help for E182CC linestage/driver

[Tyimo]

Hi Paolo!
Back to the mosfet:

If you make a choke loade mosfet amp
in common source mode you need to have a choke reactance of 3-4 time the speaker impedance at the lowest freqency you need it to operate at. For example 200mH at 20Hz = 25.12 ohms
8ohm speaker : 25.12 Ohm reactance = 0.318


By the choke loaded tube preamp you make the same but with higher values, because you drive also higher loads.

Greets.

Tyimo

 

[inertial]

Thanks Tyimo!!

so, back to the 6N6P example

suppose we use a coil of 50H - 20Hz limit

Ra=2*3,14*20*50= 6280 ohm that is sufficient for plate resistance of about 1800 ohm, am I right?


P.S:: about the cathode bypass: I have used 4*22microF =
88 micro Solen MKP . F3 measured= 5Hz

I do not know how much people have comparate real MKP capacitor versus LED

Cheers,
Paolo

 

[Tyimo]

Paolo!

6280 ohm that is sufficient for plate resistance of about 1800 ohm, am I right?

Yeeesss!

I do not know how much people have comparate real MKP capacitor versus LED

Don't hesitate! Just try it!

Greets:
Tyimo

 

[inertial]

dear Tyimo,

OK. Good day to learn something very useful here!

You are right , I will try it.
But , only on my power follower I shoud be experimentate:
BUZ instead IRF.
eliminate input cap
Chocke (air core) instead CCS
Mono PSU instead stereo ( now is stereo) !!!
Chocke input ( air core) PSU instead actual CLC PSU
finally, a new cabinet

Do you think I can seriously testing all this stuff without go crazy in the next xx months?

Puff, I need moral help here!

Cheers,
Paolo

 

[Tyimo]

Paolo!

You should try step by step to hear which change what give.

BUZ instead IRF.

Be carefull! BUZ has different Vgs!

eliminate input cap

No problem.

Chocke (air core) instead CCS

Gapped Irion Core is better! Air core has high DCR!

Mono PSU instead stereo ( now is stereo) !!!

No problem.

Chocke input ( air core) PSU instead actual CLC PSU QUOTE]
What?!? I don't understand what you mean...

finally, a new cabinet

No problem....

Tyimo

 

[inertial]

You should try step by step to hear which change what give.
[/B]

Fortunately this is my expertise! My ear is my only talent!

Be carefull! BUZ has different Vgs!
[/B]

Please, what does I have to modify in the circuit ?

Gapped Irion Core is better! Air core has high DCR!
[/B]

I'm not worried by DCR.
Air is my obsession!


[/B][/QUOTE]


thanks,
Paolo

 

[inertial]

Hi Paolo!
Back to the mosfet:

If you make a choke loade mosfet amp
in common source mode you need to have a choke reactance of 3-4 time the speaker impedance at the lowest freqency you need it to operate at. For example 200mH at 20Hz = 25.12 ohms
8ohm speaker : 25.12 Ohm reactance = 0.318

Tyimo,
excuse me, I do not understand why I have to considerate 8 ohm
instead of the internal resistance of the mosfet ?
Excuse mine ultra-newbie questions, but I would be learn

thanks,
Paolo

 

[Tyimo]

Sorry, I wanted to write:

If you make a choke loade mosfet amp
in common source mode you need to have a choke reactance of 3-4 time the speaker impedance at the lowest freqency you need it to operate at. For example 200mH at 20Hz = 25.12 ohms

25.12 Ohm reactance : 8ohm speaker = 3.14

I do not understand why I have to considerate 8 ohm
instead of the internal resistance of the mosfet ?

Because You have to push the power across the sepaker.

Tyimo

 

[inertial]

Because You have to push the power across the sepaker.

Tyimo

OK, make sense but in the case of choke loading of the 6N6-P
( with the right chocke) why you have considered only the Rp of the tube?
The tube has to push the power across the next stage, for example
my power follower( who has a Z in of 100K ohms). Am I saying a stupidity?

Cheers,
Paolo

 

[Tyimo]

Am I saying a stupidity?

No.
It is just a rule.
Good question!
Sorry, I dont know the correct answer.
Do not thinking too much! Build!!

Tyimo

 

[inertial]

Yeah, excuse me guys, mine second name is " WHY"?

cheers,
Paolo

 

[Tyimo]

Yes, I understand you!
I like to understand how amps works too.
But unfortunately I am not enough wise.... yet!

 

[inertial]

Hey Tyimo, just curious, what sort of speakers do you drive with your SEWA? I always have found terrible difficult employ one only amplifiers
for my speakers
Like raw drivers, seems to me some circuit works well only in restricted zones
To say SE triodes on the mid- tweeter, big solidstate complementary on the woofers and so on.
This is mine empirical evidence but I do not have a clear explanation about why this happens
At least with drivers you see easily issues in "bandwith", distortion, dispersion, etc, but in electronic circuits what can we see ( exerpt limitations of output transformers for example) ?
This make this field so ....interesting!

Cheers,
Paolo

 

[Tyimo]

Hi Paolo!

what sort of speakers do you drive with your SEWA? I always have found terrible difficult employ one only amplifiers

I have many loudspeakers, but my favorite is a BLH in Replikon style with a 6 Ohm dualconcentric driver. I have also some BLH and TML and BR loudspeakers with my own 6" paper cone driver and Vifa tweeters.

I like hybrid amps, but not in that way what you wrote.
For me the best is: tube voltage stage + mosfet power stage.
I have no problem to drive my speakers.

Greets:

Tyimo

 

[inertial]

Oh, I understand why, High efficency !
Instead my speaker are low efficency, this is why I need power ...and power.......and more again!

Back to the topic,
If I chocke load the 6N6-P , what's happen to his Gain ? ( upper?)
and what about output impedence ? ( lower? and how much? )

Thanks for precious help

Paolo

 

[Tyimo]

Hi Paolo!
I don't know the real answer, but choke (and transformer) loading give much better efficiency than resistor loading.

I think the gain will be a bit higher and the Zout a bit lower, but it depends on many other things....

Greets:
Tyimo

 

[inertial]

Thanks tyimo,

yup, maybe is better if I post a specific question in another thread

Cheers,
Paolo

 

[Akita]

Hi,

I notice that 6n6p tubes have a screen at pin-9. Do it need to be grounded?

 

[Bandersnatch]

Paolo,

Start with the data sheet. R_P is approx. 1.6 KOhms. Get the superior O/P drive you crave by DC coupling an IRFBC20 source follower to each of the common cathode gain stages. With buffering, 4.7 KOhm load resistors should be enough.

hey-Hey!!!,
I'd roll the plate load into the follower with a MOSFET ccs like Gary Pimm has done much work on. Take output at lower source( the mu output ) and leave the tube running constant current( instead of CCS minus load current ). I've heard very nice things from this arrangement.
cheers,
Douglas