Completed JohnH Attenuators?

Gene Ballzz

Well-Known Member
Joined
Feb 19, 2013
Messages
3,784
Reaction score
4,539
Location
Las Vegas, NV
Now, these I would not be embarrassed to have sitting on top of my amp, onstage! Although, these two were built for a couple friends!

My sincerest thanks to @DeluxeReverb for the inspiration to switch over to countersunk metric screws, for resistor mounting and to @Dblgun for the "gutter grate" idea! I think both ideas brough the cosmetic and functional level up a couple notches! :cheers:

And of course, a special thanks to @JohnH for all the brilliant work and support!

Contact me privately with any questions.

Still Attenuatin'
Gene

IMG_0681.jpeg IMG_0682.jpeg IMG_0683.jpeg IMG_0680.jpeg
 
Last edited:

JohnH

Well-Known Member
Joined
May 31, 2008
Messages
5,110
Reaction score
3,328
Location
Wilton NSW
Hi Gene, these new units look really good - great work!. Im proud of them too!

Getting to a place where we have such a well executed and proven design continues to be a great ride. I really enjoy the collaboration and none of us would be here on our own!

Onward!
 

Gene Ballzz

Well-Known Member
Joined
Feb 19, 2013
Messages
3,784
Reaction score
4,539
Location
Las Vegas, NV
Hi Gene, these new units look really good - great work!. Im proud of them too!

Getting to a place where we have such a well executed and proven design continues to be a great ride. I really enjoy the collaboration and none of us would be here on our own!

Onward!

@JohnH

You are certainly correct my friend, about the collaboration factor! I've developed and nearly worked out the bugs for drilling templates, for this size or any larger box! You simply print them out on peel & stick project paper, put them on the box, punch the marks and drill it! Saves a lot of time and effort on layout! Yeah, it still requires a variety of drill bits and some holes are clearly marked as countersunk (for component mounting), but I've allowed for those mounting holes to be just enough oversize to accommodate the slightly different mounting hole centers of various resistor suppliers! Worst case is that the Vishay/Dale resistors made in Mexico end up ever so slightly skewed from the others! I'm gonna go crank my guitar/amp setup, in both 8Ω and 16Ω modes on both 8Ω and 16Ω units for sonic comparison. I'll keep you posted on the results!

Thank Again,
Gene
 

C-Grin

Well-Known Member
Joined
Nov 8, 2020
Messages
884
Reaction score
2,520
Location
edge of the Mt. Hood national forest
There it it sits, I am really impressed. Great design and execution. I was concerned that the compensation for the high end loss would sound off, but not at all. It is a thing of beauty and works beyond my expectations. I am very grateful for the thread the designers and the builder (you know who you are). I was skeptical when I first saw the thread as most of the devices I have tried over the years left me disappointed, but no more.

:cheers:

IMG_1157.jpg
 

pietro.castelli

Active Member
Joined
Aug 18, 2021
Messages
55
Reaction score
102
Hi Folks,
I’m very interested in the simple attenuator.
I would really like to build one to tame the plexi 51 all access I’m finishing, but I’m afraid the 50w version will be struggling to deal with the amp.

Has anybody succesfully built a 100w version of the attenuator? What changes are required over the standard?

I apologize if this has already been discussed in the original thread, but the latter gee almost 150 pages long

Thanks to anybody willing to help!
 
Last edited:

JohnH

Well-Known Member
Joined
May 31, 2008
Messages
5,110
Reaction score
3,328
Location
Wilton NSW
Hi @pietro.castelli

For 100W amps, we double all resistor power ratings, get a coil based on 16 gage wire and add a fan. The simplest way to do that is a 12 Volt DC fan, and run it to a 9V wall wart. Use a thick aluminum diecast case and plenty of holes for venting. Please post in main thread if any questions.
 

emann

New Member
Joined
Aug 24, 2022
Messages
24
Reaction score
12
Just finished an M2 with a bypass switch on the back. I know that vent holes in the top are ideal, but I’ve got lots of holes on the sides and bottom, and I’m using it with 20w or less amps (Deluxe Reverb, SV20, etc.). Even after 2 hours of running the amps at 60% and at heavy attenuation, the top of the case where the components are mounted only got to body temperature. Seriously, my cat is warmer.

My bases of comparison are a Weber MiniMass and the attenuator built into my 12w Aiken Tomcat, and this M2 is the best of the lot! Lettering to come later.

Oh, and Hello all from my first post! I joined this forum based on the attenuator design thread. Thanks, @JohnH and the others who contributed to this project.

Update: My total cost for this build was right around $185USD. I went with Mouser for the enclosure and resistors, Parts Express for the inductor, and Antique Electronic Supply for the remainder of the components. I could have saved money by ordering from eBay or other sources, but I’ve had a lot of experience with the suppliers I used for this build, and I knew I’d get the parts quickly.

Oh, and I did end up wiring a connection from the enclosure to the shield of the amplifier input jack after these pics were taken. Before that, touching any non-painted part of the enclosure like the switches or exposed screws would make a super-loud oscillation noise through the speakers. Having a chassis connected in this way is pretty common for attenuators, so it’s the first thing I tried and it completely resolved the issues I was having. Using an ordinary Switchcraft-style jack at the amp input would’ve solved the noise also.

View attachment 106726 View attachment 106727

View attachment 106724 View attachment 106725
Hello,

I am interested in this build and note that you also mention the Deluxe Reverb. I have a Fender 65 DRRI myself too and wanted to ask you how does the attenuator work with this amplifier.

I am currently checking out some prices for suppliers in Europe and want to build the unit based on the circuit with the lineout so that I can connect to my audio interface and record in the DAW.

Can I ask you what type and size of case did you use please? Also, what is shown in the circuit as the L1 pad - is that the coil of wire you have in the middle of the case attached with tiebacks?

Finally, what is the purpose of the black knob, this does not show in the circuit that I am following.

Thanks for your assistance.
 

Latest posts



Top