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Grid and Anode Chokes

SET12

SET12

Super Member
Hello everyone!

Well, One day I got to reading about the benefits of grid chokes.

#1 Low impedance to ground meaning less noise.

#2 Better recovery from clipping as the cap can discharge faster due to the low DCR.

#3 The generation of a substantially larger load for less distortion.

#4 Of course this was the big one for me greater dynamics, sheer punch!

Little did I know just how much they can effect the sound!

Especially in an SE amp like mine.

My amps 811-10's are hard to drive because they run in Class A2 and the 811 has a 39k grid resistor so when the grid goes positive it pulls current.

I use a 6EM7 tube to drive it with which it is essentially a 6SL7 and a 10 watt power triode with a 700 ohm plate impedance which is darn near like a 300B only this is used as a cathode follower to drive the 39k grid resistor.

Now with the new grid choke we are talking about 100's of thousands of ohms while still providing a low DCR path for the grid current.

Another issue I had with the Cathode drive was the loading I use which is a 12K cathode resistor which is much of a load.

Now with the Anode Choke, the Cathode Drivers loading is 100,000 ohms plus.

Whats the significance of this all?

Well, It was jaw dropping to say the least!
picture012fk.jpg


Got the grid chokes for $50/pair with free shipping from ebay.

Sorry, I can't post ebay links in the forum..

The Anode Chokes for $100/pair also free shipping from the bay.

Sorry, I can't post ebay links in the forum..

The grid choke was inserted at R6,

And the Anode was inserted at R10 the Anode choke has a 2.3K DCR so to keep the voltages and operating conditions nearly the same I paralleled 3 27K 3 watt resistors

I also include here the latest version I think of Erics 811-10 amp. I might add my own version uses very little of the original design and is far more powerful My best description borrowing a descriptive word from Dennis Had would be "Explosive"

Its like a whole different animal now it was powerful before competing with many SS amplifiers watt for watt but now its just gone literally ballistic.

But the cool thing is how much more informative and silky smooth it is as well, you might even say it was compressed before in contrast to the chokes now.

You could spend a lot more money for these chokes but these are just superior to any resistor IMO.

Cheers

SET12

Improved 811-10.JPG811-10 amp edit.GIFPicture 013.jpg
 
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jaymanaa said:
Nice write up, and timely, I've been doing some reading on this same subject.
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Thanks Jay,

I think these are some of the most affordable around, Yeah there may be better but at a 3-4 times the cost. And these just do so much!

Hears some of my notes.

Everything was virtually improved!!!!!

More space, air, resolution, decay's, image stability and coherency, impact!

The impact just totally blew me away, My amps were gutsy before, but I can hardly believe them now!

The sound stage is larger, virtually huge, really huge, going well past my side 18ft wide walls, speakers are 9ft apart.

Layering is nothing short of phenomenal.

Resolution of information, harmonics, textures, body, image outlines were greatly enhanced. They were good before but they are just so more real like.

I was afraid I might not like what I heard "Tonally" boy was I wrong!!!!

Talk about sweet! These amps now have more warmth at start up then with several hrs of listening. And the top end is silky smooth!!! Oh My God smooth!!! yet there is more information.

The Bass lines are dramatically enhanced. I hear more pitch definition along with longer decays, the skin of the kettle drums from Master and Commander were absolutely spectacular.

The amps clipping characteristics were enhanced. I used the Titanic sound track to investigate the enhancement and wow! recovery is something else.

When clipping occurs in my amps, it has a hang time to a certain extent that you can hear! Well that hang time was dramatically reduced. This helps with the amps integrity of the music!

Overall its as though the amps have a far greater sense of ease and extension of notes I especially hear this with the bass, its as though some of that subterranean stuff is now even more evident to the point of feeling it in my chair on recordings that were not formally known for it! Down right spooky stuff!

Also its one thing to have deep bass but I swear it seems wider and more defined from any part of the sound stage, holy cow!!!

I have heard inter-stage transformers but man I'm starting to think this maybe a more dynamic combination perhaps because of the higher inductance's.

I use a Bottle Head C4S current source for Plate loading of the first stage of the amp.

So now everything has very high loading. Its key to dynamics. Or dynamic conductance as it's called (Trans-conductance x Load)

SET12
 
I've got a stereo SE 6336/6528 amp where I use both grid chokes and plate chokes,
they do work rather well, in the works is an EL86 triode strapped preamp using plate
chokes for it's load. Iron in these circumstances can be mighty nice..
 
Kegger said:
I've got a stereo SE 6336/6528 amp where I use both grid chokes and plate chokes,
they do work rather well, in the works is an EL86 triode strapped preamp using plate
chokes for it's load. Iron in these circumstances can be mighty nice..
Click to expand...

Yep, I agree 100%, very,very nice. :thmbsp:

Thanks for your comments Kegger! :D

SET12
 
So Guys, SET emailed me a few days back and told me about this but man, I love what I have now! Should I drop the $$ and try the mod on my 300Bs??? I might have to pay you a visit SET and listen, I'll wait for more posts from the rest of the lurkers on the topic I guess.
 
Dave C said:
So Guys, SET emailed me a few days back and told me about this but man, I love what I have now! Should I drop the $$ and try the mod on my 300Bs??? I might have to pay you a visit SET and listen, I'll wait for more posts from the rest of the lurkers on the topic I guess.
Click to expand...

What can I say Dave!

You certainly can come and hear it for yourself!

Its new ground for me certainly. The Grid chokes are just $50 including shipping one could spend 3-4 times what I spent for better ones like these from silk. For what they can do dynamically and tonally its a no brainer from my point of view. I questioned myself on purchasing these! And as I have said I was worried about the sound from something at this low cost! But these at $50 are one of the best part purchases I have ever made!

These Silk grid chokes are $160 a pair from

http://www.diyhifisupply.com/node/627

Grid%20Choke.JPG


The resistors I was using were just plain harsh in comparison.

As for the Anode chokes these are expensive normally as well and still one could pay a lot more! and there alternatives like the C4S current sources that I use at $35 a pair But The Anode choke was a very easy mod and extremely effective at boosting the tubes loading which is key to stunning dynamic response.

I know what your thinking like when does it end?

I don't know! Have my amps gone as far as they can go? No, I don't think so!

From monetary stand point I would say the improvement was worth a couple of thousand dollars to my ears and that's a lot of return on $150 and some of my time but even the $50 is a very serious improvement for listening to Digital IMO my high frequency response has neve sounded this smooth and I thought it was good before but the grid chokes took it to a whole new level!

Just take a look at the iron on these Luxman 300B amps That sold new for $10,000, These were on ebay and the asking price was $10,000 and they are 25yrs old! there is good reason for the asking price. I believe they are using an inter-stage transformer which yields similar results.

mypic971.jpg


mypic973.JPGmypic975.JPG
 
Actually I'm not advocating the use or really benefit to grid unless on a tube that could
really need/warrant one, and what I mean by that is a tube that has the very low rated
grid circuit resistance then a grid choke can work rather well.

I'd say if the grid circuit resistance is rated for 100k or higher then a traditional resistor
should be fine and I don't really see much benefit to the grid choke approach. IMHO

The grid choke can be very very useful on those tubes with "low" grid resistance specs
as it presents a much higher impedance for the previous stage then what small resistors
would have done if going by the spec for the tube so that stage drives easier.

Some tubes have really low grid circuit specs, an can draw grid current plus runaway if
that grid circuit resistance is to high, in that regard the grid choke makes a low dc path
for the grid to ground but a high ac path for the signal. Excellent use for the grid choke.

Anytime an Anode choke can be subbed for a plate load resistor I'd say the chances are
quite good for a benefit in the sound department, if good/up to the task chokes are used.
 
This is rather timely! How would those Anode chokes work out for a 12B4 pre I wonder? The schematic calls for a DCR of 2K. and 130H The ones I purchased turned out to be rather puny looking!
 
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For the anode choke I'd suggest at least 100-200H, don't know what has been posted
here, myself I'd like to see 200H or higher there. (then obviously proper current rating)
 
SET, I think I'll wait till you come over and listen to what I have. Hope to see you the end of the month on your Wausau trip.
 
"Kegger, This is the one i'm going to built. (without the Phono stage). Gotta light up me some OD3's.
http://www.audiovib.net/Designs/Audi...honoOption.pdf"

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That looks pretty darn good to me, and along the same lines I would be suggesting.
(the current rating on there choke is pretty tight though, I'd rate higher there)

They specify a 150H or higher anode choke, sounds good to me, that dc resistance
spec really doesn't mean all that much, that just specifies how much voltage will be
dropping from the power supply, if you have beefier chokes the resistance would be
lower an you'd get a little more V onto the plates of the 12B4, would be nice to see
say 120v on the plate instead of just the barely 100v they show, but should be fine.

An 200H plate choke rated for say 30-40ma or higher with an resistance of say 1K is
probably a dream choke in that preamp environment. (300H "maybe" a bit better)

But if the chokes yu have at least meet the current requirement might as well try um.
 
mashaffer said:
Interesting approach. How do you think this would compare to traditional transformer coupling?

mike
Click to expand...

Thanks for asking!

Mike, I have wonder myself!

With the inter-stage you get rid of the caps!

The clipping recovery is even faster.

But I typically am not hovering around audible clipping.

Inter-stages have only so much inductance 50-60-70H not even close to the anode and grid chokes with 500-2000H

For me its all about loading! Greater loads produce greater dynamic impacts IMO.

And I found this out when experimenting with SRPP circuits! Clearly the greater the loading the more dynamic I heard the music as well as other benefits.

To me if I use the a current source like the C4S that I'm using which can create a 5 million ohm plate load then couple it to a 47k resistor of the next stage I loose dynamic response. The 47K resistor is considered in parallel with the 5 million ohm load even if it were a 100K it still is a loss for me! While there are still benefits of having the current source the dynamic response is poorer to my ears.

I'd much rather have a million ohm load! It is possible to create a 5 million ohm load from a grid choke! The silk above can do that!

The two working together does the trick for me! I hear what some call a very organic like sound quality! From the two working together. Very round very full with well developed harmonic information, good decays without being chopped off sort of speak!

I prefer fast supplies and when using such (lowest possible DCR's) the amplifier is really free to express itself simply because it can move the energy faster. The slower the supply, The less your likely to hear the full benefits of using the two combined IMO.

Think of it this way! If you need to make a 10 volt signal across a 100K load its going to take a .1 ma. change in the circuits current flow.

Now imagine that same signal with a 5 millon ohm load like the C4S that I use that same signal can be reproduced with .000002 ma. But if its loaded down by the next stage, not quite! In my case my C4S is direct coupled. So it has a better impact reproduction.

So IMO grid chokes and anode chokes work even better together.

SET12
 
Hey SET, suggestion for yu, :)

Try putting the plate choke on the plate of your driver instead of the cathode, then
adjust the cathode resistor to get current your after, then connect the output tube
grid to the plate of the driver instead of the cathode, now that you have those grid
chokes the cathode follower connection may no longer be a benefit or wanted there.
(curious if you try this and how well it works out)

-------------

Another thing you can try, replace the C4S with a plate choke, Quite often the plate
chokes are preferred over the solid state ccs load as far as "sound quality" goes here.
(not necessarily technically better but the subjective and better "sounding" one)

--------------------

Also as far as loads go, only so much is going to make a difference for the output, in
that I mean once you load to certain point times the plate resistance of the tube yu
get no extra performance going any larger on the load, only so much gain can be had.
(I tend to build with low plate resistance tubes so there loads are easy to fill out to)

----------------------------

On amps like yours and many transmitting tube amps the grid choke can be utilized to
to a nice improvement over the low value resistor quite often needed there instead..:thmbsp:
 
I was "spd rdn" down through the pages of new posts and thought I was going to learn how to "Grill Artichokes"! :D
 
John James said:
I was "spd rdn" down through the pages of new posts and thought I was going to learn how to "Grill Artichokes"! :D
Click to expand...

ducati_EL34 said:
That discussion has been moved to the Cooking & Spirits section of the forum. :D
Click to expand...

What can I tell you guys! Its a lot like food and I'm still craving more of it!

I ordered another pair of Grid Chokes yesterday! These will go on my inputs of my amps.

There are a few unique applications that they can be used in! Especially the Silk Grid choke! Notice the 3 terminal posts, see the connection possibilities on the right of the Silk photo

Grid%20Choke.JPG
Grid-Choke-1.jpg

Cheers

SET12
 
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