Project Carvin V-16: Morphing from PCB to Point To Point Turret Board

This type PPIMV works by inserting a normal 1meg volume control between each of the PI outputs & power tube control grids. Each half of the pot acts as a "voltage divider". Note that the dual pot is isolated from the PI & power tubes by the 0.1uf caps before & after each half of the pot.
You wont actually "hurt" anything by using a dual 500k pot & it will still work, though you may experience some differences (overall volume, frequency response). I would use the dual 1meg. For your homework assignment read up on voltage divider values & frequency response. Cheers
 
I think I'm going to abandon the idea of retrofitting the current amp chassis. I spent a lot of time thinking this out, and I'm not feeling confident about achieving good and worthwhile results. However, I would like to build this circuit into a new chassis. Which also means there would have to be a new head cabinet or even a new combo cabinet, which I prefer. The search is on!

Reasons for not retrofitting the chassis:

1) All the tube sockets need to be relocated to allow enough room for a PTB circuit board and its components, and allow more spacing between the tubes themselves. Relocating the tubes, especially the preamp tubes, closer to the power tranny is not good practice. I would also have to relocate the output tranny too.

2) The location of the IEC for the AC cord is stupid. It should be on the other side of the power tranny. Relocating it opens up other unappealing issues.

3) The chassis is made of steel. I would prefer aluminum.

4) The size of the original combo cab is small and cute and very portable. Unfortunately, this compact size limits the performance of the 12" speaker.

To be continued... Hopefully... :fingersx:
 
syscokid said:
I think I'm going to abandon the idea of retrofitting the current amp chassis. I spent a lot of time thinking this out, and I'm not feeling confident about achieving good and worthwhile results. However, I would like to build this circuit into a new chassis. Which also means there would have to be a new head cabinet or even a new combo cabinet, which I prefer. The search is on!

Reasons for not retrofitting the chassis:

1) All the tube sockets need to be relocated to allow enough room for a PTB circuit board and its components, and allow more spacing between the tubes themselves. Relocating the tubes, especially the preamp tubes, closer to the power tranny is not good practice. I would also have to relocate the output tranny too.

2) The location of the IEC for the AC cord is stupid. It should be on the other side of the power tranny. Relocating it opens up other unappealing issues.

3) The chassis is made of steel. I would prefer aluminum.

4) The size of the original combo cab is small and cute and very portable. Unfortunately, this compact size limits the performance of the 12" speaker.

To be continued... Hopefully... :fingersx:
Click to expand...

I believe that the choice to go with a head type configuration is a good decision.
That way you are not limited to what speaker setup you may want to use with the amp.
You are also correct about the current cabinet not letting the speaker perform at its peak.
I bought my son and grandson one of those amps and felt the same way the first time I played through it.
 
ChasFred said:
I believe that the choice to go with a head type configuration is a good decision.
That way you are not limited to what speaker setup you may want to use with the amp.
You are also correct about the current cabinet not letting the speaker perform at its peak.
I bought my son and grandson one of those amps and felt the same way the first time I played through it.
Click to expand...
Yeah, the downside of having a 1x12 combo that is small, very light, and very portable, is that they ain't much foundation to provide some nice depth coming from the speaker.
 
ivan H said:
Do you have any chassis & headcab in mind, or are you thinking of fabricating your own? Cheers
Click to expand...
I'll start researching later today. There has to be a chassis out there with similar front panel controls and five 9-pin size tube socket holes for the three 12AX7's & two EL84's. If you, or anybody else here has any ideas or suggestions, please let me know.
 
ChasFred said:
look at this

British 18 Watt Chassis
Click to expand...
I like that... (y)

Wonder how much it would cost to get a custom faceplate and backplate?

Or just leave it bare with the unused chassis holes exposed?

Currently, the RAW control is on the backside of the chassis. I could easily move it into one of those extra input jack holes... :unsure:

Add a on/off switch for the original NFB that was removed as part of the Hasse mods... :unsure:

:woohoo::woohoo:
 
syscokid said:
Yeah, the downside of having a 1x12 combo that is small, very light, and very portable, is that they ain't much foundation to provide some nice depth coming from the speaker.
Click to expand...

When I started using the Electro-Harmonix 12VR75, the entire character of my DSL40C's changed. The depth is incredible.
 
When I assembled the amp back together a couple of nights ago, I couldn't resist doing another mod. I relocated the 10-watt 350 ohm "Choke resistor" to a much more open area. This resistor gets pretty hot, and will heat up anything near it... including the filter caps. A poor design, IMO!


IMG_1850.JPG
 
syscokid said:
When I assembled the amp back together a couple of nights ago, I couldn't resist doing another mod. I relocated the 10-watt 350 ohm "Choke resistor" to a much more open area. This resistor gets pretty hot, and will heat up anything near it... including the filter caps. A poor design, IMO!


View attachment 32768
Click to expand...
Excellent move I would say.
 
if money is not an issue, MojoTone has a pre-punched chassis.
If you have access to the tool to punch or drill size for all all the holes and a mill for the access the transformer then go for it.
My self I would get the pre punched chassis.
 
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