Attenuators... Will Likely Need One

[Fingolfen]

So... I'm finally getting into amp building and am looking at some of the higher wattage amps that I likely won't be able to use straight in the house...

I've been looking at various attenuators, and they vary greatly in price / capability / mode of operation...

Any one have thoughts? Advice?

I'm likely going to be trying to get to where I can use things like 100W Hiwatts, Two-Rock, etc. in the house... At this point 5W is okay when others are in the house... and my AC15 turned down is okay - but I don't get to play at higher volume levels...

 

[Barry]

I had a Rivera Rock Crusher for a while, was pretty good. Years ago I had a Hot Plate which also worked fairly well. Now days only the dog is bothered if I play loud.

 

[Giorfida]

I liked the THD hot plates quite a bit.
Just remember to bias a bit cold or you’ll be redplating the tubes.

Another option is the good old post-phase inverter master volume. Very few amps actually distort the power tubes (phase inverter collapses first). Much better for power tube and transformer life. Just my opinion based on a few blind tests I did decades ago.

 

[MattG]

If you want to keep your DIY cred, you must build your own.

Take a look at the JohnH passive attenuator in this thread Simple Attenuators - Design And Testing on the MarshallForum.

I built one a year ago, see my build report. It works great, I use it almost every day with my DR504 clone.

 

[owlexifry]

So... I'm finally getting into amp building and am looking at some of the higher wattage amps that I likely won't be able to use straight in the house...

I've been looking at various attenuators, and they vary greatly in price / capability / mode of operation...

Any one have thoughts? Advice?

I'm likely going to be trying to get to where I can use things like 100W Hiwatts, Two-Rock, etc. in the house... At this point 5W is okay when others are in the house... and my AC15 turned down is okay - but I don't get to play at higher volume levels...

Fryette Power Station \m/

 

[giovanni]

I have a Tone King Imperial which has a built in Ironman attenuator which I really like.

 

[chris.knudson]

If your amp has an effects loop, you can get away with something like the JHS Little Black Amp Box. It's an effective and inexpensive solution that still lets you drive your amp's front end without rattling the windows.

 

[drgonzo1969]

I have been using a Radial Prodigy for the last 6 years. Love it. No complaints

 

[Barry]

If your amp has an effects loop, you can get away with something like the JHS Little Black Amp Box. It's an effective and inexpensive solution that still lets you drive your amp's front end without rattling the windows.

You can easily build one of those, it's just a 100k pot and two jacks.

 

[RetiredUnit1]

Standard Hiwatt DR103 (100w) or DR504 (50w) don't overdrive. There is no preamp or power tube distortion, and they sound the same from 1/2w to 100w. Although at highest volume you will get speaker breakup, unless you have very high rated speakers.

Now if you build a Marshall 2203...... You can just build your own!!!

This is a link for the instructions to a DIY reactive load attenuator

Simple Attenuators - Design And Testing

Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...

www.marshallforum.com

 

[Giorfida]

Standard Hiwatt DR103 (100w) or DR504 (50w) don't overdrive. There is no preamp or power tube distortion, and they sound the same from 1/2w to 100w. Although at highest volume you will get speaker breakup, unless you have very high rated speakers.

Now if you build a Marshall 2203...... You can just build your own!!!

This is a link for the instructions to a DIY reactive load attenuator

Simple Attenuators - Design And Testing

Background Passive attenuators are wired between the amp output and the speakers. Their function is to absorb most of the output power of the amp, feeding a smaller amount to the speaker itself. This allows the amp output stage to run at higher power, letting the glorious tone of a good valve...

www.marshallforum.com

Even most classic black and silver fenders you won’t get any power tube breakup (you will get some preamp and a lot of phase inverter grunge), but the phase inverter simply won’t drive the power tubes even close to distorting.
And as you said, Hiwatts don’t break up at all unless you really drive the bejeezus out of them (like an echoplex preamp or other pedal)- and at that, it’s only the first gain stage breaking up, nothing past that.

 

[drgonzo1969]

I have been using a Radial Prodigy for the last 6 years. Love it. No complaints

Update: I had always used the Radial prodigy attenuator with 20w Marshall origin head. Recently I started using the Radial Prodigy with my Carvin X100B and the 100w might be overloading the Prodigy. It gets pretty hot damn hot to the touch after about 20 minutes of playing. I turned the amp off when the plastic started getting aromatic. I emailed Radial to see how much heat is normal. I bought the Radial Prodigy used on reverb 7 years ago. Anyways, I might be in the market for a new attenuator. we will see.

 

[owlexifry]

Update: I had always used the Radial prodigy attenuator with 20w Marshall origin head. Recently I started using the Radial Prodigy with my Carvin X100B and the 100w might be overloading the Prodigy. It gets pretty hot damn hot to the touch after about 20 minutes of playing. I turned the amp off when the plastic started getting aromatic. I emailed Radial to see how much heat is normal. I bought the Radial Prodigy used on reverb 7 years ago. Anyways, I might be in the market for a new attenuator. we will see.

doesn't the X100B have a master volume?

 

[drgonzo1969]

Each channel has its own volume control. I had the volume on about 4 or 5 on each channel. The amp has it's own "attenuator" switch in the back for 100% power, 50%, or 25% but it sounds terrible at 25%. Haven't tried 50% in a while.

 

[drgonzo1969]

I also rarely actually use a cab. I use headphones 99% of the time. Cab still plugged into to attenuator but its silent when headphones are plugged in.

 

[Giorfida]

doesn't the X100B have a master volume?

They do…and trust me you want to use it! The way they stage some of the solid state components in the amp, you will get some nasty clipping before the power tubes start really work if I remember correctly (of course that may vary depending on revision…the one I had was the grey rug covered version with the “pull hot rod” vs the “pull hi lead”, and was only around a couple months before they revamped their whole line)

Update: I had always used the Radial prodigy attenuator with 20w Marshall origin head. Recently I started using the Radial Prodigy with my Carvin X100B and the 100w might be overloading the Prodigy. It gets pretty hot damn hot to the touch after about 20 minutes of playing. I turned the amp off when the plastic started getting aromatic. I emailed Radial to see how much heat is normal. I bought the Radial Prodigy used on reverb 7 years ago. Anyways, I might be in the market for a new attenuator. we will see.

I have always heard that you want to always overrate the attenuator to the amp. So a 100w attenuator should be used on 60w or less. Theory is that the amp rating is at the point where clipping starts, and where we really crank them, we are often putting up to 150% of rated power to the speakers.
Personally, if I was slapping a sticker on an attenuator saying it can handle 100w, I’d build it to handle 200w continuous.. And I’m sure all manufacturers do things differently
Hopefully they will hook you up. Otherwise, shouldn’t be too hard to repair, unless they do like THD did and essentially epoxy the wire resistors into the aluminum housing.

 

[drgonzo1969]

Radial said it was fine…. False alarm.