Hey dude,
Took the chassis out of the headshell, & took some pics....I found an explanation about the switches online too, here's a copy/paste of it:
ERA provides 3 tonal options. You can think of this covering 3 different decades of tone. In the middle position, the amplifier
will be cleaner, less compressed, and very woody. We consider this our late „60s mode, as it very accurately captures the
sound of original Plexis. The right position is our „80s voicing. This adds saturation and compression, and is reminiscent of
„80s modded Plexis coming out of LA. This voicing is great for hard rock, thrash metal, etc. The left position is our modern
voicing. This adds even more saturation and compression, and also smoothes the top end response thus preventing any harsh
overtones with this amount of gain. We love this mode for all things metal.
NOTE - Just like the original “Jose mods”, these different modes will impact the taper response of the MASTER control. In
other words, some settings might seem louder than others. In reality, equal volumes are happening sooner or later on the
control. The „60s mod hits stage volume soonest, and the Modern voicing hits stage volumes latest. Don't be afraid to turn up
the MASTER control in the „80s and Modern modes!
GAIN 2 adjusts the signal strength coming out of the second gain stage, and going into the third tube stage. Think of this as a
“saturation” control that will impact pick attack, compression, and feel. Depending on the BRIGHT 2 setting, you can also use
this to shape the high and low frequency response of your Chupacabra.
BRIGHT 2 is a high-frequency boost that can be used to add sparkle and gain to your tone. In the middle position, BRIGHT 2 is
defeated. In the left position, it boosts upper mid and high frequencies, and adds noticeable gain. With the toggle switch in the
right position, it boosts extreme high frequencies, and adds less gain boost than the right position. In conjunction with an active
Bright 2, lower GAIN 2 settings will also trim the bottom end. This high frequency boost / low frequency cut is more prominent
as GAIN 2 is turned down.
GAIN 1 adjusts the signal strength coming out of the first gain stage, and going into the second tube stage. Think of this as a
global “gain” control. Depending on the BRIGHT 1 setting, you can also use this to shape the high and low frequency response
of your Chupacabra.
BRIGHT 1 is a high-frequency boost that can be used to add sparkle and gain to your tone. In the middle position, BRIGHT 1 is
defeated. In the left position, it boosts upper mid and high frequencies, and adds noticeable gain. With the toggle switch in the
right position, it boosts extreme high frequencies, and adds less gain boost than the right position. In conjunction with an active
Bright 1, lower GAIN 1 settings will also trim the bottom end. This high frequency boost / low frequency cut is more prominent
as GAIN 2 is turned down.
FOCUS control is a push/pull switch located on GAIN 1. With the control pushed in, it is defeated. Pulling out the GAIN 1
control engages FOCUS. FOCUS will reduce bottom end, reduce saturation, increase midrange, and accentuate pick attack.
So, that explains it all to me dude, & I was flipping out looking for the bias trimpots inside the amp, but they're located next to the power tubes, so really, I can bias the amp without taking it out of the headshell (unless I wanna read the plate voltage & do it correctly that is...)...I did check the plate voltage & bias today, & it's fine (if I did it correctly....LOL)...The plate voltage was 430V, & I did the math, then biased it to 36mV DC, which is 65% dissipation...To be honest, I checked the bias points before reading the plate voltage, & it was set to 37mV, but, at least I do know how to do this, & it'll help me in the future when I have to change power tubes....
Here's some gutshots:
Bias trimpots:
Pussy Trimmer wheel/pot:
JJ EL34's:
EH 12AX7 in V1:
Mesa-branded 12AX7 in V3:
I didn't post a pic of V2, it's got an EH in it like V1, but I've already changed those out, I put my Mullard in V1, my Baldwin in V2, & my "hot" RCA in V3, & it seemed to have smoothed it out a little, which I like....I'd say the guy had some decent glass in there, but took 'em out, & sent me his low-end tubes (which I don't blame him)...Not gonna get into the tube rolling thing, I was actually trying to see if I could reduce the noise a little, which it did just a little, but the noise is probably something I'm gonna have to live with, which is fine....
Looking at the transformers & tags, looks like this amp was built in 2010...
I'll try to do this with the DSL in a little while, if I can stop playing through this amp long enough....Lovin' it man, just lovin' it...I'm figuring out the switches/controls a little more, & getting it dialed in....It's a beast of an amp IMO....
.
