Marvel Posted July 10, 2006 Share Posted July 10, 2006 This will make it hard to get through the rest of the day, but my Moondogs arrived from James. Everything got here in one piece. I know what I will be doing tonight. So... can someone tell me how to adjust the bias on these? Please? Bruce Quote Link to comment Share on other sites More sharing options...
Cut-Throat Posted July 10, 2006 Share Posted July 10, 2006 The bias is self-adjusting. No bias adjustment on them. All you have is a hum pot on top. Adjust that by ear. As you turn it you will hear increase/decrese hum in the speakers. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 10, 2006 Author Share Posted July 10, 2006 Thanks. Will be fun tonight. Bruce Quote Link to comment Share on other sites More sharing options...
fini Posted July 10, 2006 Share Posted July 10, 2006 How exciting! (Bruce, I still have not run across the thing I want to send you. Dang!) Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 10, 2006 Author Share Posted July 10, 2006 How exciting! (Bruce, I still have not run across the thing I want to send you. Dang!) I hope it doesn't break when you run across it! Quote Link to comment Share on other sites More sharing options...
lwhaples Posted July 10, 2006 Share Posted July 10, 2006 Marvel, Congrats! I just got home to find a box inside the shop. It should be a Dynaco MK IV I've been waiting for. Good Luck with yours! Larry Quote Link to comment Share on other sites More sharing options...
jbsl Posted July 10, 2006 Share Posted July 10, 2006 Glad to hear they made it!! Let me know if you have any questions. Quote Link to comment Share on other sites More sharing options...
sheltie dave Posted July 10, 2006 Share Posted July 10, 2006 Congats, Bruce! I hope they give you some sweet sounds in the house.[] Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 10, 2006 Author Share Posted July 10, 2006 I managed to survive installing the tubes and getting everything swapped out in the living room. I figured I would try the Sovteks first. First impressions... the hum trims out pretty well, but is still there a little bit. Seated on the couch I can't hear it all all, especially once the music starts. A lot more hiss that I really expected. Same with it though, once the music starts it's masked. (My cheap SS amp is an Alesis RA100. You can't tell it is on with your ear right up to the tweeter, and that is one of Bob's CT125 tweeters) The Merlin is dead silent. Turning it up or down all the way has no effect on noise. First CD up was something I knew they could probably handle. David "Fathead" Newman -- Mr, Gentle, Mr. Cool A tribute to Duke Ellington. Sounded excellent. This is a really good recording, too. Perhaps a bit more space around the instruments compared to the SS equipment. Fell asleep listening to it. Went to extremes with the next CD. Bela Fleck and the Flecktones -- UFO TOFU This has some of Victor Wooten's incredible bass on it, with the sharp attack of Future Man's drums. These amps really held their own pretty well. Not the authority of the 75wpc SS rig, but still okay. I didn't notice any compression per se, but perhaps just a bit softer. The bottom end was there, but the whack wasn't quite as crisp. Third up. Textures / Art Johnson jazz guitarist, with his quartet featuring Gary Scott on sax. This album is on a label owned by a friend of mine in San Diego. Very nice CD. Acoustic bass is right there. All handled better than the Flecktones CD but that one is a hard one to get totally right on a system. The LaScalas bass is sounding really good. If the bass mod adds to this experience, I will be doing it sooner than later. Maybe when I swap my crossovers I am building back in to replace the ones on loan from John Albright. Went out for dinner after that. Now I have to get to bed. I t will require more listening, but I am pretty sure I will be keeping these. Bruce Quote Link to comment Share on other sites More sharing options...
Cut-Throat Posted July 10, 2006 Share Posted July 10, 2006 Bruce, Do me a favor and try this. Take a cheater plug on one of your Moondogs and lift the ground and then try to hear any hiss coming from your speakers. And I mean ear right up to the speaker. I am betting that lifting the ground will remove all the noise of this amp. These 3 prong plug amps are notorious for creating ground loops. Once you know that this is the problem you can locate an expert that claims he can find it! - I can't find mine! Let me know, I'll be interested. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 10, 2006 Author Share Posted July 10, 2006 I'll try it tomorrow when I get home from work and post back. The youngest is headed for the livingroom to get in some trumpet practice now, and I don't want to discourage that in any way. [] I do like them. They barely light up too. That is a bit surprising. Not at all like the Dynaco, that turns into a furnace in the corner. Bruce Quote Link to comment Share on other sites More sharing options...
jbsl Posted July 10, 2006 Share Posted July 10, 2006 The first time I turned them on I thought some thing was wrong the tubes did not look like they were on. Did you try adjusting the knob on the amps to adjust the hum? Do you have your La Scalas in the corners? Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 11, 2006 Author Share Posted July 11, 2006 James, The hum is not the problem. As I already pointed out, it trims out quite well. One LaScala is in a corner, the other not. The musical balance is great. The volume it great. Hiss is almost audible at the listening position, but is masked by music as soon as it begins (didn't I say this already?) As I said, I am not unhappy at all. EDIT: I just tried one with a cheater plug. Absolutely no difference. Hiss is only audible when probably five feet or closer to the cabinets. I will also try reorienting my cables and get them a bit better organized. All just a bit different than the SS (Duh! well, of course). Bruce Quote Link to comment Share on other sites More sharing options...
leok Posted July 11, 2006 Share Posted July 11, 2006 Bruce, Congratulations on the Moondogs. That amp chain (2 6SN7 stages and a 2A3) doesn't have to hiss. i've never experienced the problem. What are the 6SN7 tubes? And, as pointed out, the grounding may be involved (hf oscillation in a Gnd loop could sound like hiss). Anyway, when you're done, hiss shouldn't be an issue. Enjoy the Moondogs. Leo Quote Link to comment Share on other sites More sharing options...
SET12 Posted July 11, 2006 Share Posted July 11, 2006 Marvel, Congrats on your SET arrival and listening pleasure, Even with what I refer to as a classical design appoarch, can be enjoyed by most people these type of amps are one of the easist to modify and alot of fun. I learned alot of out of the box principles of design from my own I guess your just sitting back and enjoying them as they are and perhaps as they always will be. If you have any interest in moding please feel free to drop me a line. Enjoy! SET12 Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 11, 2006 Share Posted July 11, 2006 Bruce: I'm glad your impressions are positive so far. Even more than that, it's great you are encouraging trumpet practice! Ground loops: It's usually characterized by 60Hz hum, but I have had other RFI/EMI problems that have caused a variety of noises. I also used to lift the safety ground on an amp to help reduce ground loop hum, but have never experienced any change in the least regarding tweeter hiss. Grounding problems seem to differ from one situation to the next, but slightly higher than normal low frequency hum (possibly some buzz) is the only noise I have heard related to it. As the responses have indicated, each situation is going to be different. My components share a common power strip, which is plugged into one outlet. That's what helped here. Some manufacturers encourage lifting safety grounds to prevent ground loop hum, but I can give as many or more instances where cheating the earth ground is very strongly discouraged. Ultimately, I would rather have a slight, low-level hum that vanished when music was playing than compromise the built-in safety features of my components. You mentioned that you still have a tiny bit of hum from the AC filaments even when the pot is balanced. That's normal, but, if it was real bother, it would be possible to use regulated DC on the 2A3. My moth amp uses that, and it's just about as quiet as the Teac digital amplifier -- WITHOUT defeating the safety ground with a cheater plug. All this grounding info. and other things aside (as you said, things are good!), enjoy your new amps! Erik Edit: another approach that's helped here is using two-conductor plus shield interconnect. With this type of cable between components, the shield does not have to also serve as the ground return the way it does in convential coax cable. The two conductors are signal and ground, and the shield is grounded at one end only. I actually now use some of th least expensive IC Radio Shack carries, and still don't have ground loop problems -- however, they tend to be poorly sheilded, if shielded at all. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 11, 2006 Author Share Posted July 11, 2006 Leo and Erik, Thanks for the input. I have everything on one aoutlet strip, for the very reason Erik mentioned. I am also not a big fan of lifting the grounds on equipment, but thought I would give it a shot. I also have a fairly large isolation transformer, which I bypassed, just to see if there was any difference (there wasn't). It is all tolerable, and I don't want to give the impression that I don't like these. Even beyod the fact that this is the most expensive piece of audio gear I've bought other than the LS. (I'm leaving out the ADAT 8 rack digital recorder and the like -- different uses, needs and designs) Leo -- the 6SN7s are Philips (I think - I'm now at work) Erik -- I was hoping you would check in on these since you have had them at your place. Doing DC may be something I will try later. I'll just listen to them for a while and enjoy. May try the other IC ideas. I am also using cheap RS ICs and have never had any noise issues previously. I've even had much cheaper ICs on stuff with no problem. Got to get some work done now - that's what they pay me for. Bruce Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 11, 2006 Share Posted July 11, 2006 Went to extremes with the next CD. Bela Fleck and the Flecktones -- UFO TOFU This has some of Victor Wooten's incredible bass on it, with the sharp attack of Future Man's drums. These amps really held their own pretty well. Not the authority of the 75wpc SS rig, but still okay. I didn't notice any compression per se, but perhaps just a bit softer. The bottom end was there, but the whack wasn't quite as crisp. . Bruce Bruce, The softness your hearing on these bass notes is SET compression very mild and easy to live with. You really have to over stress them to get them to become obnoxious sounding. This compression or distortion will actually give you very plump full sounding bass with the Lascalas. It kind of takes the folded horn and makes it sound like the ported cabinet. If you can't hear the hum/hiss at your sitted position I agree it's no big deal. I wouldn't spend to much time worrying about it. Craig Quote Link to comment Share on other sites More sharing options...
mark1101 Posted July 11, 2006 Share Posted July 11, 2006 Bruce, Congrats on the amps. LaScalas are very hard speakers to hush with their sensitivity. You will probably never get them dead silent. Tolerable should be acceptable. I had amps that were pretty quiet on my cornwalls, but also pretty noisy on the LaScalas. The Las are just really revealing. My experience with hiss has been that it has always been in the tubes. Noisy tubes. The biggest culprits in my system were the preamp tubes. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 11, 2006 Author Share Posted July 11, 2006 Craig, It isn't an unlikeable thing for sure. Just different. I don't listen at really loud volumes anyway. If I do 90db it is getting up there for me, so they work well. Symphonic music will go on tonight. I am sure the Bach will be okay. Brahms maybe. Shostakovich may push a little bit more. The later one gets and the larger the orchestra... I don't just listen to the 'little girl with guitar' music. The soft compression is okay. Pleasant would be a word some would use-- other may say mushy (where is Paul?). I'll live with them for a while and try a lot of different material on them. They look cool anyway, but I'm not really into having them just for the looks. The VRDs look cool too, and would obviously have that 'slam' factor. I just couldn't afford those. Haven't seen you around much. Hope things are getting back on an even keel. Bruce Quote Link to comment Share on other sites More sharing options...
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