Voodoo Amps Marshall JTM-612 Mod

2 footswitchable channel EL 34, 4 12AX7 tube amp with reverb.1 12 combo. Seperate EQ and reverb. Master presence control. Effects loops (serial and parallel)Ext speaker out (16 ohm only). Has all the features that I'm looking for.

I bought the amp sight unseen at Songbird in Ottawa and had it sent to Trace at Voodoo amps for modification. I do own the 30 (jtm30)watt version and for the most part like the tone of it, but was looking for something punchier and with better note clarity on the gain channel. It seemed like buying the 60 watt version and having it modified to further improve the tone would be a good move. The modification involved removing the diode clipping circuit in favor of all tube punch.

Unfortunately when I got the amp back there was little headroom on the clean channel. With the master and clean channel volume dimed, the volume was about equivalent to that of an unmiked acoustic guitar. Also there was a fizzy nature to the clean tone. This "fizziness" is similar to a tube amp dying out when its being powered down. The gain channel was fairly punchy but somewhat bland sounding. There was not much harmonic content to the gain. These comparisons are based on the unmodified JTM 30 that I own.

I contacted Trace and he said that one of the other technicians had remarked about the lack of volume. I spoke to Songbird in Ottawa where I bought the amp (over the internet). They said they thought the amp may have been like that when they had it. However the modification voided the warranty. There was however a 24 hour approval period after I purchased it. I had asked Trace to check the operation of the amp when he received it from Songbird.

Anyway, without the headroom to gig with, the amp is basically useless, and probably worthless. So I took the amp to the local repair shop (Musicstop) to have it checked out. Their senior tech wrestled with it for days. During this time Trace had emailed the schematics to us, and even spoke to the local tech here on the phone. In the end however he determined that the amp had to have the mod removed. The mod was fully removed and now the amp sounds decent if not spectacular. The volume of the clean channel is on a par with the gain channel now. The amp is still a little bland sounding to me, but sounds and works much better with the mod removed.

I don't believe these are one of the more reliable of the Marshall products

Trace is a very willing guy to work with. Unfortunatly this whole project was a poor experience for me, based on the fact that I did not get a good result

I bought this amp in December for $700 Canadian + shipping to and from Voodoo Amps. The modification cost $300 US. I paid $225 Canadian to have the mod removed. The whole cycle took over 3 Months. I'm very dissapointed that this did not work out as I had hoped and expected.