Pavel Dudek's (Upupa Epops) amplifiers

[Upupa Epops]

Yes, no problems... 😉 But whatabout stability by much more faster ones ?

 

[peranders]

BF 469/470 and BF 471/472 are types, which are readily available. Sanyo's types are 2SA1371 and 2SC3468, but you can use alternative fast type, which have collector at pin 2 ( if you can use original PCB configuration... ).

Last time I checked BF469, 470, 471, 472 are obsolete.

 

[oharmath]

There are several options:
- faster
MJL1302/MJL3281 (30MHz)
2SA1943/2SC5200 (30MHz)
- slower
MJL21193/MJL21194 (4MHz)
2SB817P/2SD1047P (10MHz)

 

[Upupa Epops]

Now I'm using Sanyo's ones, P-A, but I must say honestly, that with BF I've got the same results ( distortion around .001 % )...
Good results make mainly well designed circuit and not only some " supertransistors ", how many people think...

 

[peranders]

I have also used BF471, 472 with good results in my old QRO mosfet amp but last time I looked those BF471,472 were impossible to get hold of.

 

[Jan Dupont]

BF471/472 are easy to get in Denmark 😉

 

[peranders]

You mean "new". Who manufatures them these days?

 

[Jan Dupont]

Frankly I don't know 😀
Have to look at the codes on them, when I sometime get home 😉

 

[helloworld]

Hello, Pavel. I have decided to repeat yours DPA-222, but I do not know what transformer to use for its feed. Whether there is any description?

 

[PMA]

AFAIK Pavel is just preparing a "renewed" version of the DPA222.

 

[Upupa Epops]

Transformer for DPA 222 : 200 VA, secondary winding 2 x 32 V AC ( by no load ) - one for each channel. 😎

 

[helloworld]

Thanks! And where it is possible to find figure of the printed-circuit-board of high quality?

 

[Upupa Epops]

Be patient, will be new one....

 

[helloworld]

Where you take such radiators? At us it is a greater problem 🙁

 

[jmd01]

Hi Oto,
IMHO if you use faster a 2x pairs of output transistors in TO3P, then they need small resistors to base for stability

 

[hienrich]

😉 pavel hi,

just a simple question that I really need to know..

about Q11 and Q12 in your DPA222 amps,

what are these tranies doing in the VAS ? are these

also like

the beta enhanced topology in some other amps?

what possibly are the advantages with this type of

ckt?

thanks

Macweb
😉

 

[Upupa Epops]

These transistors boost OLG, 'cos Q4 and Q9 are less loaded...

 

[hienrich]

😉

actually your designs are so close to some or even

most Dynacord and Electrovoice designs.....

which actually I am about to clone,

well for personal enjoyment.

which also makes me very interseted on your DPA's...

so what would be the effect of boosted

OLG's on sonics, would it enhance the lows or the highs

or the main audio spectrum of the system ?

I'm so sorry if I am asking you a lot, but there are still

so much to be learned.


thanks


Macweb

 

[Upupa Epops]

I don't like verbal characterization of sound...😎 By well designed amp, higher OLG bring less distortion, which is audible, that's all...

 

[helloworld]

Who compared sounding DPA-222 and DPA-386? What of them is more preferable for collecting? Also it would be desirable, if it is possible, to see characteristics DPA-386