Gene Ballzz
Well-Known Member
Thanks, and if it gets hot with a more powerful amp I could put the case on its side - with a chimney effect!
Or drill some "decorative" holes in the top and bottom?
Just A Thought,
Gene
Thanks, and if it gets hot with a more powerful amp I could put the case on its side - with a chimney effect!
Did you wind your own inductor?I’ve been using my first M2 8 Ohm 50W attenuator a lot with my Tweed Champ style amp so I’ve built another one for it.
I mounted all the Rs on a thick piece of aluminium and then into a aluminium case made from a shelf from Pete’s greenhouse. The connections use solid core wire - this made the soldering much easier. The reactive stage resistors are scaled back for an attenuator that handles 25W.
At home I’m typically using 10.5, 14, 17.5 or 21dB of attenuation even on this 4W amp. It all works perfectly with all the amp settings - eg NFB off and extra preamp treble boost switched in. The loudspeaker is a 12” Eminence GA-SC64
Thank you @JohnH for sharing your design, I’m playing my guitar much more now.
View attachment 86418 View attachment 86419
The inductor came from qtasystems.co.uk - great service from them.Did you wind your own inductor?
Yes, they do. I was thinking about laying them out on an aluminum plate & mounting it inside the amp.They're gonna have a pretty large footprint!
Just Food 4 Thought?
Gene
Hey I'm about to order supplies for the M2 8 ohm version. I've read this thread a few times and it's fantastic. I have questions because the "switched jacks" concept eludes me still even though I try to read about it. I understand it for switched DC jacks in pedals, but in amps I don't. I don't even know how to phrase questions lol! I did read that you don't need them in this attenuator build, but I'm also about to kit together a 20w amp head...
So in general, can someone give me info or a link on when and why I would use switched jacks in an amp build? I'm trying to understand it in terms of an amp's "speaker out" being "switched" for safety reasons if a cabinet is unplugged so it doesn't hurt your amp. I thought I read that somewhere. For some reason I can't grasp this subject. Where does the signal go when the jack is unplugged and is a "closed circuit" I guess? Thanks for this thread and trying to understand my question!
Hi @dougie tamson , great stuff and thanks for posting. That's a serious looking piece of kit!
On heat and fans, I reckon that with the thick AL box and ventilation then we are ok up to around 50W without fan, and at a 100W one might be warranted depending on how hard it's driven.