Homemade Attenuator

George · Post by **George** » Thu Jan 27, 2011 11:30 am

Apparently you can make a homemade amp attenuator with one of these...

http://cpc.farnell.com/jsp/displayProdu ... 2-00001000

You just need an enclosure and two jacks, and another speaker cable if you don't have one already. Apparently you can add other bells and whistles like headphone and treble bleeds. Has anyone tried this? It sounds awesome and cheap.

I've wanted one for a while but don't want to spend Â£150 on a Weber MiniMass.

timhulio · Post by **timhulio** » Thu Jan 27, 2011 12:11 pm

Got a circuit diagram? I wouldn't mind trying this with my MM bass amp.

Post by **Mike** » Thu Jan 27, 2011 12:25 pm

hahah. Tim it's an L-pad.

FFS. Call yourself a pedal builder.

timhulio · Post by **timhulio** » Thu Jan 27, 2011 12:28 pm

Never heard or read that term until just now. 'Voltage divider' is what I know.

http://amps.zugster.net/articles/attenuation

Post by **Mike** » Thu Jan 27, 2011 12:35 pm

Bootweaker.

George · Post by **George** » Thu Jan 27, 2011 12:36 pm

I'm trying to find one with treble bleeds and what not, but all I can manage is this basic one which is probably patronising to pedal builders

All the threads I can find are c. 2006 and link to borked 404'd pages, or people say "I ADDED CAP LOL BUT NOT TELL YOU HOW"

Post by **Mike** » Thu Jan 27, 2011 12:40 pm

Look up "high pass filter", "low pass filter", "Marshall/Fender tone stack" and you should get some useful things to insert.

You'll want to insert them between the +ve and -ve connections on your speaker output diagram there - the Amp + and - terminals want to be unmolested or you'll be undoing the good work the L-Pad is doing.

I would suspect people are probably just slapping a 100p-470pF cap (high voltage rating's a must!) across the speaker terminals.

Dave · Post by **Dave** » Thu Jan 27, 2011 12:42 pm

timhulio wrote:Got a circuit diagram? I wouldn't mind trying this with my MM bass amp.

Likewise.

So is this kind a of thing a real contender to achieve what those Hotplate thingies can do for tube amps at low volume? [/total layman question]

George · Post by **George** » Thu Jan 27, 2011 12:47 pm

Mike wrote:Look up "high pass filter", "low pass filter", "Marshall/Fender tone stack" and you should get some useful things to insert.

You'll want to insert them between the +ve and -ve connections on your speaker output diagram there - the Amp + and - terminals want to be unmolested or you'll be undoing the good work the L-Pad is doing.

I would suspect people are probably just slapping a 100p-470pF cap (high voltage rating's a must!) across the speaker terminals.

Saaafe! I'd consider making that switchable between two different caps and a no cap switch like the Weber MiniMass. Is it possible to stick a pot in there to do the job?

Post by **Mike** » Thu Jan 27, 2011 12:52 pm

Dave wrote:
timhulio wrote:Got a circuit diagram? I wouldn't mind trying this with my MM bass amp.
Likewise.

So is this kind a of thing a real contender to achieve what those Hotplate thingies can do for tube amps at low volume? [/total layman question]

They'll add cooling (Heat WILL be a problem), and tone shaping (you will be amazed how shit attenuating an amp like this will sound), and reliability. I wouldn't touch it with a bargepole as a builder.

# Impedance:8ohm
# Power Max:100W

This is the rating of this L-Pad. I wouldn't use it with anything over 50W RMS as peak output will be greater than 50W (that's what the RMS is telling you), and if you're using an attenuator, odds are you're going to dime the amp.

Further reading:
http://amps.zugster.net/articles/attenuation
http://diy-fever.com/misc/l-pad/ (includes treble bleed)
http://www.regiscoyne.com/ampwell/

Personally I think it's all nonsense. The amp will sound not great at bedroom volume, you need to move some air to get an amplifier to sound nice in a room generally.

If you want low volume good tones, look no further than Hardware or Software modeling of Amps. Pod, iRig, Tech21 Character Pedals etc.

I've seen Hotplates used for great sounds, but they were getting dirt out of SF Fenders at gig volumes.

George · Post by **George** » Thu Jan 27, 2011 1:04 pm

Yeah, I chose 100W there because my amp is rated 30W and have heard of heating issues and what not.

This is definitely food for thought though. The thing is my amp has this annoying kick in point where the tubes actually start working and sound good, so I'd like to rein that in, as well as hear what it sounds like cranked. Sadly, even at giggable volumes my amp still doesn't break up! At around Â£30 a go this could be pretty useful. A few pounds more and you could stick a PC fan in there. Or maybe not...

lorez · Post by **lorez** » Thu Jan 27, 2011 1:06 pm

wouldn't the pc fan add noise in there that you wouldn't want?

George · Post by **George** » Thu Jan 27, 2011 1:08 pm

If it was a seperate circuit, operating on a low setting it'd be alright wouldn't it?

mellowlogic · Post by **mellowlogic** » Thu Jan 27, 2011 1:37 pm

I would think the pc fan would only be an issue if you were recording. Not sure about the classic 30's, but my classic 50 has a fan in the back. You can hear it if you try, but it's not really all that noticeable.

Edit: I should add that, like everything else, they make pc fans of varying quality. If noise was a big concern, you could get a nicer fan with quiet bearings.

Dave · Post by **Dave** » Thu Jan 27, 2011 2:44 pm

Mike wrote:If you want low volume good tones, look no further than Hardware or Software modeling of Amps. Pod, iRig, Tech21 Character Pedals etc.

I've seen Hotplates used for great sounds, but they were getting dirt out of SF Fenders at gig volumes.

Thanks for the explanation Mike. I think the bit quoted above is the main lesson shall take away from this and go get the iRig instead!

Post by **Mike** » Thu Jan 27, 2011 2:51 pm

I really should make a demo of how iRig sounds with the Fender amp and outboard pedals - it's amazing, you just wouldn't think it.

http://soundcloud.com/jpflower/hangover/

This is the unmixed DI output of the JamHub we've been using for practise at Sell Crazy Towers.
My guitar is going through iRig (with an MBM Echo Base for delay on the start of the song and MBM DLS for dirt in the rocky bit), Gareth is on the left and using GuitarRig on a Laptop.

The guitars aren't mixed all that loud but you get the general idea.

Thom · Post by **Thom** » Thu Jan 27, 2011 3:39 pm

Mike + Les Paul looks weird!

benecol · Post by **benecol** » Thu Jan 27, 2011 3:47 pm

I'm a little pressed for time, so could you all just imagine that I've photoshopped out the iRig and replaced it with a massive, spunky biscuit.

blacktaxi · Post by **blacktaxi** » Thu Jan 27, 2011 3:53 pm

hey Mike, that stuff sounds great. thanks for sharing.

Post by **Mike** » Thu Jan 27, 2011 4:06 pm

benecol wrote:Predicatble snide

It seems you're threatened by there being more than one person in the room making music, and them being male - you Dandy.

Cheers blacktaxi, it's one of the tracks from the new album we're in the process of recording (over weeks and months and years), really excited about the new material.