luvdunhill

just curious, has anyone tried using other tubes in the Blue Hawaii than the 6CA7/EL34? I ended up with a set of boards, and was looking at some datasheets over the weekend. I started looking at the 6BG6GE, 3D21A/WB/7403, 12E1, EL360, 6146, etc.... I started looking more at the 3D21A, but noted that the one major concern is that the transconductance is about half that of the EL34 which means that the gain will probably be about 6dB lower than the EL34, and depending on headroom in the cathode drive circuit this could result in significantly higher distortion. (Also, I might not get enough voltage swing without making other changes that would raise the source impedance of the amplifier.) Other specifications seem reasonable, but I can at best make a guess as to its suitability as there are no triode curves provided for this type. Then I looked at the 6BG6GE which seems like it might work, but has some of the same concerns as above.... Both of these two tubes look like good starting points... anyways, has anyone gone down this path?

psu:

KG: sure! I'm about ready to build a preamp.... so good timing. I'm thinking about this one: Any opinions on it?

If this is the case, the 6BX7-series of tubes on the high-power setting is calling your name. If even after listening to these (they're cheap, so pick up a pair) *then* perhaps the high-voltage setting isn't for you Or maybe a trio of '51 Hytrons My MPX3 has a not-so-high voltage setting on it and it sounds wonderful with the 6BL7GT which on my other MPX3 SE with the standard high voltage setting sounded dark and surripy. I'd still look for a pair, as they're hard to find these days and worth trying (and hoarding). I could never get the 7062 driving the 7119s to really work... it sounded like something was broken, so I quickly removed them In addition to tkams idea, I'd try the 12bh7 (RCA or Brimar) driving a pair of Sylvania 5687s...

wow, sounds like a fun day! I've went though a handful of BAT preamps and I really liked them. If I had my choice, I'd go with the VTL 7.5 but I'm not sure the extra price tag is worth it these days. I really love the Ayre amps and maybe one day I'll pony up for Charles' new amps. They sounds amazing. I went through a similar journey with my Whest phono stage. At this point, it's just sitting there as I have fallen in love with another. I need to list it at some point. Anyways, it went back across the pond 3 times and finally they got rid of a few issues. At that point, several phono stages in my rig, a Klyne, Pass and an Herron. The Whest is very nice and was the first to convince me that solid-state is the way to go in a phono stage. I'd love to try the Ayre, and almost bought one a few times but I'm happy at this point. Just curious Thanks for the reply.

For output, I'd try the side getter RCA 6BL7GTA or (even better) the older CBS/Hytron 6BL7GT (non-A) tubes. For input, Tung-Sol 5670 or (even better) Ericsson 396A if you have the adapter needed for these two or pinched waist Amperex 7062. These combinations sound awesome on all headphones to me. I like detail and things a bit on the bright / hot side. edit: I thought you were looking for a recommendation Sorry, ignore the above as it looks like you have a combination that sounds great with your setup! enjoy!

Karhu: There are some "simpler" (i.e. cheaper) projects here: http://high-amp.de/html/frame.html

Tom: Just curious, did you have the Ayre phono stage at some point? I think I might have say it on the auction block a few weeks (months?) ago. What did you replace it with? I'm thinking about a SP preamp as well. I have had BAT, Ayre and VTL preamps at some point or another... at this point, I'm thinking about going back to BAT or maybe trying a Pass preamp. shrug, lots of choices. Also, does anyone know how much voltage gain the various Singlepower preamps have? Would they be enough to drive speakers through Nelson Pass's F4s (i.e. no voltage gain)?

Howdy pabbi1! I've been lurking / stalking KGs posts to see if anything cool shows up over here ... yup, I built a few JTs, I really like them. Only problem with the JT I've seen is playing the input / output impedance game with them. Haven't thrown one on the new KGSS. Nice segue though. According to Russ, the input impedance of the JT attenuator ranges from approximately 2.2K to 10K and the output impedance is 750R (this is for the 50k "version" of the Joshua Tree, this obviously is not set in stone, and there are resistor calculators on diyaudio). The original KGSS schematic has 500K input resistor for Zin. I was wondering if this combination will "work", or if I should look at reconfiguring the JT? With the relatively high Zin of 500k that the KGSS/BH uses by default, is either output offset (I assume not) or noise a problem? By noise, I mean noise due to stray capacitance between the input terminals and the board inputs? I have heard that this can be a problem when using high values for Zin and that this could have an effect on the high frequency response. Also, has anyone experimented with a RF filter (R+C) right off the jacks on headphone amplifiers such as these? Of course upstream impedance might have to be calculated and the filter "fiddled" with a bit...

I just had the option of hearing a preamp with a Alps HQPro and then it was switched out with a standard stepped attenuator using Riken resistors. Yeah, I'd take the HQPro any day... random, but I noticed that there's one for sale at diyaudio with pics http://www.diyaudio.com/forums/showthread.php?s=&threadid=112437