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Old 22nd December 2007, 03:22 PM   #31
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Default Re: Transistors are 2N5401, 2N5551 into the differential

Quote:
Originally posted by destroyer X


The input diodes are dangerous....having oscilation cut the damn thing out!

regards,

Carlos

Hello Carlos

Do you still suggest to take out the input diodes ?

Thank

Bye

Gaetan
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Old 22nd December 2007, 03:28 PM   #32
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Hi Carlos

It has been a long time since we last emailed

I'm glad to see that your Amp has turned out so well
It's very interesting and I might build it and test it

Keep posting
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Old 22nd December 2007, 03:28 PM   #33
Nordic is offline Nordic  South Africa
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Also where will AGND be?

With the diodes I assome it is just north of the diodes...
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Old 22nd December 2007, 03:51 PM   #34
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Default No Monsieur Gaetan. not to remove them

Remove them ONLY and IF you find problems.

I have listened reports, from other friends, that those diodes detect Radio Frequency... also i had problems once, and recently i had problems even into the simulator.

It is difficult to me to explain things in English.... keep them in place IF you face some problems.... remove them, as the first suspect, if you have unstabilities.

I had....but..they are very protective to the 10 ohms resistance... and when that resistance burns the problems are very big...so... diodes are nice thing... they are needed...they are a nice solution...they are a clever solution..but they have shown problems.

Telling clear.... if you face unstabilities and crazy behaviors when measuring your amplifier, remove those ones, disconnect one side of each one of them to check if they are the problem.

Not to remove them....KEEP them in place...BUT, understand they can be a problem..attention on them!

regards,

Carlos

.................................................. ..................................................

Jan Dupont

Compare to you, i am a student trying to do something.... try and error and small calculations, not going more deep than ohms law and some things i have learned during experimentation.

Your amplifier, is superior technically.... it may sound better than this one.... but...maybe will be interesting to you... to have some fun...it is cheap, easy to make and Nordic is providing us, cheap, cost price, boards.

I feel deeply honored... and you know the respect i have by your person... i told this many times.

Do not expect something that can beat your design...but, at least will not be a shame too.... sounds very nice, will not measure alike yours.

thank you,

regards,

Carlos

.................................................. .................................................. .

Dear Nordic

Good people, in our forum, some enginneers, some Masters and others use to suggest some modifications... the diodes was one of them... years ago Pavel already mentioned the need... and i know people that made that and had problems with Radio Frequency pick up... so.... some ideas can protect, but can produce some consequences... some side effects.. alike drugs.

Another example is the protection into the VAS.... people said..may blow...i tried to blow and could not blow...but peoçe re-calculate and said..for sure can blow..and i have tried real life and have not blow... so much they insist with that, i decided to include the protection... will not blow anymore.... will be technically better..but will sound worst... reason why i said...wanna protection?... use it.

But switch the damn thing off and listen.

The protection circuit, even well adjusted, compress the audio... the sound turns worst... and you can listen that high volumes switching the protection on and off.

There are decisions, token under the name of reliability, that kills the sound...it is a matter of decision, if the guy want an amplifier huge as a war tank or and amplifier that plays sound in a beautifull way.

Those diodes have caused "recall" of sold amplifiers... so... you see they are dangerous.

Do they protect?.... Yeah!
Are they nice solution?... Yeah!
Technically correct?... Yeah!
Politically correct?... Yeah

Do you trust in those diodes?.... not too much...just a little.... and scared.

There are many folks that knows more than i know...they may be rigth and i can be wrong...because of that you have introduced the diodes and you have not istened my complains about the subject.

regards,

Carlos
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Old 22nd December 2007, 04:00 PM   #35
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Hi carlos :-) Thanks friend

You know I'm not the judgement type
I know that I always can learn more, and I'm open for new designs and ideas......

I know that my LYNX/PA-34 may be better in some areas than your DX, however there is an Amp for every purpose, and yours is much cheaper to build, and will suit many here

I wish you all the best for this amp and a merry christmas
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Old 22nd December 2007, 04:05 PM   #36
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Default 100 percent agreement on that Jan


You are welcome...and thanks once again.

regards,

Carlos
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Old 22nd December 2007, 04:21 PM   #37
Nordic is offline Nordic  South Africa
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Yeah Carlos I also have my doubts over active protection which interacts with the amps performance, like a big airbrake.

I do like the idea of a relay protection driven by a low current sense wire like on the chipbased boards I showed recently.

I am toying with building them into the PCB as the cost of components is under $5 but they can save $100s of dollars in blown drivers, when something dies in the amp.
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Old 22nd December 2007, 04:24 PM   #38
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Default Your protection is great... i suppose will not create problems


Good relay and good circuit will be fine...and yours are beautifull and very well made.

regards,

Carlos
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Old 22nd December 2007, 04:31 PM   #39
Nordic is offline Nordic  South Africa
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I have been asked to bring my amp to the party this new year, that killed the big Sansui last year...

Time to test those large heatsinks, they never go more than about 4C above ambient.

But those guys don't need volume control, they just plug in full volume... I'll put some spare speakers in the car's boot to take out when the amp kills their speakers.

I should actualy put in some plain DX boards for the party, but they will definatly kill their speakers and my hearing with that.
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Old 22nd December 2007, 04:36 PM   #40
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Default Hey Nordic!...be nice nephew and produce pictures..put you Canon to run


zip them all and send me.... say... this party...were the Dx will be pumping.

They will need power...hehe... not quality...put wire jumpers...links into the rail transistors..from colector to emitter...ahahaha. full power.... distortions too..full!

Better, in advance, to install one more pair into the output...they can use speakers that have valleys of impedance low as 3 ohms.

Your input already has 10uf...so... the Devil's hammer will hit them!

Good test.... produce images..they will have value of documents...no VAS protection will operate...we gonna see if will burn when clipping...let them clip all nigth long!

Yessss!

regards,

Carlos
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