cap value for 6X4 rectifier?

[PeteMcK]

Hi Guys,

I'm slowly converting an old radio into a guitar amp;

it has a 6X4 rectifier tube, & I want to replace the PS capacitors.

I have some 82uF (400v) on hand, would these be too big (cause to much start-up current)?

I'm thinking of using 3 all up in the B+ chain
(rectifier - cap - R - cap - R - cap)

(I'll probably eventually replace the tube with diodes, - but it's there, wired, & I'm very lazy....)

cheers,
Pete McK

 

[Simpleton]

The maximum capacitor value for this rectifier is 40uF. You can series connect 2 of your caps to make one 40uF cap for a first and from then on the others may be larger value.
Good luck!

6x4 - 40uF - R- C - R - C

 

[PeteMcK]

Thanks Simpleton,
I'll look for a smaller cap then.

cheers,
Pete MCk

 

[Geek]

Hi,

I've used a 47uF in my headphone amp after a 6X4 and she hasn't quit even after years of service. Plenty of on/off cycles 🙂

 

[Zen Mod]

Hi,

I've used a 47uF in my headphone amp after a 6X4 and she hasn't quit even after years of service. Plenty of on/off cycles 🙂

you certainly use wimpy xformer 😉

that can be explanation for long life of (nearly ) abused 6X4

 

[anatech]

Hi Geek,
I have to agree with Zen Mod. High transformer resistance saved it.

Why not go a little lower in value with the first cap (because there is a minimum supply resistance in those specs) and filter a little heavier later on?

-Chris

 

[arnoldc]

Hi choky!

I have a 6X4 rectifier which is somewhat noisy. Any tricks to make it silent? (not by changing it)

 

[alexmoose]

What will happen? because I am making a project using a 6X4 Rectifier, that shows using 50uf caps in two LC filters

30H----50uf----30H----50uf


will it explode?

 

[Zen Mod]

Hi choky!

I have a 6X4 rectifier which is somewhat noisy. Any tricks to make it silent? (not by changing it)

try to place some resistors in anodes (series with secondaries 😉 ) and also few nanofarads across "diodes" (A to K and A to K) ;if that no helps,than change it
6X4 must be dirt cheap ,even from your place ......

 

[arnoldc]

Choky, thanks for the info. In my place, beer is cheaper than tubes 😀

 

[Zen Mod]

What will happen? because I am making a project using a 6X4 Rectifier, that shows using 50uf caps in two LC filters

30H----50uf----30H----50uf


will it explode?

in your case L is buffer for excessive current hogging of wimpy 6X4.
in most books critical amount of capacitance for rectifier is implied for cap input filter;
with same logic-if you have cap input filter-use what is advised for rectifier in case,and after next R or L series element (with enough ohms or henries) ,you can put even Farad...............without harm....except that you'll must power up your gadget few days before listening

 

[Zen Mod]

In my place, beer is cheaper than tubes 😀

yes-I can see that-from list of toobz on your site 😉

 

[anatech]

Hi arnoldc,

Choky, thanks for the info. In my place, beer is cheaper than tubes

I guess you're going to have to buy lot's of beer and not worry about the 6X4! 😉 😀

Choky, er .... Zen Mod (I liked Choky better) was right in his approach to getting rid of the noise. As far as "wimpy" goes, how much current do you need??? I like it as a rectifier for small equipment. They are reliable and work just fine. Of course you could opt for a 5U4, or some larger types.

The choke input filter works very well for both the rectifier and transformer. I wouldn't change the arrangement at all.

-Chris

 

[arnoldc]

Hi Chris, I also like choky better 😀 re: beer, like Tony who posted on the Sy I give up thread, I like San Miguel Beer (and Corona too 😀) and during my younger days, I only have one serving for the night- a Mini Barrel 😀 😀 😀

I'll try the 6X4 again with choky's recipe. I used it once- choke loaded and cap loaded, just don't have the patience (at that time) to troubleshoot. I like it though, it's cute 🙂

 

[alexmoose]

The sad Part is that I as well think the 6x4 is cute, that why I am using it instead of Sand. also, Tubes work better for Point to point Soldering than diodes. It also looks weird to have only one tube (its just a stereo preamp, using only 1 tube would look awkard)

 

[anatech]

Hi,
I think the trick is to minimize the current spikes, allowing for a higher ripple voltage initially. You can get the ripple voltage down later. For a preamp, a regulator springs to mind. Why not? All critical circuits for test equipment and better audio have use regulators.

More tubes for your chassis alexmoose. And they will be there for good reason.

-Chris

 

[alexmoose]

Is there a good tube-based regulator that comes to mind? I see a good SS regulator on Gamie's Audio Lab

But I am trying to find something that allows for simple Point-to-Point soldering and I have heard great things about the 30h-50uf-30h-50uf with the preamp I am going to use

 

[Zen Mod]

Is there a good tube-based regulator that comes to mind? I see a good SS regulator on Gamie's Audio Lab

But I am trying to find something that allows for simple Point-to-Point soldering and I have heard great things about the 30h-50uf-30h-50uf with the preamp I am going to use

what final voltage and current you need?
VA ratings of xformer?
hehe,shunt with toobz is always on my mind 😉

 

[anatech]

Hi Zen Mod,
At this point I generally use sand and PC boards to conserve on current. There is typically no extra heater current available.

alexmoose,
Try the L-C-L-C out. You an always try other circuits later. Keep in mind you need a minimum current draw to keep the inductors working as inductors. That will be specified by the manufacturer, but you can calculate it.

-Chris

 

[alexmoose]

The power Transformer is 250-0-250v at 60ma. the desired operating point on my 5687 tube will be at 140v, at 11ma, so 22ma for both halves of the dual triode.

-Alex