Express: Power Rating Choke Replacement

[dways]

Hi,

Thanks first of all for sharing all the information!

I am getting together all the parts for an Express clone and have problems to find the choke replacement resistor - R25 in the schematic - with the correct values (I live in Germany). I am able to get that "cement" resistor with 1k & 10W.

To be honest I am not an expert though I am obviously able to put together parts in the right manner successfully but I wonder if R25 needs to have a load capability of 25W. According to the schematic the voltage drop is 15VDC (B+1 to B+2) and together with the 1k resistance the current should be 15mAmps, right? For the power I need to multiply voltage and current which is much less than 25W. So will I be fine using a 1K 10Watt resistor? If so, why is the original rated higher? Or where am I wrong?

Thanks in advance for your help.

Cheers, Dan.

[geetarpicker]

In an Express if you push the amp into a fair amount of overdrive (very easy to do) that 25 watt resistor can get hot enough to burn you. I would keep with the 25 watt rating AND make sure no wiring touches the resistor as you don’t want to melt anything!

[M Fowler]

Dan,

PM me your mailing address and I will send you a 1K/25w cement resistor.

Mark

[dways]

Excellent...

[dways]

... R25 has arrived... bloody awesome Mark!

One of the few last missing parts for build no. 2. For build no.1 I had ordered a complete parts package from rj which I can highly recommend. He is a pleasure to work with.
And except for the transformers - which I have again ordered from rj - I was curious and wanted to try to get all the parts locally for build no. 2. But it turned out to be not that easy if you try to be 100% correct (see above). Let's see where I end up.

No. 1 was just fun and sounds oustanding so that I wanted to built another one. And I wanted to take the opportunity to say thanks to all of you for sharing all the information and being so helpful to each other. I totally dig this! Without this forum I would have not been able to realize my Express Clone. And for those who are interested I'll attach some pictures of my first build. Thanks.

Cheers, Dan.

[M Fowler]

Looks good congrats on a nice amp.

Mark

[Mark]

Looks good. Where are your earth wires without a bus bar across the pots?

[dways]

It's the PEC stainless pots, hence I've been using ground lugs with long legs to connect the ground buss wire (recommended by rj), you can't see on the picture but it works great

(and btw the tape was for fixation and removed at the end)