jhoak Posted August 14, 2010 Share Posted August 14, 2010 Well today I got them to a stage where I can fire them up and give them a listen. It's a pair of Dynaco MK4 monoblocks. I've had them for a couple of years and while they sounded great they looked like A$$. They had been rebuilt by Craig at NOS Valves in 2005 and given the new Triode Electronics driver boards at that time. All I really did is give them a "cosmetic" makeover. They got new stainless steel chassis, transformers painted, new ceramic tube sockets, power switches, power cords, binding posts, etc., etc., etc.. Output tubes are a set of Dynaco by Mullard EL34 XF-2. The driver tubes are East German 12AU7 whose logo I don't recognize. If someone can tell me who made these I would really appreciate it. I think they're RFT but I'm not certain. Here's the pictures... Yet to do is replace the bolts in the output transformers and I have a set of nice AuriCaps that I'm going to install for the coupling caps. Probably tonight or tomorrow I'll take them to the living room and hook them up to the La Scalas. Should be interesting comparing them sound wise to the vintage SS Onkyo/Integra M-506RS that I've been listening to for a while. Quote Link to comment Share on other sites More sharing options...
fini Posted August 14, 2010 Share Posted August 14, 2010 Those look sweet!! I have a pair of those I've meant to revive for years. I even have the DIYtube boards. But no good motivation. Can I see under-the-hood shots? Good work!! Quote Link to comment Share on other sites More sharing options...
jhoak Posted August 14, 2010 Author Share Posted August 14, 2010 Before I move them to the living room I'll pop the bottoms off and take an "under the hood" shot for you. I have to warn you though they're much less impressive from the bottom than they are from the top. [] I'm not real "anal" about pretty wire routing. As long as everything is hooked up to the right spot and the solder joints are solid I'm a happy guy. I do place some value in the overall appearance but most of all it's the sound that comes out of my speakers that matters to me. I got almost all of the parts from dynakitsparts.com. I have WAY more $$ poured in these guys than I can ever hope to recover out of them. On the other hand I'm seeing the EL34s selling at over $100 each so maybe just maybe I could recoup most of my investment. Quote Link to comment Share on other sites More sharing options...
Dennie Posted August 14, 2010 Share Posted August 14, 2010 Wow! A very nice job! [Y] Thanks for posting the Pictures, Dennie Quote Link to comment Share on other sites More sharing options...
jhoak Posted August 14, 2010 Author Share Posted August 14, 2010 Can I see under-the-hood shots? OK... You asked... I warned you... They've been moved to the living room and they're currently driving the La Scalas... Quote Link to comment Share on other sites More sharing options...
Guest David H Posted August 16, 2010 Share Posted August 16, 2010 Beautiful, I have always loved the MK4's Nice work. Dave. Quote Link to comment Share on other sites More sharing options...
fini Posted August 16, 2010 Share Posted August 16, 2010 I really like the simple, yet massive cabinet for the equipment. It looks rock-solid (and beautiful, too). Quote Link to comment Share on other sites More sharing options...
jhoak Posted August 16, 2010 Author Share Posted August 16, 2010 Thanks for the kind words. They really are pretty in a techno-geek kind of way. [] I spent most of the day yesterday listening to them. I played examples of just about all of the various types of music that I own. I played loud and not so loud and of course VERY LOUD. In the end the winner for me was the Onkyo M-506RS amp. On vocals in particular female vocals the MK4s are better. They just sound a bit smoother and more natural. Same with acoustic guitar music. On hard core rock-n-roll especially anything with a heavy bass line the MK4s just run out of gas. Here is where the Onkyo shines. All things considered the more I listend to the MK4s the more impressed I became with the Onkyo. It really is a very sweet sounding amp that can get up and kick some A$$ when called upon. Considering what I listen to the most I have placed the MK4s up for sale. I know that I'm probably going to regret letting them go. I can't help but wonder what a pair of Bob Latino's ST120s bridged mono to produce 120 watts each would sound like. Of course I don't have the $2500 or so that it would take to find out. Quote Link to comment Share on other sites More sharing options...
Timmikid Posted August 16, 2010 Share Posted August 16, 2010 Beautiful man! You're not thinking of selling them are you? Of course I don't have the $$ as well to make a bid, although the worms also ate into my brain... No I'm good, but jazz must really shine on those, doesn't it? Greetings, Tim. Quote Link to comment Share on other sites More sharing options...
sunnysal Posted August 17, 2010 Share Posted August 17, 2010 Nice job! I have a pair of MkIVs I like a lot, besides all the usual tweaks I have them wired with a switch that lets me strap the EL34's into triode or pentode mode. weaker but sweeter on triode as you might expect, you might want to try this mod, I almost always leave it on triode. warm regards, T Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 17, 2010 Share Posted August 17, 2010 Nice job!!! I'd say they are now worthy of some nice Auricaps!! If memory serves me correctly those came from Bill in Florida. Quote Link to comment Share on other sites More sharing options...
jhoak Posted August 17, 2010 Author Share Posted August 17, 2010 High praise indeed considering the source. Thank You!! You are correct I got them from Bill. He lives a little over an hour from me. You did the hard part. You made them sound good. The only thing I did was raise the cosmetics to the same level as the sonics. I have a set of four .22uF AuriCaps but I don't think I can use them for coupling caps. They're rated at 400V and the Triode Electronics spec for those spots is 600V. Where else would you recommend upgrading? Jeff Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 18, 2010 Share Posted August 18, 2010 Jeff, With one of the amps cold set your multi-meter to read DC volts (600V scale) and attach the negative probe to one lead of the main coupling caps and the positive probe to the other lead of the same cap using alligator clips (with the amp off). Once you have that setup turn the amp on a watch the voltage reading as the amp comes up, Depending on what way you have the probes attached the voltage will read positive or negative which doesn't concern us. Just report back what the peak voltage is as the amp comes up and then what it ends up after it warms up and stabilizes. Just to be sure repeat this test on the other main coupling cap also. We may find you can use the Auricaps. Craig Quote Link to comment Share on other sites More sharing options...
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