Name: Steve Kennedy
Email: steve@pacair.com
Subject: 212-HD 130 again ....
Thread: 74
Time: Thu, 10 May 2001 02:38:04 GMT
The phase splitter's only function is to take your preamplified guitar signal and create TWO versions of it, one out of phase from the other (180 degrees). This is where the term "phase splitter" derives.
This is necessary to drive the two (or 4) output tubes in a "push-pull" configuration. One tube (or pair) "pushes" while the other tube (or pair) "pulls", each producing one half of the total amplified output signal. These are combined into one large signal in the output transformer and coupled to the loudspeakers to make a lot of audio (effectively doubling the voltage swing of the audio signal).
Since it is in the audio path, it does effect the sound but probably not as much as you might think until output overload is approached. Output tubes driven to overload by another tube should (and do) sound warmer and more pleasant than output tubes driven to overload by transistors alone.
Being a tube, it can get weak with age and need replacement. The 12AX7A is the consumer version of the 7025 essentially. The 7025 I believe was a lower noise/higher reliability military version of the same basic tube.
These are reasonably cheap and it won't cost you much to try a new one and see how much (if any) difference you notice.
As far as I am aware, the ONLY Music Man amplifiers that have a tube in the audio path in the preamp section are the last models of the 112RD 50 and 110RD 50 that have the "limiter" control. This tube "limiter" circuit is supposed to give the solid state preamp more of a tube "feel" and warmth.
The two channels of your amp differ in a few ways.... Channel two has Reverb and Tremelo circuits, Master Volume control and a "Middle" tone knob. It also has the Bright and Deep switches.
You CAN "bridge" the inputs to use both channels simultaneously, but there won't be any increase in gain because they are in parallel. However, you get some GREAT interactions between the sections in the Tone Control area. Tone Controls alter the phase of the signal in addition to the frequency response.
When you parallel two channels with different phase shifts, you can generate many new phase cancellations and re-inforcements resulting in new tonalities not possible with a single channel! Experiment! There is much to discover here.
Simply plug your guitar into Input 1 of the first channel, then run a cord from the Input 2 of the same channel to Input 1 of the second channel. You will notice that each of the tone controls and volume controls will create a "null" somewhere in its travel depnding solely on the settings of all the other knobs. Change one knob and all the other settings will work slightly differently than before!
A new world of tonal possibilities awaits you!
Steve