FS: Pair o' ACA 1.8s fully built - $500 OBO shipped CONUS
Selling a pair of 1.8 ACAs, fully built. Wiring isn't a work of art but everything works fine. As this is a DIY site, most folks want the experience of building themselves so discounting to $500 for the pair (includes shipping). Time to go fund my next project. US sales only. Decent offers considered. Tanks for lookin'.
Selling a pair of 1.8 ACAs, fully built. Wiring isn't a work of art but everything works fine. As this is a DIY site, most folks want the experience of building themselves so discounting to $500 for the pair (includes shipping). Time to go fund my next project. US sales only. Decent offers considered. Tanks for lookin'.
Attachments
Last edited:
thanks for the well wishes. They'll move, utmost confidence when the right person sees them.
I've got the F6s done and enjoying them but the F5 boards + parts kit shows up tomorrow. Going to see what happens with a bit better damping factor. From there, it will be a F5 Turbo for more power or balanced F5s. I'm finally at that point with this hobby, I know enough to tailor the system to my expectations. Going got good!
I've got the F6s done and enjoying them but the F5 boards + parts kit shows up tomorrow. Going to see what happens with a bit better damping factor. From there, it will be a F5 Turbo for more power or balanced F5s. I'm finally at that point with this hobby, I know enough to tailor the system to my expectations. Going got good!
Pretty cool. I am working on a BA2018 now. I am having a issue with the SMDs. I bought a bunch from Mouser to make sure I had the opportunity to try it again and again... Lol
Good to hear about your progress. I thought I remember Nelson Pass saying that he has something in the grapevine that stems off of the F5 design. He seems to particularly like that design.
I want to either build another F6 amp and run two monoblocks or try have different designs etc. A mixed bag of options. That will come later though. I think my next project after the BA2018 will be another set of speakers.
I thought I remember that running balanced F5 changes the harmonic distortion characteristics.
Good to hear about your progress. I thought I remember Nelson Pass saying that he has something in the grapevine that stems off of the F5 design. He seems to particularly like that design.
I want to either build another F6 amp and run two monoblocks or try have different designs etc. A mixed bag of options. That will come later though. I think my next project after the BA2018 will be another set of speakers.
I thought I remember that running balanced F5 changes the harmonic distortion characteristics.
It has been odd, with my sudden acceptance of transistors. It has opened up a whole new area of the audio world to explore and there is no concern about blowing expensive tubes or transformers. Like you said, order a bunch of FETs or other output devices for pennies on the vacuum tube dollars and much easier to swallow the bill that goes with learning.
What I thought I understood, the balanced mode would reduce all noise but I seem to recall Nelson Pass, Z-M and others posting about reducing the even order harmonics much more prominently than the odd order. I'm also unsure how that works if there are two separate power supplies in each monoblock. I have a guess that I won't get the full benefit as speaker + and - won't have the same V+/- noise summed to cancel. The amount of spookiness I experienced with the ACAs in balanced mode got me going down this rabbit hole so we'll see where it goes. Somewhere here, my Pops is supposed to send me an o-scope so I can actually see how this all works out on the screen.
If you're not in a hurry, I may have some F6 parts posted up here later. Need to get the F5 boards stuffed and installed to make a decision. I actually have 4 channels of F6 stuff laying about. Started on balanced F6s before realizing the output impedance wasn't favorable.
What I thought I understood, the balanced mode would reduce all noise but I seem to recall Nelson Pass, Z-M and others posting about reducing the even order harmonics much more prominently than the odd order. I'm also unsure how that works if there are two separate power supplies in each monoblock. I have a guess that I won't get the full benefit as speaker + and - won't have the same V+/- noise summed to cancel. The amount of spookiness I experienced with the ACAs in balanced mode got me going down this rabbit hole so we'll see where it goes. Somewhere here, my Pops is supposed to send me an o-scope so I can actually see how this all works out on the screen.
If you're not in a hurry, I may have some F6 parts posted up here later. Need to get the F5 boards stuffed and installed to make a decision. I actually have 4 channels of F6 stuff laying about. Started on balanced F6s before realizing the output impedance wasn't favorable.
Yes, getting rid of even order harmonics sounds like a good thing. I don't know much about monoblock F5's
Send me a PM if you plan to sell the F6 boards. The F6 is my favorite amp that I have heard so far. However, it is the only Firstwatt/Firstwatt Clone amp that I have heard.
Thanks for the heads up!
Send me a PM if you plan to sell the F6 boards. The F6 is my favorite amp that I have heard so far. However, it is the only Firstwatt/Firstwatt Clone amp that I have heard.
Thanks for the heads up!
the even order harmonics give it that tube sound. Or as Zen Mod says, "the sugar".
Odd order harmonics tend to make the amp sound "harsher."
Balanced mode has the benefit common mode noise rejection. I thought it brought down all harmonic distortion equally but what I've read from Mr. Pass is that, while it does bring down all distortion, it affects the 2nd order harmonics the most. My limited experience (since balanced tube amplifiers have been beyond my budget) is with the ACAs in balanced mode. I found them to completely disappear and the recording was just "there". However, with the ACAs output impedance, they aren't a good match on the Halcyons. Bass loses control and gets boomy and woolly. This all sparked the attempt at building a 1st Watt clone as balanced monsterblocks.
The F5 parts show up tomorrow. The plan is to get them running by the weekend and make a decision on all the F6 parts. Will let you know.
Odd order harmonics tend to make the amp sound "harsher."
Balanced mode has the benefit common mode noise rejection. I thought it brought down all harmonic distortion equally but what I've read from Mr. Pass is that, while it does bring down all distortion, it affects the 2nd order harmonics the most. My limited experience (since balanced tube amplifiers have been beyond my budget) is with the ACAs in balanced mode. I found them to completely disappear and the recording was just "there". However, with the ACAs output impedance, they aren't a good match on the Halcyons. Bass loses control and gets boomy and woolly. This all sparked the attempt at building a 1st Watt clone as balanced monsterblocks.
The F5 parts show up tomorrow. The plan is to get them running by the weekend and make a decision on all the F6 parts. Will let you know.
Sometimes I feel like Goldie Hawn, a bit overboard. Some research is still needed as I'm rusty on much of my circuit topologies and unsure I'm overkilling the build for no reason. I seem to have a recollection that balanced helps null out the PS noise since you have 2 of the same signal w/ opposite phase "compared" at the speaker inputs. Need to take a little time and draw it out.
Bi-amping is on my list. A nice NP designed active x-over feeding some F5s or F6s sounds like a good idea. Especially with these well behaved Mark Audio Alpair 10p's. I'm hoping the F5s will provide a little more detail up top and a lot more control down low.
that it will do. But if the speakers themselves do not have the 2nd order to help vocal reproduction in the midrange with a bit of "the sugar" it is a net loss (to me). Bi-amping with F5 at the bottom (if no more power is required to drive the bass section) and having an ACA, F3, Aleph, VFET, M2 and alike for the mid/top beats it any day. Even if you wanted to single amp then BA3balanced with say 3-deep F4 sections in the output stage and an input stage of your choice (BA3 FE, Impasse, pumpkin, Juma designs, etc) is a better choice than f5Turbo IMHO. Good luck.
I've got a pair of 4U mini-Dissipante chassis which can support a stereo setup in each. I've thought about doing a couple monsterblock configs like two F6 boards running balanced or two F6 boards in passive or active bi-amping. I could do an F6 and an F5 or some mix of the various 1stW clones. All sorts of options and I'm starting to sense I will need to try all of them. Especially when I start revisiting my speakers. I like the MarkAudio Alpair 10p but I think the woofer section could do better, possible a dipole config given that I need to mitigate bass spillover.
So beyond the F5 and F6 boards on hand, any suggestions to mixing and matching for a full-range paper driver with bass support?
So beyond the F5 and F6 boards on hand, any suggestions to mixing and matching for a full-range paper driver with bass support?
Last edited: