amp15 picture thread

[more10]

Haha ... funny guys. What exactly is a vandal-safe switch? Waterproof and latching?

You cannot remove it from the outside, and the IP class is to protect from other things than water :-)

[V-bro]

Ok, I had the idea that IP classification also had to do with watertightness, I see the approval added to boxes quite often. Boxes like the Hammond ones, with seal they get the approval...

Well anyways, we don't plan on getting our amps wet anyway are we?

Latching? This means the switch has two states, on and off. With momentary they just make short contact. I am planning on making a flopflop based latch that works on mains voltage directly without transformer. It'll switch a relay on and off by pressing just the one button. Mostly these switches are microprocessor based, but we don't want that in our amps and these always need a certain voltage that is not always there...

Momentary switches are cheaper, more compact and come in many more kinds...

[more10]

Very interesting V-bro!



http://se.farnell.com/panasonic-ew/t...ing/dp/1175720

for latching, it is 24=, together with



http://se.farnell.com/finder/44-62-7...vdc/dp/1169305
for power to the transformer

with a simple rectifier, a voltage divider and a small capacitor. Relays are together about 12 €.

You can add an rc-link and a low voltage relay for muting the amp and another rc-link and and a higher voltage relay for speakers.

[more10]

If there are no pictures, it is because www.warp7.se hosting them is down.











2 fuses in the mains socket, and one fuse for each secondary winding on transformers.



Happy now V-bro :-)



Top plate is only 1mm thick, and it rattles :-(



Space left on right side for another amp15, for biamping. Shielding transformer from amp, does it make any difference?





Shielded cable for inputs. Overkill?





Soft start with 470 ohm 100W current limiting resistor.

[V-bro]

Very interesting V-bro!

with a simple rectifier, a voltage divider and a small capacitor. Relays are together about 12 €.

You can add an rc-link and a low voltage relay for muting the amp and another rc-link and and a higher voltage relay for speakers.

Yes, that's pretty much what I meant, a mechanical flip flop works ok too Then rectify mains....

I was more looking for something with minimal electrolytic caps...

I was thinking using two coupling caps to the mains, then rectify... this would provide full mains isolation at least, for safety...

[V-bro]

It's quite a magnificent piece of engineering that amp man!!

[Kalium]

Does everything look okay?
How am I supposed to do with the jumpers on the front of the board and with the wires on the back? I'm a bit confused. And C43 and C44 are missing, are they important?

[V-bro]

Looks good mate!

All it needs is the bottom wiring done, the two large traces coming from the big caps end in two holes per trace marked + and -

You need to solder a long and a short wire in each side and solder it in the four holes near the green SMD resistors. Basically connect all + holes together and all - holes....

The two missing caps are not needed...

All the jumpers that need to be connected are the BBM, 5V test, unmute, and the one beside the little ferrite bead, which connects the PGND and AGND together at one point through the ferrite bead.

BBM is very important as it should be 80ns, lower will likely kill the fets.





Sorry about the resolution there on the second pic, had my cam on a very low one....

[Kalium]

Alright, the wire soldering seems simple and I'll get to that as soon as I find some wire to use.

Excuse me, but what is BBM and how do I measure that?

And by the way, I'm not 100% sure I connected the LED in proper polarity. Is there any way I can check that?

What is the recommended transformer for this amplifier? 2x36V 800VA or more? Is 40V okay too?

[krilli]

Excuse me, but what is BBM and how do I measure that?

BBM means "break before make". It's an interval measured in nanoseconds. As I understand it, the BBM spec defines how long a time passes between one output transistor being turned off and the other one being turned on. It is not measured, it is defined and set by a pair of jumpers. You want the default, which is 80 nanoseconds. IIRC the pins are marked for the default.

And by the way, I'm not 100% sure I connected the LED in proper polarity. Is there any way I can check that?

I wondered about that too - the thing is that the LED symbol on the board indicates polarity.

What is the recommended transformer for this amplifier? 2x36V 800VA or more? Is 40V okay too?

Depends on what kind of power you want to take out. If it's the standard Amp15, then the recommended upper limit of the rail voltage is 50V, with a hard-ish limit of 60V. I used a 36V with mine for just about 50V. 40V should work too, but there is a greater measure of risk - you could be seeing more than 60V on the rails if you take edge cases into account. Unlikely though. Then again, the amp is proooobably able to momentarily handle a bit higher than 60V .

800VA is pretty hefty, and should be sufficient for any 4 Ohm load at full power. As far as I know, you'll need or want a soft-start circuit for a transformer that size.