Elrog 300B vs Takatsuki 300B tubes

07-08-15: Tmmvinyl
I know very little about multimeters; mine is the Commercial Electric, Digital Multimeter, Model # MAS830B purchased at Home Depot.

Using the 200V measuring range, accuracy is listed as +/- 1.2% rdg +/- 10dgt.

Given that the meter displays four digits on that scale (for example, 120.1 volts), the accuracy of readings that are in the immediate vicinity of 120VAC would therefore be:

+/- ((0.012 x 120) + (10 x 0.1)) = +/- 2.44 volts

For your worst case reading of 123.1 the accuracy would be +/- 2.48 volts

So the actual voltage when you measured 123.1 could have been anywhere from 120.6 to 125.6 volts.

This information comes from the Takatsuki Denki website for the Takatsuki 300B tube.

Type: directly heated triode vacuum tube
Filament voltage: 5V/1.2A
Maximum voltage: 450V
Maximum current: 100mA
Maximum consumption: 40W

These numbers, representing maximum ratings, are identical to those which appear in the 1939 datasheet I cited earlier for the original Western Electric 300B. My impression is that the 1930's WE 300Bs are among the most robust 300Bs ever produced. Kevin Hayes designed the VAC Renaissance amps based on the characteristics of those tubes. And as noted earlier those amps drive the 300Bs extremely hard, yet tube life is MANY thousands of hours for tubes which are truly WE-spec compliant.

I can share the test results for one of my matched pairs if that would be helpful.... The plate volts Ep vdc test result was 300 for each tube; DC plate current lp mAdc was 73 and 73.1 for each tube; AC plate current lp mAac was 6 for each tube, Bias volts G1 vdc was 60 for each tube; Grid #1 leakage uA was 0.29 and 0.27 for each tube; Tube gain Mu was 3.6 for each tube; Plate resistance RP ohms was 0.6K for each tube.

I don't see any concerns in those numbers, and the numbers for which corresponding figures appear in the 1939 WE datasheet are roughly similar. Although these are results of tests that were performed at a plate voltage of 300, and we don't know what the results might have been if the test would have been performed at 390 volts (474 - 84), which George measured across the tube in Joe's Franks.

Also, the plate dissipation in the Franks which can be calculated for the Takatsuki from George's measurements is 32.0 watts (rather than the 33W that was indicated), and the plate current can be calculated as 82 ma. Those are reasonable figures, although not on the gentle side of the spectrum. Although of course George measured a line voltage of 119.4, and I have no particular feel for how much those numbers might increase if your line voltage actually approaches the upper limit of your measurement +/- the meter inaccuracy.

Finally, we have to consider that we can't say with 100% certainty that your particular tubes, or other Takatsuki 300Bs for that matter, conform to Takatsuki's published maximum ratings, especially given that the indicated tests were performed at a plate voltage considerably less than the voltage the tubes see in the Franks, and much less than the maximum ratings.

So the bottom line seems to be that there are considerable grounds for encouragement, but there are no guarantees. Apart, perhaps, from the warranty :-)

Best regards,
-- Al

Slight correction to my previous post. When I said...

For your worst case reading of 123.1 the accuracy would be +/- 2.48 volts

... I should have said:

For your worst case reading of 123.3 the accuracy would be +/- 2.48 volts

The rest of the calculation remains as I had stated.

Best regards,
-- Al

Slight correction to my slight correction :-)

When I said in the long post prior to the correction:

So the actual voltage when you measured 123.1 could have been anywhere from 120.6 to 125.6 volts.

I should have said:

So the actual voltage when you measured 123.3 could have been anywhere from 120.8 to 125.8 volts.

Best regards,
-- Al

Thank you Al. Your feedback has been reassuring.

I have an electrician coming to my home within the next few days to inspect the electrical installation to and in my listening room. Hopefully, he can get a more accurate reading on my voltage fluctuations. The voltages I measured today were comparable to the voltages I measured yesterday; today's highest reading remained at 123.3.

I may decide to revisit the idea of utilizing power regeneration in my system. The Pure Power 3000+ is near the top of my list because it has considerably more operating headroom than the comparably priced PS Audio P10 Power Plant.

This thread has been an education for me. Individuals like you make this Forum a pleasure to visit. Thanks again.

Only thing I want to point out is that the PS Audio units have linear power supplies which is great. I have a NO (or at least very limited) SMPS acceptance policy. I can ALWAYS hear them doing bad things to other gear. Some are much less offensive when well designed but overall I will take a linear supply over a noisy high speed switching supply any day. I have even compared class D amps with SMPS's vs class D with Linear and you guessed it, the class D amp with the Linear supply was far superior.

Perform the following test: While listening to a really well recorded piece of music, plug something in with a SMPS near your audio gear. Most likely the sound will take on a harder colder non-musical signature. The further the outlet powering the device with the SMPS the better. I have experienced this countless times with few exceptions. The Berning Resonant supplies are very very good, the iFi power supplies are much better than most but most others are horrendous. I literally unplug my PS3 (which is not part of my stereo but rather is used as a blue ray player) because it completely destroys my sound (even when it is off). I would never ever buy an expensive piece of audio gear with a SMPS (Resonant Power Supplies are a different animal) unless I could try it in my system with a full money back guarantee.

Wierd example of chopping-power (power supplies) messing up the sound: several years ago I had the excellent sounding Diverter HR in conjunction with my former MSB Power Dac and Meitner Bidat Plus. Everthing sounded wonderful but then one eve while listening I noticed the magic was gone. I went through everything in the chain and found no problem. Through the process of elimination only one change came to mind. I had decreased the brightness of the display on the Diverter. I can hear the scoffers already but the moment I took it back up to full brightness my system was singing again. I talked to Josh the brilliant designer of that awesome piece of gear and he mentioned that the way he reduced the brightness was to employ switching principals.

Just sharing my experiences with someone who may find them beneficial.