ChrisK Posted January 22, 2003 Share Posted January 22, 2003 I stopped by Dr. Bruce Edgar's shop on my way home from work today today to say howdy and shoot the bull. He is such a great ol' guy. A perfect example of the "Greatest Generation". Anyway, he sent me home with an amp to try out. It is the prototype of a Cyrus Brennaman designed EL34 based 15/15 watt stereo amplifier. Here are a few pictures (please excuse my poor photographic skills), then a couple of questions - First off this amp sounds very nice. Seems much more effortless than my Cary. The Cary is a little more detailed, but I could easily live with something like this. I am considering going to seperate monobloc amps with a preamp. Up until hearing this I was pretty set (excuse the pun) on some sort of 300B based SET amp. Dr. Edgar tried to explain why PP can be a better choice for high effciency speakers, but alas my techno-ignorance came shining through. He talked about headroom, distortion, feedback, 2nd (or was it 3rd?) order distortion, etc., etc. He might as well been Shaq O'Neil speaking Chinese. Can somebody possibly explain the pros & cons of SET vs PP (Reader's Digest condensed version) and maybe offer a few opinions? Thanks, Chris BTW This amp (with a few modifications) is going to be available for $1,500. Only problem is neither Dr. Edgar or Cyrus B have a website or distributors to order from(Sounds like a job for Kelly.). I have to say that the much more expensive Cyrus Brennaman electronics teamed with Dr. Bruce's Titan horn system creates the finest stereo sound I've ever heard. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 22, 2003 Share Posted January 22, 2003 Wow nice looking amp !! Actually sounds like a pretty good price ! What I can't figure is why they used a 6AN8 phase splitter tube yuk ! I would love to be in your shoes and be able to roll by and have a chat with such a interesting person as Edgar. I met him once at one of the Chicago horn club meetings. Seemed real nice but I really never had time to really chat with him. I would love to hear his opinions on PP versus Set. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 22, 2003 Share Posted January 22, 2003 You know the thing I see that would vastly improve the looks of that amp and would hardly cost much at all. Change out those cheap looking transformer bell bolts and nuts to something black and also lose the silver screws holding the transformers in they just look out of place with that nice black chassis. Craig Quote Link to comment Share on other sites More sharing options...
ChrisK Posted January 22, 2003 Author Share Posted January 22, 2003 Craig, DBE said that there were going to be modifications on any prodution units. He mentioned changing tube types. Something about getting ahold of a slew of Siemens NOS tubes that were very, very good and also inexpensive. Yes, it is a treat to be able to drop in on Dr. Edgar. He is a true treasure to be around. If you're going to the Lima show, get a group together and take him out to dinner. He'll talk your ears off. Today he showed me the monster bass horns he's building for Lima and a few other projects he's working on. Regards, Chris Quote Link to comment Share on other sites More sharing options...
lynnm Posted January 22, 2003 Share Posted January 22, 2003 Nice looking amp ! I run a PP amp and am open to trying a SET but if Dr. B. told me that he liked that amp that would do it for me as far as any research goes ! Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 22, 2003 Share Posted January 22, 2003 I think you have a typo, you mention EL-34's. Some big ol' trannies for a El-84 PP. I'd try to con Bruce out of it, and keep the Cary too. Can't have enough tube amps. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted January 23, 2003 Share Posted January 23, 2003 Whats the Lima show? Tom Quote Link to comment Share on other sites More sharing options...
Deang Posted January 23, 2003 Share Posted January 23, 2003 I'm not about to cross swords with Dr. Edgar. More power with push-pull, so -- more headroom. There are however, a ridiculous amount of variations with push-pull, and generalizations are difficult. Basically though, with push-pull amps, one tube does half the waveform, and the other tube does the other half. They are therefore subject to some crossover distortion. They also produce predominately 3rd order hamonic distortion. There are good push-pulls and mediocre push-pulls. Very good ones are Class A with zero feedback. However, the Scott 299's and Eico's are well liked here -- and they are Class A/B with a moderate amount of feedback. I'll save the triode, pentode, and pentode wired in triode bit for someone else. SET amps are always Class A, and one tube does the whole waveform - so, no crossover distortion. SET amps produce 2nd order harmonic distortion, and tend to be more euphonic in nature. Within their designated power range, they should have less distortion than push-pulls. However, once out of that range -- distortion goes through the roof. Dr. Edgars comment to you regarding push-pulls and SET is odd, since he also believes horns typically only need miliwatts to function properly. As far as SET amps go -- they are all not created equally, and the quality of the transformers become critical. Because of my love for some higher than normal SPL's at times, I dealt with the headroom issue by going with high current SET. In their original configuration, my amps are capable of 18 wpc. However, I run them in 4 ohms, and so get a whopping 9 wpc with my RF-7's. I have no trouble clearing the kids and wife out of the room when I want to. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 23, 2003 Share Posted January 23, 2003 I have been pondering this question for a while now and came up with a solid conclusion a few months ago. Most of the wonder was brought about by new experiments with my vintage EL-84 amps and a host of other amps that have come in and out of here over the last year, these all in comparison with the various single-ended triode amps I have heard, including my 2A3 SET monoblocks. In answer to your question about what is the best and which direction you should turn regarding SET and push-pull, I have found the answer that works for me: Both have their merits and I will always have good examples of each. With push pull, however, I have discovered I much prefer the sound of the vintage amps. I have come to the conclusion that the iron is just better for the most part, and in order to get the same quality in current iron, the price has to go up quite a bit. Consequently, one has to spend a lot more on the PP amp to come near the quality of the vintage amps. Amps like a tweaked, up to spec, EL-84 offering like the EICO HF-81 can be extremely rewarding via the Heritage horns. FRankly, I have had thoughts that if this was ALL there was, I would not be that unhappy at all; indeed, I would actually be more than happy. I think some of the vintage EL-84 amps put a good percentage of the modern push pull amps to shame, despite preconceived notions to the contrary. While the EL-34 used to be my push pull tube of choice, and is STILL a favorite of mine, the EL-84 has to be the body and soul of the PP pentode world (although more than a few might suggest their own favorites). The good vintage PP amp can have a bit more drive and power in the lower mids on down. What it WONT have is the same immediacy and intimacy as the good SET amp. It might actually have more soul depending on the unit but there is a certain magic about SET reproduction that is just not equaled by ANY PUSH PULL AMP, not matter what the configuration. There is this purity and ultimate unfettered quality to a good SET amp that is its own domain. The sense of the see-thru nature and expanding sound run hand in hand with the SET amplifier. Still, Obviously, some are better than others here. That is why I ultimately will have BOTH on hand and I frequently listen to BOTH every day. Ultimately, I leave my 2A3 monoblocks in the main system with the PP in my second system. I personally like the 2A3 more than the 300B on the whole and find the my version of the Moondogs which feature Jensen Copper Oils and Audio Note Tantalum resistors with tube rectification to be amazing in the low end, bettering the 300B in definition. The 300B, on average, has very full sound but does not equal the low end definition of the 2A3. The 45 tube is a good one but I believe you need 104dB to make it sing. If I were you, I would opt to get the best SET you can and also procure a great PP alternative. If you opt for the amp(s) pictured above, I think you will like the sound. On the other hand, I think the vintage option is great as well. I like the outputs and the rectification aspect of that amp. With even the best push pull, you wont get the same thing you can with a quality SET, though. Its hard to give that aspect up once you are used to it. I find I always want both on hand, however. kh Quote Link to comment Share on other sites More sharing options...
ChrisK Posted January 23, 2003 Author Share Posted January 23, 2003 Dean, As far as your statement "Dr. Edgars comment to you regarding push-pulls and SET is odd, since he also believes horns typically only need miliwatts to function properly." goes, Dr. Bruce works very closely (It appears to me.) with audio electronics designer/builder Cyrus Brenneman. Both of these guys are only interested in one thing, good sound. Dr. B mentioned that Cyrus and he had recently come to the conclusion that even highly efficient horn speakers need "about 40 watts". When I asked him a question similar to your statement, he said that low power was fine for most music. But for "more involved classical music" and such, you need more headroom and therefore power. He also talked about the EL84 tube as being his favorite for music reproduction. I believe the close professional relationship with Cyrus B. has been very enlightening for both sides. Please take my interpretations of Dr Edgar's attempt to educate me with an appropriate grain of salt. While I am learning more and more about the technical side of home audio, much of what the Doc says to me goes WAY over my techno-idiot head. Now if you ask me about the Agriculture industry, that's another story... Kelly, I have a Scott 299(A) on it's way to me for initial evaluation and then on to Craig for "the once over". I also have a Fisher X-101 currently at Mike Z's awaiting my locating of an output transformer, which will finish it's resurrection. When I get both of these amps back in tip-top shape, the Doc has agreed to let me bring them to his shop for a listen and some measuring. The Doc's attitude towards them when I mentioned them to him was lukewarm at beast. We'll see... BTW, I think you would be the perfect guy to put Cyrus and Dr. Edgar on the web. I even mentioned as much to him. But since I don't know how you would feel about it, I left it at that...a mention. Thanks as always, for your contributions to my audio education (?), Chris Quote Link to comment Share on other sites More sharing options...
Dale W Posted January 23, 2003 Share Posted January 23, 2003 DEAN: Very nice looking amps you have, I'm with you on the extra power issue. Helps in the grandstanding area if you catch my point. I'll reserve any tech opinions till another thread and the arrival of my pp from craig. My personal tube knowledge is growing slowly but at a steady pace, in the last month and a half i've read 7 complete books and dozens of published articles. Some day i hope to be able to add an educated 2 cents worth to some of these threads but for now i'll continue to sit back , reserve my opinion and farther educate myself. I wish i had a guy like the old dr in my backyard to chew the fat with. He's likly forgot more than most know . lol Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 23, 2003 Share Posted January 23, 2003 One thing you will learn right off the bat; everything you read and will be told, more often than not, will be contradicted. Those that stand by hard fact and measurements are the least likely to have listened and retained an open mind. Also, from my experiece so far, all integrateds are not created equal. Ditto with vintage amps in general. There are no hard and fast rules here, nor measurements that always tell the story. Going by some set of criteria will likely be problematic as it will be shown to be wrong in certain situations/setups. The idea that you need 40w minimum is incorrect in my view, only in that it sets a solid figure, something that I have found to be shortsighted. I have heard 3.5w sound as solid and refined as 50w. I have heard 14w PP sound more refined and musical than some 8w SET. I have had top notch 30w-80w push pull amps in my system, both triode and UL, and so far, I have achieved the best sonics with SET with certain vintage PP coming in close second and first in some areas. As for my experience with guality SET, dynamics have NOT been dead, this in my 100dB CW. Again, how can I make this any more clear in that all SET amps are not created equal. And a 3.5w amp with zero feedback and EXCELLENT "air gapped" IRON can sound VERY different from another 3w amp. Again, I dare not make hard and fast rules as I have heard them all broken. I will differ with Mark in my own experience with this. The type and quality of the output transformers is PARAMOUNT. We just have never agreed here but that is ok. I agree with the EL-84 tube choice and the use of tube rectification for a damn nice push pull. I used to prefer the EL-34. By the Way, I would be happy to do their website! Drop me a line. I sent you a mail. kh Quote Link to comment Share on other sites More sharing options...
sunnysal Posted January 23, 2003 Share Posted January 23, 2003 As I am sure you all know Kevin Hayes at VAC is a strong proponent of PP versus SE designs. his renaissance 30/30 PP 300b based design has been very favorably reviewed in the past. I have heard that one, it sounds great! (too expensive for me) he has written a short description which includes his reasons for opting to go PP versus SE (he obviously could build SE if he wanted). the url is: http://vac-amps.com/page0004.html interesting stuff. I think stereophiles review of the 30/30 also reviewed the reasons why Hayes is convinced PP is superior to SE. regards, tony Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 23, 2003 Share Posted January 23, 2003 Ditto with Mike Sanders at Quicksilver. I like Quicksilver but dont agree with all of Mike's statements. Neither do I with Kevin of VAC, who used to be right down the street from my house when they were in Durham, NC for years (they just moved). But I will say again, they dont sound like each other. The answer is to have BOTH. Make no mistake that once you DO have a great SET amp, you always want one around. They are two different animals altogether. Please also be aware of the tremendous cost difference between good air-gapped SET output iron and PP outputs. Dont trust all manufacturers here to give the "straight" dope just as anyone here to know the whole unbiased story. As I have found, hard and fast rules dont apply. kh Quote Link to comment Share on other sites More sharing options...
castironandtubes Posted January 23, 2003 Share Posted January 23, 2003 I'm running a 5 watt SET (Zen SE84C) with my Heresy's. This is my first tube amp so I can't offer a comparison with PP, but I can relate my experience. Some of the above posts would suggest that my SET ought to be hopeless with anything other than solo guitar music at nominal volumes. I will say this, it does pretty well with large orchestral passages. I have some Classic Records Shaded Dogs that have some very significant dynamic ranges and complex passages, and listening at levels as high as I care to it sounds great. Put it this way, I don't get it loud enough to hear distortion. The dynamic peaks don't quite jump out like they would with high power, but again, it does quite well. In all honesty, for my power level I would prefer more efficient speakers (over 100db) so someday I'll do that, but for now I'm getting great sound, dynamics, bass with my 96dbs. Again, I'm not putting down PP and maybe someday I'll check that out for the extra slam once in a while. Many people will certainly be happier with PP than SET, I just want to illustrate that however it looks on paper, SET sounds pretty darn good in every way with the Heresys. Dave Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 23, 2003 Share Posted January 23, 2003 Mark, ditto with that last paragraph from my end as well, especially regarding SET. It was a LOT harder 10 years ago. At least now some have tried it. It has taken many YEARS to dig out of the watts misconception. When people had 86dB speakers with dips into the 2ohm range, lowe powered amps sounded horrible as they tracked the plight of the speaker. The same can be said for a lot of amp theory. Bruce Rozenblit is a perfect example of someone that has had to back peddle with the best of them or wave his arms higher. And his love of OTL amps is a tribute to fingers on fretboard over musicality. I find that people are just now feeling their way out of that quagmire although the audiophile take on sonics enjoyed a healthy marriage for years (and is still going strong with many). Your feeling about clarification with PP is the same I feel about the single-ended triode (and I love PP too). Years ago, the idea of the different types of distortion was more in the dark, publically speaking. Distortion was distortion and all BAD. No distinction was made between different types of distortion and the way the ear/brain perceived it. Yet the measurements brigade enjoyed the supposed backing of science in all their arguments. We have come a long way but have a long way yet. Keeping a completely open mind is great in dispelling myths as well as expanding science (and experience). kh Quote Link to comment Share on other sites More sharing options...
Triode Pete Posted January 23, 2003 Share Posted January 23, 2003 GENERALLY SPEAKING, A push pull amp will tend give more of a slam & authorative sounding bass response whereas a SET amp will provide that sweet midrange that most push-pull amps cannot give. Remember what PWK said, "Midrange is where you live." Circuit topology & parts used is very important as stated by the other posters. A good push-pull amp will sound "better" than a fair "SET". Not all amps or topologies are created equal. Generally, I prefer SETs over push-pull, but I have heard properly designed push-pulls sound much better than some SET's. My favorite amplifiers for the Klipsch Heritage line are 2A3 based, both push-pull & SET! Triodes Rule! My $0.02, Pete Quote Link to comment Share on other sites More sharing options...
fini Posted January 23, 2003 Share Posted January 23, 2003 Hey, Pete! Way off topic, but have you given any more thought to those organ parts/transformers, and how they could be used in hifi applications? fini Quote Link to comment Share on other sites More sharing options...
Dale W Posted January 23, 2003 Share Posted January 23, 2003 KELLY !!! KELLY !!! KELLY !!! I hope not all of BRUCE ROZENBLIT ideas and thoughts turn you off. I just finished stuggling through reading his book ( twice ). Audio thuths revieled / myths debunked . Quote Link to comment Share on other sites More sharing options...
Allan Songer Posted January 23, 2003 Share Posted January 23, 2003 There is a upper mid-range sweetness and magic you get from a really good 6L6 based amp with really killer tubes that I have never found in any other P-P configuration. I still don't know why this type tube never really got off the ground in hi-fi. There were a few odd-ball British amps and a couple Fishers and Scotts from the mono era and a couple of McIntosh offerings and that was about it. Really too bad--because if there ever were a "king" of pentode tubes, the really great 6L6 offerings would be up there on the throne (EL37, early 6L6G, GEC KT66, WE 350B). Don't get me wrong, I love the EL84, but none of them can hold a candle to the mighty 6L6!! Quote Link to comment Share on other sites More sharing options...
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