Orange Micro Terror pre-amp valve

Rocker

I have a soft spot for Orange amplifiers. In the 1970s my late father and I had an Orange PA valve amplifier and it was simply amazing and absolutely reliable. It never let us down and might still be working as far as I know!

With that somewhat coloured perspective, I bought an Orange Micro Terror about six months ago. This amplifier worked brilliantly with an Orange 4 * 12 cabinet in the shop, but lack of space resulted in me buying the next best sounding speaker cabinet, a Blackstar 1 * 10. I don't gig so all my equipment is setup permanently in the music room, the Micro Terror compliments my ever present self built Dennis Cornell kit – a 1 * 10 6L6 SE combo. Two very different sounding amplifiers indeed!

A few months ago there were posts on the now offline MR site that decried the sound of the Micro Terror, describing it as tizzy. One poster said that some improvement in the sound was obtained by changing the pre-amp valve [a 12AX7]. To be honest I agreed with most of these posts, the tone gets tizzy when the drive is wound up but if the drive is not advanced beyond the 12 o'clock position, that tizziness diminishes. At least on my sample it did. The Micro Terror is no Marshall or Fender but it does not claim to be either and is priced accordingly.

Curiosity got the better of me however, I got together a few 12AX7 valves to test this tizziness claim and to see if the sound could be improved. The amplifier PSU is connected to the mains by a Russ Andrews power cable. I am not sure if this makes any real difference to the sound but as the cable was unused and available, I put it into service. Thanks to a good friend who gave me a few valves to try out, Harma, Ei [Yugoslavia] and a couple of unknown and unbranded valves.

To get access to the valve, requires the removal of a total of 12 screws. Looking at the circuit board I concluded that the build was 'not too bad' and probably about average for the price charged for the amplifier.

The amplifier, sans the cover or flat plate, was connected to the Blackstar speaker in the usual manner. I set all the controls at the 12 o'clock position and left them there. Guitars used were my Fender USA Telecaster, my Fender Custom Shop Stratocaster and my Epiphone Les Paul which has Seymour Duncan pickups fitted. The guitar tone controls were set at 10 and the volume control was initially at 10 but backed off as needed. The tests, which were 100% subjective, were the stock valve against each of the other valves I had. Tedious work switching valves, testing with the guitars, change the valve and testing again. Using the stock valve gave me a 'reference' and kept me honest! What I was looking [listening] for was tone, perceived volume and general sparkle to the sound. And noting anything else that jumped out at me.

First things first, on my amplifier every valve tried sounded 'better' than the stock valve. By better I mean richer tone, less tizz or fizz and with more 'weight' to the sound. The Ei sounded amazing, a real jump up quality wise on the Harma (which was very good). A valve branded 'Precision' ran the Ei a very close second and as the Ei had to go back to its owner, the Precision is now in situ in the amplifier.

An interesting observation was that the Tele never sounded its best through the Orange/Blackstar setup whereas it was fine through the combo. No matter what valve was used, the hoped for classic sound of a Tele did not happen. The Strat sounded amazing through the Orange/Blackstar setup especially on position 4 [middle and bridge pickups]. Lovely traditional country sound, think Merle Haggard, Jonny Cash, John Fogerty etc. The Les Paul almost exploded in my hands. Grin inducing sounds especially with power chords and harmonics literaly jumped off the fretboard. Instant crunch, to clean up the sound I had to back off the guitar volume control to between 1 and 2.

So that is my experiences with the Orange Micro Terror amplifier. Your mileage might vary but I would hazard a guess that simply changing the stock pre-amp valve to any 12AX7 or equivalent will improve the sound no end. The Micro Terror may not be the greatest thing since sliced bread but, correctly valved, it is a fine sounding amplifier. Considerably better sounding than any modelling amplifier I have tried, I would rate it a pretty decent backup amplifier for any gigging guitarist. Especially suitable for the smaller venues or if the guitar is miked through the PA system.

ROOG

Have you tried it with one of the lower gain variants? I would be interested to see if that has much effect on the sound.

Moltisanti

i have a 12 AT7 knocking around that i might try in mine, from my tests you wouldn't need to mic up the MIcro Terror, through a 2x12 or 4x12 it's insanely loud, i bought it specifically to back up a main head and it sounds fantastic considering the size and cost.

ROOG

I recently prised some vintage tubes out of a 1960's bit of kit, (was still working up until then!) I can't remember what manufacturer they are by but some are "medical instrument" grade. I have an 'AT'  and an 'AU' I believe the latter has a very low amplification factor, but the 'AT' may be worth a go.

thermionic

Ei valves had a great reputation for working in Vox amps a few years ago IIRC, but they seem to have disappeared. Can you still get them?

ThePrettyDamned

I really loved these amps until I compared side by side with a peavey bandit!

That said, it is wonderfully portable and ideal backup or first gig rig. It's nice to know a valve change can help things out.