Pavel Dudek's (Upupa Epops) amplifiers II

[GEirin]

Hi Upupa.
I´m very curious. Sorry for the question.
Your early amplifiers use feedbak error correctiond (NPN+PNP, Vbe multiplier type). Now, your DPA 222-A use a Sziklai Vbe multiplier. For you, Sziklai is the best Vbe multiplier for a amplifier?
Thanks.

 

[Upupa Epops]

I had try this circuit many ears ago in my copy of Dynaco 400. Results was comfortable and from this time I use this type of circuit at all my bjt amps ( it can easy set up slope of thermal sensing ).

 

[Page.P]

Let's see at my new DPA330MkIV on double layer PCB.

Thank you Upupa Epops for your time and advices.

 

[Juergen Knoop]

interesting way to mount the TO-3, thanks for the inspiration!
regards

 

[VivaVee]

interesting way to mount the TO-3, thanks for the inspiration!
regards

It looks very neat, but the heat must conduct through a very circuitous route before it gets to the heat sink fins.

 

[Upupa Epops]

You are mistaken, difference between pad below transistor and top of nearest heatsink is only 3°C, measured by digital thermometer after long time thermal shock....

 

[PMA]

How about instantaneous high transistor power stressing shocks, how would look a time dependence of transistor temperature compared to conventional placement directly on a big heatsink?

 

[Upupa Epops]

Mass of pad is sufficiently great, is able to absorb it....it is the same case like fitting transistors directly on prisms, which I use in other types of amps...several tens second is amp able to give full power without heatsink, which facilitate assembling and repairing...

 

[PMA]

Thanks for the answer, Pavel.

Regards,

 

[Bonsai]

Wow, awsome looking boards. I look at my boards and think "yes, Bonsai, you are making progress" and then I see boards like this and know I still have much to learn . . . .

You have my respect!

 

[bogdan_borko]

Hi Upupa Epops, does EC sounds better with mosfets or bjt`s?

 

[Upupa Epops]

I have no experiences with bjt + EC, Bogdan...original Hawksford's design was with bjt ( darlington ), but at this time ( mid of eighties ) wasn't possible to get some really good ones, so better way was mosfets...results was amazing, so I was stay with them...

 

[VivaVee]

You are mistaken, difference between pad below transistor and top of nearest heatsink is only 3°C, measured by digital thermometer after long time thermal shock....

Could you explain what you mean by 'long term thermal shock'?

 

[Upupa Epops]

Yes: after one hour of full output power into eight ohm...

 

[Federmann]

Yes: after one hour of full output power into eight ohm...

What is full output power ? Undistorted music production, or sine signal?

 

[Upupa Epops]

Nominal output power, i.e. in this case 120 W into eight, Federmann....

 

[Federmann]

Nominal output power, i.e. in this case 120 W into eight, Federmann....

I understand correctly, medium - an effective exercise power listening to music is 120W? Peak power output of 1kW far over?

Or peak power output of 120W and medium - efficient performance power listening to music is the 10W?

You never explained this

 

[Sendy]

Dear UE, ignore him... don"t feed the troll...
http://bookreviewsbybobbie.files.wordpress.com/2009/08/do-not-feed-the-trolls.jpg

 

[BV]

Try to "learn at home" what mean "continous RMS power". But You are teacher at technical school.

 

[Federmann]

Try to "learn at home" what mean "continous RMS power". But You are teacher at technical school.

You're right, the acoustic signal, the dynamics of a middle power - RMS is a fraction of peak performance, so I asked.