Guest wdecho Posted August 2, 2018 Share Posted August 2, 2018 On 7/31/2018 at 10:44 AM, rjp said: I purchased a Dynaco PAS 3X from ebay and a VTA SP12 kit from tubes4hifi. I am really looking forward to building the SP12 kit! If I realized I could get the basic board for under 200 bucks I would have skipped the PAS option. Well, it will be fun to try both. I'll keep the one I like and sell the other. They will both be in super amazing condition when I'm done owning them. So...I intend to be in serious preamp mode shortly I have a number of pre's, buffers I have built both tube and SS. I generally use a SS buffer or pre with tubes being that most all the tube pre's I have built introduce some more 2nd harmonic and all but one of my tube amplifiers is a PP with enough 2nd harmonic as is. This is easily verified with a spectrum analyzer and it does not have to be an expensive one. Some of the software version such as Arta are really very, very good. Here is one you may want to take a look at. https://community.klipsch.com/index.php?/topic/172851-korg-nutube-6p1/&tab=comments#comment-2199617 A true triode in a very different look. For a tube pre it is really clean with only a touch of 2nd harmonic unlike my SRPP tube pre which still has quite a bit of 2nd harmonic. Pete Millett has a board you can buy on Ebay with a complete build guide. Sounds really nice and different with a SS amplifier vs a SS preamplifier. Gives more of a tube sound to a SS amplifier. http://www.pmillett.com/Nutube_buffer.html I am the one that suggested to Pete to add gate stoppers on the transistors preventing oscillation of which I had on my build. Surprisingly it was not something he had ever heard of and his remedy before I told him about gate stopper resistors was another type of transistor. Always something new to learn in electronics. Gate stopping resistors are common in SS builds on Firstwatt clones. I suggested 1K ohm ones for Peter to add but I still noticed a touch of oscillation on one of my channels with no music playing and went to 2K ohm gate stoppers and fixed that quite easily. https://www.ebay.com/itm/DIY-PCB-plus-Tube-Buffer-PCB-using-the-Korg-Nutube-6P1/162427314046?hash=item25d16c1f7e%3Ag%3A9eoAAOSw32lYxB4p&_sacat=0&_nkw=korg+nutube&_from=R40&rt=nc&_trksid=p2380057.m570.l1311.R2.TR2.TRC0.A0.H0.Xnutube.TRS0.TSS0 Easy, quick, cheap build with great results. Nelson Pass has a slightly different schematic, where I heard about the Nutube, but no board as of yet to build with. https://www.youtube.com/watch?v=sCqAvYDpbKQ&t=3452s About the 8 minute mark. It has been awhile since I built but unless I am mistaken the transisors are used simply as buffers before and after the nutube which should not significantly add anything to the sound. Quite nice tube linestage and even though it is call a buffer it does have gain. Quote Link to comment Share on other sites More sharing options...
Schu Posted August 2, 2018 Share Posted August 2, 2018 11 hours ago, Emile said: OK; put my VTA ST70 in the garage sale section to see if anyone is interested. Just made someone an offer for a Pioneer SX-1250 ... big beast (and big $$$) Just easier when playing with multiple speakers and multiple components That was quick... 1 Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 2, 2018 Share Posted August 2, 2018 On 8/1/2018 at 11:49 AM, richieb said: holy grail "gain with wire" sound. Passives don't achieve it either! Quote Link to comment Share on other sites More sharing options...
rjp Posted August 2, 2018 Share Posted August 2, 2018 Why do people think gain with wire is best? I mean, we're talking tube amps here. It's all about signature and coloration. The "best" is your favorite color Quote Link to comment Share on other sites More sharing options...
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