The F5 does get the respect. I’d bet that out of all the Pass amps out here, the F5 is the most built. It has one of the longest threads in the Pass forum and I recall it was extremely popular until the M2 and newer designs with comparable power outputs were released. It will work for a wide range of speakers and like all Pass amps, it will sound fantastic. We are truly spoilt for choice here.
Absolutely. Just wanted to make sure the OP didn't think the F5 was not a good option. It really is.
Which BA-3 output stage did you build? Obviously, the push-pull stage is almost identical to the F4. I'm curious about the single-ended output stage.
I just built the BA-3 and it is edging out an 01a-based pre.
Which BA-3 output stage did you build? Obviously, the push-pull stage is almost identical to the F4. I'm curious about the single-ended output stage.
I just built the BA-3 and it is edging out an 01a-based pre.
In no particular order, BA-3, Aleph J, M2x.
You cannot go wrong with any of the Pass designs in general.
F4, F4, F4
I was looking at F4, and came across this:
FIRST WATT
It is tempting to settle for F4! From the spec, it seems that 4 ohms is acceptable for F4.
Edit: Adding Aleph J also into my short-list. So I think it is down to F4 vs Aleph J or alternatively just do F5 which is the easiest of all!
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I thought you'd never ask
Speakers are two way JBL 2226 15" woofer passively coupled to 2380/2445. F4 driven by the 01a pre and now the BA-3. DAC is the ADI-2 Pro and analog front end is Technics SP-10 MKII with diy pivoting tonearm and Dyna 10X5 cartridge into Pearl 2. Speakers are corrected using FIR filtering and plus some more MS processing and phase tricks to improve imaging and tonality. The 01a pre (can also employ the 26 tube) is an all out DHT pre, with Coleman regs and separate heater trafo, two chokes in the B+ supply, gyrator load. Even with the 26 tube, it was the best sound I ever had in the system. And before that, after building the F4 driven using the DAC was the best sound I ever had. The 01a took it further than the 26. But the BA-3 takes it even further.
The BA-3 has an even more accurate tone and just seems more free. And the imaging is absolutely amazing. It has a way of casting the soundstage that is extremely pleasing. I am now a believer about songs having a right and wrong polarity. Not all of them, but definitely a majority of them. And the coupling capacitor also makes a big difference. These differences were previously either inaudible or much less audible. Previously strident recordings, especially of horns in a symphony, which could get annoying after a certain SPL now can be played much louder, more than 6 db louder without issue. You still get the shrillness of a horn, it's full tone is there, but somehow it is cast in the soundstage and you can hear it for what it is.
F4, F4, F4
Yeah!
I thought you'd never ask
Yeah!
Could you share your passive crossover and FIR filtering and MS processing?
I use too 2226 2445h and 2380 with 6db series crossover and CD compensation for the rolloff of the horn
Penny for Penny, if cost is a concern and if you have standard 8 Ohm speakers then I cannot recommend the Aleph J highly enough.
It is easy to build with no complicated component matching or awkward to get parts.
I wasn't impressed by the F5, it didn't like my speakers.
The Aleph 4 is also an impressive amp but requires careful matching of the output Mos-Fets.
It is easy to build with no complicated component matching or awkward to get parts.
I wasn't impressed by the F5, it didn't like my speakers.
The Aleph 4 is also an impressive amp but requires careful matching of the output Mos-Fets.
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Hanair- F4 is an excellent choice IF you have a preamp that can drive it to the listening levels you like.
F4 has no gain (in fact, it has very slightly negative gain...) and the preamp must have the gain AND the voltage swing at the preamp output necessary to reach the volume you enjoy. If you have something tube-based you’ll almost certainly be great, and if you have a SS preamp and some strong source, and don’t listen at 11, it will likely work as well.
To sum up, F4 is fantastic amp, drives anything, has essentially no sound of it’s own, has no gain, sounds exactly like your preamp because that’s what’s actually providing the voltage swing.
F4 has no gain (in fact, it has very slightly negative gain...) and the preamp must have the gain AND the voltage swing at the preamp output necessary to reach the volume you enjoy. If you have something tube-based you’ll almost certainly be great, and if you have a SS preamp and some strong source, and don’t listen at 11, it will likely work as well.
To sum up, F4 is fantastic amp, drives anything, has essentially no sound of it’s own, has no gain, sounds exactly like your preamp because that’s what’s actually providing the voltage swing.
See attached pic for the crossover. It is a 6 db/oct filter for the 2380/2445 combination and the woofer is a 3rd order filter. The horn has natural roll off in the 600 Hz region and with just a single cap and a resistive divider to adjust for sensitivity, there is a very smooth transition. I saw this in a JBL spec sheet for this driver/horn combo. I tried higher orders, but this works best so far and there is no sign of the horn/driver being in trouble at lower frequencies. There is nice phase overlap--the most important thing with crossovers--between the woofer and horn, but the response through the crossover region is not flat. However, the FIR correction takes care of this. The filter is derived using multiple measurements around the listening spot and then corrected using DRC and a tailored target curve for my room, which I arrived at through trial and error.
The MS EQ is shown in the second pic. It is based on Wesayso's work in his towers thread. It started with my corner line arrays and I kept it for the horns, where it works equally well. It improves the center image tonality and the image localization. Finally, I've been playing with a 45 deg phase delta in the HF. See here: https://www.diyaudio.com/forums/multi-way/277519-fixing-stereo-phantom-center-99.html#post6225137. Would be interesting to note what you perceive, if you ever play with it.
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Yeah, I was quite shocked by the BA-3. I put many hours and $$$ into the 01a pre. As I was waiting for other parts for a second build with the 801a tube, I built the BA-3 because I had the parts and the PCB. It is so simple to build and the parts in total cost less than maybe four good 01a tubes. Just incredible. But of course, I should've expected nothing short of exceptional with one of Nelson's designs. I just didn't expect it to edge out a DHT pre with an extremely linear tube, which many consider to the best out there.