Standard specifications that any classic tube transformer would use? Right?? Nothing special I don't think; Heck maybe you could even salvage some used.

Hi!

We'll see what those transformers specs must be..

You can start designing the board layout. The rule is simple: if the pieces are connected exactly as in the schematic, then it's ok. I mean check that the nodes (where more pieces are connected) in your design are the same as in the schematic. Try to organize your pieces on the board as organized and logically as possible, so you won't have to use a lot of wire.

For example:

Usually, most of the point-to-point circuit boards look almost the same:

1. You have a line of terminals up and a line of terminals down. In some places you also have terminals in the middle.

2. All the pieces are vertically mounted (between a terminal on the down line and the one of the above line).

3. First come the 2 cathode resistors (with cathode capacitors if there are any), then come the 2 plate-resistors (each soldered with one end on a terminal from the above above and with the other end joined together on a middle-terminal. From the above-terminals of the 2 resistors comes down a coupling capacitor (the 22uF in the jcm800 preamp for example) connected to the down terminals.

a.......b.......c...............e
o...... o.......o...............o......o
|.......|.......|..\........./..|.......
|.......|.......|.......o.......|.......
|.......|.......|.......d.......|.......
o.......o.......o...............o......o

a - cathode resistor of the first stage (first half of the 12ax7-like tube) (pin 3 of the first tube). If there is also a capacitor in parallel, then instead of b it comes the capacitor, and connect both ends to the ends of the resistor.

b - the cathode resistor of the next stage (pin 8). The same goes here: it might have a capacitor. If so, the pieces in the right are moved further right.

c - this terminal comes directly from the first plate of the first tube (pin 1). One plate resistor goes to d (where it is B+) and to the down-terminal, it goes the coupling capacitor.

d - B+ voltage - from the power supply (the above line in your schematic).

e - same as c. It is connected to pin 6 of the first tube (the second plate). It also connects to d through a plate resistor and to the down terminal line thsough a coupling capacitor.


The pieces that go to grids (pins 2 and 7) are not usually present on the board. We prefer to attach them directly to the tube sockets. These pieces are ALWAYS connected to the parts before them (in the way that signal travels) through SHIELDED WIRES.

Basically, that's it. Try to design a nice layout. We'll check. But do it for the whole amp. The preamp will then be easy to extract.

Good luck!

Ovi

Hi Ovi

Thanks for all the explanetion!!!!!!

I'm working right now in the Lay-out, i'm drawing in a paper and then i going to draw it in Corel Draw so i can change anything.

Many Thanks!!!!

Juan

Hi People!!! I finally make the Layout of the Ampeg B25b, for my was a lot of work!!! Ovi Thanks for the advises, some values are missed (like the hum control pot that I suppose that is lineal ) but I copied the values from a Ampeg B25 schematic that is practically too similar. The list materials I going to publish next time.
I have some questions, if you can see the B25B have differences between the channel one and the two channel, in the B25 both are identical and in the B25B they have differences. I talk about this because Ovi tould me to erase the channel two, I was searching videos in YOUTUBE and I found one that show the channel one was more cleaner than the channel two also have an overdrive ¿?

Here is the youtube web to see it:

http://www.youtube.com/watch?v=5VM-A1w6yJY

have some questions about the Layout amp:

1)is the tube connections ok? I don´t know if the V6,V2,V1 were right.
2)the power section that I want to build is in 220v not in 110v how can I do it?
3)what is the polarity switch in the power section? is use full?
4)I have doubt about the plug connections (they are in red circles) they are right?
5)In the power section they are some components that I don´t know (they are in red circles) what they are and what value do I use?

Thanks
Juan

Edited by Rob: Used Attachment Feature

Its hard to read your layout.........let me address some quick and easy concerns. For 220V connection just follow the hook up diagram from your PT or look that up on the web, since different makers wire stuff differently. Polarity and Hum pots are no longer needed, since now we all use grounds, in the old days they did not use a ground and the old plugs were two pronged and could be plugged in blk to white causing a polarity hum. What you should do is for all common hook up stuff follow one of our layouts, and you will not see that stuff, instead of a hum ballance pot you will see 100-Ohm resistors from the heaters CT to ground. But no polarity switch. Some of the other stuff in red are OK to use, though again look at our layouts for help in that area. Some of those items are to stop pops, but I have not needed to use them. Again I just took a quick look.........