My DIY Fender '57 Twin tube amp

[LI XIN]

Hi,everyone!
I am so happy to have an opportunity to be here,and I hope I could be your friends in the future.
I have play guitars about 10 years and have studied wireless and guitar amp diy for some years.I like blues music so much!

This is my new DIY tube amps,Fender '57 Twin amp.Would you please tell me what defect in my amps and how to improve the defects?Would you please give me some suggestions?

The photos are in the attachment
Hoping your suggestions.
Thank you!
Sincerely,
LI XIN

[loudthud]

Are you in the USA? Your amp appears to have a USA type mains plug. What is the green wire dangling near the left rectifier tube? Is that the ground wire from the line cord?

[loudthud]

Your amp looks like a 5E8 schematic was used. The wiring looks very nice and neat. The power supply in this model is unusual in that the choke is placed before the feed to the output transformer. Most people prefer the more conventional arrangement where the choke is between the plate and screen filters. I have shown this in the attached schematic. I have added 470 ohm 1 watt screen resistors and a pot in the bias supply to make the bias adjustable.

[frank62]

Nice neat work, who supplies these kits?

[LI XIN]

Are you in the USA? Your amp appears to have a USA type mains plug. What is the green wire dangling near the left rectifier tube? Is that the ground wire from the line cord?

No,I am in China.
I send you a photo about the green wire and I hope you could understand.
Thank you!


Thank you!

[LI XIN]

Your amp looks like a 5E8 schematic was used. The wiring looks very nice and neat. The power supply in this model is unusual in that the choke is placed before the feed to the output transformer. Most people prefer the more conventional arrangement where the choke is between the plate and screen filters. I have shown this in the attached schematic. I have added 470 ohm 1 watt screen resistors and a pot in the bias supply to make it adjustable.

Thank you for your suggestion!
I have studied the circuit you give me,the plate and screen filters are linked together are the classic circuit

[LI XIN]

Nice neat work, who supplies these kits?

Thank you！
I have bought all the parts by myself

[frank62]

Thank you！
I have bought all the parts by myself

Did you buy the parts locally, who's the supplier? I'm interested, You have done a neat job.
All the best
Frank

[LI XIN]

Did you buy the parts locally, who's the supplier? I'm interested, You have done a neat job.
All the best
Frank

Hello,Frank,
Most of the parts is bought from USA,the suppier is CE,www.cedist.com
Thank you!

[frank62]

Thanks for the link, I'll check it out.

Frank

[LI XIN]

Thanks for the link, I'll check it out.

Frank

You are welcome

[LI XIN]

Hoping your suggestions

[jmaf]

Li, your build is very neat, congratulations.

How does it sound?

One suggestion: as LoudThud noticed, your ground mains is dangling and you shouldn't play the amp like that for your safety - do connect it to the chassis ground, preferrably soldering it so time doesn't rust your safety ground.

Regards,
JMAF

[Steve Conner]

Very nice! I can't see any "defect" there.

I think the dangling ground wire is an extra one for grounding the foil on the rear panel. It's dangling because the rear panel is removed for the photo. I can't see where the ground wire in the power cord goes.

Loudthud: I was in Shanghai on business last summer, most outlets had weird shaped holes that looked like they would accept either a British, American or Chinese plug. I don't know why the UK one. Of course they all would get 230v, 50Hz.

[loudthud]

I think the dangling ground wire is an extra one for grounding the foil on the rear panel. It's dangling because the rear panel is removed for the photo. I can't see where the ground wire in the power cord goes.

Loudthud: I was in Shanghai on business last summer, most outlets had weird shaped holes that looked like they would accept either a British, American or Chinese plug. I don't know why the UK one. Of course they all would get 230v, 50Hz.

I hope the amp is properly grounded and there is an extra green wire that insures that the foil on the back board is always grounded as well. I've seen some automobiles where there is such a ground wire that grounds the engine cover (hood). Did you notice near the fuse it says "F 1.6A 250V". That is a nice touch that tells me the chassis wasn't made for use in the USA.

Some novice builders take the 50 year old Fender schematics too literally. They do not meet current safety standards in the USA. As far as safety is concerned, it is really up to the builder to construct the amp in a way that meets current safety standards in the country in which it will be used. This almost always means connect a safety ground wire to the chassis and do not install the "Death Cap", a capacitor from one side of the power mains to ground.