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Old 28th May 2011, 09:45 AM   #1
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Default PASS DIY F4 beaten hands down by my class D amp, what's wrong?

I bought a DIY version of the F4 and added a Burning Amp front end (schematic here http://www.diyaudio.com/forums/attac...-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?
 
Old 28th May 2011, 10:11 AM   #2
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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.
 
Old 28th May 2011, 10:11 AM   #3
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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.
 
Old 28th May 2011, 10:28 AM   #4
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My question would probably be:

Why would it not since the Class D may be superior in almost every parameter?
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Old 28th May 2011, 10:31 AM   #5
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I guess that is the question.
 
Old 28th May 2011, 10:34 AM   #6
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Quote:
Originally Posted by UrSv View Post
My question would probably be:

Why would it not since the Class D may be superior in almost every parameter?
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.
 
Old 28th May 2011, 10:50 AM   #7
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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.
 
Old 28th May 2011, 11:16 AM   #8
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Quote:
Originally Posted by buzzforb View Post
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.
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.

Quote:
Originally Posted by Andy5112405 View Post
1. Do your ears prefer the sound of the Class D amplifier ?
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.

Quote:
Originally Posted by Andy5112405 View Post
2. Is the F4 / BA working properly.
remains to be checked. look at this as a sanity check, something like "given everything is working right, can this really be?"

Quote:
Originally Posted by Andy5112405 View Post
3. What do you mean exactly by "beaten hands down"
see above.

Quote:
Originally Posted by Andy5112405 View Post
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.
maybe it's the 86dB speakers? I would suspect that would cause loss of dynamics but not that feeling of removed detail and clarity,

Last edited by mr_push_pull; 28th May 2011 at 11:19 AM.
 
Old 28th May 2011, 11:17 AM   #9
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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.
 
Old 28th May 2011, 11:31 AM   #10
Luke is offline Luke  New Zealand
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Quote:
Originally Posted by Andy5112405 View Post

My F5 has got 2 x 1000W transformers, 12 x 33000uF Caps it can melt nails.
There are folk here who might think a smaller transformer would sound better
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