OR 15 Turret Conversion Project

[Titi1506]

Hi guys,

I follow this forum since many years and I'm also the proud owner of a 45/100 Limited build by George.

I've recently bought an Orange OR15. It's a nice little amp and AFAIK loosely based on a JCM800 preamp circuit and an AC15 power section. I like it as it is but I'd really like to convert its PCB board to a nice turret board with higher grade components (carbon comp resistors, Sozo caps, choke,…). The amp doesn't really require a conversion, it's only a "just for fun" project.

I've found the schematics but I'm not a turret board layout expert. I would be very happy to get some help to design the turret board (single or split board, components layout,…).

I have some soldering skills, I've read a lot about tube amps, repaired or modded some of them and built some pedals. But I've never built an amp "from scratch" and would appreciate some help.

Would anybody here be interested in the project and be so kind to share his experience and knowledge? I would be very thankful!

Thanks a lot in advance for your feedback guys!

[Haze13]

http://forum.orangeamps.com/viewtopic.p ... ainsidejpg
Use Sozos in the soud path only (when signal goes through the cap), in other positions use 5% Polyester - it will help you to save the money. For the B+ (High Voltage) use Metal Film Resistors 2-3 watts, for plate resistors 1/2 watt.
Carbon Comp - they drift with the time, so if you want to buy NOS some values will be not as they should be, check every one of them.
For the POT's - sealed will last longer but they are expensive (RV4 type), CTS works very well too. I don't like "Alpha"s, but that just me...
If your amp is works and you want to check some thing, work only with one hand!!!

[Titi1506]

Thanks a lot for your precious tips. I'll start sourcing the parts when I have the board design ready.

The guy on the orange forum has changed the circuit design for a 18W TMB. I'd like to preserve the original OR15 circuit. I couldn't find any turret board layout on the internet… I maybe could start with a JCM800 preamp board design and an AC15 power amp since the schematics seems to be pretty similar but I really would appreciate some help regarding some points:

• Should I design separate boards for pre and power amp
• Do you have any tips about grouping or separating some components on the board (high voltage, signal, etc…)

I'm a little bit lost and don't know where to start? Reproducing the schematics on a turret board or starting with existing boards as inspiration…

Here is the schematic that I've found: https://www.dropbox.com/s/gr9xe3qzaiiec ... V-230V.pdf

[Haze13]

Start with a Pencil and Sheet of paper. Try to draw the layout. Use already existing layouts as a starting point...

I don't think that you should separate the boards, but you can use another board for filter caps.
* Signal wires should be as short as possible.
* Input resistor have to be soldered to the socket directly with a shielded cable, so don't think of placing it on the board. This means that there are components that you can solder "Point-to-point" (one component directly to other) and you will save some space on the turret board. Cathode bypass caps can be soldered on the resistor too, and so on...
* Do not solder buss wire to the backs of the pots, it creates ground loop, and they are very RADIO-friendly...
* Heater (filaments) wires should be twisted very tight!!! More info about on GOOGLE Use 18 AWG wires for this work.

!!! Do not waste your money on exotic stuff (Silver wires, gold-plated sockets, NOS components, Sprague caps...) !!!

As for the grounding... There are topics on this forum about this stuff, so feel free with "Help" button, because there is no "the only one method".

Chassis have to be "Closed" with a sheet of metal. If there is one on the bottom in your head cabinet that's good, but if there is not... Well... Find one.

[Titi1506]

Thanks a lot Haze. Your tips are very helpful! I'll start to design the board and as soon as I have something ready, I'll post it here to get some feedback.

About the parts, I don't plan an Alessandro clone. So I'll pick up good parts but I'm not crazy about exceptional ones

Thanks a lot again