Neve Current Draw?

[CJ]

I want to bias up this Neve iron with some dc so I can find the saturation voltage.
Does anybody know how much current flows through the 2N3055 and winding?
I went thru the Neve meta but came up empty.
Thanks!
:guinness:

 

[Winston OBoogie]

...

 

[PRR]

There is a bias setting. The final adjustment is for nice clipping under load, but the initial setting tells you to trim some voltage. Work out the 3055 current with that bias setting, and assume that final trim will be +/-20% from there. Basically test at setup current, then check that the iron won't punk-out if final trim leaves it 20% higher.

 

[CJ]

Thanks Winston!
I will use 50 ma to be safe (these pups are on loan) and beat the heck out of them with the ac.
Pictures at eleven!
:thumb:

 

[Winston OBoogie]

...

 

[CJ]

Yes Joel, I know to paralell the primaries!
Don't sweat it.
Thanks PRR also.
cj

 

[jrmintz]

CJ,

My BA283 cards draw about 110-115ma each with Carnhill output transformers.



:thumb: :thumb:

 

[rascalseven]

70mA.

Good stuff, CJ, thanks!

:thumb:

JC

 

[CJ]

OK, this setup isn't working so I am just going to ,load down the secondary.

The ac from the variac/isolation transformer was going through the blocking caps and into the transformer like they should, but then they were flowing into my dc power supply and causing problems. :twisted:
I have a 130 ohm 2 watt resistor in series with the power supply that was getting hot.

I got an idea! :idea: I am going to run the dc thru one pri, and the ac into the other one and decrease the current a little.

 

[CJ]

No, that won't work either. The ac is going from on pri. into the other and int the supply.

Back to the sec. load down idea.
:evil:

 

[CJ]

OK, 1 k resistor on the secondary and 60 volts in dosen't even make this Marinair blink.

Time to hook up the sig gen to the power source and bring her on down to 10 hertz!
If this don't do it, nuttin will. :grin:

This is where the Carnhills are supposed to poop out anywho.

 

[CJ]

Success!

The 20 hz is bending the crap out of the mag current wave!
Saturation complete!
Had to rewire the iso tranny to 120:240 out because the power souce dosen't like the 20 hertz much so I can't drive it as hard. But that did the trick.
:grin: :grin: :grin: :grin:

 

[CJ]

Careful! At 60 volts in and 20 hertz, these pups start to get a little warm.

Hey all you Neve owners out there, how hot do the outputs get with that bias curent?

 

[soundguy]

the output transformer? not noticably hot on any of mine.

the output transistors, noticably warm with the heat sink.

dave

 

[Tekay]

I remember that Avedis at Brent Averill did some measurements and that the distortion in the output transformer rised at 15 Hz / +20dB, less at 10 or 20Hz.