NAKD...: V2 Amplification 'Caldera"

syscokid said:
Fast-forward over a year and a half later after completing this build, I finally got the chance to demo this amp at serious volumes a couple of days ago. My Tootsie, the Esquire... into the Caldera... into a 1x12 pine cabinet with a Scumback M75LD. And to test the amp's fx loop... A Fender reverb pedal (Marine Layer) and a Boss chorus pedal (CE-2w).
View attachment 82952

Now keep in mind, that I'm demoing at my good friend's occasional jamfest at his converted garage into jam room. Blistering volumes is par for the course at his jamfests. For the short time I played, I had the 30 watt amp turned up about half-way: Gain about 6, EQ's at 5, and master volume about 5. Now normally, I would consider these settings on this amp very loud. But I could barely hear myself unless I moved into the middle of the room.

After a pizza break, I offered a couple other friends to take the helm of my rig while I can kickback and listen to the rig in a more balanced position and make adjustments on the fly. And the results of that was: "Turn up the amp's volume more, you dumb-ass!". Bumped the gain to 7, but bumped the master volume of this 30-watt amp to 8! Yup, this baby is running hard, yet it was still tight with a saturated blooming tone that was catching a lot of attention from everybody else, including me. I also observed that even in this amp's more extreme state, the power tubes looked normal with no excessive heat and the power transformer was barely luke warm. Could not feel the Hammond output transformer's temperature for lack of maneuvering space.

And today, I decided to fire up the amp, which is back home safely, and measure the volume of the amp at the settings that was used at that jamfest. In all fairness: My friends jamroom is about 400 square feet. Syscokid's mancave is about 120 square feet. And the results... drumroll please... 115dBs! o_Oo_O

Conclusion: Killer amp y'all... :cheers:
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Very cool!! Nothing like a road test to help you enjoy the results of your work! Time well spent indeed!!
 
Jay said:
I tried to design it with a usable Master that can get louder beyond 10:00 on the dial :)
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I can vouch for that... :cheers:

Usually in most tube amps with master volumes that I've tried, when the preamp is pushed hard, the volume doesn't noticeably increase when past halfway on the master volume control. The tone will thicken and saturate more, but the overall volume seems to be the same. But with my Caldera, I thought that with the MV at noon during the jamfest, that there was no more volume to squeeze out of the amp. And while somebody else played my rig, besides messing with the different voicing switches, once I bumped the MV to 1:00, I heard a very noticeable increase in volume and was surprised by this. Then I bumped the MV to 2:00... then finally to 3:00 oclock! Yup, more volume! What a cool AND LOUD surprise!

Also...
As far as I can tell, the fx loop worked flawlessly. I had the reverb pedal dialed in for a mellow Hall-type of reverb. And during a mini-break in between songs, the guitarist on my rig started slamming open E chords and immediately muting any sustain from the chord. This is when I got a real good evaluation on how natural the reverb sounded even at crazy volumes.
 
Jay said:
I tried to design it with a usable Master that can get louder beyond 10:00 on the dial :)
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I reach the conclusion that an attenuator works better than a master volume.
Anytime the master volume is turned down, it prevents the output tubes from overdriving.
I don't really hear the sound until the output tubes are overdriving.

The attenuator should be part of the amp.
The attenuator should replace the master volume control.
One of my favorite attenuators is the flux tone speaker.
In other words the speaker magnet is adjustable by the master volume knob on the amp.
 
AFAIK, a master volume circuit that is inserted before the phase inverter is a very simple and cost effective to add to an amp. Designed to allow you to overdrive just the preamp circuit only at reduced volumes.

A MV circuit after the PI, is a little more complicated. Designed to allow you to overdrive the preamp and the phase inverter only, at reduced volumes. The more the signal is reduced, the more the presence circuit becomes less controllable. Both MV circuits at more than 50% attenuation will prevent the power tubes from hitting their sweet spot.

Attenuators allow you to drive the amp as hard as you want, but capable of reducing volume to whispering levels. The harder you drive the amp, the harder it's going to be on the tubes and transformers. Some well-featured attenuators have EQ options to compensate how our hearing perceives lower volumes. Some amp manufacturers do offer the option of an added attenuator to some of their amps. Dr Z amps and Tone King amps are a couple that I've seen do this.

Enter POWER SCALING technology! I know very little about it, and is a much more complicated system. I think power scaling scales down the voltages to the power tube's plates and screens, while also compensating the power tube's bias level... uhm, I think! Supposedly, this method is a lot easier on the power tubes and transformers and works as good or better than any attenuator or an amp with just a MV... I think! Suhr, Morgan, Fargen, Reeves, are some that implement power scaling.

My...
20220418_083356.jpg
 
My preference is for a pre-PI master in conjunction with a reactive-load attenuator (like the Tone King Ironman II). The post-PI master can be useful too, but as a designer I don't like to deactivate the NFB loop after I go to the trouble of setting it up :)
 
Face-lift, or more accurately... Faceplate-lift for my V2 Caldera!!!!

Before:
DIY V2 Logo (2).JPG


After:
New Faceplates 9-26-22 (1).JPG


IMO, the new faceplates makes the amp look better and meaner. Plus, the lettering is much more legible.

Besides supplying me with the new set of black faceplates, our TTR's @Jay of V2 Amplification will be sending me an official V2 Amps badge and some suggested mods that I might be interested in... (y)
 
syscokid said:
Apparently I gave out some wrong info due to my lack of proper education on these things. And since I asked John McDonald about posting pics and details of his product here at TTR, he has been checking out how this thread is going and corrected me by stating this in an email a few minutes ago:
"PS. some notes about the amp (in reply to some of the posts on TTR):

- the heaters are AC with DC elevation. This means that the (artificial) center tap is connected to a high positive voltage (~50-75V) rather than ground. Seems to swamp noise. Also helps cathode followers. But don't untwist those nicely twisted wires... :)
- the OT is a hi-fi design with full-rated power down to 30 Hz. It's rated for 20W for hifi, but for guitar amps, it'll easily handle 30 watts.
- I don't rely on OT core saturation for limiting output power. Instead, it's a balancing of B+ and the primary impedance of the OT (here 6.6k rather than the usual 3.4k in EL34 designs..)"
I also suggested to John to hop on board at TTR. The more amp nerds, the merrier... right? :cheers:
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Elevating filaments does not get rid of all the noise.
Only some of it...

The power transformer was not designed for a DC elevated filament center tap, besides which losing the isolation between B+ and filament windings.
which leads me to believe this isn't a very good idea.

One of the better strategies is to change the layout of the filament wiring...
Use DC filaments in the first 2 preamp tubes...
Or use other methods that cancel the noise. (there are other ways)
 
syscokid said:
Face-lift, or more accurately... Faceplate-lift for my V2 Caldera!!!!

Before:
View attachment 86228


After:
View attachment 86229


IMO, the new faceplates makes the amp look better and meaner. Plus, the lettering is much more legible.

Besides supplying me with the new set of black faceplates, our TTR's @Jay of V2 Amplification will be sending me an official V2 Amps badge and some suggested mods that I might be interested in... (y)
Click to expand...
Mmmmmmmmmm!!!!!!!!!
 
syscokid said:
Happy New Amp Kit Day to me... :woohoo:

From Mr John McDonald & V2 Amps, and all the way from Vancouver, Canada, I will now attempt another amp assembly/build. This one is called the Caldera: "a large volcanic crater, especially one formed by a major eruption leading to the collapse of the mouth of the volcano." Single channel, 30 watts, 2x EL34's, 3x 12AX7's, effects loop, DC heaters, Hammond output transformer & choke, and a SumR toroidal style power tranformer.

If I'm successful with this build, this amp has the potential to sound like this:

More porn coming soon.... :wink:
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Very VERY Nice!! Excellent in fact! Congrats Greg on this beautiful beast!
 
syscokid said:
Happy New Amp Kit Day to me... :woohoo:

From Mr John McDonald & V2 Amps, and all the way from Vancouver, Canada, I will now attempt another amp assembly/build. This one is called the Caldera: "a large volcanic crater, especially one formed by a major eruption leading to the collapse of the mouth of the volcano." Single channel, 30 watts, 2x EL34's, 3x 12AX7's, effects loop, DC heaters, Hammond output transformer & choke, and a SumR toroidal style power tranformer.

If I'm successful with this build, this amp has the potential to sound like this:

More porn coming soon.... :wink:
Click to expand...
Man , the guy playing it is going off !
Marshall topology I would guess ?
 
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