Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: rbc3 on April 25, 2015, 03:18:41 AM
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Sophia Electric has these 300B tubes that are 2.5V which they claim are for use in 2A3 amps. Will these work in a Stereomour?
http://www.sophiaelectric.com/pages/se/carbon_300b_25v.htm
http://www.sophiaelectric.com/pages/se/300b-25v-spec.htm
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Just in case, maybe I should ask about whether or not the Sophia 2A3 Mesh Plate will work in a Stereomour.
http://www.sophiaelectric.com/pages/se/2a3-specification.htm
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I don't trust the datasheet at all. 2.5V/1.2A can't be a correct specification.
In any case, these are specified as 2A3's, I can't figure out why these wouldn't work.
-PB
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Yeah that is interesting. The second post with a link to their mesh plate 2A3 looks more like the standard 2A3 at 2.5V and 2.5amp filament current.
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I was comparing the specs of their 2.5V 300B to the standard 300B. The standard 300B is 5V at 1.2A filament current. I'm no tube expert, but my guess is that the filament design of the 300B is why the filament current is 1.2A even when running at 2.5V.
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I have been using that tube in my paramours for years. Sounds great. I am fairly sure it draws 2.5 amps.
Michael
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Michael,
You have your Paramours wired for 2A3 tubes and you're running the Sophia 300B 2.5V tubes in them? Have you tube rolled other tubes for comparison? If so, what are your thoughts about the differences between the different 2A3 tubes in Bottlehead amps?
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I use them in my Stereomour...no problems.
Different tube, different flavor...all good
Only your ears can decide which might be better
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I was comparing the specs of their 2.5V 300B to the standard 300B. The standard 300B is 5V at 1.2A filament current. I'm no tube expert, but my guess is that the filament design of the 300B is why the filament current is 1.2A even when running at 2.5V.
5V at 1.2A is 6W of filament power. 2.5V at 2.5A is 6.25W of filament power (about the same)
I'm sure it's a typo in the datasheets, and I wouldn't worry about anything strange happening in the Stereomour.
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I decided to get a pair of Sophia Princess Mesh Plate 2A3 tubes. They are an improvement over the Sovteks, mainly in the clarity of treble, and some improved detailing. But the're not as significant as tube rolling 300B tubes in Paramounts.
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By the way, another interesting observation to me anyway, is that the lowest voltage I can get with my multimeter when adjusting the hum balance with the Sophia Mesh Plate is that the lowest I can get it is 1.3mV. The Sovteks can get down to .7mV. The champs are my AVVT 32B in my Paramounts that measure 0mV through the whole hum balance adjustment except at the end.
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The champs are my AVVT 32B in my Paramounts that measure 0mV through the whole hum balance adjustment except at the end.
DC powered filaments in the Paramounts make this data point a little irrelevant in evaluating 2A3's in the AC heated Stereomuor.
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I completely admit I don't have enough knowledge to explain why the AVVT 32B measure almost no mV when adjusting the hum balance in the Paramount.
Back to the Stereomour and the 2A3 though, I spoke a little soon on the sonic differences between the Sophia Mesh Plate 2A3 vs Sovtek 2A3. I invited a friend over today to listen through my tubes and amps. I started with Stereomour with Sovtek 2A3 driving Omega Hemptone 8 monitors and then switched to the Sophia Mesh Plate 2A3. He was blown away by the differences. Then I played him the same music through the Paramount 1.1 with Sophia Mesh Plate 300B and Tekton Design Seas Pendragon and his brain melted. Point being that he heard a much more definite improvement over the Sovtek 2A3 and Sophia Mesh Plate 2A3 in the Stereomour. So much that his exact words were, "I can't believe all you changed were the tubes!" I do agree that the Sophia Mesh Plate 2A3 tubes give much higher highs with more detail and clarity to the point of delivering more dimensional and airy sound than the Sovtek 2A3. The Sophia Mesh Plate 2A3 are an amazing paring with the Stereomour and do a fantastic job driving even the 95dbn 1W@1M Seas Pendragon to volumes loud enough for the neighbors to hear.