Another amp

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Them diode is a safety. To protect the Capacitor.
A capacitor destroys of too high voltage
or some volts negative.
Diodes make voltage never can go more than +-2 volt.

Normally diodes is not working.
If you use bipolar cap or Polypropylen, than there is no need, I think.
 
Drafrance007

JensRasmussen said:
Well, I thought that it destroys the Q (In a possible LC cuircuit) , making the thing not oscilate.
\Jens
This is the correct answer Drafrance007.
Jens Rasmussen knows this. He have studied these things.
He should know.

But to more mortal souls, like me and Drafrance007
the answer could be flying some bit over our heads.

A good teacher speaks same language as his pupils.
doesn't he?
:confused: :confused: :confused: :confused: :confused: :bawling:
 
Disabled Account
Joined 2002
Re: Drafrance007

halojoy said:

This is the correct answer Drafrance007.
Jens Rasmussen knows this. He have studied these things.
He should know.

But to more mortal souls, like me and Drafrance007
the answer could be flying some bit over our heads.

A good teacher speaks same language as his pupils.
doesn't he?
:confused: :confused: :confused: :confused: :confused: :bawling:
O.K.I Can.t say i comlete understand this but it it's purpose was bothering me. One intresting stuf...why so many out transistors...i...polled out 200w with 4 transistors bd911/912, maybe 6...mje...OK...but WHY 8 transistors... ???
 
Hello again,

I see that some questions have appeared here,
and thay have already been answered by others!
Thanks for your interest!
Regarding the 8 output devices: yes, this number
may seem exaggerated. The amp will probably work
well with 6 or even 4 transistors, especially
for an 8 ohm speaker.
My intention when using 8 transistors
was to make the amplifier rugged. The maximum
power that the transistors can handle decreases
with increasing temperature. The 8 transistor
configuration is intended to allow for safe operation also when the amp is run hot.
Also, paralleling many output devices reduces
the effect of 'beta-droop' as described
e.g in Douglas Self's book.

Best wishes to all of you!

Marcus



:)
 
Drafance007 said:
Now, Just one more question.....if you pull-out the short-circuit protection....could the amp give twice as much power on a 2 OHM load....wit a beter power supply ???
why would you need twice as much
if there is already much

Are you gready (want more and more and more, never satisfied)
or are you an
poweroholic (an power addict)
 
halojoy said:

why would you need twice as much
if there is already much

Are you gready (want more and more and more, never satisfied)
or are you an
poweroholic (an power addict)
No, No, I Am Just a guy that likes to buid amplifiers but there are may "SO(SELF) CALLED" DJ's around me and diskoteks that ask me for that much power so i wanted to know since i don't have proper tanformer is it Posible ????
 
Dragance007 said:

there are may "SO(SELF) CALLED" DJ's around me and diskoteks that ask me for that much power so i wanted to know since i don't have proper tanformer is it Posible ????

Hehehe, I know those guys :D!!!
just for fun:

Just let them hear a good 100/200W amp with good speakers (with high sensitivity) and play at almost full power (the whole room is thrilling) and ask them 'how many watts' they think that's playing. They would be amazed that it's 'only' a 100 or 200W.

HB.
 
Dragance007 said:
No, No, I Am Just a guy that likes to build amplifiers. But there are many "SO(SELF)CALLED" DJ's around me and discoteks that ask me for that much power. So i wanted to know since i don't have proper transformer, if it is Possible?
Yes, Dragance007,
I understand.
I figured it was something like that.
For PA, public announcement.
With Live Band Shows or Disco, with big room, big volume

100 Watt and PA-speakers is very much!
PA-speakers need not so much watt as homespeakers

Homespeakers have SPL 86-90dB for 1 WATT (8 ohm)
PA-speakers maybe SPL 98-102dB for 1 WATT (8 ohm)
SPL = Sound Pressure Level = "Volume" that we hear

1 WATT 98-102dB SPL, and your neighbour will call Police!!!!!
Or you have called the Ambulance yourself. For blood comes out of your ears!!
better to test 100 WATT, in a lonely villa-house far far away in the forrest

;100 watt in -PS- speaker with SPL 100dB, is the same Volume as
1600 watt in home speaker with SPL 88dB

difference 12dB (100-88) every 3dB need 2x power less
2^(12dB/3dB) = 16 ,, sixteen times less Watt needed for PA
 
Disabled Account
Joined 2002
I tottali understand the way that SPL of speakers can do a miracle of even a small amp....My Friend has a BASS-BIN...- 2 of them...with 15W554K RCF Speakers....this is 500w and i belive 102DB/1W1M....fantastic sound...but the speakers are 8 ohm ones...so we figurem maybe 4 of this paralel speaker on a M250 could be a blast for a biggest doskotek.
 
questions on the M250

Hi, please forgive the novice questions, but I am curious about the inductors on the output of this amp. 1) are they for impedance matching, or filtering maybe?? 2) Does anyone know what standard inductance value these are? 3) if not, I dont see a value for the diameter of the windings which would be critical for the inductance value. I am a little nervous about winding my own coils on this so I would rather just buy an inductor. Any feedback would be appreciated.
 
Suggestions on component types

I think that this is the Amp I've been looking for! But, being a newbie on amp design, I would welcome suggestions on Cap types & Voltages, resistor types & wattage for this design. I have the layouts and info from the website, but I was wondering if anyone had a better view(s) of the PCB? Or anything for the Protector circut for the speakers?

Many!, Many! thanks to Marcus for Putting His "Baby" out on the Net for all of Us! :D BRAVO! :D

Thanks To All!
Tall Shadow
(Mark Ray)
 
The one and only
Joined 2001
Paid Member
Re: questions on the M250

TaylorG said:
Hi, please forgive the novice questions, but I am curious about the inductors on the output of this amp. 1) are they for impedance matching, or filtering maybe?? 2) Does anyone know what standard inductance value these are? 3) if not, I dont see a value for the diameter of the windings which would be critical for the inductance value. I am a little nervous about winding my own coils on this so I would rather just buy an inductor. Any feedback would be appreciated.
The usual value is about 10 micro-Henrys (uH), wrapped
around a 5 ohm or so power resistor. Do yourself a favor,
and leave it out.

Sorry to disagree, Pierre, but all the electrostats I've seen
are inductive above 20KHz or so. The coil in question here is
for stability into LC type resonance at higher frequencies.
Personally, I consider it a hangover from the original RCA
designs, kept on because designers figured it must do
Something. I've left them off for about 30 years, and
never missed them.
 
Hi all,

Here are some details about the components used
as requested by TaylorG and Tall Shadow.

C5,C7,C8 200V or more
All other caps can be low voltage (16V or more)

R9 1/2W
R31 2W
R32 2W
All other resistors 1/4W

Coil L1 is 20mm diam, from 10 turns
2mm diam copper wire = 20mm long as well


Thanks to Mr. Pass for this comment regarding
the output coil. This was designed into the
circuit from the start, as recommended in
many sources. I have not tried running the
amp without it. My page was originally intended
as an inspiration, rather than a finished
recipe, so feel free to experiment, and please
tell me if you make improvements.

I will try to update the page with the DC
protection and power-on delay circuit asap.
Right now is a busy time with postdoc
applications to write.

All the best,

Marcus

:)
 
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