Some feedback from a recent Lamington builder

I continue to receive very favourable feedback from builders of Lamington amps as to how happy they are with how the amp sounds. To some degree, this is a little surprising, as the Lamington amp was developed to be a low cost introduction to valve guitar amp building and not necessarily to be a tone monster. That it sounds so good is a real bonus, and makes it doubly worth building.

This email is typical of responses I receive:

Hi Grant,

Just wanted to let you know that we fired up the lamington last night, and….

 …it was amazing!

 I was truly taken with how great it sounded. We ran it through my 4×12 with celestion vintage 30’s and it was really great. The tone is excellent and I was loving how responsive to touch it was. It seemed nice and clean with gentle playing, and then you dig in a bit and it rips your head off… Seems at first play like it has great cleans (with the right amount of chime) and great bluesy overdrive. 

I think you are really onto something with the lamington, which of course you knew! (I’m not sure I did!)

 Any plans for other amps…? (Yes, the Lamington III design is now released)

Thanks again for all your help with this – it’s truly one of the best amps I think I’ve played.

Kind regards,



Tips for keeping your amp in top condition

I came across these tips for maintaining your amp some time ago – some good advice for keeping your amp in top condition!

1. Always make sure the speaker is plugged in properly before turning on your amplifier. Failure to do so may cause damage to your output transformer or output valves.

2. Make sure your amp is properly grounded check the mains power cord to make sure it is not damaged.

3. Have your power output valves (6V6, 6L6, 6BQ5, 6550, 6CA7, EL34, EL84 etc.)  changed or checked if you notice a dullness in your sound. If you see glowing red plates in your output valves, STOP! You either have faulty valves or circuit trouble, and failure to turn the amp off usually results in major blown parts ($$$). The preamplifier valves, 12AX7 and 12AT7 etc should last for several changes of output valves. If you hear jingles, rattles, pops, squeals or if the gain or attack decreases, it may be time to have these valves changed or checked.

4. Transport your amp on a padded surface. Amps transported on the bare metal floor of a van or unpadded boot of a car may have the elements in the valves shaken loose and cause microphonic rattles or worse, short when next powered up at a gig. Treat your amp gently and it will last longer!

5. Follow the amplifier manufacturer’s recommendations about fuse changing. Never, ever use a fuse of a higher rating than called for, or you may wind up with a ($$$) blown power or output transformer.

6. If your amp has an impedance selector, such as Marshall, HiWatt, some Ampegs, etc., place the amp in standby before changing the impedance. Also, be sure to select the correct impedance for the type and number of speakers being used.

7. Use a thick wired cable for speaker hookup. Don’t use thin coaxial guitar cables as speaker wire if possible. This is especially true for bass, where damping factor, tone and watts could be easily lost.

8. If you hear your amp cutting in and out, reduce the amp volume then wiggle the speaker cord. If this influences the cutting in and out, STOP! An intermittently open or shorted speaker connection or cord might damage your amplifier.

9. Keep all cable ends clean. Dirty input jacks cause intermittent crackles and hums sometimes attributed to more serious problems.

10. After powering up your valve amp, look at the output valves (the bigger valves). If the valves’ plates are glowing red hot, STOP! This symptom takes moments to show up and just a few more moments to destroy the output transformer or other parts. The problem could be as simple as faulty valves, or you could have other trouble, such as bias supply failure. A new set of output valves plugged into a seriously malfunctioning amplifier can be ruined in a very, very short time. When in doubt, have your amp tested by a competent technician.

11. Give your amp plenty of ventilation. A fan blowing on the output section of the amp will keep things cooler and generally increase the service life of the electronic components in the amp greatly. An easy way of accomplishing the cooling process is to purchase a small table fan at a discount store (around $20) and place the fan behind the amp blowing into it. The cooler your amp runs, the longer it will run. Your capacitors will especially love you if you keep them cool. Never place the amp with its back against a wall. This will severely limit the natural ventilation the manufacturer has hopefully built in.

12. Do not move your amplifier immediately after shutting it off. Let the amp cool down for a few minutes before moving or transporting it.


A very cool amp design tool

For those who have not yet seen it, Duncan Munro has available a very cool amp design tool at his website:

The freeware Tone stack calculator program allows you to play with a range of virtual tone stack circuits – you can see several tone stack circuits from Fender, Marshall, Baxandall etc and adjust each “virtual” component to see how it changes the response of the tone stack.

Here is what it looks like:


I encourage anyone to download it and “plug in” your favourite tone stack and see visually how each component shapes the sound. I use TSC on a regular basis to check different tone stacks I am planning for different amp designs – recommended!