Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: Ivan303 on January 09, 2025, 04:17:43 PM

Title: Shunt reg voltages close, but a bit low...
Post by: Ivan303 on January 09, 2025, 04:17:43 PM

MJE 5731 A: .  Side A = 197V. Side B = 193 V

Close?

Low?

Any thoughts?

Title: Re: Shunt reg voltages close, but a bit low...
Post by: Paul Birkeland on January 09, 2025, 04:51:36 PM

How are your Kreg voltages?  These are a bit low, but pretty close.

Title: Re: Shunt reg voltages close, but a bit low...
Post by: Ivan303 on January 10, 2025, 03:05:55 AM

Kreg A = 1.83. Kreg B =1.84

Try a different 12AU7 and is if it makes a difference?

Title: Re: Shunt reg voltages close, but a bit low...
Post by: Ivan303 on January 10, 2025, 03:49:52 AM

And who can resist the chance to do a bit of tube rolling?

Not me!

More like A=240V and B=233V or there abouts!

OK, long plate 12AU7 GB (Mullard) made Bugle Boy in a. Standard Brands box but with my handwriting saying checks OK (decades ago)..

Title: Re: Shunt reg voltages close, but a bit low...
Post by: Paul Birkeland on January 10, 2025, 04:44:33 AM

Those Kreg voltages are a bit low, but they will increase when you attach the rest of the circuit off the shunt regulator.

Title: Re: Shunt reg voltages close, but a bit low...
Post by: Ivan303 on January 10, 2025, 05:07:25 AM

Which may explain the HUGE variation in the voltages between tubes.

Will re-measure all of this when the rest of the circuit is in place.