Owen, it is not PCL86 (or any other heater version of the same tube) but I'm not saying any more
PCL86 (and PCL82, and all incarnations of it with different heater specifications) is already going down the way of EL84, ECC8x, EL34, KTxx, 6x6, etc. The tube I have in mind costs about $1-2 apiece, shipped, and doesn't come with a relatively high power pentode in the same bulb.
Posting names always runs the price up, it's not because a specific tube would be a fad, it's because tubes in general have become a fad and people are too stupid to make their own circuits so they copy existing designs and use their money to buy whatever tubes these design employ. Broskie is kind enough to post his design because that helps him sell his boards and software (d'uh). Since such designs (posted by people genuinely interested in tubes) are honestly weird extremes of what's avaliable, things that those people would never post if they were made with "ordinary" tubes, this drives the demand up rapidly and same happens with price.
im not ashamed of being stupid but i do like the sound of tubes and i'll admit that i have been severely hosed and misled by speculators and con artists. but im glad that there are decent chaps who will help an invalid like me to audio bliss heaven.
that 13em7 tv tube sound great to me. i just got two more in the mail for 5 bucks and they are very strong tubes with black plates (the seller said that this was good though i have no idea why) i notice that they produce more sound that the other 13em7s i have.
what do you think of a 1 watt amp with little 98dB patio outdoor speakers.
i feel a lot more comfortable listening to the tv tube amp because i know the tubes are inexpensive
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I think this is just what the doctor ordered
Seriously, extremely efficient speakers such as the ones you mention and ~1W of honest to God RMS output power is enough to make one's ears hurt in a closed small room, and enough to make up for all the music listening I do in larger room/space. I bought Klipsch RB-61 on advice of a fellow forumite and my ~1W per channel amplifier (it just so happens that it's a "spud", utilizing PCL82 in triode mode) is loud enough at 75-80% of input volume with a single speaker ... I have redesigned the PCB for straight pentode mode so I can put the input volume potentiometer to some use Some very specific tubes aside there aren't any "TV" (or other application) tubes really. They are devices with certain parameters and just about any tube fitting certain criteria can be used for audio, much more so if it is useful for TV (TV function implies higher frequencies, which can mean unwanted HF behaviour when working only in AF role, but it also means top performance at the top and above audio band, where SS enthusiasts swear by their gear and measure its response in square wave up to 200 KHz and whatnot
). Care must be taken to avoid the negative sides and you get a whole new world of less-valued tubes to experiment with.-----
By the way, I don't want to sound too off-topic but writing of my reply somehow reminded me of Johan Potgieter for some inexplicable reason - I haven't seen anything from him in this forum a while and I miss his posts, does anybody happen to know if Johan is still alive and kicking ?
The cheapest PCL86 I can find is $6 apiece + $6 S&H, and this is some Polish stuff, I prefer Philips or EI or some similar brand manufactured on Philips equipment. You're not very far though, keep looking, but please don't post the answer. Said triode matches parameters (rp, mu, S, operating point Ia) exactly or very very close and has similar low voltage (under 50V Va) characteristic.
I think this is just what the doctor ordered
i read that 3dB is doubling the volume in the logarithmic scale. im using 89dB speakers now so with the amp turned up to 10 i will get 10*2*2*2 the volume with 98dB speakers. that is like turning the amp up to 80! LOL!!
is there a difference in sound quality with higher efficiency vs lower efficiency speakers? i read that some speakers are more tube friendly than others. i wonder how tube friendly these patio speakers will be.
Your calculation is correct, but you don't percieve double the SPL as twice as high a volume, it is only marginally higher (= you are not likely to notice an increase smaller than 3 db at all, 3 db is the first noticable step). The volume knob sweeps entire dynamic range so if it had 10 steps, each step would be 10+ db.
There is a difference in sound quality between different speakers so by extension it is quite conceivable that there is a difference between model A higher efficiency speakers and model B lower efficiency speakers.
The difference of those extra 9 db/W in efficiency is that a couple of watts, easily avaliable from just one single-ended output tube per channel, will sound just as loud as 20W or more would into lower efficiency speakers, but such power would require far more complicated and bulkier amplifier design, more generated heat, run at higher voltage, etc.
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