WPM Posted January 18, 2007 Author Share Posted January 18, 2007 The QS lower cost amps are dead simple almost to a fault IMHO. I wouldn't hesitate to upgrade the caps if I was you but don't expect miracle changes in sound. Also give whatever you try at least 100 hours to break in and with any TFT type 500 hours! The options are endless and the opinions will be also. V-cap TFT will indeed set you back a bundle. Sonicap platinums would be another TFT option that costs less but still pricey. The Russian film and foils would be a great bargain upgrade but sourcing can be fun these days (very few of the Russian caps are really PIO's). Jensen's PIO's will warm things up for sure. I'm sure I will get some frowns out of this comment but it would surprise me knowing what I do about QS designs that I would describe the horn mono's as super horn friendly in my book. I've replace the QS V-4's with VRD's on speakers "Von Schweikert's" that could use the near double power they make over the VRD's and the customers was not disappointed in the VRD's except when cranking thing up past the VRD amps abilities. Craig Hi Craig, Indeed, you are correct... the QS amps have a very simple design and literally lend themselves to mods/upgrades. I think they basically sound pretty good, as is, but they can certainly be improved upon. That's the trouble when components are built to a price point... something has to suffer. With the QS amps it must be in the caps and resistors, as their transformers are of very high quality, which, in my opinion, is where it matters most. Everything else can be addressed by the DIYer. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /> I love the idea of the Jensen's, but the 250 hour lifespan scares me to death. I double checked the Jensen website and, sure enough, it's posted right there. I can put 250 hours on my amps in a few months, and I just can't see me soldering in new caps every quarter, that's just insane. I've heard about these German made PIO caps called M-Caps, and am trying to get some info regarding their lifespan. Perhaps they will last a bit longer than the Jensen's? Still, I may have to give something a try or I'll never know. I may go ahead and replace the resistors in the amps with Riken Ohms, as well, as there are very few of them inside the amps, too. I appreciate you chiming in, Craig, as I knew you'd give it to me straight. And thanks to everyone else for sharing your comments, too. If, and when, I do undertake this little mod project, I will be sure to post my findings. I'm sure Chuck will be very interested. William William, Glad you took my comments as intended! If I was you I would at the very least slap some mid level caps from reliable capacitor or similar. Go Film and Foils if you want percicion or PIO for sweetness (blurring). By the way the 250 hour rating is for full maximum conditions on all parameters. Chances are the Jensen caps would run for years and years in your amps without issue. PIO caps don't like heat but I would be surprised if your QS amps break 100 degrees on the inside of the chassis. Another great option for caps is the mundorf line. Craig Hi Craig, I've been reading up on the Mundorf line of PIOs, very intriguing, and they seem to be well received by the audio press, too. I am leaning towards the Jensen line, if only because I am familiar with their products and reputation. On a side-note, I just installed a pair of Tung-Sol 12AX7s in my preamp recently, and this alone raised the musical bar in my system a few notches. Wonderful tube (IMHO) in case anyone is wondering. William Quote Link to comment Share on other sites More sharing options...
anarchist Posted January 18, 2007 Share Posted January 18, 2007 I am now thinking I will put M cap silver/oil on my Mark III's. What to do with the Auricaps I already have is now the questions. If I don't use them, there went $60.00. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 19, 2007 Share Posted January 19, 2007 I talked myself into using the Jensen Coppers. Just ordered the 0.22s. They're so purdy, I may just mount them on the top side of the boards.[] Rick Quote Link to comment Share on other sites More sharing options...
WPM Posted January 19, 2007 Author Share Posted January 19, 2007 I talked myself into using the Jensen Coppers. Just ordered the 0.22s. They're so purdy, I may just mount them on the top side of the boards.[] Rick Hi Rick, Where are you purchasing the Jensen's from? I was going to go through Welborne Labs, but I see they do not sell Jensen's any longer. Thanks. William Quote Link to comment Share on other sites More sharing options...
Tarheel Posted January 19, 2007 Share Posted January 19, 2007 William.. Did you see the QS line stage preamp on audiogon.com for $550. Another deal. I have decided my next system build will be to get the best sound at a very reasonable price by shopping used equipment and building the speakers. I think a very good system can be put together for less than five grand if you go this route. Its amazing how quickly the price of stereo equipment drops in a year or two. You are probably right about calling Mike Sanders. He will probably say to leave well enough alone. One of the reasons I like my monos is the reliabilty and I haven't had a seconds problem with mine so I guess he builds them to last and be trouble free. Let us know what you do with the caps and the results....until then keep squeezing everything you can from your already great system. BTW there is an interesting thead on updates and modifications about someone who has tweaked ad infinitum and is still disillusioned with the results. Its a pretty good read. Its about recapturing a sound he remembers from college days. Anyway.....have a great weekend. Chuck Quote Link to comment Share on other sites More sharing options...
Tarheel Posted January 19, 2007 Share Posted January 19, 2007 Sorry...that thread I mentioned is on 2 channel entitiled "can you go too far?" Chuck Quote Link to comment Share on other sites More sharing options...
meagain Posted January 20, 2007 Share Posted January 20, 2007 Anarchist - Thanks for that link. Interesting. (FYI, "V-Cap" is mentioned at the bottom of page 7. And on starting on page 12 under class-a teflon - reviewer seems to love whatever this is).... Rick - I'm confused... Did you already put Jensens in your amp, but then just bought the copper version for replacement? And... What exact caps are you running in your AA crossovers? And.... Can you or anyone describe what "Mac-like bass" means? thx Has anyone used the copper Jensens in crossovers? Or is that designed more for amps? Quote Link to comment Share on other sites More sharing options...
anarchist Posted January 22, 2007 Share Posted January 22, 2007 V-cap is the new way of spending big bucks - I think Dean has used some on his cross-overs but I am not certain. Maybe he will chime in. There is some member here who has V-caps in his cross-overs and loved them but I don't recall which ones he used. Rick has a Poseidon driver board he is installing in his Mark III's. They require three caps. Rick decided to use the Jensen coppers. Rick is also, I believe, doing something cool using a pot in association with those boards to be able to "tune" the nfb and I keep waiting for him to explain exactly what he is doing, what it buys, and how to do it. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 22, 2007 Share Posted January 22, 2007 Let's see if I can answer those questions in order. I bought the Jensens from a guy on Ebay. I've bought from him several times before. The prices are similar to Parts Connexion with cheaper, faster shipping. Lisa, I don't run AAs. I am using ALK Universal Type As and tweeter attenuators. I was told the other night that I have "The best sounding system in Rhode Island." from a guy whose system is no slouch. Mac amps have a reputation of being a "warm" amp. That means that the bass is slightly emphasized and the overall tone is not sharply "etched" smoothing the mids. It is not a sound that everyone likes (what is?) but, many find the combo with sharply etched horns "musical". I find the 6550/KT-88 tubes to inherently possess an etched quality. To me, the additional warmth should be welcome. Craig uses his own, proprietary, circuit to get the best sound from the KT-88s in his VRDs. Dean has built a couple of Jensen capped networks I think. Robert, Shannon incorporated an adjustable feedback feature into his ST-35 plans. I like that feature. His instructions state: "Adjust the feedback for the best square wave at 500 Hz but let your ears be the final judge." That assumes that one has a signal generator and O-scope which I do. The ear part allows all to get the best sound from the little amp. Plus, Craig has been chiding us all to reduce the NFB on these boards from any source. The pot allows for up to almost complete elimination of NFB up to the design specs. Rick Quote Link to comment Share on other sites More sharing options...
meagain Posted January 22, 2007 Share Posted January 22, 2007 Rick - What caps are you using in your A's then? And... where on the hz spectrum does your tweeter attenuators hit? And how many db do you tweak to with those? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted January 22, 2007 Share Posted January 22, 2007 "Adjust the feedback for the best square wave at 500 Hz but let your ears be the final judge." That assumes that one has a signal generator and O-scope which I do. The ear part allows all to get the best sound from the little amp. Plus, Craig has been chiding us all to reduce the NFB on these boards from any source. The pot allows for up to almost complete elimination of NFB up to the design specs. Rick Yes I have been hammering you with that for a while now. You really need to visit the feedback issue with KT-88's!! They do not need the massive feedback that most of these boards apply and also what most companies apply in there amps. This is where that etched quality your talking about comes from. Lower the loop to very little then be creative with local feedback if you need to add some. Forget the 500hz only tuning. The square waves tell a good story 10hz to 20khz and beyond. Of course you have to use your ears to guide you in the end........the test equipment just makes the starting point for you. Look out for ringing at any frequency especially in the HF regions. Also look for frequency bumps even beyond the audible range with sine waves. The amp also has to be stable driving any load especially from the company selling a product stand point. Adjustable feedback is a PITA from a company standpoint. Just another control for people to screw up the sound with [] but the hobbyist may love the control in place but I would make it temperary and then once the best spot is found yank it out and replace with the fixed quality resistor. Craig Quote Link to comment Share on other sites More sharing options...
3dzapper Posted January 22, 2007 Share Posted January 22, 2007 "Adjustable feedback is a PITA from a company standpoint. Just another control for people to screw up the sound with but the hobbyist may love the control in place but I would make it temperary and then once the best spot is found yank it out and replace with the fixed quality resistor." Hahaha! You sound like PWK! Don't give 'em something to screw up![] Rick Quote Link to comment Share on other sites More sharing options...
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