awsjr Posted July 29, 2008 Share Posted July 29, 2008 with an impending purchase of some 2A3 amps I have brought my Moondogs out of hibernation.....then a brief search finds many mods that can be done fairly easily....mine are original the way they were built in Nov 1999.....electra-print iron, AB resistors and so on.....one small problem.....I cannot find my manual / assembly / schematic book....can anyone help me with replacement ?.....Ron does not reply to emails regarding this.....TIA -Al Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 30, 2008 Share Posted July 30, 2008 Great! The schematic is available, I believe, but I would rather not post that information. Perhaps try Welborne Labs again. The assembly manual probably suggests twisting the AC filaments for 60Hz hum rejection. Your amp looks nice, though. Moondogs can play very loud with Klipschorns, and I bet they are wonderful with Oris horns. I wish I went for a pair of those to use with my PM2As. They are the reason I first got a pair of La Scalas. I was going to use the bass bins with Oris 150s or open baffle. Good luck. edited. Erik Quote Link to comment Share on other sites More sharing options...
Guest srobak Posted July 30, 2008 Share Posted July 30, 2008 Quote Link to comment Share on other sites More sharing options...
awsjr Posted July 30, 2008 Author Share Posted July 30, 2008 hi Erik.....thanks....Welborne is a not going to answer....tried many times.....the Moondogs play loud and sound pretty good with these too....but if you get a chance for some Oris horns you won't be sorry...if you ever come by Austin be sure to stop if you can... Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 30, 2008 Share Posted July 30, 2008 I honestly don't know what is going on with W. Labs. I just remember the time a decade ago. If you need a copy of the schematic and parts list, I would be happy to send them to you, as I did for another forum member. Just let me know. I believe congratulations on another pair of SET amps -- that is neat, and the Horus is really a wonderful sounding amplifier. It's open to some modification, too, as I had done with the pair I built, but any of the changes, as you have seen on the forum, can always be reversed. Leok's shunt-feed Moondogs were very, very similar to the Horus I built as far as the output stage, but the 5687 driver in the Horus is pretty nice, I think. That in conjunction with a grid choke on the 2A3 instead of the more common resistor makes for a special sound, IMO. I used the MQ grid choke (FAR more expensive than its grid-leak resistor counterpart) in my Moondogs, too, that had also been modified with the DRD Ultrapath (I'm sure you're familiar with that). That 'ultrapath' part of the DRD goes back many, many years, just like parallel-feed outputs. I'm building a component right now, that, while not an amplifier per se' nevertheless uses the same approach, along with a plate choke on the output tube. Thanks for the invitation, Erik Quote Link to comment Share on other sites More sharing options...
kev313 Posted July 30, 2008 Share Posted July 30, 2008 hi Eric.....thanks....Welborne is a not going to answer....tried many times.....the Moondogs play loud and sound pretty good with these too....but if you get a chance for some Oris horns you won't be sorry...if you ever come by Austin be sure to stop if you can... Correct. Ron will NOT answer. If he does, though, please remember to ask if he will either send me my amps or refund my $1800 from September of 2006. Quote Link to comment Share on other sites More sharing options...
awsjr Posted July 31, 2008 Author Share Posted July 31, 2008 hey Kev...yeah, sorry to stir that up for you again...what are the odds..... Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 31, 2008 Share Posted July 31, 2008 I can supply the schematic and parts list. That's really pretty amazing that you haven't gotten your amps yet, Kev. Had they been shipped and lost, I wonder.... Quote Link to comment Share on other sites More sharing options...
awsjr Posted July 31, 2008 Author Share Posted July 31, 2008 good morning Erik....parts list and schematic would be great......I did find a 1998 and a 2000.... mine look more like the 1998.... I would also be interested in the MQ grid choke if you can provide some information on that.....feel free to email me if its better to communicate off the forum.... thanks -Al alwsjr at gmail dot com Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 31, 2008 Share Posted July 31, 2008 Hi, Al: The Moondogs are generally very similar, although there was of course the change from MQ transformers to EP. I think my Moondogs are the very same vintage as yours, and also use EP iron. The color coding for the output transformer secondary connections is different between MQ and EP, so what I'll send will have the correct color-coding if you ever want to change those. If you're familiar with the Bottlehead stuff, you can check out some specifics about the 2A3 grid choke. It's used in place of the grid lead resistor, which is connected between the grid and ground. It looks like a small filter choke, and can be attached on a side wall of the amp. They are a little expensive, but for me this is really a design change, not just a part substitution. Since I sold my Horus amps (the grid choke is part of that design), I no longer have them in my Moondogs. I have to say, though, just like many of these modifications, they are subjective. I see things advertised as 'having all the mods,' which to me sort of means that some things were changed from the original design -- perhaps not necessarily always for the better. I'll send the Moondog info. today. Erik PS: I wish I hadn't seen that picture of the Oris horns. Started me thinking about them again! Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 31, 2008 Share Posted July 31, 2008 AL: My schematic is from 1998, but there is very little change. Do you still want a copy of it? Erik Quote Link to comment Share on other sites More sharing options...
awsjr Posted July 31, 2008 Author Share Posted July 31, 2008 hey Erik....check these out....Oris....joespride rig.... http://cgi.audiogon.com/cgi-bin/cl.pl?spkrfull&1222612880 sweet.... Quote Link to comment Share on other sites More sharing options...
kev313 Posted July 31, 2008 Share Posted July 31, 2008 hey Erik....check these out....Oris....joespride rig.... http://cgi.audiogon.com/cgi-bin/cl.pl?spkrfull&1222612880 sweet.... That is joessportster here on the forum. Erik - Yeah - One was lost in shipping. Ron told me to send it back to him for a refund. After that he went into hiding. Literally. Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted July 31, 2008 Share Posted July 31, 2008 Kev: That entire situation is really unfortunate -- I'm sorry it never got resolved. Al: I did come across those very recently. They look really awesome. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted July 31, 2008 Share Posted July 31, 2008 I have to say, though, just like many of these modifications, they are subjective. I see things advertised as 'having all the mods,' which to me sort of means that some things were changed from the original design -- perhaps not necessarily always for the better. I agree with Erik here. I understand there is absolutely no love for Ron Welborne lately, but the Moondogs are Moondogs nonetheless in spite of Ron ditching. A good stock pair of examples will hold more value than a pair with extensive mods. They already seem to have high quality parts used, and the one in the pic appears to be well built. (constucted) If you you think the amps have some objectionable things going sonic-wise that you think can be improved with modifications, then maybe flog the pair and then contribute towards a DIY project with whatever topology of interest. Otherwise, you got pretty good examples of 2A3 SET topology. Quote Link to comment Share on other sites More sharing options...
awsjr Posted August 1, 2008 Author Share Posted August 1, 2008 hi Mike....thanks....those are mine as built in Nov 99....not the "ultimate upgrade" but spec'ed with Allen Bradley resistors and Jensen caps.....walnut bases with 1/8" brass top plates.... a little bit of hum but otherwise excellent amps...my first set amps... Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted August 1, 2008 Share Posted August 1, 2008 Al: "a little bit of hum but otherwise excellent amps" If you haven't already, try: - Thoroughly re-tightening the screw that hold the ground ring terminal to the chassis. Also related to that: W. Labs did not remove the clear overcoat on the brass plates for that important ground connection. Remove enough in that area so the ground makes solid, metal-to-metal contact, and use a star washer so it bites into the metal. - Readjust the hum null pot (I know you know that!), but more importantly, TWIST the yellow wires that extend from the out two solder terminals on the pot all the way over to the 2A3 filaments. Those things carry heavy 60Hz current, and twisting can really help with that. - You have 10,000uf filtering the rectified AC for the 6SN7 heaters. Try paralleling another 10,000 cap of about that same value. Many Moondogs I've seen added an extra cap, and Ron. W. has suggested it to others in the (long distant) past, too. - The twisted red and black leads are of course from the RCA jack over to the grid of the input stage. Double check the ground connection of the black wire. You can also try using a length of shielded cable intead of that, which might help. The shield is connected at the RCA jack end, but floats on the otherside. However, you still have to have a ground connection for the jack. If it's ground loop hum, there are some safe ways of dealing with that. - Leaving the speakers connected and the amps off at first, remove the RCA jack connected to the inputs, and in its place use a shorting jack (just any cheap jack/cable can work for this. If you don't have a shorting jack, make one with an old IC cable: Short signal and ground. Plug in that shorted jack, turn the amps on, and listen for noise again. In other words, are the amps the source or something else? Mike is right about these classic SET amps. They are really very high quality in all respects. Erik Quote Link to comment Share on other sites More sharing options...
awsjr Posted August 3, 2008 Author Share Posted August 3, 2008 thanks Erik....I can revisit the ground and make sure it has contact with the plate....for some reason I remember the instructions mentioning to make sure the washer digs in....and I can twist the yellow wires for sure.....the paralleled 10000uF cap is a change from the 1998 schematic to the 2000....mine are 1999....when I order stuff I will get some....the RCA's look good....thanks for your advice -Al Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted August 3, 2008 Share Posted August 3, 2008 Al: You're right, about confirming that connection is tight. Scraping off the clear coat was help to me, so I just thought I would mention. Honestly, it's nice to see a well-built pair of these amps. I almost sold mine once, and am really glad I didn't. Erik Quote Link to comment Share on other sites More sharing options...
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