Münster, a diy copy with modifications of an old Sony, have some suggestions?

[MikeB]

Hi carlos,

The only problem with the 36volts-version is the max-Vce rating
of the bc546/556. The +/-36v gives max vce of ~70v, 10v above
the rating of the bc546.
There should be no other problem, biasing should stay correct
as i use ccs.
The sa970 could be a good substitute. The max-vce is only a problem
with the cascodes and predriver. All other transistors keep in range.

What is the maxrating of the bc547 ?

Mike

 

[destroyer X]

Take a look MikeB, i may be wrong, please correct me if i am.

You are thinking in Peak to Peak...but you have to think that you will never have more than the peak voltage related to zero point...the other half cicle...the negative...also will be maximum 36...so...the junction will see only 36 volts maximum of potencial difference.

Carlos

 

[destroyer X]

Those 36 Volts will appear at different moments...not the same time as we do

As we do when we are measuring Peak to Peak.... in the scope we will have two half cicles or more.....but the never reach more than 36 volts in one fixed moment of time.

I am using higher voltage on them.....guaranteed, no problem Mike.

Carlos

 

[MikeB]

Hmm, i think you must look peak to peak...
For example, the amp puts out 30v, supply is +/-36v, so both
emitters on output have ~30v. This means the upper has vce of 6v,
the lower has vce of 66v. The same is for driver/predriver, and similar
for vas.

Mike

 

[destroyer X]

Yes MikeB, my error, you are rigth and thank you again

You are turning very instructive to me.

It is clear, whe the top one is saturated you will have plus and minus supply less the saturation voltage..

You are rigth.

So, mine BC556 are stronger than normal...hehe.

Some "good tollerances" from production selection.

regards,

Carlos

 

[MikeB]

Yes, i think these ratings are guaranteed, so none of the devices
will break down below this voltage...
But i think it's risky ?

Mike

 

[darkfenriz]

Your "currentfeedback" comes from the vas, it modifies negrail for diffamp

hey MikeB
as far as i know, this resistor combined with huge cap is a quasi integrator and gives a diffamp extra rail stabilisation

hallo Carlos
to be honest i didnt read all the posts but i have some questions:
- in munster you have huge cap in paralel to small resistos on the emitter of voltage aplifying transistor
are you sure it should be there????-this would make an amp terribly slow
- the diffamp input is biased by a voltage divider- so you have to worry about offset dc-this may wor for exactly these resistors but if they are a bit different???

much respect

 

[destroyer X]

No darkferinz, i am not sure about that capacitor

Was used to improve gain and to make the amplifier good to 5 hertz.

But this is simulation results....real life hearing can be deceptive.

Thank you Dark.

regards,

Carlos

 

[darkfenriz]

yeah, sorry Carlos
this cap doesn't slow anything down but reduces DC-feedback
...the piont??...no idea

one tip for you-don't build it...
even if it works properly it won't be anything 'sophisticated'

 

[destroyer X]

Darkferinz, you made think a lot!.... and not exactly your question, but...

I could imagine that we do not need to worry too much with rising speed, or even distortions, as speaker is destructing all.

I will put this at Speaker forum...they will dennie.

The reason is obvious!.

If you spend your all life doing not what you want, because God is looking at you all your lifetime.....and someday, do not know how, you have some "insigth" and discover that God do not mind to take a look in no special person...that he looks the Universe as one whole thing.... making it stable only.

You will dennie this God!...because if you do not...you will have to believe that your life was a shame....you left your life passing.... believing some inspector are watching you....you left good things to do...that girl....that other....that moment...no!...he is watching us!!!!

But i will post anyway.

regards,

Carlos

 

[destroyer X]

Second text part

Here is:

 

[destroyer X]

Third text part

Here is:

 

[destroyer X]

Fourth text part

Here is:

 

[destroyer X]

Fifth text part

Here is:

 

[destroyer X]

The sixth part

Here is:

 

[MikeB]

Hi carlos !

You are right, it's impossible to reproduce a perfect squarewave...
No mechanics is able to make such a movement !
Even electronics is not able to do this, but this is simple mathematics.
A real squarewave contains infinite high frequencies.
And for example, if you playback a 22,05khz squarewave with a
good cdplayer, guess what you get... A simple and nice sinewave !
That's because it filters out all frequencies above 22,05khz...
So the amp or tweeter will never see a squarewave, unless you
connect the amp to a signalgenerator...

Checking an amp with a squarewave is only for checking it's stability.
With a squarewave the amp easily shows it flaws and weaknesses.

In my amps i have limited slewrate to about 20v/us, that's enough to
reproduce a clean sinewave at 250khz for 20volt swing.
I could increase slewrate, but not without getting overshoots.
It seems that an amp with overshooting tends to sound bright/harsh.
Anytime i optimized my amps for not overshooting, they sounded better.

Mike

 

[destroyer X]

Thank you MikeB, some informs i really did not knew till this moment

I thank you very much for the technical support, as i cannot go deep to explain what i mean.

But you translate to words that the more skilled guys will understand better.

regards,

Carlos

 

[destroyer X]

Well friends, this is the Münster thread

So, as i openned a thread related to speaker problem, i will ask you, please, to go there if wanting to write something about that subject.

So, the Münster is already alive.

Also in Loudspeaker forum i openned one thread related that subject too.... there, things will have a lot of movement of peoples visiting.

Moderators, seeing too much movement, will join those threads, i expect this one, the Münster, can survive in this place.

The reason why i post the speaker matter here, is because Darkferinz made me think, so, this was made for him, that shake my mind.

I thank you Dark

Carlos