5w tube guitar amp sechmatic

[kldguitar]

I want to build one 5w tube guitar amplifier.The schematic is attached.
would you mind giving me some advice. I will make 5w tube amp in hand wired.(point-to point). One 12ax7, one 6L6, it is simple .but the tone is good in PCB layout, so I want change it in P-to-P self.
http://www.kldguitar.com

[tubeswell]

Look at the fender amp field guide schematics and layouts under 'Tweed Princeton 5F2A'.

Your circuit diagram has alot of extra technical boxes and switch contacts and other paraphenalia that seems superfluous to me. The simpler the better.

[Enzo]

I think that is just the way it is drawn. SOme of the boxes are just test points on the schematic, and some represent connectors onthe circuit board. And all that switching over by the headphones jack represents all the cutout contacts on the phines jack. Like on those 9-leg jacks Fender used a lot. The amp is pretty simple really.

COnsidering the low power expected and the low B+ voltage, I wonder why use a 6L6. If you use a 6V6 or an EL84, there will still be plenty of power tube capability. And those tubes use less current from the power transformer for their heaters. That would allow a smaller transformer to be made for it.

On the other hand, if you have lots of 6L6 in stock, it would work.

If your circuit sounds good on a circuit board, then I see no reason it won't work well hand wired. This is a simple circuit, so there should not be a lot of [problems with layout. Keep the power stage wires and speaker wires away from the input stage. And follow good hand wiring practice like twisting the heater wires and routing them away from the signal wires.

[kldguitar]

Thanks for your advices

I think that is just the way it is drawn. SOme of the boxes are just test points on the schematic, and some represent connectors onthe circuit board. And all that switching over by the headphones jack represents all the cutout contacts on the phines jack. Like on those 9-leg jacks Fender used a lot. The amp is pretty simple really.

COnsidering the low power expected and the low B+ voltage, I wonder why use a 6L6. If you use a 6V6 or an EL84, there will still be plenty of power tube capability. And those tubes use less current from the power transformer for their heaters. That would allow a smaller transformer to be made for it.

On the other hand, if you have lots of 6L6 in stock, it would work.

If your circuit sounds good on a circuit board, then I see no reason it won't work well hand wired. This is a simple circuit, so there should not be a lot of [problems with layout. Keep the power stage wires and speaker wires away from the input stage. And follow good hand wiring practice like twisting the heater wires and routing them away from the signal wires.

Yes. I agree with you. EL84 and 6V6 is good, But EL84 is expensive, 6v6 is difficult to buy in china, so I select 6L6

[Enzo]

Really? 6L6 is less expensive for you than EL84? I am surprised.

[DirtyGeorge]

The input circuit is overly complex. Most guitar amps don't have a blocking cap (C22) on the input. Even with the cap I don't think you need R7. I would remove R7 and make R22 1M.

I would make C15 a higher voltage, at least 50v.

What is the purpose of C6. If it is intended as a bright cap bypassing the volume control then it should connected between the wiper and signal leg, not the ground leg on the pot.

DG

[J M Fahey]

Hi DarkGeorge.
As I see it, C6 is an "anti-bright" cap, or , if you like it, a "dark" cap.
It?s purpose is to remove some of the harshness present when overdriving the preamp and setting a low output volume with the Master (called "Volume" here).
The schematic looks like it was pulled from a commercial product?s manual.
Obviously it can be hand-wired.
I?m surprised, but not so much, by the reverse difference in tube costs, but I think the EL84s or 6V6s must be imported and the 6L6s local.
I hate to think about the *real* factory price there, they must cost only a couple of bucks.
As a similar case, here, in Argentina, you can buy two pounds of prime quality "New York Steak" or 3 pounds of "TBone Steak" for the price of one Big Mac combo (around 7 U$S).