5654 (6ak5) line stage in triode mode - Page 2

francoiacc · 30th November 2010, 07:34 AM

Thanks everybody for the comments and info, honestly I've a bunch of this tubes and I'm triyng to understand if I can use them not only for a CD Buffer stage (http://www.diyaudio.com/forums/tubes-valves/96681-tube-buffer-6j1-5654-6ak5.html).
Looking at the curves of this tubes I already realized that the main issue is the input signal, 2V is little bit high ! Unfortunately I'm not so good in theroetical issues, and may be some alternative idea may take these tubes to a different life.
To me the curves in triode mode looks good enough, what I don't see a good idea is to use it as pentode.
I know that in triode mode the gain is low, but this is what I want, at the moment I've a 300B amplifier with a 6SN7 line stage in mu-follower configuration, and to me the gain is too high.
For sure any tube may be better, but why don't try it? It wouldn't be the best line stage but, as any other tube, it could have his character!!
So let's go on with ideas, in a couple of week I would start building a first prototype.
Thanks again.

Wavebourn · 30th November 2010, 08:55 AM

It is a nice tube. It can work on very low anode voltages. When triode connected it is very similar to 6S1P tube:

http://www.cqham.ru/tubes/soviet/pdf/6s1p.pdf

DF96 · 30th November 2010, 05:16 PM

I have now had a look at the triode curves, as suggested by DT. Triode connection seems to improve things more than I expected, so you could use it as a line stage although there is not much margin for error and the gain would be rather high. An active load would help reduce distortion. So perhaps I was wrong, but not seriously wrong?

Wavebourn · 30th November 2010, 05:30 PM

Quote:

Originally Posted by DualTriode

Hello,
The 6AK5 triode connected plate curves look like it can be biased for 2 volt input to me.
http://www.mif.pg.gda.pl/homepages/f...138/5/5654.pdf (see the last page)

Hmmm... I tried again, but it still says, "Page not found"...

taj · 30th November 2010, 06:05 PM

Works for me!

Wavebourn · 30th November 2010, 06:49 PM

It works now, thanks!

francoiacc · 1st December 2010, 08:03 AM

I really apologize for my ignorance, what do you mean for actve load? a Tranformer? If so which charateristic should it have? Do you have an example or some documentation I can look at?

DualTriode · 1st December 2010, 02:35 PM

Hello francolacc,
A Mu-Follower is a example of a classic actively loaded common cathode amplifier. The top triode is the active load.
The Valve Wizard -Mu Follower
For starters keep it simple try the circuit in post number 3. You will need a capacitor at the input ~ 0.47 uf. You will like the results.
DT
All just for fun!

sulcorebutia · 28th December 2010, 12:47 PM

Quote:

Originally Posted by euro21

Try this operating point.

Hi Euro21!

triode connecting 6ak5, mu = 20, everything looks very promising of your 6ak5 design.

As I have some 6ak5 , rca 1619 sitting around in my tool box, I am tempted to build a SE amp based on your design. However, it seems to be difficult to sequeeze more than 1W or so from 1619 triode mode. Do you have any recommendation of 1619 working point?

or any modification of the following circuit?

francoiacc · 28th December 2010, 05:11 PM

I finished a first prototype right now, and..... WORKS! It's still without a transformer since I'm waiting for it and was too impatient, but I've to say that the result is good. As soon as I've the transformer I'll test it and after I'll build the definitive 5654 line amplifier. I'm also planning to make a second stage with a cathode follower, I've to think about witch tube use... do you think that a 5654 should be a goof one? If so please help me with some example. Anyway the schema is the one at post 3.

30th November 2010, 08:55 AM	#12
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	It is a nice tube. It can work on very low anode voltages. When triode connected it is very similar to 6S1P tube: http://www.cqham.ru/tubes/soviet/pdf/6s1p.pdf __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

30th November 2010, 06:49 PM	#16
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	It works now, thanks! __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

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30th November 2010, 07:34 AM	#11
francoiacc diyAudio Member Join Date: Aug 2010 Location: Italy	Thanks everybody for the comments and info, honestly I've a bunch of this tubes and I'm triyng to understand if I can use them not only for a CD Buffer stage (http://www.diyaudio.com/forums/tubes-valves/96681-tube-buffer-6j1-5654-6ak5.html). Looking at the curves of this tubes I already realized that the main issue is the input signal, 2V is little bit high ! Unfortunately I'm not so good in theroetical issues, and may be some alternative idea may take these tubes to a different life. To me the curves in triode mode looks good enough, what I don't see a good idea is to use it as pentode. I know that in triode mode the gain is low, but this is what I want, at the moment I've a 300B amplifier with a 6SN7 line stage in mu-follower configuration, and to me the gain is too high. For sure any tube may be better, but why don't try it? It wouldn't be the best line stage but, as any other tube, it could have his character!! So let's go on with ideas, in a couple of week I would start building a first prototype. Thanks again.

30th November 2010, 05:16 PM	#13
DF96 diyAudio Member Join Date: May 2007	I have now had a look at the triode curves, as suggested by DT. Triode connection seems to improve things more than I expected, so you could use it as a line stage although there is not much margin for error and the gain would be rather high. An active load would help reduce distortion. So perhaps I was wrong, but not seriously wrong?

30th November 2010, 06:05 PM	#15
taj diyAudio Member Join Date: Feb 2005	Works for me!

1st December 2010, 08:03 AM	#17
francoiacc diyAudio Member Join Date: Aug 2010 Location: Italy	I really apologize for my ignorance, what do you mean for actve load? a Tranformer? If so which charateristic should it have? Do you have an example or some documentation I can look at?

1st December 2010, 02:35 PM	#18
DualTriode diyAudio Member Join Date: Aug 2009 Location: Sacramento	Hello francolacc, A Mu-Follower is a example of a classic actively loaded common cathode amplifier. The top triode is the active load. The Valve Wizard -Mu Follower For starters keep it simple try the circuit in post number 3. You will need a capacitor at the input ~ 0.47 uf. You will like the results. DT All just for fun!

28th December 2010, 05:11 PM	#20
francoiacc diyAudio Member Join Date: Aug 2010 Location: Italy	I finished a first prototype right now, and..... WORKS! It's still without a transformer since I'm waiting for it and was too impatient, but I've to say that the result is good. As soon as I've the transformer I'll test it and after I'll build the definitive 5654 line amplifier. I'm also planning to make a second stage with a cathode follower, I've to think about witch tube use... do you think that a 5654 should be a goof one? If so please help me with some example. Anyway the schema is the one at post 3.