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Old 21st May 2012, 08:25 PM   #11
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Hey Ale,
Have you considered making a small Circlotron with these tubes? Would be more complicated though, as an input transformer or input tube would be needed.
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Old 21st May 2012, 09:06 PM   #12
mogliaa is offline mogliaa  United Kingdom
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Quote:
Originally Posted by Bigun View Post
Looks interesting to me !

I know you like this tube, but perhaps the 6BX7 gives more headroom for anode dissipation.
Hi Bigun,
On the last edition of Morgan Jones' book he found that 6BX7 shows a big variance in distortion so these need to be manually chosen for audio use...
Cheers,
Ale
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Old 21st May 2012, 09:08 PM   #13
mogliaa is offline mogliaa  United Kingdom
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Quote:
Originally Posted by TheGimp View Post
What if you combined the diodes with a pair of 62mA pico fuses in series with the supplies. You might need to drop your bias current slightly to be sure you don't blow the fuse during normal operation.

Increase R2 to 35R and R4 to 60R and your bias current drops to 52mA, Zo is around 17.6R, and THD is 0.12% at .109Vrms out. Anode plus screen dissipation drops to 7.8W

Hi Steven,
Many thanks. Looks like a sensible approach! Will need to breadboard this to find out how it sounds then....
BTW never used pico fuses, are they easy to buy?
Cheers,
Ale
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Old 21st May 2012, 09:10 PM   #14
mogliaa is offline mogliaa  United Kingdom
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Quote:
Originally Posted by revintage View Post
Hey Ale,
Have you considered making a small Circlotron with these tubes? Would be more complicated though, as an input transformer or input tube would be needed.
Hi Lars,
I'm not familiarised with the circlotron, it's in my To Do list! Any recommended reading like "circlotron for dummies"
Cheers,
Ale
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Old 22nd May 2012, 06:24 AM   #15
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Hey,
Did another testsim. By parallelling two 6E5P and using them in SY´s Heretical topology(sand CCS) you get Zout below 20ohm and about the same distortionfigures as the White.

But note that no input cap is needed if an input transformer is used.

What 6E5P modelo do you use? These are the models discussed at Slagles forum: :: View topic - 6E5P triode-strap. I suggest using Dmitrynizh´s.

Last edited by revintage; 22nd May 2012 at 06:42 AM.
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Old 22nd May 2012, 06:50 AM   #16
mogliaa is offline mogliaa  United Kingdom
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Hi Lars,
I used a basic model from a library, definitively not Dmitry's. I will do so. Can you please post your circuit or ASC file?

What input transformer you recommend here?

Thanks
Ale
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Old 22nd May 2012, 08:42 AM   #17
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Hey Ale,
Where did yoiu get the 90mVrms figure? The phones have a sensitivity of 98dB/1mW into 32ohm. This is 16mW at 110dB(max needed) and corresponds to 0,72Vrms, if I´ve done my homework right. Could you please doublecheck?
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Old 22nd May 2012, 01:37 PM   #18
mogliaa is offline mogliaa  United Kingdom
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Hi Lars,
As said in first post I'm not sure but remember I did a quick test and 100mVrms was loud enough to me. I may need to rerun the test over the weekend...
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Old 22nd May 2012, 02:25 PM   #19
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I just assumed the stage should be designed to take what I have seen in some specs being max level. Just did some Googling and found these high levels are hazardous to your hearing. So I back off: Why not design for 98dB=180mV?

You listen at a low level as 100mV corresponds to something like 92dB. Good enough, you will keep your hearing intact.
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Old 22nd May 2012, 04:37 PM   #20
mogliaa is offline mogliaa  United Kingdom
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Do you think we can 180mVrms with low distortion out of your proposed circuit using two valves and cathode CCS as per SY's circuit?
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