CCS and the TUBE

[Kit]

-96db.... thats good, I can live with that.

I have no problem with a transistor CCS. Its just that i have got all these dual eccXX triodes laying around. Might as well put the "other half" to use.

I see you are using pentodes for this one. Do you really need the extra "push" from the CCS?

 

[analag]

I'm just putting my spin on the V72 machine, using the original concept of a stiffened up plate current on the output tube without resorting to the use of a choke. Thus smaller size, better hum rejection and a whomping sound. A resistor will work, but an NChannel MOSFET is a dismal failure in this particular application. This is a dumb CCS, in that it is not interacting with the tube in any way. It's just set to pull the (user) specified current regardless of what the tube is doing. Closer to the workings (I did not say sound, no rounding of edges here) of a choke, me thinks.

analag

 

[Winston OBoogie]

Interesting.
On first glance, aren't the output pentode and the CCS fighting against each other a bit...?

Original V72 output valve had about 260ish V on the anode which, together with the effective doubling of this with the retard choke, gave a pretty decent output swing. What's the expected swing with your specified 150 anode V and no coil? Yes, you do have a lower ratio OP traffo but:

4:1 ratio output traffo is quite a low load for a pentode.

Like the re-location of the impedance coupling cap on the 'cold' side of the traffo but it might need a re-sizing due to the lower reflected load. (edit: clarified in post below)


Thanks for posting the schem.

 

[analag]

[quote author="Winston O'Boogie"]Interesting.
On first glance, aren't the output pentode and the CCS fighting against each other a bit...two sources of current butting heads?

Original V72 output valve had about 260ish V on the anode which, together with the effective doubling of this with the retard choke, gave a pretty decent output swing. What's the expected swing with your specified 150 anode V and no coil? Yes, you do have a lower ratio OP traffo but:

4:1 ratio output traffo is quite a low load for a pentode.

Like the re-location of the impedance coupling cap on the 'cold' side of the traffo but it might need a re-sizing due to the lower reflected load.[/quote]

With an 250H choke the output swing is identical. Are you sure we need to change the value the cap due to it's location?
Cap location corrected...good catch.

analag

 

[Winston OBoogie]

"With an 250H choke the output swing is identical."

Using a choke in an 'impedance-coupled' (Parafeed) configuration allows the output to swing above and below the power supply voltage. How are you getting your CCS to do this?


"Are you sure we need to change the value the cap due to it's location?"


No. I meant because of the lower reflected load due to using a lower turns output traffo.


"Cap location corrected...good catch."


Actually, in this circuit I really do think it sounds better when it's on the 'cold' side as you had it before.

A pentode sinks current fairly constantly. Your anode load is also supplying current constantly. I think you may find some issues with this arrangement when you build it.

Ciao.

 

[Winston OBoogie]

Hey Marik,
"I actually tried an expensive Lundahl one and... did not like its sound at all :grin: Ended up with a $10 one. :green:"

Interesting :razz: Was the $10 choke one of these Hammonds?:

1/ Rating: 150 Henries, 8 mA
Max. VDC: 400
Resistance: 3,700 ohms

2/ Rating: 60 Henries, 8 mA
Max. VDC: 400
Resistance: 2,750 ohms

Haven't tried these myself but intend to.


"To me resistors have some fuzzy qualities in sound I don't neccessarily like."


Rock 'n' Roll baby! I could see how it wouldn't be the best for what you do yourself though.

"chokes tend to pick hum"

That they do :roll:

Thanks for your thoughts on the sonic differences. I think we come to the same conclusions although I hadn't thought of choosing the topology based on microphone type :thumb:


Hi Gus,
Yep, I also think there's something wonderful about using a Higher High Tension with the appropriate resistor.

Ciao.

 

[analag]

[quote author="Winston O'Boogie"]
A pentode sinks current fairly constantly. Your anode load is also supplying current constantly. I think you may find some issues with this arrangement when you build it.

Ciao.[/quote]

So does a transistor, and I think not.
Everything that you stated concerning the choke showed up in simulation, only in the CCS theory you slid off the road. I will do the experiments to prove my ideas.

Let's say you have a basic pentode voltage gain stage, if you put a bypass cap on the cathode will the gain increase or will it remain the same.

analag

 

[Larrchild]

This is a limiter question, but it fits perfectly here. if one desires to not use a plate resistor on the vari-mu stage, due to concerns of voltage swings inparted by bias-changes, and instead use an interstage xfmr...

In lieu of a fussy interstage xfmr, how about a pair of chokes in parafeed to the PP mu tubes, eh? More constant voltage, variable current scenario, than a resistor, yet still allowing capacitor coupling (Leyden or otherwise) to the next stage.

Would the price of 2 chokes be better than some wicked-exotic interstage?

 

[Winston OBoogie]

[quote author="analag"][quote author="Winston O'Boogie"]

Everything that you stated concerning the choke showed up in simulation, only in the CCS theory you slid off the road.
[/quote][/quote]

:grin: OK, if you say so.

FWIW, if we allow that a 10M45S is a fair substitute for your own CCS:
I built up your circuit this evening by re-working a V72 type amplifier I have on hand...

I'm sticking with the choke on this one.

Ciao.

 

[Winston OBoogie]

[quote author="Larrchild"]

In lieu of a fussy interstage xfmr, how about a pair of chokes in parafeed to the PP mu tubes, eh? [/quote]

Lar! :green: I had the very same thought earlier as I was fiddling with a batch of Altec 436's.

Seems like it's a good idea to me.

post scrotum: Gonna try your "20Hz and a scope" trick for balancing.

 

[analag]

[quote author="Winston O'Boogie"]
FWIW, if we allow that a 10M45S is a fair substitute for your own CCS:
I built up your circuit this evening by re-working a V72 type amplifier I have on hand...

I'm sticking with the choke on this one.

Ciao.[/quote]

No we don't allow...the CCS cathode circuit cannot be connected to the pentode's plate. Collector to plate, just like I got it. I'll do the experiment this week. (2) PNP (4) diodes just like that.

analag

 

[Larrchild]

> Seems like it's a good idea to me.
Clearly, Hammond is going "Gee nobody ever ordered these much before" right now as we speak.

Gonna try your "20Hz and a scope" trick for balancing.

And I, sir will be trying your Eclair and Rope Trick , poste-haste!

 

[Winston OBoogie]

[quote author="Larrchild"]
Clearly, Hammond is going "Gee nobody ever ordered these much before" right now as we speak.[/quote]

Yep.

Don't have any Hammonds here but did have time to quickly try a pair of 400H,12K DCR chokes in a modified 436B. As best I could tell from the quickie test, it looks promising. Might be cheaper still ($12?) to use an Edcor IT's primary just as a dual choke and leave the secondary out of it.
Hmm? or how about using the secondary to feed the side-chain amp?

Wrong thread no doubt.

Good luck with the 'eclair-o-rope'...

 

[Larrchild]

Might be cheaper still ($12?) to use an Edcor IT's primary just as a dual choke and leave the secondary out of it.

Yeah, I've done that too. good one. :thumb:

 

[Larrchild]

Winston:

On first glance, aren't the output pentode and the CCS fighting against each other a bit...?

Rowan:

So does a transistor, and I think not.
Everything that you stated concerning the choke showed up in simulation, only in the CCS theory you slid off the road. I will do the experiments to prove my ideas.

Lassie is trying to tell you "Timmys trapped in the Mine"
And all you are hearing is "Woof, Woof"

Triode

Pentode
When you hook a constant current source to the bottom image with the flat horizontal line for current consumption (pentode), they interact.
Woof!

 

[Winston OBoogie]

That was the...ggrrrRRRROW! ROW, ROW! erm? :? ...point I was trying to WOOF! make yes.

Could anyone throw this tennis ball for me?

 

[CJ]

Check distortion with the Hammond choke, if any of you solder junkies messin around with this have a distortion meter.

I would be curious about the orig V72 and cheaper models.
Asymetric properties can be introduced by unbalance C's if the choke is not wound properly.
C to core, C to ground, interlayer C, turn to turn C, could all play with the sound.
Also, I believe the hammond is dipped. V72 stock is free windings, maybe a little mechanical feedback going on.

Also, does the feedback in the V72 cause the output impedance to be lowered?
If so, tuns on xfmr can be reduced.

 

[analag]

What about the results of my experimentation. Why must I be a Christopher Columbus, proclaiming the world is round when "ALL" the wise men say it's flat. History repeats itself.
Put away your graphs and rulers, start your soldering iron and venture into my world, oh yea wise and learn-ed men.
Too bad this is literary endeavor where it's hard for my practical approach to prevail against the text book engineers and their arguments, but I've debunked some of the "BEST" brains around here, simply because they believe the graph is greater than the soldering iron.

Nothing more to be gained here...on to the next thread.

analag

 

[solder_city]

im sorry... ive been trying to be cool and stay out of your threads but ive had it with this nonsense

I've debunked some of the "BEST" brains around here

you keep sayin that
but when it comes to proof, you aint posted ****
'because i said so' does not count as proof
boasting is not the same as debunking
delusion of granduer does not equal genius

oh, and you have a serious persecution complex there, columbus. dont post designs for discussion if you dont want them discussed! -and i mean scrutinized more closely than 'gee analag that looks great'

the reason your threads always end up like this is not because THE MAN is trying to keep you and your brilliant designs down. its cause you talk a lot of **** and approach the whole thing with a paranoid hostile attitude.

nobodys tryin to keep you down analag. in fact- until you have something more to show than simulations and your giant ego- no one really gives a **** eithr way!

 

[Marik]

[quote author="analag"]What about the results of my experimentation. [/quote]

Analag,

So what about the results? It seems you never posted them (or did I miss it?)

What are the figures, what about sonics, and also, what is the noise performance? If you would've provided all that, then it proves the text book engineers are wrong, and then we all would say to Larr: "F@kk your graphs". :razz:

Instead, you chose to go easy way just "slamming the door".
May I ask you, what did you prove with that?

I know to hold the soldering iron and as I've said before, was experimenting with SS CCS's and chokes with triodes.
I did not try C4S (the one your schematics based on) yet, but was intended to, when have time.

Oh wait, Winston seem to try this one.
Hey Winston, do you mind saving me some time and sharing what you've got?