• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Pavel Dudek's super Gainclone group buy

Colour of the pcb

  • Black

    Votes: 31 37.8%

  • White

    Votes: 12 14.6%

  • Red

    Votes: 14 17.1%

  • Blue

    Votes: 13 15.9%

  • Yellow

    Votes: 3 3.7%

  • Green

    Votes: 13 15.9%
  • Total voters
    82
Jump to Latest
peranders

peranders

Member
Joined 2002
sjostromaudio.com
Paid Member
Yes! :)
 

Attachments

  • pa03_blue.jpg
    pa03_blue.jpg
    280.8 KB · Views: 313
A

AndrewT

R.I.P.
Joined 2004
If you start with two 60W into 4ohms amplifiers, you have three choices:
a.) power two 4ohms speakers independently and you get 60W+60W into 4+4ohms, equals a total of 120W
b.) arrange the two amplifiers in parallel so that they are able to deliver twice the current at the same voltage. You now get 120W into 2ohms.
c.) arrange the two amplifiers in bridged format so that they deliver the same current at twice the voltage. You now get 120W into 8ohms.

Note that for all three options, the total power delivered from any combination is 120W. All the amplifiers deliver the same maximum voltage and deliver the same maximum current, since they are the same amplifiers.
Which option you choose depends on the capability of the amplifier and the impedance of your speaker/s.
 
Last edited:
jvhb

jvhb

Member
Joined 2013
audioberg.dk/
AndrewT said:
(...)
Note that for all three options, the total power delivered from any combination is 120W. All the amplifiers deliver the same maximum voltage and deliver the same maximum current, since they are the same amplifiers.
Which option you choose depends on the capability of the amplifier and the impedance of your speaker/s.
Click to expand...

Theoretically yes, but I think in real life, around 100W total output will be maximum. The 2x60W in 8ohm is using 35V power supply, and 0,5% THD - so on the ragged edge you might say..
PerAnders recommends using 33V DC (24VAC x 1,41 and rounded off) as maximum to avoid excessive heat dissipation from LM4780.

Also I get the impression from TI datasheet, that even 33V is too much if bridging. See attached excerpt from page 14. As I read it, if you want to bridge, it is best to stay around 25V (unless your speakers are very high impedance, like 10-16 ohm), and for parallel use around 33V (and max 35V) is ideal.

So it would be best to decide the mode of operation before buying transformer. And the deciding factor here, is the loudspeaker impedance curve: If it is 8 ohm or higher (without significant dips) bridging can work well, but else parallel configuration is better. If you want to keep all options open, use 25-26V PS. All in my humble opinion, and more experienced people may know better.
 

Attachments

  • LM4780_Typical_performance.JPG
    LM4780_Typical_performance.JPG
    195.5 KB · Views: 251
S

shaffenmeister

Member
Joined 2016
Recommendation for PA03 volume potentiometer (non inverting operation)

Hi all,

what would the recommended impedance of a volume potentiometer for the PA03 in non onverting mode look like? I plan to use PA03 directly driven from a line level source without pre amp.

PA03 input impedance: 20k.

From my own limited experience I would have chosen a value smaller than 20 k but have seen that people use the PA03 directly driven with potentiometers up to 50 k in non inverting mode.

Any hints?

Thanks in advance!

Christoph
 
You must log in or register to reply here.
Top Bottom