AnalOg Posted May 12, 2003 Share Posted May 12, 2003 I installed the PS Mod, last night. Incountered a problem, it turned out to be a wire grounding to the chassis. Anyways, found it and fixed it today. Did a little listening tonight. OH yes, much better. The brightness is gone, much blacker background, and more transparent. It's not as tubey sounding as the Scott ( which is not a good or bad thing), the sound is clean effortless and dynamic. That magic sound of tubes exists with the mod, more so than with the original PS cap. It really allows the characteristic of the preamp to shine. This is a definite doer if you own a stock Mark. The front end boards will go in after about a week of listening. Thankx Tom Quote Link to comment Share on other sites More sharing options...
dbflash Posted May 13, 2003 Share Posted May 13, 2003 Tom, What mod did you do? Today I am thinking about gutting the whole Mark III down to xformers and use the full blown Curcio Audio mod kits. It changes from day to day. Any info would be greatly appreciated. I have had these things for a month now and have not even powered them up yet. Danny Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 13, 2003 Author Share Posted May 13, 2003 I recieved the mods from Triode Electronics, front end boards & SDS Labs power supply boards.They were not as pricey as Curcio so you will have to do a little research to see what you like. These can be found at Triode, do a google search they will come up. I first totally disassembled the units cleaned them all up painted the transformers a chaulk board black. With the guidance of Craig from NOSvalves rebuilt them replacing the hookup wire with 22awg magnet wire & what ever else was out of specs, i.e resistors & caps, selenium rectifier to diode and so fourth, set it up for the dual bias mod (also got that from Triode). I first built it back up stock to listen for about a week or so. Then I just added the SDS board which replaces the original can cap. As you read above does make a big difference in the quality of sound. I'll listen to it for a while till I get the itch to install the rest of the mods and see what transpires. If you have any other questions don't hesitate. This project was fun. And got great results so far from the time and parts put into it. These mono's are special little beasts when brought up to current PS design. Tom Quote Link to comment Share on other sites More sharing options...
dbflash Posted May 13, 2003 Share Posted May 13, 2003 Tom, Thanks. I've checked both Curcio and Triode and I'm not sure what I'm going to do. I can't wait to make a decision. I go back and forth. They have both gotten good reviews. I am using a pair of Wright's now and I want to hear what the difference is between a SET and a PP amp. I am going to make up my mind in the next month or so. AS you continue your mods keep posting and if I ever get started I will do the same. Danny Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 13, 2003 Author Share Posted May 13, 2003 Danny, The difference between SET & PP. Two words, HEAD ROOM DYNAMICS Sorry thats three words! Tom Quote Link to comment Share on other sites More sharing options...
dbflash Posted May 13, 2003 Share Posted May 13, 2003 Thats what I'm thinking. Talk to Keith brought his Scott over to the house and I could tell a difference. The next day I started looking for the Mark III's. I was very impressed with the Scott, but I fell in love with Dale Walkers Marks. So if you are thinking about getting Scotts I think you will be happy. Danny Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 13, 2003 Author Share Posted May 13, 2003 Danny, I own a Scott, rebuilt by Craig. It has its own sonic signature, that I wouldn't want to compare to the Marks. I like them both, and could live with them both at this point in time. The two things that stand out for me in the Scott is the Phono stage & the natural bottom end that it is capable of. As for the Marks, all the mods are not done yet so I can't fully comment on them. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 13, 2003 Share Posted May 13, 2003 Tom, You haven't even begun to upgrade those Marks !! The front end board will bring it up to another level !! But what will really shock you is when you drop them down into triode output !! You will freak what I believe really happens here is by cutting the max output the 30 Watts the Mark III is able to be run in its sweat spot with klipsch speakers. In its stock form at 60 watts it is just to powerfull at least for my Lascalas !! For Mark III's I would even think of using a Curcio board !! There a better option for a ST-70 maybe ! But the Mark III the triode board is awesome ! Craig Quote Link to comment Share on other sites More sharing options...
AnalOg Posted May 13, 2003 Author Share Posted May 13, 2003 Craig , I think I understand what you mean about running them in there sweet spot. They sound good at low volumes, no doubt. At higher volumes, say about 95db & up, they really begin to breath. By cutting the watts in half your getting to the best performance of the amp at a more reasonable db level. Tom Quote Link to comment Share on other sites More sharing options...
dbflash Posted May 13, 2003 Share Posted May 13, 2003 I didn't want it to sound like I didn't like the Scotts. I really was surprised at how good they sounded. I am hoping that the Marks are in a whole different league. They should be for how much they are going to end up costing once I'm done. Danny Quote Link to comment Share on other sites More sharing options...
rtaylor Posted May 13, 2003 Share Posted May 13, 2003 I'm doing a mkII rebuild also. Took the chassis and bells to a chrome outfit today after work, he estimated 200 hundred dollars for all 10 pcs. Didn't sound too bad so I left them there. Like you doing the PS, front end and dual bias controls. Stuffed the front end board this weekend and am waiting for the PS now. Mine are the older MKII's but will be doing the mods to make them MKIII clones. Probably end up changing out every resistor and capacitor before it's all done and said. Anybody know how to make a varistor? Randy Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 13, 2003 Share Posted May 13, 2003 Randy, Why do you want to make a Varistor ?? You can buy them unless I don't understand what your meaning. Tom, Yup you have it right. When I did Dale's Mark III I was not really impressed until I put them in triode. They sounded good but seems like they really opened up when you pushed them the problem with that was they were just to loud for normal listening for long periods. Once in Triode they were sweat from 80Db to 115Db on my Lascalas. I have litterally missed them ever since I shipped them to Dale. I have to keep myself in check as to not drive Mark crazy waiting for mine to get here. But I have to save some cheese up to buy my upgrades also ! Danny, You didn't sound like you were saying anything bad about the Scotts and yes the Mark III's are in a different league but like you said they should be with preamp and mods its easy to have $1500 to $2000 in them and that is doing the work yourself ! Craig Quote Link to comment Share on other sites More sharing options...
rtaylor Posted May 15, 2003 Share Posted May 15, 2003 To power up the old tube gear slowly.Isn't that the best way to go working with old gear? Randy Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 15, 2003 Share Posted May 15, 2003 Old stock gear that is sat unused yes a variac is a must have to bring them up slow while monitoring current draw. Craig Quote Link to comment Share on other sites More sharing options...
Deang Posted May 16, 2003 Share Posted May 16, 2003 Craig, What about large value NOS electrolytics that have been sitting on the shelf for decade or so -- should they be brought up on a variac before use? I don't think I can go along with the tube sweet spot thing. Yeah, I'm an expert. Seriously though -- The average plate dissipation goes up with audio output -- the sweetest spot is the one with the least distortion. In other words -- less distortion at 20 watts with a 50 watt amp than there is with 20 watts on a 30 watt amp. My guess is that those big Heritage horns just can't handle the full bandwidth of a good Ultra-linear amp without yanking the ears off. Quote Link to comment Share on other sites More sharing options...
rtaylor Posted May 17, 2003 Share Posted May 17, 2003 WOW, that's not nice! Got the ps parts friday,have to do a side job today so maybe tomorrow will get a chance to start on them. Don't know when the chrome will be done. going to Myrtle beach next thursday for a little golf.Anybody hail from down there? Randy Quote Link to comment Share on other sites More sharing options...
sunnysal Posted May 17, 2003 Share Posted May 17, 2003 triode strapping the dynacos is the key to making them "amp killers", once triode strapped my mkIVs moved right up the ladder close to the "real" amps. when first using an vintage dynaco old the electrolytic caps DO need to be formed, if not replaced. I think unless really cash strapped going for one of the multi section cap replacement boards for the PSU is one of the "core" upgrades. I like the sound of the 7199 so I never changed it but many swear by going to 6922 on the front end. though my main system now sports the PP 2A3 amp, I still cannot believe how good a tweaked MkIV can sound! from what I hear a MkIII is nearly as good. (joe curcio says the MkII has perhaps the most potential, though I am not sure why, better output trannies?). regards, tony Quote Link to comment Share on other sites More sharing options...
NOSValves Posted May 17, 2003 Share Posted May 17, 2003 Sunny, from what I hear a MkIII is nearly as good. (joe curcio says the MkII has perhaps the most potential, though I am not sure why, better output trannies?). regards, tony I find this hard to believe !! The Mark III from everything I have ever heard is known to be the Holy Grail of Dynaco's. I just can not figure why Joe would say this he doesn't even make a upgrade board for the Mark II ! Maybe he thinks it was the best Stock sounding of the Mark series ? Quote Link to comment Share on other sites More sharing options...
rtaylor Posted May 17, 2003 Share Posted May 17, 2003 I emailed Joe C. a couple of months ago about upgrading my MKII's. His reply stated that his upgrade was for both the MKII and MKIII. I dunno, just a sheetmetal worker here. Randy Quote Link to comment Share on other sites More sharing options...
rtaylor Posted May 17, 2003 Share Posted May 17, 2003 Help! Working on the power supply boards tonight and left the instructions at work. Does the positive capacitor trace go to the negative sides of the diodes? It makes sense but I'm not sure.Randy Quote Link to comment Share on other sites More sharing options...
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