Eiclone measurements

a DIY, modified Mullard 5-20 monoblock design

Re: Eiclone measurements

Postby Shannon Parks » Sun Aug 08, 2004 9:38 am

Wodgy wrote:Has anyone done any measurements of the Eiclone (frequency response, THD+N, distortion vs. power output, etc.)? I realize that any measurements are going to depend on what bias the builder chooses, etc., but I'd still be interested in seeing rough measurements before diving in. Thanks!


Hi Wodgy,

I have all this data and then some. I've just been too lazy to post it. :sleeping:

But while testing out a linestage this morning, I realized that I need to change my audio analyzer software control to 'cal out' the THD+N from the source. The listed specs are .05%THD+N for the HP 8903B, but I just measured it (against itself with a jumper) and I was getting .19%THD+N with a 100mVrms output. Dang! This is good though, because before I realized this problem I had only been able to tweak my linestage (see the post in Tube 101) down to .25%THD+N across the band. While I was bummed out, now I know I'm actually under .1%THD+N. Mind you, I'm not a spec junkie, but an audio analyzer helps me zero in on the most linear tube operation.

Let me fix my code and I'll re-sweep an Ike.

Shannon
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no problem

Postby Shannon Parks » Sun Oct 10, 2004 9:36 am

No problem, Wodgy. Squeaky wheel gets the grease! :thumbup:

http://www.diytube.com/IkeData.pdf

For full disclosure, this data was taken this morning on an Ike with my CCS mod as I have modded both my Ike monoblocks for listening tests. Rest assured that up to 60W, the data is identical between this one an the stock Ike, which uses a resistor in the long tail. Though I have original data from months ago taken on a stock Ike, this data is more accurate as my calibration method for my audio analyzer had a flaw back then. The CCS mod is meant more for a 6B4 design which requires lots more drive.

Shannon
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Postby DortoH » Sun Oct 10, 2004 9:56 am

Any information like this for the ST35?
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Postby Shannon Parks » Sun Oct 10, 2004 10:34 am

DortoH wrote:Any information like this for the ST35?


Yes - let me sort out what is current and what needs to be re-taken. You can search the forums for earlier tests - search for 'transformer shootout'.

I also have some excellent, stock ST70 data taken, which I would like to contrast with the Ike.

Shannon
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Postby Andrea80 » Tue Dec 05, 2006 2:31 pm

Hi Shannon,

you have done this measurements with EL34?
If no, which are the power output and bias voltage with this tube?

Thank you so much,
Andrea
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Postby Shannon Parks » Tue Dec 05, 2006 7:42 pm

Andrea80 wrote:you have done this measurements with EL34?
If no, which are the power output and bias voltage with this tube?


Most of the early Ike data on was using EL34s - a quad of beat up, well used Sovteks that still put in a stellar performance. The more recent data may be KT88s, also Sovteks, as I was looking for mega watts with a 85% idle bias KT88. Anyhow, the EL34 can really handle the abuse of around 500V and high dissipation, like in the Eico HF89 which is the Ike or Eiclone namesake. Output for this configuration is usually 60W at 1%THD. The B+ is around 485V and the idle current close bewteen 60mA and 65mA.

Many frown on this abuse, but the more these power tubes sweat, the sweeter they sound. I lowered the bias current to 50mA in this circuit once for a test and the distortion was measurably higher. With $40 quads, I'm not worried. :)
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Postby erichayes » Tue Dec 05, 2006 10:25 pm

Hi All,

On my "Eiclone" prototypes, which are essentially the same as Shannon's except for wiring and power supply, I run the JJ KT88s at 72 mA per tube and, when I was running EL34s, ran them at 60 mA per. And you thought you were abusive, Shannon.

If your power supply's stout enough, I'd recommend y'all trying it, if only for a half hour or so just to hear the difference. Be aware, however, that your transformers are probably going to get quite warm--if not downright HOT.
Eric in the Jefferson State
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Postby Andrea80 » Wed Dec 06, 2006 6:46 am

Many thanks Shannon for your informations!

EL34 works better if biased hot? I am right?
More power -> lower distortion...how it can be? :o
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Postby Shannon Parks » Wed Dec 06, 2006 7:24 am

Andrea80 wrote:EL34 works better if biased hot? I am right?
More power -> lower distortion...how it can be? :o


You got it. The trade off is lower life, but I'll take better sound every time. Maybe I'll be easier on the Blackburn Mullards, though.

I think I better schedule a Boonton test showing this phenomena.
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Postby dhuebert » Wed Jan 31, 2007 9:32 am

I'd be interested to see a shootout between Sovtek KT88, 6L6 and a few different brands of EL34. Find the sweet spot for each tube and compare best for best. Something else that might be interesting would be to compare a well matched set of what ever with a badly mismatched set. Or a KT88 with an EL34 or a Mullard EL34 with an E-H EL34. I wanna see some fireworks at someone elses expense.

Don
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