JohnA Posted January 2 Share Posted January 2 Why isn't/couldn't high power broadcast tubes be used to build a high output SET amp? Say 50 watts from a 3-500xx? I still think 50 watts of good power is what Heritage speakers ought to have. Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted January 2 Share Posted January 2 I disagree. I have yet to find the limits of my 8 wpc 300B amp. I can listen to Tool, Black Sabbath, ZZ Top etc. at any level I care to in my 26 x 16 room and it never breaks a sweat. I'm not going to give you the novice mantra of "no distortion". But I will say I can hear ZERO compression at levels that would be dangerous for extended listening sessions. Of course that's not what SET amps are about anyway. But it's nice to know it's there when I want to let 'er rip. But there are 845 and 211 amps that can give you ~25 watts/channel. Even that is overkill for 100 db + speakers. 2 Quote Link to comment Share on other sites More sharing options...
JohnA Posted January 3 Author Share Posted January 3 This is actually a question about tube amp design and performance. Have you seen an audio amp designed around a 3-500 or similar triode? Quote Link to comment Share on other sites More sharing options...
richieb Posted January 3 Share Posted January 3 Not a broadcast tube but the Russian 6C33 military based tube is a formidable candidate. BAT uses this is many designs a do several others. I personally owned two or three pairs of the Audio Mirror SET monoblocks using this tube. An amazing triode capable of 45 watts + - running in parallel, 2x each mono. Rugged as hell, hotter than hell, once and maybe still used in MIG fighter aircraft. Shakey had a pair of their baby brothers using the 6as7 tube for 20 watts. Quote Link to comment Share on other sites More sharing options...
JohnA Posted January 4 Author Share Posted January 4 On 1/2/2024 at 9:44 PM, richieb said: Not a broadcast tube but the Russian 6C33 military based tube is a formidable candidate. ....... An amazing triode capable of 45 watts + - running in parallel, 2x each mono. Rugged as hell, hotter than hell, once and maybe still used in MIG fighter aircraft. ..... That is just the thing I was looking for. So, 2 tubes, run in parallel as SET can make 45 watts? I did not know SETs could be paralleled, thus the question about broadcast tubes. And I was curious as to whether a broadcast tube could sound good. Quote Link to comment Share on other sites More sharing options...
richieb Posted January 4 Share Posted January 4 1 hour ago, JohnA said: That is just the thing I was looking for. So, 2 tubes, run in parallel as SET can make 45 watts? I did not know SETs could be paralleled, thus the question about broadcast tubes. And I was curious as to whether a broadcast tube could sound good. I haven’t been to the Audio Mirror site in sometime but you might find much more technical information on this particular design. There’s actually a pair currently available on USAudiomart. Each mono are quite heavy at around 45 lbs.The transformer/power supply are enormous. But yes, 2x 6c33 per mono + (1x 6sn7; 1x 6sl7) make 45 single ended watts. So I’m only assuming this is considered a parallel circuit? And I’m sure much like a 211 or 845 they do run extremely hot. Just to pick up one tells you they are indeed an “industrial” , heavy duty tube. After all they were used to run the avionics in MIG fighters. Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted January 4 Share Posted January 4 Keep in mind that once you use two output tubes per channel you are back into push/pull territory. With our speakers, there is no need for such output. The clarity and immediacy of an SET can't be matched even by using SET tubes in PP configuration. Yes, those amps can sound very good too, but it's not the same sound. I still say if you long for high power while maintaining one tube per channel, look to the 805 or 845. Cary Audio and Line Magnetic have some good offerings. I haven't heard the Cary but I did own the Line Magnetic 518ia for a while and it's a very good amp. 1 Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 4 Share Posted January 4 9 hours ago, JohnA said: That is just the thing I was looking for. So, 2 tubes, run in parallel as SET can make 45 watts? I did not know SETs could be paralleled, thus the question about broadcast tubes. And I was curious as to whether a broadcast tube could sound good. I have heard of 2 tubes being used in parallel used in a SET but it is for a different purpose than more power which I will not get into. As Shakeydeal said, when you see 2 power tubes per channel 99% of the time it is going to be a push pull amplifier and not SET. What you are going to see in the majority of SET amplifiers is a power rating of 5 to 7 watts. Anything more than that you are looking at transmitting tubes used in broadcast radio stations of old. Extreme high voltage and cost for a well made one and not practical for home use. And yes I know plenty here that have those kind of amps but they are not the common retail ones being offered for sale. There are $25K SET 300b's being offered in the market for a reason. The 300B is the one most desired to have because it was one of if not the best audio tube ever built and by Western Electric of old. Just to add, a SET amplifier with 5 to 7 watts are perfect for our horns. If not exactly what speaker would they be good for? Duh, most all other speakers do not have the efficiency of our speakers. With most of us, we never get out of the 1 watt window of use no matter what else you hear. Test by some of the best in the industry have proved this to be true. Free market though so buy what you think you need and makes you happy. Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted January 4 Share Posted January 4 1 hour ago, Shakeydeal said: Keep in mind that once you use two output tubes per channel you are back into push/pull territory. As mentioned by @richieb tubes can be paralleled and still be used single ended. I had a McAlister Audio PSE that used sweep tubes for 15 watts/ch, an excellent amp. There have been a few PSE amplifiers made and sold as regular production by known brands and builders like Dennis Had will make them on request. Just like any amplifier they have their strengths and weaknesses. Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted January 4 Share Posted January 4 Agreed. But parallel single ended does not sound exactly like single ended. Both can be good, but for that "lit from within" purity, you'd want a true SET. At least that's the way my ears hear it. Quote Link to comment Share on other sites More sharing options...
OO1 Posted January 4 Share Posted January 4 there 's a Canadian EE in Ontario who has a lot of experience building SET amps with the Russian 6C33C-B power tubes , with 4 tubes , his base model SET amplifier delivers 12 wpc although it sounds like a 4x more powerful tube amp , he also builds custom designs email fluxion.biz@gmail.com Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted January 4 Share Posted January 4 I tend to agree that a single tube is usually better as it eliminates needing very well matched pairs/side or circuitry that helps the 2 tubes to play nice with each other. When made right PSE can be very impressive. My experience with PSE amps parallels (pun intended) @OO1's statement about them sounding much more powerful than the watts/ch would indicate. Paralleling tubes reduces the output impedance by half which may be beneficial with some speakers. Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted January 4 Share Posted January 4 Agreed that speakers posing a more difficult load would benefit. But as @henry4841 said above, if our speakers can't play nicely with single digit power, what in the world could? Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 4 Share Posted January 4 Not everyone can hear or appreciate what a SET tube amplifier like a SET 300B brings to the table. Understandable and will save them a lot of money . Not a large market being it takes a very efficient speaker to work properly but with horn speakers that reveal the subtle details of music along with a SET tube amplifier which also provides an unmodified audio signal it can be a wonderful experience. Those with a trained ear with experience in the audio world do hear what is so wonderful a sound and detail they present. That being said though I can and do appreciate the difference in sound a PP tube or transistor can make. A serious audiophile will benefit from a good SET and a good PP amplifier for a difference in sound. I will use a SET for a few weeks, months and love the sound then put in a PP amp and think boy this sounds great then after a few weeks, months do the same with a SET and say the very same thing. All can sound good but my preference is a SET tube amplifier with the music I prefer. Enjoy. 1 Quote Link to comment Share on other sites More sharing options...
richieb Posted January 4 Share Posted January 4 Now I’m wondering about running two triode power tubes per channel is actually a “parallel “ circuit. I’ve looked at the Audio Mirror site where his new 6c33c monos are $19K/pr. and the Lamm Electronics site where their 6c33c amps are many multiples in price compared to AM. My point is never do any of these producers describe their single ended amps as a “parallel circuit”. Class A single ended is as descriptive as it gets. So two power tubes are used in each channel are automatically a “parallel “ circuit? I’m not so sure that’s a given at this point - Quote Link to comment Share on other sites More sharing options...
henry4841 Posted January 4 Share Posted January 4 2 hours ago, richieb said: Now I’m wondering about running two triode power tubes per channel is actually a “parallel “ circuit. I’ve looked at the Audio Mirror site where his new 6c33c monos are $19K/pr. and the Lamm Electronics site where their 6c33c amps are many multiples in price compared to AM. My point is never do any of these producers describe their single ended amps as a “parallel circuit”. Class A single ended is as descriptive as it gets. So two power tubes are used in each channel are automatically a “parallel “ circuit? I’m not so sure that’s a given at this point - I do not see how 2 output tubes in a SET amplifier could be used in another way. That is if they are the same tube. I have seen schematics where let's say a 300b power tube is used to drive one of those big transmitting tubes and one could call that two power tubes in series where one drives the other. When I see two identical power tubes in one channel in a SET amplifier I just assume they are being run in parallel running more current for the output circuit. But there is a lot I have not seen when building electronic circuits though. A schematic and someone with enough talent could tell exactly how two identical output tubes are being used but not seeing the schematic I will assume they are being run in parallel until someone says and shows me differently. If two identical power tubes are run in series one would naturally think that one would overdrive the other tube if everything else is equal. Most if not all SET amplifiers are two stage amplifiers with just a driver tube circuit and the power tube circuit. Simplicity is what makes them so sweet sounding. Nelson Pass in some SS Firstwatt amplifiers utilize just 2 stages for the very same reason. Quote Link to comment Share on other sites More sharing options...
richieb Posted January 4 Share Posted January 4 The F3 I’m currently listening to is a NP singe stage I believe. And like much of the gear ‘round here it sounds “okay” - Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted January 4 Share Posted January 4 2 hours ago, richieb said: Now I’m wondering about running two triode power tubes per channel is actually a “parallel “ circuit. I’ve looked at the Audio Mirror site where his new 6c33c monos are $19K/pr. and the Lamm Electronics site where their 6c33c amps are many multiples in price compared to AM. My point is never do any of these producers describe their single ended amps as a “parallel circuit”. Class A single ended is as descriptive as it gets. So two power tubes are used in each channel are automatically a “parallel “ circuit? I’m not so sure that’s a given at this point - Who said 2 triode power tubes per channel is automatically a parallel circuit? Obviously you can use 2 triode tubes in a push pull amplifier, but then it is no longer SE (single ended). Dick Olsher in his review of the Audio Mirror calls it a PSE amplifier. Ever know of any stereo equipment manufacturers that keep things close to the vest or get creative in their descriptions of product? For another poster: when a tube that is normally considered an "output tube" is used as a driver tube it is no longer an output tube driving the speakers, but simply a tube used to drive the output tube. Therefore the amp remains a single ended amp with 1 output tube per channel. Quote Link to comment Share on other sites More sharing options...
82 Cornwalls Posted January 4 Share Posted January 4 6 hours ago, Shakeydeal said: ....if our speakers can't play nicely with single digit power, what in the world could? I was listening to some jazz the other day and was curious, so I got the SPL meter out and did some calculations. My average power was @ 1/20 of a watt. Quote Link to comment Share on other sites More sharing options...
richieb Posted January 4 Share Posted January 4 7 minutes ago, 83 LSIs said: I was listening to some jazz the other day and was curious, so I got the SPL meter out and did some calculations. My average power was @ 1/20 of a watt. There’s a reason Nelson Pass uses the name First Watt for his “skunk works” amplifier designs - Quote Link to comment Share on other sites More sharing options...
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