NAKD...: V2 Amplification 'Caldera"

syscokid

syscokid

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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:
 
To my surprise, the amp kit came with the 3 trannies already installed. I'm thinking that this was done to ensure the integrity of all the parts through shipping:
IMG_2391.JPG

IMG_2392.JPG

I like those plastic grommets for the OT:
IMG_2393.JPG


Most of the hardware and the heater wiring was installed a couple days ago:
IMG_2394.JPG


Busy work area:
IMG_2395.JPG


Faceplates and buttplates:
IMG_2400.JPG

IMG_2401.JPG


This is where I'm at today: Stuffed the power supply pcb and wired it:
IMG_2402.JPG


There will be 3 more pcb's to stuff and then wire. The 'Main' board, the Tone stack board, and a tiny pcb for the power tubes. Still have all these little boogers that need to find a home:
IMG_2404.JPG

I always make sure that all resistors and cap values are verified before installation
 
syscokid said:
To my surprise, the amp kit came with the 3 trannies already installed. I'm thinking that this was done to ensure the integrity of all the parts through shipping:
View attachment 45915

View attachment 45916

I like those plastic grommets for the OT:
View attachment 45917


Most of the hardware and the heater wiring was installed a couple days ago:
View attachment 45918


Busy work area:
View attachment 45919


Faceplates and buttplates:
View attachment 45920

View attachment 45921


This is where I'm at today: Stuffed the power supply pcb and wired it:
View attachment 45922


There will be 3 more pcb's to stuff and then wire. The 'Main' board, the Tone stack board, and a tiny pcb for the power tubes. Still have all these little boogers that need to find a home:
View attachment 45923

I always make sure that all resistors and cap values are verified before installation
Click to expand...

That looks like a freak'n blast of a time, man. Enjoy, enjoy...
 
eclecticsynergy said:
That's a nice sounding design. Super tight chunk, and very effective tone sculpting.
The demo amp used two 6V6s - wouldn't a pair of EL34s make it a 45/50 Watt amp?
Click to expand...
Good question... and I really don't know for sure. I'm guessing the Hammond 1620A is too small to produce that type of power. It's definitely rated for 20 watts when using a pair of 6V6's. Looks like the OT was designed for 6V6's and 6L6's. John must have compensated the circuit to operate on EL34's properly.

In comparison, my Allen Amp's Sweet Spot is also a push-pull with 6V6's at 18 watts. With a change of a couple resistors and a re-bias, 6L6's can be operated at no more than 25 watts. The OT is limiting the output power to just that.
 
Looking good Sysco. Just a quick FWIW, with a DC heater supply there is no need to twist the heater wiring, we can simply string them from one socket to the next. Twisting them won't hurt anything though.
I always meter all components before fitting them too. It's simply good practice.
I'm not right up there on OT design principles, but do know that the core can saturate (magnetic), the primary winding & secondary windings can also saturate & all can limit output power.
The PT can also limit output power. The output tubes can't output any more than the PT can supply current for.
Limiting drive to the output section is another way that output power can be limited.
Looking forward to seeing more progress postings. Cheers
 
eclecticsynergy said:
That's a nice sounding design. Super tight chunk, and very effective tone sculpting.
The demo amp used two 6V6s - wouldn't a pair of EL34s make it a 45/50 Watt amp?

Fun to watch it taking shape.
Click to expand...
ivan H said:
Looking good Sysco. Just a quick FWIW, with a DC heater supply there is no need to twist the heater wiring, we can simply string them from one socket to the next. Twisting them won't hurt anything though.
I always meter all components before fitting them too. It's simply good practice.
I'm not right up there on OT design principles, but do know that the core can saturate (magnetic), the primary winding & secondary windings can also saturate & all can limit output power.
The PT can also limit output power. The output tubes can't output any more than the PT can supply current for.
Limiting drive to the output section is another way that output power can be limited.
Looking forward to seeing more progress postings. Cheers
Click to expand...
67plexi said:
A Soldano SLO-100 heaters
Click to expand...
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:
 
Ah, it's a good thing you did twist the heater wiring then, & yes, elevating the heater supply does get rid of AC heater induced hum as it makes the heaters positive in respect to the cathodes. I also agree with the more amp nerds the better. Cheers
 
syscokid said:
To my surprise, the amp kit came with the 3 trannies already installed. I'm thinking that this was done to ensure the integrity of all the parts through shipping:
View attachment 45915

View attachment 45916

I like those plastic grommets for the OT:
View attachment 45917


Most of the hardware and the heater wiring was installed a couple days ago:
View attachment 45918


Busy work area:
View attachment 45919


Faceplates and buttplates:
View attachment 45920

View attachment 45921


This is where I'm at today: Stuffed the power supply pcb and wired it:
View attachment 45922


There will be 3 more pcb's to stuff and then wire. The 'Main' board, the Tone stack board, and a tiny pcb for the power tubes. Still have all these little boogers that need to find a home:
View attachment 45923

I always make sure that all resistors and cap values are verified before installation
Click to expand...

So you are running 12 Volts DC for the preamp filaments, and 6 volts AC for the output tube filaments?
 
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