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Old 28th July 2008, 03:01 PM   #21
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Default i dlike to complain once more .....

i am from nature a very happy guy ...it really a pity that forum members are so far away from eachother and some of us if meet will make so grate things ....also find out that what i say is true ...i am a very happy guy ....i dont like to scream to people or be negative but some times i really have to !!!!!

line up :::::
except that i like you so much as a person and always read your posts since 99.9% i will learn something from them ......

why add base stopers ??? they werent in the schematic any way then your comment about variac is absolutelly wrong since when you shut down the amp and since there no input or load to it capacitor bank will act as a variac since there is no load ,rail voltage will drop and then amplifier will shelf distruct

cbs 240::::

thanks for the math ....but your calculations must be wrong since this is a WORKING AMPLIFIER !!!!! what i am trying to say is that this schematic is a clone of existing comercial HILL AUDIO CHAMELEON 900 AMPLIFIER so it was working any way ......

i will listen to all coments that might say that this amp is crappy or unstable or what ever since this is not against me but against the original designer

THE SOLUTION .......

YOU CAN CALL ME COLOUR BLIND ..... BUT I WAS PRETTY SURE THAT THE RESISTOR I USED FOR R26 R27 WAS 15K ....WELL IT WASNT ....IT ONLY LOOKED LIKE IT IT WAS 1K5 THAT WAS THE PROBLEM .....

now that we have an original working amplifier we can talk as much as you like about improovmets .....

here is a foto od the stupid resistor ....for sure looks like 15K

after all i have to thank all forum members for helping any way .....
Attached Images
File Type: jpg resistor.jpg (14.5 KB, 611 views)
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Old 28th July 2008, 03:20 PM   #22
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Default read the post

Quote:
Originally posted by wg_ski
Yes, there is a lot worng with the schematic. First off, R6 and R7 need to be some sort of thermistor or diode stack with that can be adjusted for proper bias. If you overbias it'll burn out or run away on you.

As-is, the output will be limited to +/-13V. The outputs are configured as followers the way you have them drawn. To make this simple circuit work, you need to turn the main power supply inside out. GROUND the collectors of the output transistors and take the speaker out from the center tap of the +/-79V supply. Then reverse the input phase (swap the + and - of the op amp). Do not use a TL071, it cannot provide enough drive current - the 5534 can. And the +/- supply for the op amp should remain isolated from the main supply (don't just use regulators, use a separate supply). You can boot strap it off the main supply, but that gets a little tricky if you've never done it before.
this is a working device clone from original schematic ......



a wonderfull 50 volts reading in my rms avc voltmeter with 80+80 volts rails under resistive load problem free up to 28500 hz .....
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Old 28th July 2008, 04:33 PM   #23
wg_ski is offline wg_ski  United States
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At first I thought it was a QSC-circuit drawn wrong. Upon further study - it's a Tiger with an op amp in the front end. Do be careful, Tigers are prone to bite!
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Old 28th July 2008, 05:03 PM   #24
lineup is offline lineup  Sweden
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Default Re: read the post

Quote:
Originally posted by sakis
this is a working device clone from original schematic ......
a wonderfull 50 volts reading in my rms avc voltmeter with 80+80 volts rails
under resistive load problem free up to 28500 hz .....
Great, sakis
was only a small resistor problem
Hehe
And me and others was doubt this amplifier is good
You were right sakis. Me was wrong.

line up :::::
except that i like you so much as a person
and always read your posts
since 99.9% i will learn something from them ......


Thanks. I learn new things from other, too.
From you, sakis, and fotios and CBS240.


why add base stopers ???
they werent in the schematic any way
then your comment about variac is absolutelly wrong since when you shut down the amp and since there no input or load to it
capacitor bank will act as a variac since there is no load,
rail voltage will drop and then amplifier will shelf distruct


Base stoppers is always normal. For good power amplifiers.
Without base stoppers is not normal.
But if you can do without. No problem. Your way!

Variac.
Well, you see those 4 resistors: those before Q1 / Q2 drivers.
Now if you turn up slowly Variac voltage,
it takes very long time when Q1/Q2 will put current into output.
But again .. if works with your Variac, I may be wrong .. again


Regards and happy you find problem. One resistor.
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Old 28th July 2008, 06:08 PM   #25
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Default thats ok line up ....

i often sound like very pissed off and often kind of arrogant but really dont have bad feelings with any one .....

only thing that some times drives me mad is that people ( probably out of kindness) jump with an opinion like "change this " "change that " ....and i dont understand why should i do that on a working device .....

on the other hand you may say that this a terible working device but thats another story ....it can be discussed later ....

any way i think you are from sweden ???? are you ??? i had one of the best summers of my life in your country .....

been to broma vastervick oxelousond solna and some other places .....

amazing place and very nice people

thanks line up
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Old 28th July 2008, 07:23 PM   #26
CBS240 is offline CBS240  United States
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Quote:
As-is, the output will be limited to +/-13V. The outputs are configured as followers the way you have them drawn.
I thought this as well at first but the way the schematic is drawn had me confused. Feedback to the voltage gain stage is separated into two loops, one for Q1 & one for Q2. R16, R20 & R17, R21. The votage amplifierís gain is 45. I doubt that using a different op-amp would affect the DC bias, but could cause oscillation. Do you have access to a scope? You could easily tell then. If the Ft of the output transistor is high, you may very well need base stopper resistors for each output transistor so it does not oscillate. Sometimes if you replace a transistor with a faster one, they tend to cause oscillations and require base resistors. You might play with the frequency of Cdom and the zero that are around the driver transistor as well to try to tame it, but you will need a scope.


As always, PCB layout is very important to stability.....
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Old 29th July 2008, 01:09 AM   #27
lineup is offline lineup  Sweden
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Default Re: thats ok line up ....

Quote:
Originally posted by sakis
i often sound like very pissed off
and often kind of arrogant
but really dont have bad feelings with any one .....
--------------------

any way i think you are from sweden ???? are you ???
i had one of the best summers of my life in your country .....
been to broma vastervick oxelousond solna and some other places .....
amazing place and very nice people

thanks line up
I am from Sweden.
From north part. Where is high mountains and snow .. like in north of Canada.

I do not find you agressive, sakis.
Irritated on some people's posts, yes. But you are still a good Gentleman.
There are those men, that are not gentle = not kind in manners.
But You and I and Eveybody here in forum
should be like Gentle Man with each others

There are also Gentle Woman .. but this you know I suppose

See you tomorrow, maybe.
And we talk more.

Regards to Hellas (Greece) from Sverige (Sweden)
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Old 29th July 2008, 06:24 AM   #28
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Default thats ok cbs 240 and thank you

Quote:
Originally posted by CBS240


I thought this as well at first but the way the schematic is drawn had me confused. Feedback to the voltage gain stage is separated into two loops, one for Q1 & one for Q2. R16, R20 & R17, R21. The votage amplifierís gain is 45. I doubt that using a different op-amp would affect the DC bias, but could cause oscillation. Do you have access to a scope? You could easily tell then. If the Ft of the output transistor is high, you may very well need base stopper resistors for each output transistor so it does not oscillate. Sometimes if you replace a transistor with a faster one, they tend to cause oscillations and require base resistors. You might play with the frequency of Cdom and the zero that are around the driver transistor as well to try to tame it, but you will need a scope.


As always, PCB layout is very important to stability.....
i am cooking as we speak another version with one pair of transistors more to see how its going to be ......

your comment about base resistors has a point which i ve noticed when i made a p68 from rod elliot but with mj 15003-4 outs which have simular output configuration and up to 2outs per units all working fine but with more base resistor were required .....

i am cooking on it and let you know ...still i think another pair is not enough with 70-80 volts rails

also one thing i dont know is how critical is the rail voltage of the op amp since i am using seperate power supp for it but only brings out 14.3v per rail ( that was available) but in the schematic stated 16.5 any comments on that ????
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Old 29th July 2008, 06:32 AM   #29
lineup is offline lineup  Sweden
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+- 15 Volt DC dual.
This is the standard used by majority of audio op-amps.
This is often also the recommended level.

You keep that voltage.
Wont change anything if make higher.
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Old 29th July 2008, 07:10 AM   #30
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Default yes of course

i know that +-15 is the standard but in this schematic there are some wierd precicness like base resistors 51R ..... and op amp 16.5 volts and so on ...there must be a reason

first i will finish with the extra transistors version so i got at least 6 per board and then will see about the details give me a couple of hours .....

i miss sverige line up ...... people were so friendlly and polite eventhough i was a "svartzcale" everywhere you go to buy cigarets for example people understand that i was a tourist and speak english to me in HOLLAND everybody was speaking dutch to me HA HA HA ( WAY TO GO JACO !!!!!! ) summer was perfect white nights and everything but also winters magic so quiet very nice i am coming there again sometime ....allready been there for 7 times from 15 -40 days per time ...really nice
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