What to do with class A amplifiers to avoid some mufled treble

[destroyer X]

Of course if you do not perceive this way.... do not loose your time here..jump to another thread because you probably will not be helpfull saying they are not mufled when i know.... i have sure...they are!

I have made several models along the ears... and i have always perceived (this is perception, not measurements) treble mufled.

Do you feel this way?

Do you have solution for that problem (if you recognize this as a problem and have perceived same way i have perceived)

Sometimes i feel that driver output current does not modulate the power transistors input bias current.... because of class A operation, we have big current into colector to emitter, you will have also big current from base to emitter... seems to me some impedance or transference problem there..... as treble use to be very small in comparison with basses into the normal music.... normally not more than 10 percent when bass goes to 60 percent... sometimes i imagine the small audio current does not "modulate" the input base bias current ...and this disturbs the high frequency amplification.

I could not feel that with steady tones.... measuring the amplifier is linear...but listening it is not....mufled into the high frequencies...daugther said there's a pillow over the speaker cloth front grille... i felt the same... and this is something very old into my mind... was always that way....but so many people using, producing, and loving class A that i felt myself confused.

Maybe some lower impedance drive to the output..... do not know what to do and asking for ideas from you..... things happens dinamically...it seems the low level, high frequency signal, is having problems into the power input base... some reaction is happening there... erasing, reducing, opposing.... do not know exactly what happens..but i know how this thing sounds.

Please folks..... mosfet lovers..... i have not complementary...if you suggest me something using mosfets, then please offer a quasi complementary option.

I would be happy to know what to do to increase trebles into class A amplifiers..... really i have tried several...maybe 100 or more.... and i do not want to go trying more hundred units.... so...the question is:

Have you perceived that?

Could you fix that?

What have you done to fix that?

To offer to me to build Quasi amplifiers... the nice thread or something is not the solution... i have already tried several options...i am searching for solution, not to give space to the chance to find some amplifier that MAY have good trebles.

Of course i have assembled the most simple ones to the sophisticated ones.... something from JLH, from Nelson Pass and some single stage amplifiers too..... also some Krell.... well....i am not searching for a miracle amplifier folks loves... i am searching for good treble reproduction....or ... fair balanced equalized reproduction when strong basses does not kill the treble reproduction beeing stronger and dominant...of course do not want only to reduce bass into the input condenser....i want to try something to increase the trebles...not to reduce the basses.

Thanks in advance from your kindness to read and spend some time with me.

regards,

Carlos

[destroyer X]

An excelent amplifier....one of the best class A i have ever listened...BUT, despite beeing one of the best..... also i have perceived some of this effect.... and i want to know the causes... as the consequences i already know.

Roender output is conventional.... have only bigger current into the drivers, and i have tried CCS there too.... i found not the cause...the reason why.

Roender amplifier, of course, was one of the ones i have built and listen.


No!... old uncle charlie speakers are not mufled!... i have tried others...and the one i use has the fouth driver operating above 12 Kilohertz (modified from the original.... capacitor increase to this upper treble driver)..... my speaker is not exactly flat...and even having extraordinary "goodwill" related trebles i am still perceiving that.

Of course DOZ was made.... will be a hell to remember all i have made...but for sure the most famous were made.... several Krell also..... Krell sounds alike Leach amplifier with mufled trebles

regards,

Carlos

[lumanauw]

Many treble details lost in AC coupling. Try DC coupling or something like F below. I got it from Walt Jung's article.

[destroyer X]

Are those options to substitute input condenser or to couple from driver to output transistor?

I think i am confused, as i do not know if this to inter stage coupling or to input coupling.

Thank you by your attention and help.

regards,

Carlos

[destroyer X]

Do you have the link, or can you upload the article to me?

panzertoo@yahoo.com

regards,

Carlos

[sakis]

working so many years with AB amps created some identity in your ears ....

but before that let me ask you one question .....
to any of these class A amps you builted ....what is your opinon about bass ????

do you find it the same tight, enough, rich , colourless like you had in a class AB design ????
better or worst ????

often human ear can perceive lack of bass as too much high

( its like when you make mixing for a live show and the quitar player is asking for more treble in his monitor ....there is a very good possibility that he actually wants less bass )

you get the point ????

by the way uncle charly !!!!!!!!!!!!!!!!!!

THANKS FOR WONDERFULL ANIMATION !!!!!

[destroyer X]

is already a step over the others.... the voices are spectacular.... the treble are very good despite mufled...needs some increasing in level i think... and bass is a little too much to my taste.

Nothing that we cannot arrange reducing the input condenser... reducing the bass entering.

I think they are superior... nothing has even touched the Class A performance inside my mind.... an old Macintosh had made better service...but do not know if was class A or not.

I do not use them because too much hot...because too much low power.... because too much basses and because too small trebles.

But for sure it is better than AB...... but, when AB plays low level the result is not so different.... so, we have a class A amplifier inside each AB amplifier we listen.

No amplifier has ever touched the Mac Intosh tube amplifier performance i have listened down the sixties.... i am still seaching for something so good or better than that.... but cannot be class A (too much hot) and cannot be Tubes (too much expensive).

Roender amplifier had "eated" many amplifiers..it is a very good example of "majesty in sonics"..... i still would like more treble.

Let me correct on time...not Roender's amplifier.... but the Doctor Roender excelent Class A design.... you see that even Hugh Dean appreciates and respect this guy a lot...me too!

regards,

Carlos

[destroyer X]

Here is the picture.... i have made it rigth now.

regards,

Carlos

[tryonziess]

Carlos, Which particular amplifier are you using as a reference? What is the class and layout of the reference amplifier? Are the treble tones muffled on all music types even the simple very explicit classical music.
In a way of comparison I have always thought the chip amps were to bright in the treble department.
This is not good news. I am 70 percent finished with a mosfet A-75 amp and would not be happy with substandard results. I am sure you know what diy constructors expect from our pet projects.
Keep experimenting and posting it is very helpful for us not so experienced to here comments from those like yourself who have been at this for such a long time.

Tad

[destroyer X]

I have tried the solution by myself.... years trying..... one month trying and 3 monthes doing other kind of amplifiers...then returning to class A.... i have tried to find by myself but i could not.

Now a days i give up to find by myself.... i see i could not...no reason to insist into the silence...it is time to ask some help from other guys... they have ears too...for sure some of them have perceived something.

There are some "universal trues" that we do not discuss... they are not "politically accepted" things.... but finally i want to have it better, ... i could not fix... asking help.

Do not worry about less than perfect things... all them are this way...i have build more than 4400 units... and felt no one perfect...one is good for bass, other is good for mids..other for treble..other has some harshing..others unprecise bass..others loosen bass...others has tigth controled bass.... some have mufled voices..unclear trebles, .... and you have the super trebles and poor basses and almost all combinations, including dinamics, speed, frequency response (audible response...what results from the amplifier while playing into speaker and human listening..not measurements)...power headroom....harmonics... kind of distortion... well.... a lot of combination.

I cannot point you the best one..... I felt Aksa 55 Nirvana the best...but it looses for LM3866 into the bass if you accept comparison into 10 watts....if you try 35 watts than Aksa smashes the LM3866 sending it to the "toy department".... something ridiculous to compare... you will felt pitty related to National Semiconductors.

To listen voices i would love to listen the Precision 1... mine unit...but JLH from 1969 had smashed my beautifull amplifier.

To dinamics there are many.... alike Symassym, also my DHR Turbo is good.... the GEM is a killer.

Well..... i cannot point you the best...but for sure to 10 watts operation you can be happy with LM3866, the chip gainclone.

I have tried a single Pass amplifier...i dislike Field effect transistors..all them mufled to my ears...something i cannot stand for...so have tried once and never tried once more...and felt that Pass is the great one into those amplifiers, not only class A but also Fets.... and if his unit was perceived by me (subjective, personal, my ears, my taste, my music, my speakers, my environment, my listening position, etc) as mufled (a little).... i think will be hard to others to beat.

Roender gave me something more..but not enougth to scape from the mufled feeling i always have.

Maybe this is ME.... reason why i am asking others.

Sorry my dear... i know that beeing old into those things our ideas have value..sorry to bother you.

regards,

Carlos