AnalOg Posted May 25, 2003 Author Share Posted May 25, 2003 "A good compromise for driving full range speakers, expecially efficient ones, is to set the AB1 amp to a "rich" or slightly hot bias" Could you clarify on what you mean when you say "AB1 amp". Tom Quote Link to comment Share on other sites More sharing options...
Deang Posted May 25, 2003 Share Posted May 25, 2003 Tom, Don't be offended, but you don't have K-horns, Belles, Scalas, or even RF-7's. Run those amps the way Hafler intended. Your RF-3's will thank you. Leaving them in Ultra-linear gives you 7-10 watts of Class A, raises your damping factor, and gives you some much needed headroom. Keep in mind that you need 40 watts to do what a Heritage Big Horn can do with 10. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 25, 2003 Author Share Posted May 25, 2003 I put the 470 ohm resistors back in checked the voltage points on the boards, left in triode mode and biased it up to .72, a little hotter than specs. I don't want to even start trying to figure out what happened before, but it does sound sweet. i have a stepped attenuator on my Foreplay, on the first step its plenty loud, I can take it up to 100db at about half volume, and it still sounds clean & sweet. I will listen like this for a while. I want to put a switch in to go back & forth between settings. I'm stii waiting for my Svetlana's to show up along with my NOS Tungsol 12bh7's. I'm sure this should make some difference, altough it sound nice now. Thankx, Craig(your a pain in my a$$) Mdeneen (For the explanation) Dean (I don't get offended over stereo equipment, its all for fun) Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 25, 2003 Share Posted May 25, 2003 Tom, Now that Dean mentioned it he is probably correct with your RF3's you may very well be better off not running your amp in Triode output. 7 to 8 Db less efficient speakers makes a big difference in how hard you have to push the amp. Craig PS: Your a much bigger pain in the A$$ then me !! Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 25, 2003 Author Share Posted May 25, 2003 Craig, Now that everything is in proper running order, I'll wait on the new tubes and listen for a while. Then I'll impliment a switch so I can go back and forth from UL to triode. Thankx for all the help, Tom Quote Link to comment Share on other sites More sharing options...
greg928gts Posted May 26, 2003 Share Posted May 26, 2003 Thanks everyone for the info on the Dynakit amps. I don't know what I'm going to do. I'm all messed up right now. After years of enjoying a chest pounding 200 wpc McIntosh 2205 on my khorns, and being very happy with it, I stumbled on this puny Audio Electronic Supply SET amp. I just can't believe the sound quality of this little thing. It is so much better than the two other tube amps I've tried, all in the last month or so (a Scott 299 and the Dynakit Stereo 70). My living room's a mess, I have equipment all over, my wife's not happy, and I don't know what the hell to do. I just can't believe what I've been missing all these years. The detailed sound that the SET produces is luxurious. Just not enough power. I don't listen to music nearly as loud as I used to, my ears just won't take it anymore, but I still need to feel that kick, that wave of energy move your pant legs, and my SET just doesn't do it. I just bought an active crossover. More stuff in the living room. Greg Quote Link to comment Share on other sites More sharing options...
mike stehr Posted May 26, 2003 Share Posted May 26, 2003 What's the primary impedance for the output transformer of a Dynaco MarkIII? Quote Link to comment Share on other sites More sharing options...
Marvel Posted May 26, 2003 Share Posted May 26, 2003 This is the Magnequest replacement for the MarkIII OPT: MQ-431-CL Upgrade replacement for Dynaco Mark 3 and Mark 2 amps.Also replaces original on 60W Sunn amps that came with Dynaco output xfmrs. Matches to 2 6550, EL34, or KT88 tubes. Rated 60W, 4300 ohm impedance with 43% screen taps. Note, this unit has 4, 8 & 16 ohm taps (the old A-430 only had 8 & 16 ohms). $189 each. They are supposed to be pretty accurate replacements, but mdeneen should could be correct. This is from the Triode Electronics site Marvel Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 26, 2003 Share Posted May 26, 2003 greg928s4, What exactly has been done to your Scott 299 and ST-70 I'm sure hoping you are not comparing a 40 year old stock component that hasn't been properly rebuilt with QUALITY parts by a qualified tube guru or yourself with proper guidance to a rescently manufactured SET amp. While I have no problem with a SET amps sounding slightly better at moderate volumes there is not going to be a night and day difference between a properly rebuilt and working properly 299 or a properly modified and rebuilt ST-70 with a nicely mated Preamp. Been there heard it and know for a fact the differences are small and subtle. Craig Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 26, 2003 Author Share Posted May 26, 2003 I'm going to agree with Craig on this. Although my SET experience is limited to a DIY Paramours, at moderate listening levels,pound for ounce the only thing the SET experience has over PP is a slight increase in what I would call intemicy. The Dyna's have the best all around performance for what ever your in the mood for. Suttle sweetness at low volumes and incredible air moving sound at higher volumes. By the way putting the 470k's back in and biasing a little hot is oh, man the ticket to what Craig has been praising about in these little bad boys!! Tom Quote Link to comment Share on other sites More sharing options...
Dale W Posted May 27, 2003 Share Posted May 27, 2003 4 12AU7'S ???? My mark III'S from craig are running 1 12au7 and 1 12bh7 . Are you using the same driver boards from ned ? Mr ostby may have a new set of toys but mine will kick his butt . lol Quote Link to comment Share on other sites More sharing options...
Marvel Posted May 27, 2003 Share Posted May 27, 2003 Mark, Those tranny prices are high aren't they. Small shop I guess. I wonder how they compare in the real world with some Hammonds. They are very reasonably priced. It's all Hammonds in Tony's PP 2A3. At least the interstage transformers. Marvel Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 27, 2003 Share Posted May 27, 2003 marvel, I see three brands of trannies in there. two lundahl which I think are interstage...the power and output trannies are magnequest and there are four hammonds...jeff mentioned that he will try some magenquest Interstage trannies and let me know if they provide any improvment. he seems quite happy about the lundahls and the magenquest choices. (though he said I could go for cobalt models for the output at some later date)...regards, tony Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 27, 2003 Share Posted May 27, 2003 Dale, You can run 2 12AU7's in these boards but optimally a 12AU7 and a 12BH7 is what there designed for . Craig Quote Link to comment Share on other sites More sharing options...
Marvel Posted May 27, 2003 Share Posted May 27, 2003 Tony, I finally got another look at the pic of the inside. Pretty interesting. I guess the Hammond logo was so visible in a couple of the pics that I jumped to conclusions. Marvel Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 27, 2003 Author Share Posted May 27, 2003 Dale, I have the NOS Tungsol 12bh7's coming in the mail. I just installed the Svetlana kt88's tonight. They loosen up pretty quick. I feel like I gained another octave in the lower and upper end. No compression at any volume, room filling sound, and all I have is these crappy little RF3II's. P.S. My amp can kick your amps a$$ any day!! Tom Quote Link to comment Share on other sites More sharing options...
mike stehr Posted May 27, 2003 Share Posted May 27, 2003 I wanna pair... Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 27, 2003 Author Share Posted May 27, 2003 Mike, What RF3II's, or the Mark's? Tom There quite a few a ebay right now. Quote Link to comment Share on other sites More sharing options...
Dale W Posted May 27, 2003 Share Posted May 27, 2003 There is a guy who's always selling 12bh7 tubes on e-bay. RCA'S for hammond pipe organ is what he advertises. Pacific tv from vancouver B.C if my memory serves me correctly. I bought 2 pairs from him and they work well in the mark III. So do the 12au7 mullards or ken rads , i have both . If you run into a good supply of tung sol grab me a pair and i'll give them a try as well. P.S My amp's are shinier than yours . lol Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 27, 2003 Author Share Posted May 27, 2003 12au7's I've rolled RCA black plates & clear tops, Tungsol 12au7 which is not as bottom heavy, great mids. Some new JJ Tesla 12au7's didn't do it for me. Maybe they need some break in but not very musical to my ears. I picked up the Tungsol 12bh7's on ebay, I'll keep you in mind if I come across any more. Tom My amps are HOTTER than yours!! Quote Link to comment Share on other sites More sharing options...
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