Last Call on Siemens 6BM8

This post may bore you and 6BM8 tube amps are somewhat rare anyways.

My amp uses 6BM8s and I tested every 6BM8 ever made. Nothing sonically compares to the Siemens 6BM8. I doubt any amp under $1.5K can compare for quality sound to my amp. Not upgraded Scott 272, Scott 299, Fisher amps, etc. I have not found a better sounding tube amp yet. I am sure $5K would do it, but I do not want to spend $5K.

Anyways, no tube dealers have any Siemens 6BM8 left in stock in the USA. Three RCA label Siemens 6BM8 exists on ebay that state made in Germany. One more Siemens label 6BM8 is in Italy. Sellers are not aware the RCA are made by Siemens. At times some Siemens 6BM8 show up from Germany. I believe this is it for Siemens 6BM8 for sale. I have three spare sets that will likely last 30,000 hours, so I am all set.

You may want to consider these last four tubes for a serious upgrade to your 6BM8 amp. Matsushita, AWA Thorn and others just do not compare. Mullards are terrible.

 

I bought about every Siemens 6BM8 on the planet. Only one Siemens tube at a time is available and four separate tubes are not available. Some RCA are true Siemens, other RCA are Telefunken so be careful. And, some RCA are true RCA built. RCA built tubes do not have the 'U' shaped getter support. Ask if a diamond mark is on bottom glass in-between the pins. Those diamond marked tubes are Telefunken. I suggest only buying EL84 amps now, not 6BM8 amps. EL84 tubes in upgraded Scott 299 amps series sounds as good as upgraded 6BM8 amps with Siemens 6BM8. Other 6BM8 tubes just do not get it for best sound. The 6BM8 are two tubes in one and the triode section is likely the culprit for less than great sound from other than Siemens tubes.

 

Thanks for the info. It looks like even Siemens branded tubes can also be Telefunken.
I bought some earlier to try in my AN Kit PSU. Do any of these look legit?

 

BTW- is the 6BM8 in the Audio Note simply a voltage regulator? If so, the tube type would not effect the sound.

 

Yes, I believe it is. Some say they do have an effect on the sound, we'll see if I can tell after it's broken in and I start tube rolling.

This site talks a bit about the ECL82/6BM8
Audio Note Kits L3 Line Pre

 

Oops. One on left Siemens, center and right tubes in picture are Mullard.

 

I'm glad that I don't have any amps which use this tube. I hate having anything which requires unobtainable tubes to sound good.

I'm also glad that in my ignorance, I have absolutely no clue how these actually sound. Because if these should sound as amazing as you claim, I might feel compelled to follow you down this road.

 

Appreciate the update! Everything is sounding so good, I have not tried swapping the EH out yet. Not that it should make any difference, lol.

 

Svetlana 6BM8 is close, but I do want the best tubes and the Siemens has a sharper mid/treble response. Both tubes are that ultra low distortion sound I seek. I have one new set of 6BM8 in the amp and two spare sets of Siemens. Took me 3 months to find the spare Siemens 6BM8s.

I guess I have about 30,000 hours use of Siemens 6BM8 with the spare tubes. But, I now recommend a Scott 299A amp with Russian K40Y-9 coupling capacitors that sounds about the same as the Allied 333 with the Siemens 6BM8. I do not have a preference of either the Scott 299 or Allied 333. It is that close in performance. The Scott used Russian EL84 tubes that are common & sound fantastic. The Scott 299A has smaller audio transformers vs the B,C & D series. If the low bass is sufficient, the smaller audio transformers usually sounds better. Less inter wiring capacitance with smaller audio transformers, but large audio transformers play lower frequencies stronger.

 

Interesting. One of these days when I rebuild my Scott 299 I might give those caps a shot. Although A friend of mine and I did some extensive listening test on a bunch of different capacitors a few years ago, and we found that while none of the polypropylene caps we tried sounded like the Russian PIO caps, we barely could tell any difference between the PIO and a multicap RTX polystyrene cap. So I decided to go with those when I recapped my MC225. And I could not be happier with the results.

 

I find polypropylene types in certain brands about as good as the paper in oil K40Y-9. I try to use all K40Y-9, but sometimes use polypropylene small values in the amp tone controls as an upgrade. Tone control rebuilding with quality caps is as important as any audio coupling cap.

 

Hi @allied333 .

I have been checking out this thread as well as your May 2018 thread on the same tube. I wonder how you concluded that the middle 6BM8 in @waterclocker 's photo above to be a Mullard? I have a Mullard 6BM8 and it doesn't look like that inside.

Furthermore, from my research (erm.. ie. googling), that middle tube shares quite a bit of similarity with the Amperex 6BM8. It also look *exactly* like a made in W. Germany RCA that I got, and I have suspicion that it is a rebranded Philips Miniwatt. I understand that you previously says Philips Miniwatt is made in Australia with Mullard tooling, but that doesn't explain why RCA looks identical to it internally and it also look like Amperex and labeled as made in W. Germany.

 

I can see the tube manufacture by the shield design on top of tube.

 

My RCA labeled one turned out to be a Telam. That's a 100% match based on physical.

And it matches the middle one from waterclocker.



My Mullard one while similar, has distinct differences. namely the size of the O getter, the support point spacing on the mica, the location of the rib on the plates, and the wiring structure at the bottom.

 

The Siemens picture are not Siemens manufacture.

 

Yes. I suspect they are Telam or Amperex or Philips.