DIY attenuator?

[Vince]

This is kind of a request and some advice.

I've seen a few of these on eBay that apparently work through the effects loop as a master volume. Not for Laney amps though apparently. I was wondering if anyone has any experience with them? more so if they're safe etc? ... If so, they seem pretty simple devices and maybe worth a request for a layout if they do actually work?

An example.
http://www.ebay.co.uk/itm/ATTENUATOR-A3-FOR-MARSHALL-ELECTRIC-GUITAR-AMPS-/251216791911?pt=UK_Guitar_Accessories&hash=item3a7db00967

[Madferret]

There's a company in London that does a mod similar to this on Blues Juniors, I've looked at it but to be honest seeing as it's only 18 watts it's not been an issue for me. I've heard plenty of good things about attenuator mods but I've never seen a pedal like this before. From the description it seems like it's just a volume pot that sits between the pre amp and power amp sections, letting you cook the tubes in you pre amp to get the overdrive but not get the volume from the master section. It says it doesn't need a battery so it can't be anything too complex.

[JaviCAP]

Don't really know hot this attenuator works, as is intended to be used trough the effects loop.

I built some time ago an attenuator for my tiny Black Heart. This one is set between the amp's head and the cab.

It just uses a l-pad (15W, 8ohm for the black heart) and a 47uf bipolar cap.

Very simple build:



You can get all the sound of the valves without tearing down the walls of your room :)

BR

[Jon the Art Guy]

I have a Bitmo Attenuator in a bag somewhere, I should take a couple shots of it. I made the circuit but never put it into the enclosure.

It uses a switchable treble boost, at L-pads tend to suck out the treble. It's in essence a very fat veresistor, if I remember correctly.

[dodido]

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[Vince]

I was thinking there MUST be a difference between the £25 and £250 devices!... I only use a DSL 15 at home so my volume isn't really a problem. It is still really loud though so just thought it might be cool idea.. I'm not too keen on the effects loop idea. It was just a thought in case I decide to pull the trigger on a JCM 800 in the future, so I suppose it's better to bite the bullet and invest in a 'proper' attenuator etc..

Thanks for the replies ;o)

[Jon the Art Guy]

well no, that's technically not right. An L-pad can sit between the power section and the speakers. Its job is to dissipate the load to the speakers by converting the energy to heat. The more attentuation, the more power is robbed going to the speakers and is burned up in a resistor. You have...HAVE to have an L-pad rated for more than the wattage your amp is pushing, preferably 2x. The L-pad I have for my Valve Jr is rated at 15w.

there's a lot of different ways to do this. The L-pad uses a set of resistors inside it to soak the power, letting less go to the speaker. You can also accomplish this with a switch and a big-ass ceramic resistor, only you would attenuate to one volume instead of a varying amount. This is a form of a Dummy Load, AKA something for the power to push through, but it ain't a speaker.

You can use a lightbulb. Wire a lightbulb socket in series to the speaker. Apparently not only does it attenuate, but it also compresses in an interesting way. f I have my vjr around, I'd have done this a while ago.

A reactive load is a nice way to go. essentially, it's a speaker magnet that's not attached to a speaker cone, with some extra components to account for the added load the cone provided. You can then tap the residual power to line-out to a mixer or P.A. and it sounds pretty accurate to your amp, minus speaker sound.

I would suggest checking out Webervst. they have schematics and kits for all of these things. There's also a ton of designs out there on the webs. In essence, it's all just an attempt to soak the workload the amp is putting out to the speaker before it gets to the speaker.

[IvIark]

Yes I've got an LPad somewhere, just haven't built it up into a box yet, but it certainly seems like the way to go for a low cost and easy homemade attenuator.  I was a bit worried about dissipation of heat but I just got the 100W one so I knew there was plenty of capacity (I'd only use it with a 50W amp maximum and wouldn't dime it anyway).

I have a Torres Power Soak which uses the big power resistors and has a stomp switch to switch between two preset levels, and had a Weber Mass.  I really didn't like the Mass though despite it getting good reviews from others, I found the attenuation made the amp sound very unnatural whereas the Power Soak does it's job much better for me.  The LPad seems like a great option for variable resistive attenuation.

[dodido]

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[IvIark]

Yes the "attenuators" Vince linked on eBay is just a pot in a box and pretty much useless, and completely useless unless you have a series loop.  I thought we'd moved on to real attenuators.

[Jon the Art Guy]

sorry, I derped. Yea, that sounds like an excellent way to waste some money. Especially since L-pads cost about the same.