Old school tech meets new school, sort of

My latest purchase was a blend of old school technology (vacuum tubes) and new school, or at least newer than tubes (MIDI integration). I recently purchased an all tube guitar amplifier from Marshall (JVM210H).

It’s a 100 watt tube power amp with ECC83 tubes in the preamp stages and EL34 tubes in the gain stage.  First of all, the amp sounds amazing with my Paul Reed Smith custom 22 10 top.  The clean channel is remarkably clean for a Marshall amplifier which was one of the main selling points for me.  It features two channels Marshall labels clean/crunch and overdrive.  Each channel has three modes: green, orange and red where each successive mode introduces more gain and coloring in the preamp.  It also features two master volumes, reverb and an effects loop that can be enabled for each channel and mode.

The part that gets really interesting is the ability to save presets on up to 128 different MIDI channels. MIDI (Musical Instrument Digital Interface) has been around since 1982 and hasn’t changed that much over the years.  I had been using an all-in-one solid-state amp modeler and effects processor from Boss (GT-6) for years and loved the flexibility and how easy it was to just choose a patch with the foot pedal and have it load the right amount of distortion and effects.

Typically with tube amplifiers, you would have to do a lot of shuffling on stage selecting your amp channel and other items on the amp’s footswitch and then any additional effects would also have to be turned on with another footswitch.  That becomes difficult to do seamlessly in the middle of a song.  The processor didn’t have that issue.  Everything could be done with one press of one footswitch pedal loading a patch or preset.  With the JVM210H, I can have the best of both worlds – ease of use and great tube sound.  I simply connect the MIDI output of the processor to the MIDI input on the amp.  I then choose the channel, mode, reverb, effects loop on/off, etc. on the amp and tell it to save on the next MIDI program change command it receives.  Then I load the patch number on the processor and the amp just saved that configuration with the program number.  The next time I load that patch on the processor, it will load all those custom settings on the amp.  That’s it.  Very cool and easy.

I tried several configurations of how to connect the processor in the loop from an audio signal path perspective.  The GT-6 in bypass mode (no effects, amp modeling, eq, etc) is supposed to be transparent but I was able to notice a very subtle coloring of the sound (a slight change in EQ).  Ideally,  I didn’t want it in the signal path all the time if I didn’t have to.   I tried two different approaches – instrument input and the four cable method.

Instrument Input Method

This method worked best.  It is also the simplest method.  This method is to have the amp effects send connected to the instrument input on the GT-6 and to have the mono output of the GT-6 sent to the effects return on the amp.  In this mode, you must choose the -10dBV setting for the effects loop on the amp and you need to choose 100% wet.  If you use less than 100% (parallel mode), you will get noticeable phasing issues because the two signals are slightly out of phase between the amp and the GT-6.  Using 100% wet resolves that issue.  By using the effects loop of the amp, it can be turned on and off completely bypassing the GT-6 when it is not needed and removing it from the signal path completely.

Four Cable Method

This method is more complex and involves connecting four audio cables.  It also requires the GT-6 to always be in the signal path which I didn’t like.  It involves using the effects send and return on the GT-6 which requires a the overdrive section of the GT-6 to be set to external.  Doing so eliminates the option of actually using the overdrive modeling part of the GT-6, although I don’t know why you’d want to use that when you have tube preamps for that.   The bottom line for this configuration was that it added additional white noise to the mix that could not be removed, it didn’t allow bypassing the GT-6 completely and it is a more complicated configuration.

Additional Analysis

I also have a Line 6 PODxt Live that I would like to try and integrate with the amp to see how well that works and how it compares to the GT-6.  If I do that analysis, I will post the results for that at a future date.  PODxt Live has better amp modeling but is more limited in the breadth of functionality and programmability compared to the GT-6.