Power amp under development

[quasi]

Originally posted by jhoel47
GUYS

BC546 is TO-92 casing style, I saw in picture T8 bc546 is TO-126 (t8 that suppose to be mounted on the main heat sink) , TO-92 dont have screw hole, is there a type of TO-126 of BC546 transistor? or use TO-92 BC546 and find other way of mounting it to heat sink?or is there a replacements for T8 ? Thanks ..

joel

This link http://www.diyaudio.com/forums/showt...468#post800468 shows a picture of how I mounted T8 on my board. It mounts underneath the PCB and into a hole drilled in the heatsink. Accuracy is a must here. Others have substituted T8 with a TO126 transistor mounted seperately on the heatsink and used fly leads back to the PCB. If you do this please check the pin-outs.

Cheers
Q

[jhoel47]

Quasi,

thanks for your replay man good idea .About 12 volts relay, I will be using 12 volts relay since this is what I only got, please send me the schematics modification for both DC protect and softstart,,, thank you very much ..

joel

my address joel_m@pimes.com.ph

[quasi]

Originally posted by jhoel47
Quasi,

thanks for your replay man good idea .About 12 volts relay, I will be using 12 volts relay since this is what I only got, please send me the schematics modification for both DC protect and softstart,,, thank you very much ..

joel

my address joel_m@pimes.com.ph

You can run the the circuits as they are with a 12 volt relay by using 12-14 volt rails. The switching times will increase but they can be reduced again by reducing the value of the timing capacitors.

Or you can run everything on 24 volts and just put a resistor in series with the relay. The value of the resistor should be the same as the resistance of the relay coil (or slightly less). This can be done for all the relays you use..

Cheers
Q

[grechejr]

Hi Quasi !

Great project !

Sorry but, I not understand the value of Q1 Q2 Q3 Q4 Q5 and the model of 24V relay in dc detect ....
Please retry to me ...

grechejr@gmail.com


thank you !!!

[quasi]

Originally posted by grechejr
Hi Quasi !

Great project !

Sorry but, I not understand the value of Q1 Q2 Q3 Q4 Q5 and the model of 24V relay in dc detect ....
Please retry to me ...

grechejr@gmail.com


thank you !!!

Hi grechejr

I have sent you some mail. The value of these transistors is shown in the DC detect circuit schematic that is contained in the document I sent you. Because the DC detect circuit is built on the same board as the amplifier I have used Q instead of T for the transistors to show the seperation between the sections.

The relay you need is a single pole double throw (SPDT) with contacts rated at 10 amps minimum with a 24 volt coil. The style I have chosen is probably the most popular in the world, is made by many manufacturers and available at most electronics stores. If you take your PCB with you, you can make sure it fits.

Cheers
Q

[rlg_200]

hi all maker of quasi amp,


does anyone try to connect this amp into bridge mode? how's it sound, and how much the power capacity @8omhs.

rlg.

[TomWaits]

Originally posted by rlg_200
hi all maker of quasi amp,


does anyone try to connect this amp into bridge mode? how's it sound, and how much the power capacity @8omhs.

rlg.

No I have not tried to bridge my Quasi amp. I would be affraid unless I had a huge array of speakers connected correctly.

Shawn.

[duran_1960]

Dear Quasi

I herewith present first image of pcb to you. At least I'll try to make your amp. with 6 fets.
Best regards

[rlg_200]

quasi & tomwaits,

can u post the technical data (specification) of ur amp.

damping factor=?
thd+n=?
input sensitivity=?
input impedance=?
ouput impedance=?


rlg.

[AndrewT]

Hi Quasi, TomW and Rig,
do not bother with damping factor and distortion specs. They are irrelevant to the sound/quality of a feed back solid state amplfier.

Output impedance might be useful to some at a selection of frequencies.

Rig,
if you knew this what would you do with the information? I don't know how to interpret it.