Does anyone care to ask an amplifier designer a technical question? My door is open.

@fsonicsmith

Ralph-you should never have entered this thread. You tried to kill the OP with kindness and camaraderie, and he spit on you every chance he got. I think most of us reading through this thread can see the OP for what he is; entrenched in the remote past and bitter. His hubris is out of bounds. I have been around long enough to suspect that there must be something else going on in the OP’s life that is causing him to behave so poorly.

As Oldtech noted, this is my thread.

Hi,

fsonicsmith., you seem to troll my threads, this is not the first time I have encountered you. Aren’t you the one who said you knew only 1% of what designers know. I was looking for that one.. It appears a lot of your responses are now missing.

Ralph has not honored the stated purpose and rather come here to once again to hawk his paradigms and unusual ideas about cartridge loading and RFI.  You are into vinyl I see. Do you agree with his loading suggestons? Dont we load a cartridge to change its sound?  That last one about loading a cartridge for the sake of the preamp was so out of the world. Most of just a juse a ferrite bead to stop RF from coming in. 

I was happy to discuss his points till it got out of hand. Ralph can run his own thread if he wants to promote his paradigms. You write well, perhaps you could edit the one on Power so it makes some sense.

I do agree, Ralph should have never entered this thread nor should you. I dont see a question and I dont see a contribution. You left, said you wouldnt come back, but you did.

I dont mind any designer coming here if we both understand electrical science in its accepted current form and speak the proper language. If you want to read made up science there are pleanty of other threads on here for that.

I have a a question for Ralph, Why have you not sent an amplifier to Stereophile for review? They have reviewed all of mine and preamps too.

What prompted my question regarding tube types was the discussion in this thread about 6sn7/12au7/6sl7/5751/12ax7 tube type use for preamps and amp inputs. But there is also the question of power output tube choices - el34/6550/kt88/kt120/kt150, etc. It appears that some designers use the same tube types in their products, however there are instances where designers switch types year to year, or even have concurrent products performing the same function (amp or preamp) but using different tubes. Consumers and reviewers, also, sometimes prefer only 6sn7 or 12au7 based preamps, or kt120 or el34 amps, for example. I was hoping to get the viewpoint of someone who makes this choice. 

@ georgehifi
" I've set a 6sn7 in a preamp up on the oscilloscope and talked at it, and watched my voice being duplicated on the scope as wave forms superimposed on the 1khz test wave, and was quite eyebrow raising just how loud it was compared to the test wave."
Very interesting!
I would also amplify - lol - the sentiment that this is truly a wonderful thread!  :-)

Roger;
I have not deleted any of my posts. Not a one. 

fsonicsmith., you seem to troll my threads, this is not the first time I have encountered you.

I think you are mistaken. I don't recall ever entering into any debate of any kind let alone some type of trolling-skirmish with you. IMO, you are once again confused. 
Let me ask you this Roger; other than one of Ralph's amps, which modern era top-tier tube amps have you actually sat down and listened to with not just your own planar speakers, but also modern coned speakers across a decent spectrum? I ask because as I have said previously in this thread, you keep referencing ancient amplifiers of the remote past which you conveniently choose to piss all over. Others have asked you this same question too and you have not responded. Are you living in a cave?
I re-entered because I could not resist. I saw that your irascible behavior has continued and not just towards me, so I felt better about re-entering. I do respect you and your knowledge base, but it also pays to be a gentleman. Towards the end of his life, Charley Hansen (you misspelled his name a few posts ago-shame on you) was very vocal about MQA and his debate with JA on another forum became quite heated. Throughout that give and take, both managed to remain polite and civil. You could take a lesson from them. 
I brought up Charley Hansen's interview towards the end of his life about his latest iteration of amps finally-in his opinion-capturing the sound of the best modern tube amps. Have you sat down to listen to any of his amps? Have you analyzed why they might sound as they do from an engineering standpoint?
I am into vinyl, thank you. I am the proud owner of a Manley Steelhead, which I bought new. I love it and love Manley. I wish the aesthetics of their amps suited me more. I acknowledge that letting aesthetics get in the way of a purchase decision seems silly. I also acknowledge that Ralph's views on cartridge loading differ from my own. But as you quoted me (accurately), I have 1% of your engineering knowledge and his too. But I have years and years of empirical experience and based upon that, I have chosen to disregard Ralph's views on cartridge loading as simply not applicable to my particular system and experience. 

@krelldreams What prompted my question regarding tube types was the discussion in this thread about 6sn7/12au7/6sl7/5751/12ax7 tube type use for preamps and amp inputs. But there is also the question of power output tube choices - el34/6550/kt88/kt120/kt150, etc. It appears that some designers use the same tube types in their products, however there are instances where designers switch types year to year, or even have concurrent products performing the same function (amp or preamp) but using different tubes. Consumers and reviewers, also, sometimes prefer only 6sn7 or 12au7 based preamps, or kt120 or el34 amps, for example. I was hoping to get the viewpoint of someone who makes this choice.

Thanks for an on point question. For years Everything ARC made used 6550s. Some makers are similarly fond of EL-34s. Some consumers are in love with that little 9 pin EL84.

Part of the tube choice is driven by, you, the consumer. I built an EL84 amp because I know there a lot of people who love that tube. I did do someting different and got 35 watts per pair rather than 17 watts. I raised the power, kept the safety and life of the tube and made somethig to this day people do not believe possible. The application is laid out in my 2018 Burning Amp presentation.

On the other hand I built the RM-9 to take any octal power tube, of which there are many. Power stays the same, only the negative bias changes. I did this so that users could compare widely different power tubes on the same platform. In my thinking how can someone say something general about a particular power tube when they are comparing it in two different amps? David Manley got very upset over the RM-9 and we exchanged several letters in pubic in the Stereophile. They are fondly known as the Manley/Modjeski letters. I hope to get them up on the HIFI school site. At the same time we coined the term "Tube Rolling" and I made buttons imprinted "Member, Nimble Tube Roller Society" This was way back in 1983 so young folks may have missed it. David was totally opposed to tube rolling.

You can take an old RM-9 and use 4 of the KT 120s or 150s instead of 8 of the earlier tubes. Will still produce full power with half as many tubes.

What I see in the market place now is that New Sensor (Tungsol) is creating larger power tubes and there are those designers who appear to get out a new amp with the new tube as fast as they can, which does worry a bit. If a designer goes for the full power of a KT-150 and you have to go back to the 120 or 88 you will loose power. If the Russians do something bad the KT 120 and 150 could disappear until someone else takes it up. You can add your own "ifs" to the list. HP and other equipment makers had a policy any part had to have at least one other supplier. Single source parts not allowed.

Tube cost is another criterion. EL84s are very inexpensive, EL 34s next. then 6550/KT88, KT 120s. However the KT150 cost to me is about twice the KT 120. The look and power are quite a departure and I will not be surprised it the next bigger KT is already in the works.

KT, stands for Kinkless Tetrode in the UK. We use Beam Power Tube in the USA for the 6550 which is essentially the same thing. The first beam tube was the 6L6, a great tube that no one uses because the public has someting against it, for no good reason.

In essence, You, the buyer are controlling the tube choice as much or more than the designer. Hope you choose well. :)