Manifesto SE: single-ended stereo tube amplifier

[HappyBear]

Manifesto SE: single-ended stereo tube amplifier by HappyBear.

Rectifier: 5U4G with parallel snubbed SS diodes.
PS Filter: LOW DCR magnetics (Hammond ICT B+ PT, Triad and Edcor chokes) LCLCRC with 38.5K shunt R.

Signal circuit: C4S plate loaded 6SL7 driving RC coupled 7C5 in triode mode. Both stages are cathode biased.

OPT: Classic Tone 40-18031 5K:8

Power Output: about 1W before onset of clipping.

HB

 

[HappyBear]

Manifesto SE: power supply and signal circuit schematics in most recent configuration.

 

[raj12345]

Manifesto SE: power supply and signal circuit schematics in most recent configuration.

View attachment 78767

View attachment 78768

I am not able to see rectifier valve 5U4G in schematics as stated by you in first post

 

[HappyBear]

I am not able to see rectifier valve 5U4G in schematics as stated by you in first post

The 5U4G tube symbol was omitted to simplify the schematic.

The snubbed UF4007 diodes are connected across the plate and filament of the tube rectifier, 2 per tube.

HB

 

[HappyBear]

Manifesto SE: attended listening mode.

Hammond ICT B+ transformer: the fuse holder and wire of unknown quality is replaced by a jumper wire consisting of 3 equal runs of Kimber TCCS clear jacket 19AWG high purity stranded copper wire.

This easy modification is said to improve the subjective listening experience for some people who have tried it.

HB would caution anyone thinking of doing this or anything that removes AC line fuse protection. Know the risks involved before trying it.

HB

 

[HappyBear]

New fuse holder with 10AWG wire by HappyBear.

The 3AWG fuse is insulated by 1200V rated 3/4" heatshrink tubing.

This provides better circuit protection for the Manifesto SE tube amplifier than the "attended listening mode" jumper wire.

 

[Hari Iyer]

New fuse holder with 10AWG wire by HappyBear.

The 3AWG fuse is insulated by 1200V rated 3/4" heatshrink tubing.

This provides better circuit protection for the Manifesto SE tube amplifier than the "attended listening mode" jumper wire.

View attachment 79212

I am with you on this. At times when I turn on the attended listening mode in my monoblocks, I forget to switch them off. So next time I turn my power on, the mains MCB will trip.

 

[HappyBear]

I am with you on this. At times when I turn on the attended listening mode in my monoblocks, I forget to switch them off. So next time I turn my power on, the mains MCB will trip.

We would like to think our bespoke DIY tube amplifiers are robust, but component failure can happen at any time resulting in dangerous conditions like a house fire. Insurance companies would have a dim view of the "attended listening" mode.

Our problem is "one inch of bad wire can ruin the musical experience" - that one inch of bad wire being contained within a standard line fuse.

What are the alternatives to the standard line fuse that sound good and are considered safe practice?

Every approach seems to have some form of compromise.

HB