How to Build A DIY Guitar Amp Attenuator

[@DogsharkGPS]

Want one? Get in touch and I can make one for you.

[@soapboxearth2]

I've built a bunch of these, and love them. , you have to be careful they dont overheat. Especially if you use them for maximum attention. If it shorts , you can lose your power tubes and output transformer. Even if you use a 50-watt amp( which can priduce way more than 50w when overdriven) with 100 watt Lpad, keep checking to see if it's overheating. Im only comfortable using my 100-watt Lpad with a 20-watt amp or less.

[@JonathanWhoever]

Phineas, I know what we're gonna do today.

[@dannydarko371]

Good vid mate, I’m gonna give it a go, cheers dude

[@buzzedalldrink9131]

The Dr Z attenuator is really a design by the late Ken Fischer called the airbrake. The layout is easy yo find on the internet. The parts are cheap , you can build one yourself. I recommend building this over an L Pad version. It is much more rugged. and can handle 100 watts easily.

[@jacobkeller29]

Thanks, I’ll get working on one of these for my 5E3 build

[@cgavin1]

I mount these inside all my 5w builds. Use the same 100w rated components and it won't even get hot. Try a 220uH (1.6-3.5A) inductor in series with the L-Pad input. I find you don't need the bright switches then. You can also cut the cost of the build down by a lot by upcycling an old 12v PSU from Hornby/Meccano. That's an aluminium housing and because its got an old flex + grommet input to the transformer, you can save on a switchcraft jack too. Those Hammond cases are far too expensive now from Farnell and co.

[@DogsharkGPS]

Ever had an L-Pad go bad on you?

[@qddk9545]

Are you sure it shall say micro Henry, that is a very small value ?

[@cgavin1]

@@qddk9545 I added the inductor to make the L-Pad react more like a speaker. An L-Pad is a purely resistive load, where a speaker is a reactive load. The L-Pad by itself looses the highs at higher attenuation levels. I added an inductor because I wanted the L-Pad to copy (in part) the way a real speaker limits the current at high frequencies. The aim was to improve the treble at higher attenuation levels. I was happy with the result and found the attenuated tone was brighter and generally sounded better. The addition of the bright caps gives a further boost at the highest attenuation levels.

[@qddk9545]

@@cgavin1 I know, but I just thought that micro Henry is a very small value, thought you might have meant milli Henry.

[@TheSifting80]

Thanks for Sharing

[@olddingodude]

Great project. How has it held up to long term rock and roll usage in the field ?

[@DogsharkGPS]

To be fair I only ever used it at home for obvious reasons. For rehearsals and gigs it wasn't really needed. But I used it a lot. A lot of my videos made between this one and the most recent were done using the 68 with this attenuator. I've now sold the amp but kept the attenuator. If I ever get another amp that needs it I'm sure it'll work just as well.

[@dsteffe74]

Hi, nice video. How do you make the 8ohms / 16ohms switch?

[@DogsharkGPS]

It starts with the L-Pad. Get the L-Pad rated for the higher impedance then just add a resistor for the 2nd value with one side connected to ground through a switch.

[@dsteffe74]

Thanks so would it be 16 ohms l-pad with a 8 ohms 100w resistor ?

[@DogsharkGPS]

@@dsteffe74 aye that would be it

[@ver251209]

Most of the adjustment happen towards one end of the L-pad travel

[@giulioluzzardi7632]

Wickedly good idea, Like the treble boost switch, let us know what the uf are on them . Do you think a second potentiometer could be wired up like a speaker tone control and work together with the volume pot?(just a thought). I think all valve cimbos should have one if those "built in" , your design specifically. I suppose if it did get hot after a couple of hours of banging the plank you could design a heat sink out of aluminium or whatever and stick it on the hottest part of the box? Thanks have to build one now cos the "Gizmo" type attenuators do alter the tone and the decent ones are too expensive and as you say (and we all agree) just more boxes and wires to clutter your brain and put you off actually playing.

[@DogsharkGPS]

2.2 and 4.7 uf caps rated up to 100v in the treble bleed

[@giulioluzzardi7632]

Thanks, so the voltage handling can affect the tone too? I can hear the difference between on and treble/more treble on the video . Ta!

[@giulioluzzardi7632]

One last thing and then I boogie off. Remind the viewers to use a proper speaker cable 1/4" jack to jack from amp to attenuator vos I have seen people use short signal cables as speaker leads. I lent my Hiwatt 100 1970s head to my bass player who used a guitar lead to hook it up to his 4x12 and in 5 mins sparks were seen, bright blue they told me.

[@jaydinbreen8476]

Is there any way i could add a line out with its own volume control after the bright switch and before the lpad? Also if i have its muted all the way for long periods of time will it wear out? Should i put a heatsink on it?

[@DogsharkGPS]

Why would you want another line out? Remember the L-Pad is taking the impedance load from the amp so if you tried to split the signal before the L-Pad to add another speaker source it would change the impedance balance. I wouldn’t do that. Never heard of an L-Pad wearing out. But sure I guess it could. It’s a mechanical part. And a heat sink wouldn’t hurt but as long as it’s well aerated like this then that shouldn’t be an issue.

[@jaydinbreen8476]

@Dogshark that makes sense, I guess I didn't think about that haha. So what about after the l pad?

[@DogsharkGPS]

@@jaydinbreen8476 what is it you’re trying to do with the extra line out?

[@jaydinbreen8476]

@Dogshark run it into my daw for Silent recording with an impulse response, I'm debating on getting a khe switcher so it would be nice to have only one line out as compared to running every head with their own

[@DogsharkGPS]

@@jaydinbreen8476 just get a two notes or an ox box. Thats not really a diy job.

[@protoolsfanatic7276]

when i click on buy on website the page won't open due to a secure link Probably because i'm in the states. how much for a attenuator do you charge?

[@DogsharkGPS]

Depends on which variant you want. Try a different browser.

[@timothy5974]

Well this is great, I own a Peavey 5150 combo and I think the 2speakers are wired to a 1/4” Jack that plugs into the amp. Would this work as well? It’s 60 watts but not sure the ohms. It has an external speaker Jack that says 16 ohms. Why not a volume pedal or something between the speakers? Nice video and thank you.

[@DogsharkGPS]

The whole point of an attenuator is to simulate the speaker load on the amp. Without this you can damage your amp. So using a volume pedal is not safe. Same as running your amp with the speaker disconnected. Don’t do this. Research speaker loads and refer to your amps manual to understand what you need if you want to attenuate your amp. And yes one of these would work with your amp as long as the impedance matched properly.

[@giulioluzzardi7632]

Are there any specs on the speakers, like 50W 8 ohm or 16 ohm. If you have the manual look it up or search the net for info beforr you do anything.

[@RenanBEreanSound]

Hi brother I just have a question, my amp head expects to see 4 ohms, but measuring my attenuator, turning the attenuation knob it varies between 8.8 ohm (max attenuation) and 4.0 ohm (min attenuation), checking with a multimeter. Is it safe to set different impedances between 4 and 8 ohms? Just wondering. Thank you

[@DogsharkGPS]

What made you take that measurement in the first place? Who made your attenuator?

[@emulgatorx]

Did you measure that with a speaker connected? The way most attenuators work is by adding a resistor in series and one in parallel. That's why there are three connectors which all need to be connected. If the one in series is low on resistance and the one in parallel is high, the speaker is basically unattenuated. Likewise, if the one in series is high and the one parallel is low, most current will bypass the speaker but the serial load will ensure that the impedance is matched. It's hard to control both resistors with the same wiper and therefore the load will vary. The numbers you report sound quite substantial though for a 4 Ohm attenuator, but could be explained if you wired your speaker in series only without taking the parallel aspect into account.

[@jajsound]

Does anyone make a 200 Watt L Pad ? Would like to build a Guitar Attenuator - The Guitar Amp is 100 Watts - Rule of Thumb is double the wattage of the L Pad.

[@DogsharkGPS]

Not that I’m aware of but I’m sure there is such a thing.

[@jajsound]

Right On ! You would think with all the 100 Watt Tube Heads out there that a DIY Attenuator for 100 watt heads would be easily available @@DogsharkGPS

[@DogsharkGPS]

@@jajsound quick google shows 200w L-pads are in ready supply

[@nigelptl]

I see I see!!!