Mark51 Posted February 2, 2020 Share Posted February 2, 2020 I just got a Pass ACA amp on eBay. It was already assembled - not a Chinese copy but the DIY store version. Sounds good with my Fortes. I'm curious if anyone has listened to both and ACA and a First Watt. How would you compare? I realize the price difference is thousands of dollars and I would expect the First Watt to sound better, but how much? Thousands of dollars better? Quote Link to comment Share on other sites More sharing options...
richieb Posted February 2, 2020 Share Posted February 2, 2020 } I’ve owned both, still have a FW F3. And you never specified - lots of flavors in the FW lineup? I really liked my ACA monoblocks which were built with vastly oversized power supplies, one for each block and much larger than the wall wart delivered with the standard design. To be sure the power supply was larger than the mono itself. In the end the F3 easily beat the ACA, which it should. Find a used FW and find out - 1 Quote Link to comment Share on other sites More sharing options...
rplace Posted February 2, 2020 Share Posted February 2, 2020 6 minutes ago, richieb said: Find a used FW and find out - You nee to find a J2 then sell it to me. I need balanced connections Quote Link to comment Share on other sites More sharing options...
richieb Posted February 2, 2020 Share Posted February 2, 2020 10 hours ago, rplace said: You nee to find a J2 then sell it to me. I need balanced connections } I’ll keep my binoculars at the ready - they pop up now and then — Quote Link to comment Share on other sites More sharing options...
EmilC Posted March 2, 2020 Share Posted March 2, 2020 On 2/1/2020 at 11:59 PM, rplace said: You nee to find a J2 then sell it to me. I need balanced connections https://www.usaudiomart.com/details/649594709-first-watt-j2/ 1 Quote Link to comment Share on other sites More sharing options...
Nos1 Posted December 8, 2023 Share Posted December 8, 2023 On 2/2/2020 at 3:22 PM, richieb said: } I’ve owned both, still have a FW F3. And you never specified - lots of flavors in the FW lineup? I really liked my ACA monoblocks which were built with vastly oversized power supplies, one for each block and much larger than the wall wart delivered with the standard design. To be sure the power supply was larger than the mono itself. In the end the F3 easily beat the ACA, which it should. Find a used FW and find out - I was contemplating ACA or F3. It is for 115db horns (only mid/high not bass) Would you mind elaborating the sound difference exactly between the two for me. I prefer a little softer very smooth and on the warm side for this revealing sensitive horn. Especially smooth upper mid range. Quote Link to comment Share on other sites More sharing options...
John Warren Posted December 9, 2023 Share Posted December 9, 2023 On 2/1/2020 at 11:59 PM, rplace said: I need balanced connections Are you running long cables at line level signals? Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 9, 2023 Share Posted December 9, 2023 20 hours ago, Nos1 said: I was contemplating ACA or F3. It is for 115db horns (only mid/high not bass) Would you mind elaborating the sound difference exactly between the two for me. I prefer a little softer very smooth and on the warm side for this revealing sensitive horn. Especially smooth upper mid range. The F3 is a better amplifier than the ACA. I have built them both. The ACA is a simple circuit amplifier designed by Nelson as a diy project for a beginner amplifier builder to get a taste of what a class A mosfet amplifier sounds like. The F3 uses what is called power J-fets which also the more modern Firstwatt J2 uses. If you want more details of the F3 circuit you can look here. https://firstwatt.com/pdf/art_zv9.pdf The Zen 9 from 2006 is the same circuit retailed as the F3. Both are very good sounding but if hearing good enough you will hear a difference in the F3. 2 Quote Link to comment Share on other sites More sharing options...
DMH Posted December 19, 2023 Share Posted December 19, 2023 I built 2 ACA amp's, set them up as monoblocks with XLR inputs and linear power supplies. They are impressive little amps! Then I built an F-5, F-6, B1K preamp and finally an Aleph J. They all sound great and are improvements over the ACA's. I'm currently using two Firstwatt F8's. They sound really good and are definitely an improvement over the Aleph J, which was my favorite of all the DIY boards that I built. Who knows what a couple of Sit-4's will sound like? I might have to find out when they become available. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 19, 2023 Share Posted December 19, 2023 I have built both of the V-fet offerings from Nelson Pass. V-fet is just another name for static induction transistors, SIT. One amplifier being single ended and the other PP. SIT transistors are extremely fast first used for radar applications. Quote Link to comment Share on other sites More sharing options...
DMH Posted December 19, 2023 Share Posted December 19, 2023 Henry, To clarify this, you built the 2017 Sony Vfet amp? https://diyaudiostore.com/collections/power-amplifier/products/sony-vfet-circuit-boards And the 2021 Vfet amp offering? https://guides.diyaudio.com/Guide/Sony+Vfet+(P+2021)/15?lang=en Have you built any of the other Firstwatt DIY amps? Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 19, 2023 Share Posted December 19, 2023 2 hours ago, DMH said: Henry, To clarify this, you built the 2017 Sony Vfet amp? https://diyaudiostore.com/collections/power-amplifier/products/sony-vfet-circuit-boards And the 2021 Vfet amp offering? https://guides.diyaudio.com/Guide/Sony+Vfet+(P+2021)/15?lang=en Have you built any of the other Firstwatt DIY amps? I was the first builder of the PP SET amplifier at diyaudio.com. I also am the one who asked Nelson for a SE V-fet design and he agreed to design one. It took a few years but he did produce it. Also I have built the majority of Nelson Pass diy projects including nearly all of the Firstwatt clones. Nelson Pass 74 year old groupie. If you like the sound of the ACA you would love the sound of the Burning Amp #1 SE amplifier with multiple output devices. https://firstwatt.com/pdf/art_ba1.pdf The Burning Amp #2 has a lot in common with the Pass Labs amplifiers. Similar to the F4 with an extra output stage if memory is correct with a front end circuit added where it will operate without a high output linestage that the F4 really needs for full output. 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted December 20, 2023 Share Posted December 20, 2023 7 hours ago, DMH said: Henry, To clarify this, you built the 2017 Sony Vfet amp? https://diyaudiostore.com/collections/power-amplifier/products/sony-vfet-circuit-boards And the 2021 Vfet amp offering? https://guides.diyaudio.com/Guide/Sony+Vfet+(P+2021)/15?lang=en Have you built any of the other Firstwatt DIY amps? DMH....Sent you a PM attached to an old PM...hope you get it. If you don't respond I'll send a new PM. Quote Link to comment Share on other sites More sharing options...
DMH Posted December 20, 2023 Share Posted December 20, 2023 17 hours ago, henry4841 said: I was the first builder of the PP SET amplifier at diyaudio.com. I also am the one who asked Nelson for a SE V-fet design and he agreed to design one. It took a few years but he did produce it. Also I have built the majority of Nelson Pass diy projects including nearly all of the Firstwatt clones. Nelson Pass 74 year old groupie. If you like the sound of the ACA you would love the sound of the Burning Amp #1 SE amplifier with multiple output devices. https://firstwatt.com/pdf/art_ba1.pdf The Burning Amp #2 has a lot in common with the Pass Labs amplifiers. Similar to the F4 with an extra output stage if memory is correct with a front end circuit added where it will operate without a high output linestage that the F4 really needs for full output. Very impressive! I'm a relative newbie to Nelson Pass's designs. I appreciate his work but I'm not even close to a "Nelson Pass groupie". Not that there's anything wrong with that. Quote Link to comment Share on other sites More sharing options...
DMH Posted December 20, 2023 Share Posted December 20, 2023 12 hours ago, babadono said: DMH....Sent you a PM attached to an old PM...hope you get it. If you don't respond I'll send a new PM. Got it. Quote Link to comment Share on other sites More sharing options...
henry4841 Posted December 20, 2023 Share Posted December 20, 2023 1 hour ago, DMH said: Very impressive! I'm a relative newbie to Nelson Pass's designs. I appreciate his work but I'm not even close to a "Nelson Pass groupie". Not that there's anything wrong with that. The difference with Nelson and the other audio engineers is he shares some of his knowledge with the electronic audio geeks. 2 Quote Link to comment Share on other sites More sharing options...
DMH Posted December 20, 2023 Share Posted December 20, 2023 26 minutes ago, henry4841 said: The difference with Nelson and the other audio engineers is he shares some of his knowledge with the electronic audio geeks. That's totally true! Let me tell you, I purchased a used Firstwatt amp from ebay that made a thunking noise when you turned it on. It was like the noise that happens when you turn on a high current bus, like in a factory but on a much smaller scale. I didn't want to return it because it sounded great. So, I looked on the Firstwatt webpage for some sort of customer service email. There was a single email address and it turned out to be Nelson's personal email address. He graciously explained what he believed may be causing it and was certain it wasn't a problematic issue. Although he encouraged me to send the amps in to the shop to have them checked out under warranty. Talk about being customer service oriented! Quote Link to comment Share on other sites More sharing options...
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