I’m a hoarder.
Hi Kevin, welcome to the 12 step program. First step was admitting you are a hoarder.
I'm a life long hoarder, just going through the garage and find a stash of unused 3 section 500V (and 450V) caps (40mf). I hadn't seen them for 20 years.
Tubes galore, sets of transistors, you name them I got them (almost).
Maybe it's a club, cause I don't see a lot of selling going on over here!
Rush
I'm a life long hoarder, just going through the garage and find a stash of unused 3 section 500V (and 450V) caps (40mf). I hadn't seen them for 20 years.
Tubes galore, sets of transistors, you name them I got them (almost).
Maybe it's a club, cause I don't see a lot of selling going on over here!
Rush
I stash everything because I've learned that parts become unobtanium when they're discontinued. Semisouth, Mullard tubes etc. I wish my retirement was invested in Toshiba JFETs.
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How about a show of hand’s from all that do inventory? I could use a lot of help in that area. There’s a recent post in swap meet that has me (and my wife) thinking about this!
test-equipment-components-wire-tubes-and-more-for-sale.409667
test-equipment-components-wire-tubes-and-more-for-sale.409667
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The problem with hoarding parts for future projects, is that the parts become so expensive I'm not really tempted to use them anymore and just save them as a retirement plan.
Working on a new tube amp with 4P1L as I got a box of 50 for $3/each, kind of scared to use my nos 801As as a daily headphone burner at $100/pop. And scouring this topic for maybe a nice schematic for a low-wattage headpone amp using SiC JFETs for a daily spotify burner instead.
Working on a new tube amp with 4P1L as I got a box of 50 for $3/each, kind of scared to use my nos 801As as a daily headphone burner at $100/pop. And scouring this topic for maybe a nice schematic for a low-wattage headpone amp using SiC JFETs for a daily spotify burner instead.
English please, thank you! Hello everyone. I need some help, please. Let me start by saying that although I am not an expert, two years ago I tried to build the J2, which I still like very much and that my friends envy.
Now I have built one exactly the same (with the same PCB as Jeff...). I have meticulously checked a thousand times everything that needed to be checked, but it doesn't work. When I turn it on everything seems fine. I was expecting the pleasant heat of the Semisouth, but nothing... it freezes... everything freezes. I tried to make some measurements, as far as a beginner can understand, but the only thing I could see is that on the offset, instead of finding something close to 0 V, I find over 20 V that cannot be adjusted with the trimmer. A monster, then...
can you tell me what to check first and then follow please???!!
thank you very much Giampiero
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Ciao a tutti. Ho bisogno di un aiuto, per favore. Faccio una piccola premessa: pur non essendo un esperto, due anni fa mi sono cimentato nella costruzione del J2, che ancora oggi mi piace moltissimo e che i miei amici invidiano.
Ora ne ho costruito uno esattamente identico (con lo stesso PCB di Jeff...). Ho controllato meticolosamente mille volte tutto ciò che c'era da controllare, ma non funziona. Quando lo accendo tutto sembra a posto. Mi aspettavo il piacevole calore del Semisouth, ma niente... si congela... si congela tutto. Ho provato a fare delle misurazioni, per quanto possa capirne un principiante, ma l'unica cosa che ho potuto vedere è che sull'offset, invece di trovare qualcosa di vicino a 0 V, trovo oltre 20 V che non si possono regolare con il trimmer. Un mostro, quindi...
puoi dirmi cosa controllare prima e poi seguire per favore???!!
grazie mille Giampiero
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Here are some photos.
Here are some photos.
I finished both channels but for now I have fixed and tried only one, as I said but it doesn't work at all.... Of course the power supply will not be that one but a better one that I didn't want to use now because it's a bit bulkier. In any case the 24 volts on the board arrive, they are there....
if you need more info and photos I'm ready.
a doubt has worried me... could it be the fake 4N35?
thanks
thanks
Here are some photos.
I finished both channels but for now I have fixed and tried only one, as I said but it doesn't work at all.... Of course the power supply will not be that one but a better one that I didn't want to use now because it's a bit bulkier. In any case the 24 volts on the board arrive, they are there....
if you need more info and photos I'm ready.
a doubt has worried me... could it be the fake 4N35?
thanks
thanks
ZM illiterate and too old, to find all appropriate posts
so, spoonfeedZM time
wanna everything in one post
so, spoonfeedZM time
wanna everything in one post
Follow ZM's advice, but also look at the schematic and do some testing to see if you have the right voltages in the right places before you spin it.