I am trying toshiba mosfets for a week.My impressions is that they have many deep bass.More than fairchilds.Maybe it shows that toshibas work better(Better frequency response)But deep bass makes me hear treble less.My friend has also same impression.He says he hears deeper bass and that makes to hear less treble.And also he says toshibas does not allow harmonics sustain(He says he heard sustained harmonics of little bells with IRFPs)I trust him because he is a hi-end audio service and listened many systems for about 25 years
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sorry folks this is OT... hopefully dispositive
Here's the bottom line on "Eric" - he has tried and sold each and every amplifier he has bought over the last decade or more except for the BEAR Labs Symphony No.1. That adds up to a lot of amps. Maybe that will tell you something?
I'm not sure, but I don't think he still has an H20...
But yes, IF I changed the resistors from say metal film to carbon comp the specs would not change very much if at all but I am pretty sure that the sound would. How many I would have to change is a question TBD, but I am pretty confident that I could change a few key ones and it would be audible.
Now, can one or can one NOT hear an input cap of high quality (pick one - MKP, ur fav botique brand polypropylene, teflon, etc.) at the input of the Symphony No.1?
If you'd like to flame on about this topic, please start a new thread in the appropriate sub section (probably "Parts", but maybe "solid state") and we can have at it. Ok?
_-_-bear
What does the frequency response and impedance curve of your speaker look like? Threat the complete package like a circuit and the answer will reveal itself.
What are you talking about Bear, i thought we were discussing resistors ( your idea ) and it's appropriate effects on sound.
Are you saying even if we can hear the difference , it's not measurable ? or are we not looking in the right place? If the sound changes from your F5 there has to be a signature somewhere, No ?
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a. wayne - the thread is about parts & implementations of the F5.
You posted something that I responded to - surely you can see what you wrote, and that what I wrote is a direct response to you?
I would expect that one could measure the sound changes that people are experiencing without too much difficulty - someone should try using a good program and sound card or application specific hardware. How about you? Maybe you will do it?
NP already posted about how this happens in this circuit.
Why don't you just build the amp - it's only 4 devices, and see what you find??
A novel approach??
_-_-bear
You posted something that I responded to - surely you can see what you wrote, and that what I wrote is a direct response to you?
I would expect that one could measure the sound changes that people are experiencing without too much difficulty - someone should try using a good program and sound card or application specific hardware. How about you? Maybe you will do it?
NP already posted about how this happens in this circuit.
Why don't you just build the amp - it's only 4 devices, and see what you find??
A novel approach??
_-_-bear
Hi F5'ers...
My friend Rick decided some time ago to try his hand at building an F5. Since he is somewhat a newbie when it comes to ground up construction, the F5 appealed to him due to the almost complete lack of parts!
So, he brought his first version, on plywood, over for an audition.
It wasn't bad, but it sounded a bit "funny" - somewhat thinish and somehow a bit "uncorrelated".
We were listening on my horn system which consists of a relatively rare Japanese compression driver from 300Hz up and a 15" midbass "filler" down to my Quadripole subs... the main amp, in this case w/F5 substituting runs the horn + woofer. Horn is 109db (padded down to meet) the 15" at ~99dB (real 99dB, not wanna be). We also ran it direct to the horn.
The beauty of this arrangement for me is that there is ~10dB sensitivity difference between the horn at 109 and the woofer at 99, which corresponds almost exactly to the gain diff between my main amp (Symphony No.1) and the F5... voila magique! Auto level matching!
Long story short, it sounded good, but a bit lackluster.
Rick stopped back several times, each time with an upgrade:
- resistors
- power supply
- wires
- layout
The details of it aren't totally important.
What is important to me is that we recently auditioned it vs. a homebrew all Tango 300B amp, a Welborne Labs 300B amp, a Cary 811-3 amp, and of course my Symphony No.1 amp.
We used WE300B and others... fyi.
Very very easy to hear what is going on with this system...
Bottom line subjective result for me is that the F5 seems rather sensitive to details of implementation but is silky smooth on the top end, beating out the SE toobes that were here by some degree, seems to not create much if any sibilance (that HF grain on the top of voices)... now I do have to find out why this is so - but even if it is a flaw it is a really really nice flaw!
Still not sure about the sense of dynamics, or if the darn thing is just super clean sounding, so that is what is going on or not...
Quite an exciting amp so far!
PS. not sure that this is really a good amp for most folks unless you have very high efficiency horns like I do, or a very very small room... bridged seems interesting though...
_-_-bear
Were you ever able to find out the " flaw " as you described ? maybe this is what Umut was talking about ..
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we're still working on it - but it mirrors what other people have reported so far in this thread and the main thread.
I think this is what Umet is finding in his implementation... also the bias point seems to be significant in terms of the resulting sound. (which, btw is puzzling to me...)
Patrick reported on the balancing the gains when using the Tosh's, although I am not sure he mentioned any change in sound...
_-_-bear
I think this is what Umet is finding in his implementation... also the bias point seems to be significant in terms of the resulting sound. (which, btw is puzzling to me...)
Patrick reported on the balancing the gains when using the Tosh's, although I am not sure he mentioned any change in sound...
_-_-bear
The famous "sweet spot" I presume
All amps I have built have always been like that
Too low bias and its cold, but some like that
Too much and mids gets muffled
Somewhere in between, and it gets just right
I adjust by ear, and monitor both dc and bias on LDR, and heatsink temperature
Seems to settle around where dc on output is also most stable
So far they have all been AB amps
Hello.I am trying different output devices on F5 amp.I had listening tests for about a week.I think toshibas are better for fast musics ,they are faster than IRFPs,they are more dynamic.IRFP mosfets are slower.They have more tube sound.It is better for jazz music.But it starts clipping when it plays 4 or more instruments.But i prefer IRFPs to Toshibas.I think IRs are better for old people and Toshibas are for youngs
That's interesting that you find a sweet spot on class AB amps, as I thought I had been imagining no or less improvement when pushing the bias on my AB amp. (I was so proud to get a calculated 4W in class A!)
What's 'LDR'?
did i really write ldr
should be DMM(digtal multi meter) 
it was late Yes, I did not know what I heard before, when adjusting bias
Until it was explained here
And it was pretty awkward of an amateur like me when I years ago told a pro that I thought his design sounded better with different bias than what he recommended
I once bought a pretty good commercial amp
I asked a pro if it was possible to have it optimally adjusted
He said that it would need a person who knew this amp inside out, or else it wouldnt better than adequate
So I thought, heck why not do it myself, and so I did
Its still working, so I guess it was ok
Tho, I have this thing about temperature
I feel better if every device is equally hot
But THAT may NOT be optimal, I guess
I adjust my motor the same way
And my speakers too ...shoot, speakers dont get hot, which makes it more tricky
I love when the master says "Luke, shut it off and trust your senses"
But my dear amps have become sensitive to noise from outside
I suspect small instability, maybe
Would surely be nice to have a scope or something to show whats going on
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oh my! now this is something interesting. I want to know why this is the case - why does bias affect sound like this when it seems 'obvious' that more bias is less distortion and therefore, better sound ????????
When changing the bias, you are moving along the transfer curve of the (output) devices, and since this is nonlinear we can see the distortion components change. Think of the transfer function decomposed into fundamental, second, third, fourth order and so forth, and each of those factors is changing along the curve, changing the composition of the distortion spectrum.
At the same time, the output devices interact, and when the bias gets lower and lower you may drive the lesser-conducting device into a part of its transfer curve where it gets starved for current - consequently, producing probably more distortion than the (DC) bias point would indicate......
And, this also all depends on how loud you are listening, and the sensitivity of your speakers since that determines how much of the transfer curve is being used for signal swing.
As Nelson pointed out, some prefer K2, some prefer K3, some more, some less, its a question of taste at some point. what is better?? you tell us....
At the same time, the output devices interact, and when the bias gets lower and lower you may drive the lesser-conducting device into a part of its transfer curve where it gets starved for current - consequently, producing probably more distortion than the (DC) bias point would indicate......
And, this also all depends on how loud you are listening, and the sensitivity of your speakers since that determines how much of the transfer curve is being used for signal swing.
As Nelson pointed out, some prefer K2, some prefer K3, some more, some less, its a question of taste at some point. what is better?? you tell us....