Odd Switch Question?

[Guy77]

Hi Gene. Hope you find the switching mechanisms you are looking for. One thing resonated with me in one of your earlier posts and that was that when you build something for someone else it really has to be bullet proof and dummy proof. This is so true!

I think the idea of going with switches instead of the large (made in china) rheostats is a great idea. I once built an attenuator using the rheostats like they do in the Weber mini mass and my friend turned it so hard it bent back all the stop tabs on the rehostat! The metal in those rheostats is so cheap!

Also have you tried the Airbrake Attenuator discussed here in length in our Trainwreck section.

Cheers

Guy

[The Ballzz]

I've tried both of the currently available AirBrakes and this one I built performs much better and currently goes to 21 db of attenuation, as opposed to the 11 db of the AirBrake. No variable option like on the 100 watt Dr.Z unit though. The reactive inductor circuit seems to make a big difference. The trick seems to be sizing the inductors and resistors carefully. Also, having each stage be a pair of resistors instead of one fixed and the other changing appears to optimize each attenuation setting! Ours currently does 7, 14, and 21 db of attenuation. The plan is to make it have 3.5, 10.5, 17.5, 24.5, 28, & 31 db to fill in the gaps and make more gradual jumps in attenuation. 7 db at a time is pretty dramatic! John and I are debating the 3.5 db stage, as I think that 7 db as the first stage is OK. For a multitude of reasons, it would make the implementation much easier/simpler.

I must admit that I'm becoming less and less inclined to want to make these, even as a small business. Realistically I see only two ways to do these, either A) A few units for friends who understand their specific usage or B) Starting an actual business, with insurance, licensing and other protections from liability and then all the headaches of packaging, marketing , etc, etc, for what would like be only a meager profit, only if anyone actually even wants them! Anything in between those two ends of the spectrum is likely asking for trouble. I guess I should just be happy that I have the knowledge and means to custom build a few for myself (one tailored to each amp I own) and just call it a day! At nearly 64 years old, I should be focusing the main portion of my available energies on my last times of being able to give ass kicking performances, instead of trying to start some hair brained business! This is after all, all about playing my guitar and no longer about attempting to build a nest egg for my old age!

Thanks Folks!
Gene

[Guy77]

I hear what you are saying in regards to business expenses especially packaging and marketing those things can creep up on you, thou this venture would be a lot easier than building and selling amps. A lot of times building and selling small things can be more profitable than selling big things that take a long time to build!

An even greater business model than building and selling things for profit is just reviewing and un-boxing them on Youtube! Get a million subscribers on youtube and you will be rolling in the $$$$

That's interesting to hear that your product sounds better than the Airbrake. I am sure many hear would be interested in your design if that is the case.
I feel like the attenuator technology for guitar amps has room for improvements such as you have discovered.
I would be interested in hearing the results you have with it going down to -31db .

I have not heard of an attenuator that can remove over 30db and sound any good and not cost over $1500cdn. Of course there is always the issue with loudness being a big factor in great tone.


Cheers!
Guy

[The Ballzz]

@Guy77
I'm gonna bet that by the time we pass the 21 db and especially 28 db mark, all bets are off for "real" tone! I've been pretty impressed and surprised at 21 though and at only 14 db, the sound is still pretty glorious with all of the several amps tested. JTM30, Tweed 5E3 Deluxe Clone, DSL40CR and DSL20CR, so far. That list comprises a fairly wide variety of tones and character and the attenuator behaved similarly at each level of attenuation on each amp. It should be mentioned that the one I built for my personal use is designed for a 16 ohm output tap on the amp and a 16 ohm speaker load, but that input impedance that the amp's output sees, only changes 1 to 2 ohms when an 8 ohm cab is plugged in place of the 16 ohm. When building a unit for an 8 ohm output tap, it gets a bit trickier for utilizing a 16 ohm speaker, instead of an 8 ohm. Though I've not personally used an 8 ohm tap version, John says that the 16 ohm unit seems to be a bit more consistent, overall and doesn't seem to care about the speaker impedance very much. Bear in mind, that when I mention speaker impedance and the impedances seen by the amp, I'm actually referring to DC resistance!

Out of curiosity, what is that Les Paul in your avatar? Got any bigger, better pics?

Thanks,
Gene

[SoulFetish]

I'm not sure if this has been mentioned yet, but the kind of mechanical switch/switching I think you are looking actually a rotary switch. Rotary switches are almost always used for more complicated mechanical switching interfaces, because they are easier to program, can be found in any number of switch configurations, and are available for high power applications.

[Guy77]

@Guy77


Out of curiosity, what is that Les Paul in your avatar? Got any bigger, better pics?

Thanks,
Gene

Hi Gene. Here are 2 more pics of my Les Paul. She is a 2016 Les Paul Studio Ebony & Gold. I tried so many and this one had a nice neck that fit my hands just right and the weight was not too light or too heavy. The pickups can be split coiled by pulling out the knobs.

Cheers!
Guy

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[Aurora]

A rotary may work, but if you insist on toggles, I am pretty sure you'll never find such switches. Being the old geezer I am, and having fumbled professionally with all sorts of electronics from dirt cheap to extremely expensive, I am pretty certain. Toggles controlling a set of relays can do what you want, if you have the space, and relays come in quite a lot of sizes...

[The Ballzz]

A rotary may work, but if you insist on toggles, I am pretty sure you'll never find such switches. Being the old geezer I am, and having fumbled professionally with all sorts of electronics from dirt cheap to extremely expensive, I am pretty certain. Toggles controlling a set of relays can do what you want, if you have the space, and relays come in quite a lot of sizes...

toggles were not a requirement. I was simply using the toggle analogy to describe what I need to accomplish. After a bunch of searching, we found some appropriate rotary switches. The thing is that when searching for something you're not familiar with, it's hard to know where to look and what the terminologies are for the search criteria! And trust, I'm an old fart too, and through a lifetime of fiddling with a wide variety of mechanical and electrical devices, I've certainly encountered some very unusual and unique proprietary items, that you could never ever find if you wanted one!
Just Sayin'
Gene

[SoulFetish]

Cool, I'm glad you found some switches which may work for you.
I apologize if this may seem obvious to most, but for those who may not have thought about it –
There are a couple of things which aren't obvious when looking at data for switches is there is usually two specs for max current for which the switches are rated. The first is the max current which the switches can actually switch while loaded. I've found this is usually the rating used with initial switch descriptions (but you'll want to double check). The second is the actual contact current rating, which specifies the max current the terminals can handle when the switch is idle. This can be quite a bit higher, but again, you probably want to double check.

The other thing is if you plan on switching on the load side of a tube amplifier, you probably want to use a "make-before-break" type of switch, which shorts the contacts while switching and prevents an inadvertent open connection which could possibly destroy an output transformer. Unless of course you're switching a solid state amplifier. Then you may want to use a "break-before-make" to prevent a short on the output. Just some things to think about.
Cheers

[danman]

I can say that this attenuator circuit does work very well. I built one of JohnH's early designs (does not include the inductors) and it sounds so much better than the Minimass that I had been using previously.

[The Ballzz]

I can say that this attenuator circuit does work very well. I built one of JohnH's early designs (does not include the inductors) and it sounds so much better than the Minimass that I had been using previously.

I too have a MiniMass and this is generally much better. With that said, the MiniMass works pretty well in some situations. It seems to have "sweet spots" throughout the sweep of the potentiometer. Different amps like different "sweet spots" and some have several and others have only one, if any. Some amps simply hate it. On the other hand, every setting on John's design appears to be a "sweet spot" on every amp I've tried it with! I think the "sweet spots" of the Weber occur when the balance of series vs parallel resistance reaches a particular balance, whereas on John's design, each setting already has provided that delicate balance!

While I won't likely get rid of my MiniMass anytime soon (it is useful in some situations), I'm really lovin' the JohnH design!

YMMV,
Gene