New case for the PP-18

I decided that the PP-18 needed a new case. I always wanted to make one that looked like the 1959RR Marshall head, you know the white Randy Rhoads one? Heres a pic of the original 1959RR:

Anyway, finally managed to knock one together. Here is a pic of it:

As you can see its not the same size as the 1959RR - its smaller. But its the same construction style, made with several Marshall parts. Tolex, corners, handle, piping,  knobs are all Marshall. The amp kit of course is an Ampmker PP-18. Modified with the "voltage mod" that allows power ratings of 2, 9 and 18 watts.

It also runs through my home built power attenuator, based on the BitMo 10-uator design.

The feet on the base are generic Maplin feet. I WAS going to put on the sprung feet that Marshall have on the 1959RR but that can wait for a bit, just to keep the costs down.

It took about a week to make, working on and off for about 1 1/2 hours a day. Lots of waiting on glue to dry! Wood is pine - easy to work with and rounding off the edges was simple.

Anyway, that's it - heres another few pics. Yes, I know it is a bit different - but it was the style I was trying to copy rather than the whole thing.

And yes, it definitely needs a logo to fill in that empty white space. Any suggestions?

Hopefully get some sound samples up soon!

SE5A and PP18

I built the SE5A two years ago - it was my first proper valve map build and it went very well. Th eamp sounds good, but I feel that the PP18 sound much better. When driven hard the PP18  has a much fatter sound.much more satisfying. What I intend to do soon is record a few short  clips comparing the two amps. In the meantime here is a pic of the two Ampmaker amps together on top of my "Marshall" 4 x 12.....

Bye for now

\m/ James Westland

Buzzing

Amp seemed to develop a noise problem the other day. Dont know how it happened but whenevcr a guitar lead wa plugged into it, there was a loud , very loud hum from the speaker. Using the test diagram and instructions on Ampmakers site, I was able to quickly diagnose the problem -  a bad earth caused by a whisker of soldered wire poking through the insulation on one of the shielded cables from the input sockets.

After this was tidied up, it all went back to how it was. Have to say, when building the amp, I found the input socket wiring to be the hardest part, definitely very fiddly. I was never terribly happy with the finished result. I may order up a new set of sockets and resistors and re-do it a bit neater. We'll see!

Test pages here:

PP18 Initial testing

Bye for now

James

Part 10: Adding the 3 way power switch

I finally got round to fitting the rotary switch mod given in this article on Ampmakers site:

3 way switch mod

The only place really for the switch is on the front panel. I would have preferred to have it rear mounted, but there isnt really a place for it. The diagrams make it obvious.

The front panel seen from the inside - plenty of room and a hole already in place!

Looking at the rear panel on the inside - no space for the rotary switch. Only other option would be further along beside the valve sockets, but that would have meant extending high AC voltage past the valves. Something tells me that would not be good for noise. Besides, its best, IMO if all the mains and hi voltage AC stuff is in the one place.

I wired the switch up and tested it all with a meter before drilling the plexi panel to install it. Note - the chassis has got holes in the right place for this, so it is just the plexi that needs to be drilled. However, and be really careful with this, despite my best efforts, I managed to split the plexi. So I will need to order up another one from Ampmaker. It is almost certainly best to try to make the hole when the panel is OUT of the amp, probably on a flat surface.

Anyway, despite that the rotary switch installed Ok and after the connections were all soldered I tested it, firstly on the bench without the valves, just to make sure the voltages were OK. After that the whole lot got put back together and tested properly.

Rotary switch in position with wires to diodes (brown and white) and wires from power trasnformer (white, yellow and blue)

Note - this is one seriously loud amplifier. Even at 2 watts it is loud. I normally run it through my attenuator to tame it a bit, although I believe that there is a bit of sound quality loss when using this approach. The alternative is to have the neighbours howling at my door....

The chickenhead knob on the rotary switch at the front left side. Note split in plexi (flash from camera makes it less obvious :-) Left position is 2 Watts. Middle position is 9 Watts. Right position is 18 Watts.

Could do with some way of indicating this on the plexi - in a more primitive age , the Dymo tape would have been applied. Maybe just keep it anonymous....

\m/ \m/ Bye for now!

Pics here:

Part 9: up to 9 watts

One of Ampmakers mod suggestions is to change the mains transformer output tapping so that a differnet output voltage is produced. By going for the 0 - 190 output, the DC HT voltage becomes 250 volts and the output power is 9 watts rather than the full 18 watts.

NB: this is still SERIOUSLY loud. Through my home-built "Marshall" 4x12 , this was pretty impressive. And it wasnt even totally cranked. Plus it was going through my "BitMo clone" attenuator.

What this lot sounds like when totally unleashed remains to be seen... Reminds me of that old Motorhead thing "Deaf not Blind!"

Anyway, heres the mod: (crap pic I know, rubbish camera...)

Showing the power transformer and the leads to the rectifier diodes - using the 0 - 190 taps rather than 0 - 275. This gives 9 watts output maximum

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! 

Part 7: First mod

One of the most notable features of this amp is how loud it is. When cranked "up to 11" it is seriously loud. One of the recommendations on the Ampmaker site is changing the wiring on the mains transformer so that the output to the rectifier diodes is less. It is explained here:

Voltage adjust mod

By using the 190 and 275 voltage lugs, the rectifier circuit provides 100v DC and an effective power of 2 watts. Those 2 watts are still seriously loud. Loud enough to drive the 4 x 12 cabinet adequately.

Here's what the modified wiring looks like:

As you can see, only the 275 and 190 lugs are used.

One of the mods that Barry (Ampmaker) suggests is the use of a rotary switch between the transformer and the diodes in order to make the voltage / power selectable. I have got the switch, but havent got round to installing it yet. That'll be in a later post!

Part 6: Finishing off the case

I had designed the case so that the chassis fitted in snugly. Four big bolts hold the chassis to the wood, from the underside. I fitted some Marshall white piping to the sides of the front with a staple gun and then inserted a panel made from plywood and covered in Tolex. A line of piping between this and the chassis finished it off:

Needs a badge / logo doesnt it?

The corner pieces were from Maplin - not the best but they do a good job in protecting it. Also, a handle was added to the top, again from Maplin. The rear view looks like:

Yes I know, the rear chassis panel is aluminium and not plexi... it was cheaper.... Anyway, the black rear panel is again made from plywood covered in Tolex and mounted using brass cup washers and screws. Simple but effective. There is an air gap for ventilation.

Rear sockets arre 8 ohm and 16 ohm speakers, plus the mains socket and the fuse.

Finally, mounted atop a 4 x12 , this is what it looks like:

That's not a real Marshall 4 x 12 by the way - its a clone I made, following some instructions I found on YouTube: 

http://www.youtube.com/watch?v=RyoA58eaM4o

The cabinet isn't quite the same as the one in the YouTube video - I'll show some pics of it in another blog post some time soon.

Part 5: Testing the PP-18

Although all the voltages checked out OK, there was something not quite right. One of the pots weas a bit scratchy. That was replaced but there was still a serious problem. The EL84 valves were "red-plating". Not good. This is not a good sign with any valve amp, so it was head scratching time.

Not only that, but the volume simply wasnt there. 18 watts is supposed to be loud....

Careful checking of the wiring revealed that the tone control / volume pot wiring wasnt quite right. I cant remember which one it was, but a wire was going to the wrong place and that was what was causing the anodes to go red

A quick bit of desoldering and resoldering and , bingo, problem gone. I plugged in the Tokai Strat, turned the volume a little bit - DEAFENING! Man what a sound.

So the moral of the story is - check check and check again. And then probably again just to be sure.  Its probably worthwhile checking it again first thing in the morning after a good nights rest. Sometimes the brain just gets tired and cloudy and you just cant see the problem. After a good nights sleep it is obvious!

Anyway, that was all the electrical stuff done - next stage was finishing off the case.

Part 4: Wiring it all together

I know that this is actually three or more separate steps but I didnt actually document it fully, so it is all run together here! Some of the wiring is quite tricky - the valve heater wires are fiddly, as was the input socket wiring. The tone and volume controls were also a bit of a pain. Care is definitely required.

However, the finished internal wiring looks like this:

Not perfect, but the final amp sounds great, with very little hum

Another closeup pic:

Volume and Tone pots, plus input sockets. Simple but very effective.

So thats all the wiring done. The next stage was to test it. Barry from Ampmaker has a very good test procedure for each kit. All the voltages recorded from the various points of the circuit were within the limits, so it was then time to connect it up and test it. Thats the next blog post!

Part 3: The Turret Board

The turret board supplied by Ampmaker is very good quality and very nice to work with. All the turrets are in place, just ready for the components to go on. As with the SE-5a amp that I built last year, my first step was to get a sheet of card, and stick the various resistors, capaacitors and so on to it, each clearly labelled with the values. This makes selecting the right value component much easier. It is worth taking a bit of time with this step. Once the components have all been identified, it is a case of soldering them to the board, snipping them to length and basically double checking everything. The board before assembly is shown on the left


The assembled turret board with all the components is below:

A close up of a part of the board:

After this, the next stage is to connect the various wires to the turret board - these are the wires that connect to the valve sockets, switches, sockets and rotary controls

Ampmakers manual is very clear in this respect. The correct lengths of wires are given and where to solder them - first class instructions. Plenty of wire is provided and there is always plenty to spare.

Part 2: Chassis Assembly

First step is to assemble the chassis mounted components such as the transformers, valve sockets, switches and so on. This is easy, but like all the amp kit stuff, it is best done on a solid bench under a very good light. Also make sure that all the nuts are tight. When complete, this stage looks like this:

Above: assembled chassis

Inside of the chassis

This bit was easy enough. Next stage is assembling the components on the turret board. See next blog post!

Part 1: Chassis and Cabinet

Instead of purchasing the full kit straight away, I decide to buy just the chassis and the Plexi control panels so that I could get the cabinet design sorted out first. The cabinet is made from pine - actually 28 mm tongue and groove flooring. Very easy to work with.

Pic above shows the basic pine wood frame, roughly finished. Once it was sanded a bit and smoothed off, I applied Marshall type tolex to it using a spray-on adhesive, from a local builder supplier, very similar to Evo-Stik. The tolex was then tacked down at the edges on the inside using a staple gun.

Pic above shows the case covered in Tolex. Once the glues was all dry, I checked it by lining up the chassis to make sure everything was OK. It all looked fine, so the next stage was getting the rest of the kit ordered and digging out the soldering iron....

Building the PP-18

This blog contains information about my experience of building the Ampmaker PP-18 guitar amplifier. As the blog unfolds I will give more information about how I tackled it, any difficulties experienced plus any mods that I tried and anything else that seems useful

I hope to include pictures of the build, so any budding amp builders can get an idea of what is involved

Any questions, just email me - I'll be pleased to hear from you!

Cheers

James Westland