Part 8: Building an attenuator

The PP-18 is a great amp but for practising it is still a bit too loud , even with the voltage change mod from the previous blog post.  Somebody on YouTube has a great video demonstrating the PP-18, but he plays it through a BitMo attenuator , the 10 watt model)

These are available as kits for self build.



BitMo site is at: BitMo

The circuit is really simply and I found the plans and parts list on the internet. It was easy enough just to obtain the bits and create a basic clone of the BitMo kit. The key component is the L-Pad  rheostat which I obtained through an Ebay dealer. A very good, fast efficient dealer I might add.

The L-Pad was found on Ebay at: L-Pad Ebay

Putting it together took about an hour and a half. Finished item looks like:

Inside the box - not a lot to see. Big square thing is the L-Pad. Also two resistors, one a huge nadger of  a thing, the other lower rated. 2 capacitors and a rotary potentiometer for the line level. 3 jack sockets. I used bits of wire left over from the Ampmaker kit. That was it really.

Not quite finished yet - needs proper labels. Speaker and Amp sockets.

Big knob is the L-Pad control - determines the amount of attenuation. Other knob controls the line out level for feeding into another amp, computer, mixing desk, home hi-fi, headphone amp. I tried recording onto a PC using Microsoft;s "Sound Recorder"  A bit nasty to be honest. Probably best to use a microphone. We'll find out soon enough....

Showing the line-out socket on the side.

So that was that. It sits between the amp and the cabinet, Rated at 8 ohms, so use the 8 ohm socket. With the amp cranked right up and the attenuation right down, you get the most wonderful crunch sound from those tamed EL-84s. Dont know how much heat this lot produces - mind you, the amp is running at 2 watts so its all well within the limits.

I'll keep you posted!