I bought a DIY version of the F4 and added a Burning Amp front end (schematic here http://www.diyaudio.com/forums/atta...4351063-f4-power-amplifier-pass-ba1-fe-f4.jpg) as advised by mister Pass himself in the above thread.
something must be wrong there because my class D amp beats it hands down. and I'm talking about refinement which it completely lacks. what could've gone wrong?
something must be wrong there because my class D amp beats it hands down. and I'm talking about refinement which it completely lacks. what could've gone wrong?
Nothing personal, but I would bet that you either did a poor job implementing the front end or you don't have other parts in the chain to truly hear the capability of the F4. I have heard people not like the Pass stuf because they preferred tube sound, but in terms of SS amps, this is about as good as it gets. I guess it is possible that you like the sound of Class D amps, which tend to be analytical and a bit cold. Either way, now worries. You are lucky, Class D is much cheaper.
There are a number of issues here:
1. Do your ears prefer the sound of the Class D amplifier ?
2. Is the F4 / BA working properly.
3. What do you mean exactly by "beaten hands down"
All amplifiers are subjective and susceptible to source and output components. I would suggest that the F4 / BA set-up may have a defect or there is something in the source / output chain that is affecting the sound quality.
1. Do your ears prefer the sound of the Class D amplifier ?
2. Is the F4 / BA working properly.
3. What do you mean exactly by "beaten hands down"
All amplifiers are subjective and susceptible to source and output components. I would suggest that the F4 / BA set-up may have a defect or there is something in the source / output chain that is affecting the sound quality.
As I said, "Do your ears prefer Class D"
Ultimately you are buying Hi-Fi to listen to. If you like the sound of it then it is perfect for YOU. There is no such thing as Hi-Fi that is perfect for everyone.
I find that when I have built/modified something my mind plays a clever game. Either I hear what I expect to hear, or if there's a lot riding on it, I hear what I fear I will hear!
Best just to accept that if there's nothing obviously wrong then your new amplifier is working fine; you'll only be able to appreciate it when you're not listening to it so critically.
Best just to accept that if there's nothing obviously wrong then your new amplifier is working fine; you'll only be able to appreciate it when you're not listening to it so critically.
please see below, the F4 is simply removing things from the sound, not the other way round.
and it's quite the contrary, the rest of the system is very revealing. with my old speakers (Dynaudio Audience 52) the difference is very subtle and I would say that with those I feel that the single difference is more bass from the F4 but with the current ones (Dynaudio Confidence 3) it is "WOW! the class D is so much better at everything".
this is what I'm thinking too, maybe I did something very wrong with the front end but what can that be? it's such a simple schematic.
it is not the kind of difference that is just a matter of preference, it simply sounds worse and makes me want to shut it off and connect the class D. others have confirmed it without any prior bias from my side. I can't really describe it, but if I try by comparison the sound of the class D could be described as clean and displaying a lot of texture with everything, chords, voices, brass etc. with the F4 that is simply gone and makes me feel like listening to mp3's instead of CD's. the imaging is not precise, the sound sounds like a poor replica of the one coming out of the class D amp.
remains to be checked. look at this as a sanity check, something like "given everything is working right, can this really be?"
see above.
maybe it's the 86dB speakers? I would suspect that would cause loss of dynamics but not that feeling of removed detail and clarity,
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Its nice to see that this thread has not dissolved into the normal argument of Class A against Class D.
If you read the threads on the merits of both they are both very capable and some serious Hi-Fi is produced by the big guys using both topologies. Class D can be very unforgiving when it comes to exterior equipment, this is not generally true of Class A. Class A is VERY SUSCEPTIBLE to Power Supply issues.
Are your Power Supplies up to the job.
My F5 has got 2 x 1000W transformers, 12 x 33000uF Caps it can melt nails.
If you read the threads on the merits of both they are both very capable and some serious Hi-Fi is produced by the big guys using both topologies. Class D can be very unforgiving when it comes to exterior equipment, this is not generally true of Class A. Class A is VERY SUSCEPTIBLE to Power Supply issues.
Are your Power Supplies up to the job.
My F5 has got 2 x 1000W transformers, 12 x 33000uF Caps it can melt nails.
With Class A the power supply must be substantial. The F5 runs at 100W which needs a 200VA supply. For good regulation the transformer needs to be a minimum of 500VA. All the 1000VA transformers do is to lower the impedance of the PSU which cant be bad.
Some guys may argue about the choice of PSU caps though. I use 3 x 33000uF caps per rail per channel. Approx 0.1F (they actually measure at nearly 3 x that (0.3F))
Some guys may argue about the choice of PSU caps though. I use 3 x 33000uF caps per rail per channel. Approx 0.1F (they actually measure at nearly 3 x that (0.3F))
If the BA/F4 merger is done properly and with testing and optimizing, then you have come to the point where you realize that you like Class D amps. If you have not tested and optimized the merger of the two, you could have major issues and not realize it. IT is not necessarily plug and play. Why not build BA2. It is essentially the same thing. The F4 is just a power buffer. Both BA amps have power buffers at the output. They are fed my differential front end feeding a PLH VAS.
I have decided to build/buy the F4 as my first venture into class A, being not completely satisfied by the class D/Dynaudio match. even the advocates of class D admit that the class A should be better but instead of having a revelation I was turned off. I've listened to other (commercial) class A amps in the past and even in comparison to my class D and the general feeling was that the A class has a thicker, more solid sound, while keeping the detail of the D. but not with the F4.
if you're willing to accept that this is not meant to be a class A bashing thread I'll go into more detail and describe the implementation.
I think Hugh from Aksa was the first person I read to comment on the ideal transformer size and bigger isnt always better. I haven't tested so its not real to me. My aleph 2 draw 300 watts a piece and I use a 1kva in each. They sound good to me. I thought a standard F5 is 70 watts a side?
Fact is, everyone likes different things. So what if Pass designs don't do it for you. I'm not overwhelmed either, I thought my MiniA was adequate. I also don't see why people spend huge amounts of money on single drivers like Lowthers, when for half the money they could get three drivers that would do the job properly. But that's just me. 
So you may not be inspired by any one particular project, (and I've built many, even of my own design that were disappointing), but there's lots of other stuff out there to try, after all, that's why we're diy'ers isn't it? It's the journey that matters, not the conclusion.
So you may not be inspired by any one particular project, (and I've built many, even of my own design that were disappointing), but there's lots of other stuff out there to try, after all, that's why we're diy'ers isn't it? It's the journey that matters, not the conclusion.
Plus the low impedance of the Confidence-3, definitely.
Unfortunate choice from the start, a flea amp requires a flea loudspeaker.
I would love to hear your impressions. I currently have AJ's driving FR Mark Audio 10.2's. They sound great, tone, dynamics, left to right soundstage are great, but they do not have the sound-stage depth that my brothers Ming Da PP had. AS a result i am going to mod my preamp a little to see if that helps and I am also building an F3, known for its tubiness. There is nothing wrong with what i have, but i have the ability to try other things to achieve exactly what i want. Perhaps the preamp mods will do it, if not, I will just have to build more.
I am merely trying to make a couple of points. First, you don't own a Pass amp. You own a clone built by somebody else. For all you know, the thing doesn't even have real Jfets in the front end(there are fakes). Secondly, if you do have a legit F4, then perhaps the marriage with the BA FE is not made in heaven, as they say. If it is and you still don't like it, then congrats, you like Class D. Who cares what anybody else thinks. IMHO, something is wrong. I can understand not liking the F4, but what you are describing does not sound like the F4 described by others. I do remember the Six Moons review talking about the importance of the preamp matched with the F4. PLease share your thoughts freely. I am personally very interested, as I have two sets of F4 boards waiting to be assembled.- Status
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