This is probably going to be hated - done 1000 times before, etc etc....
Having built an F5 years ago, I have a little more time again and looking to do another build.
My F5 is still in daily use in my 2nd system, between a valve pre and some small Spendor SA1s - where it is in perfect synergy and a delight to listen to.
Now I'm looking for an upgrade to run into my much larger Harbeth SHL5s (mid to high 80s sensitivity, about 6Ω) in place of my current Sugden A21SE - 25w Class A SE. The F5 driving the Harbeths is somewhat similar to the Sugden in the bass, but the F5 is definitely more "etched" or forward in the higher frequencies.
I really want to keep the sweetness/listenability of the Sugden, but with better, richer and more controlled lower registers. Both F5 and Sugden don't have enough "ease" for symphony orchestras. I think I am answering my own question here maybe (F5 Turbo) - but what is opinion here for that brief? F5T or F6?
In any case, I'd build mono blocks, not sure in the case of F5T if I would go V2 or V3 throttled back slightly to a ~75w operating point (for heatsink on-hand availability). So differential cost is not an issue.
Having built an F5 years ago, I have a little more time again and looking to do another build.
My F5 is still in daily use in my 2nd system, between a valve pre and some small Spendor SA1s - where it is in perfect synergy and a delight to listen to.
Now I'm looking for an upgrade to run into my much larger Harbeth SHL5s (mid to high 80s sensitivity, about 6Ω) in place of my current Sugden A21SE - 25w Class A SE. The F5 driving the Harbeths is somewhat similar to the Sugden in the bass, but the F5 is definitely more "etched" or forward in the higher frequencies.
I really want to keep the sweetness/listenability of the Sugden, but with better, richer and more controlled lower registers. Both F5 and Sugden don't have enough "ease" for symphony orchestras. I think I am answering my own question here maybe (F5 Turbo) - but what is opinion here for that brief? F5T or F6?
In any case, I'd build mono blocks, not sure in the case of F5T if I would go V2 or V3 throttled back slightly to a ~75w operating point (for heatsink on-hand availability). So differential cost is not an issue.
Aleph J for ease of presentation and long listening sessions.
F6 with a couple modifications – FQH44N10 transistors and 3x green LED voltage references. If you're set on doing this instead of the AJ.
Dual-mono power supply either way. You will be amazed if you haven't done this already with your F5.
F6 with a couple modifications – FQH44N10 transistors and 3x green LED voltage references. If you're set on doing this instead of the AJ.
Dual-mono power supply either way. You will be amazed if you haven't done this already with your F5.
Thanks. The Aleph J has so many enthusiastic comments, it must be good. For some reason I had always thought of it as "softer" in the bass - and I really do want something that has capability to deal with dynamic orchestral passages. But maybe I have got that assumption all wrong?
(Presumably the boards being "sold out" in the store is a temporary thing?)
(Presumably the boards being "sold out" in the store is a temporary thing?)
The Aleph J is presently sold out because it is so popular. A temporary situation.
The PSU has a lot to do with bass response and dynamics. I would say it is actually the dominant factor, that is why I always recommend dual-mono PSU builds. The Aleph J excels in bass response, as does the F6 with the FQH Mosfets that I mentioned. Their differences lie in the subtle nature of midrange and treble presentation.
The PSU has a lot to do with bass response and dynamics. I would say it is actually the dominant factor, that is why I always recommend dual-mono PSU builds. The Aleph J excels in bass response, as does the F6 with the FQH Mosfets that I mentioned. Their differences lie in the subtle nature of midrange and treble presentation.
F4 was out principally because I don't have enough voltage gain with the rest of my system currently. I have a Tubelab SSE board sitting around for years, I had thought of building that and bi wiring using an F4 on the output to drive the woofers only. But I quick BOM cost calc, enclosure manufacture, and total unknown sound, put me off...
Very useful input on the PSU - I was planning mono blocks anyway, so that works. Is it the relationship between PSU output impedance and load (2 ch vs 1)? Is it beneficial to go overboard on capacitance etc as well? Or just stick to the standard PSU parts, just doubled up?
Very useful input on the PSU - I was planning mono blocks anyway, so that works. Is it the relationship between PSU output impedance and load (2 ch vs 1)? Is it beneficial to go overboard on capacitance etc as well? Or just stick to the standard PSU parts, just doubled up?
With a dual-mono PSU, there isn't a real need to go overboard on the capacitance; there is already double the effective amount per channel. For a simple CRC arrangement, I like to recommend each C be a total of 33,000 uF to 36,000 uF. For a CRCRC arrangement, each C can be a 22,000 uF to 27,000 uF cap. I will add a film cap (1uF to 10uF) in parallel with the first C to catch any switching nasties from the bridge rectifier, and a 1000 uF electrolytic in parallel with the final C.
The store Universal PSU boards can accommodate all this quite well.
The store Universal PSU boards can accommodate all this quite well.
At this time it seems F5t and F5 are out of stock in the store. F6 is problematic at the moment for transformer supply but F5t has a shipment of semis going to the store very shortly.
Thanks everyone for input! I think the overwhelming consensus is always Aleph J - so I'll do that. Heck, if it's no good, with a case and PSU done, it will be trivial to swap to an F6 at least. (F5t less so maybe).
Components are such a problem generally. I thought I could just have Sowter make some equivalent transformers for me locally, but they're quoting crazy lead times. Maybe their std 600/600 1:1 is fine - haven't looked at it too closely, since I think Aleph J is the way.
Components are such a problem generally. I thought I could just have Sowter make some equivalent transformers for me locally, but they're quoting crazy lead times. Maybe their std 600/600 1:1 is fine - haven't looked at it too closely, since I think Aleph J is the way.
Before you choose ... have you tried adjusting P3 on your F5? This assumes you used a version of the boards with P3, and that you have the tools to do so. It can/may/should/kinda sorta maybe remove the "etchiness". Maybe you can try that to see if it helps. Either way, I'd still build (at least) one more amp. It's just a matter of which one. 😀
Before building the AJ (Which I adore), you may consider a BA-3 amp. It's the F4 as an output stage with the "BA-3" front end. So, you have voltage gain. It also has adjustable harmonic distortion profile if desired via "P3". It's scalable, fun, and it sounds (IMO) amazing. A great choice if you want to try an amp with more ooomph.
Anyway, if I were to choose between your two original choices... I'd go F6 with the mods previously suggested. The F5T would likely have a very similar sonic character to your F5.
Before building the AJ (Which I adore), you may consider a BA-3 amp. It's the F4 as an output stage with the "BA-3" front end. So, you have voltage gain. It also has adjustable harmonic distortion profile if desired via "P3". It's scalable, fun, and it sounds (IMO) amazing. A great choice if you want to try an amp with more ooomph.
Anyway, if I were to choose between your two original choices... I'd go F6 with the mods previously suggested. The F5T would likely have a very similar sonic character to your F5.
Unfortunately my F5 doesn’t have P3. Surely it’s not hard to retrofit? I could measure the distortion fairly easily using my USB audio interface - so that is definitely something I’m going to try in parallel.
For a new build though I’m going with Aleph J after recommendation here - and in every other thread, basically..! I’m going to build them as monoblocks and do the best job I can.
I should be getting sorted with some Zen Mod boards thanks to the amazingness of this forum, so I need to get ploughing through the main thread and schematics to see the differences…
Looking forward to the build… I will try to do a build thread but I’m typically hopeless at stopping to photograph etc when I get going.
(I might order as well the F6s, F4, BA3 and some extra matched jfets from the store while I’m there)
For a new build though I’m going with Aleph J after recommendation here - and in every other thread, basically..! I’m going to build them as monoblocks and do the best job I can.
I should be getting sorted with some Zen Mod boards thanks to the amazingness of this forum, so I need to get ploughing through the main thread and schematics to see the differences…
Looking forward to the build… I will try to do a build thread but I’m typically hopeless at stopping to photograph etc when I get going.
(I might order as well the F6s, F4, BA3 and some extra matched jfets from the store while I’m there)
Love it! When in doubt, build them all. 😀 Have fun with the builds and enjoy the tunes.
I am not sure about retrofitting your F5 to add 'P3'. The person that created the layout/schematic is likely your best bet for that question. FWIW, I am not sure it would be worth the effort. You could consider selling that set of boards and getting a new store set, but with 3 new projects already.... 😀
I am not sure about retrofitting your F5 to add 'P3'. The person that created the layout/schematic is likely your best bet for that question. FWIW, I am not sure it would be worth the effort. You could consider selling that set of boards and getting a new store set, but with 3 new projects already.... 😀
Thanks to Tungsten for putting me on to the importance of the PSU.
For the rectifier - I’d rather just go for a monolithic block - is there any consensus on PN? Or basically any 20/30A 200v option? And snubbers? In an ideal world, I wouldn’t go down the route of building the quasimodo test jig - are snubbers necessary? Or maybe even ball park it with a 20R?
For the rectifier - I’d rather just go for a monolithic block - is there any consensus on PN? Or basically any 20/30A 200v option? And snubbers? In an ideal world, I wouldn’t go down the route of building the quasimodo test jig - are snubbers necessary? Or maybe even ball park it with a 20R?
No consensus re: P/N. Snubbers are not necessary, but a number of people use them. Do you have a snubber board? If you're going with monolithic bridges and not using the rectification section of the UPS V3 boards (as one example), you'll need some sort of option to put it into the circuit. See the Quasimodo results thread where a number of people have posted their values for a lot of popular transformers if you decide to go that route and don't want to build one.
For the small monolithic block rectifier, I like p/n 26MB40A. A small value film cap, ca. 0.0068uF, works as a basic snubber. There is a thread in the power supply forum on snubber values for various transformers.
For all the noobs in the room, any easy examples of the film caps and electrolytic caps you use in parallel?
For the film caps, any axial lead polypropylene (MKP). I usually use 2.2 uF from my local surplus shop. My favorite electrolytic caps are Panasonic FC series from the same source. Easier to find are any of the Nichicon audio series - FW, KA, KW, etc.