I found a cheap 3-piece step drill bit set on ebay, and circular cutters.
OK, I'm a cheapskate.
I found a cheap 3-piece step drill bit set on ebay, and circular cutters.
OK, I'm a cheapskate.
Great, thanks for the info!
150VA might be marginal - the iron may saturate... I suppose 2 X 200VA would be perfect - ideal for Iq sitting at 2A per amp PCB, which sounds great (and dissipates a lot of heat.... 200W total).
Apart from the mods, did you see the latest posts re: correct grounding/routing of returns?
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-196.html#post6644139
.... click on each link, in the above post, for more details/photos.
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4315 PASS All aluminum amplifier chassis / Preamplifier case / AMP Enclosure / DIY box (430 *150*300/350/400mm)|Amplifier| - AliExpress
No guarantee that they're still the same because it's not shown in the photos, but I ordered the largest of these and was surprised and delighted to find
Pass Aleph Amp
Class A
engraved on the front panel.
The price has been cut by 20% since I bought it, which results in the cost of shipping to the UK comfortably exceeding the price of the chassis itself, but it's still competitive overall.
No guarantee that they're still the same because it's not shown in the photos, but I ordered the largest of these and was surprised and delighted to find
Pass Aleph Amp
Class A
engraved on the front panel.
The price has been cut by 20% since I bought it, which results in the cost of shipping to the UK comfortably exceeding the price of the chassis itself, but it's still competitive overall.
Yes, it was exactly as shown except for the engraving. Oh, and the fact that the front panel is the other way up. (The decorative groove on the right.)
Normally I'd steer well clear of anything counterfeit but I justify this one on the basis that it will contain a Pass design, and as far as I know there's no IP theft involved. I hope.
I'm struggling to get my Aleph to work though: first channel horribly distorted. So perhaps it's retribution from above.
On the topic of power transformers, my opinions have shifted over the years. My first FirstWatt clone F5, I went dual mono with two 300VA 18 + 18 transformers, about double the standard. BA3, I had on hand a 1000 VA 24 + 24 volt from a Turbo F5 group buy, seeing 6l6 used 24 + 24 in his BA3 build guide, I used it. M2, F6, Aleph J I used 500 VA 18 + 18 trandformers, all following bigger = better and so on. Then a few things happened that caused me to rethink.
I read somewhere on this fine forum, possibly Mr Pass himself getting in the conversation IIRC on hot rodding, i.e. increased rails, oversized VA transformers, cap banks etc, with the take away being you might have a nice result, but it will be different. Some of the magic of the original designs may be lost as the amp gets tighter and more powerful.
Then a power transformer (500 VA) failed in my M2 clone. Having on hand a Pair of Avel Lindburg 250 VA 18 + 18 transformers, replaced the 500 va with a single Avel Lindburg.
While obviously this amp had been sick with failing transformer, it sounded great! Then I remembered the above comments on hot rodding and wondered if at least in the case with clones of the FirstWatt amps here, if using the originally spec parts used by Mr Pass would be "sufficient"? Duh.
I found this to be the case as well with monoblocking. Did it with both M2 and Aleph J. Yup, sounded great, soundstage, etc....all I can say is that I switched them back to stereo amps and they are still that way.
My take away is I will go with dual mono on future Pass clones, but transformer size, voltage, VA and cap banks are going to stay standard, or close to it as possible.
Seems now I am more interested (and trying to learn) measuring and adjusting distortion spectra in "improving" i.e. getting closer to intended design sound, rather the bigger is better in all things method of "improvement." It's DIY, it is all good, just where ever you want to end up soundwise.
Russellc
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To be honest, I just took the parts list for the normal single PSU and doubled it (300VA x2 Antek 3218s and DIYAS universal PSUs). No science, just “if one is good...”. So I’m probably over-transformered, but it sure is lovely!
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Benefits of living in first world.
Mine was shipped on 9 April. I am still waiting. And will probably wait for 2 more months. Our local postal service is horrible, such that Amazon now refuses shipments here using local postal service, only allowing for tracked courier services.
Mine was shipped on 9 April. I am still waiting. And will probably wait for 2 more months. Our local postal service is horrible, such that Amazon now refuses shipments here using local postal service, only allowing for tracked courier services.
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Your graphic shows 1 ma for .15v, giving about 7 mmhos transconductance.
Thank you,
Mr. Nelson, I really appreciate your response and I am very flattered. ok i will wait when a matched quad is available.
Or I can buy two LSK170 / LSJ74 matched quads, but I don't think it will be the same. :confuso:
Hi Mr. Tricksters,
For an Aleph J you do not need any K170 junction FETs. No Octet needed. Only J74s: either NOS Toshiba devices or new production, Linear Systems devices (available in the diyAudioStore).
As MZM said, two pairs; within pairs, matched. Ideally, all four J74s matched, as Mr. Peppennino showed in his post, received from Ebay seller punkydawgs.
Refer to the BOM in the diyAudioStore: Aleph J – diyAudio Store
Lots of excellent information there.
For an Aleph J you do not need any K170 junction FETs. No Octet needed. Only J74s: either NOS Toshiba devices or new production, Linear Systems devices (available in the diyAudioStore).
As MZM said, two pairs; within pairs, matched. Ideally, all four J74s matched, as Mr. Peppennino showed in his post, received from Ebay seller punkydawgs.
Refer to the BOM in the diyAudioStore: Aleph J – diyAudio Store
Lots of excellent information there.
Yes. Thank you. I understand.
LSJ74 / LSK170 ± 0.1mA Matched Octet (Grade B) . Right?
No, 74 matched quartet. Ciao :
