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Master TVA30 Guitar Amp Review Cabinet

By Steve DellaSala

We opened the back end of the speaker cabinet to do some exploration. The cabinet was had a very impressive in build quality. The dovetail joints were barely visible and the cabinet was constructed of ¾” thick plywood. The speaker was secured with only four machine screws with flush mount metal inserts. I would have preferred more to help prevent resonant vibrations. I was also a bit unimpressed by the very thin gauge speaker wire.

wiring1.jpg   Cabinet

Inside the Master TVA30 Cabinet

The Chassis and Electronics

The electronics and hand wiring throughout the amp head are very high quality. This all tube, 30 watt class A power amp comes armed with four EL84/6BQ5 power tubes and three 12AX7 preamp tubes. No solid-state devices are in the signal path nor are any used for creating the rich overdrive distortion. Worth mentioning, even though it is not published by US Masters, is that the amp is self-biasing. This means that there is no need to recalibrate after changing tubes. Though, given the retail price of this amp, there’s bound to be some economic based decisions. For example, the tubes are made in China. Some would argue that the quality of their tubes is not near that of Russian; however, neither is the price. But there are a few areas that I deem unforgivable. For example, tubes are considered a maintenance item, meaning they need to be changed often (depending on usage). That said I would have expected a much more robust method of mounting the power tube connectors. As you can see in the pictures below, these connectors are mounted directly to the board with only one, very small set screw securing it. This becomes problematic when placing a new tube in the connector as the force required to secure it puts stress on the board while it flexes on the hinged design of the single set screw. This is not the same for the pre-amp tubes; however, as their connectors are more robustly secured with two screws and not mounted directly to the board.

inside2.jpg        parts2.jpg        parts3.jpg

Other items to note was that the reverb assembly was mounted with the RCA connectors facing the front of the amp. This made it impossible to remove the chassis without also removing the front cover in order to release the connectors. Prior to putting the chassis back in, I was sure to turn the reverb assembly in a more convenient orientation having the connectors pointing towards the back. Another annoyance was with regard to the “captive” nuts used to secure the chassis to the cabinet.

As you can see in the picture of the chassis, it is fabricated from sheet metal, therefore has inherent flexibility, thus making it impossible to align all the screws when placing it back into the cabinet. The poorly designed captive nuts are not forgiven with misalignments. If they are slightly misaligned with the clearance hole, it is far too easy to accidentally push them out and directly into the chassis. For obvious electrical reasons, it’s not a good idea to leave these electrically conductive nuts inside the electronics. It took me five times of mounting and removing the chassis before I was able to finally get all the screws back in without having or more pop out. This too I’d call a maintenance nightmare.

 

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