vox ac15--30-untested

[Tom_Hull]

hi


i am trying to build this and then the postings came up about schematics. and its a big stop now.what to do or add ??


its put together without the wires to the pots and switches............i may need to rewire a bit here.

now not sure what is supposed to happen with the powertubes.
 does it add a resistor to the bais or does it add 2 more powertubes and a resistor
i drew a schematic because i cannot understand his switch.the brilliance switch bugs me also.
does it look ok ..

also the talk of pentode and triode switch . maybe for the ef86.
would it matter much .its not hard to wireup with another switch .

well it you can help me it would be nice thanks
and i am not sure it would even work .if built


tom

[kagliostro]

The intention for the switch on the power tube cathode side is to have the amp switched between 2 output tubes and 4 output tubes (so you must change the cathode resistor value)

See the Weber 6d30 schematic as an example (don't consider the cathode bias switch is an option as to have both cathode bias and fixed bias)

https://taweber.powweb.com/store/6d30_schem.jpg

About the ef86 triode pentode you can also use the Merlin's Morph Control, see on the attached  schematic how to do (click on the image to enlarge)

As documentation for the 2 or 4 final tubes switch see also R11 and R12 at page 7 of the Vox AC30CC manual

http://www.el34world.com/charts/Schematics/files/Vox/Vox_AC30CC_Service_Manual.pdf

---

Here you can find one other version of the layout draw by our friend Steve

http://home.comcast.net/~seluckey/VAC15.pdf

here the original Vox AC15 layout

http://members.ziggo.nl/jheijer/AC15.htm

and here the Weber 6d30 layout (Based on Matchless DC30 but modded)

https://taweber.powweb.com/store/6d30_layout.jpg

and here the Weber 6v30 schematic & layout (Based on Vox AC30 and near exact to it)

https://taweber.powweb.com/store/6v30_schem.jpg

https://taweber.powweb.com/store/6v30_layout.jpg

K

[sluckey]

Power switch... The idea is to switch in a pair of power tubes and switch out a cathode resistor. When all 4 cathodes are connected together thru the switch you only need one 68Ω resistor connected to the cathodes. And when V7 and V8 are switched out, you need to switch in another 68Ω resistor for a total cathode resistance of 136Ω.

The color drawing is wrong. The blk/wht drawing is almost right. The blue wire between V8 pin 3 and the switch should connect to the bottom right lug, not the top right lug. Make that change and the circuit will be happy.

Brilliance switch... The idea is to connect a different value coupling cap to the VOL control. Small cap = brighter sound. The color layout cannot work as drawn, but if you tie the middle switch lugs together it will work. And if you use a DPDT center off switch, you'll have 3 combinations of coupling caps to choose from.

[Tom_Hull]

hi

excuse me i became busy

now

 well K

 thats lots to go through .. checking it all out thanks.

i did a morph  volume pot,,schematic change ..
or tryed to ..

thanks k

....................

Steve thanks so much .

 i did not do well with switches even in electronic class.


i redrew that power section. 

 i thought of a 3 way switch from doug
but maybe it would click with a switch . so maybe it may need resistors across the switch,,,,, out terminals to the in terminal . that can be done later .maybe ..


thanks

[sluckey]

it may need resistors across the switch

There were two 5.1M resistors on the color layout to take care of that. However, the artist forgot to draw leads for the resistors.

If you use a make before break switch, you don't need the resistors. Radio Shack sells a 6 position two pole make before break. Gives even more tone options. See attached...

[kagliostro]

The Tone control version with 12 position rotary switch on my previous schematic is borrowed from a Weber Kit

If you want you can use only 2 cap and a pot to obtain a Tone Control with "infinite" position

see attached schematic

K

[Tom_Hull]

hi ..

Steve , nice schematic s thanks for link and posting ...

,i now understand completely about the 5.1 m resistors purpose and switch ..
there is no,,, radio shack here,,,,

i going with a cheaper route.i try K's tone pot post



K
thanks
 i like that idea and
i need to go with your tone pot . because of cost.
and hear how that sounds .
I need to keep money aside for John's amp my son inlaw.. ampeg reverb,,started that already ,mostly planning it out ..

. he will be back in march from his ocean cruise ,,he is on military tour ,,,floating around for 8 months ..

the change also has not changed the board size ...good ..


tom


 
 

[Tom_Hull]

hi

now i need to order a few parts ,but to make an order worthwhile ,,i like to order parts.for the other amp.
And check  through this vox curcuit ,,

i believe thats the original price in pencil on the pic  
 also ..
could the larger pt power an amp with  6l6 gb for a ampeg b15n/? i have 1 nos pt ,,,,also marked ...340 vps 125 ma
Also
I was thinking of the 700 v 120ma for a ampeg rocket  reverb ,,,r 12 r , it has 2 6v6  2 6sl7 2 6sn7 ?? i have two nos pt
 
i also have a pt from doug ,,,bassman 6l6 gc
thanks

tom

[kagliostro]

Tom if this last question about transformer  is not related to the Vox circuit and you want more people look to it

is better if you start one other tread with a proper title

this will help a lot as people that has answer about can easily know you need it

Ciao

K

[Tom_Hull]

hi  kagliostro

yes .. i should start a thread ..




http://www.mif.pg.gda.pl/homepages/frank/sheets/049/6/6L6GB.pdf

[Tom_Hull]

hi

well seems to me from reading other current post. i should have that vox setup ..
so i checked the amp as it is old style ,,,most of the amp is built ..and one build of this should be enough for me //..


my amp has room to put this all in. .with little to change . more building it up ..and wires

i put up a schematic of whats  up now ..  as a board and it is 3 components longer ....

thanks .


tom .............. i change the schematic