Home » Audio » Thermionic Emissions » Boy, is this a dull forum...
Boy, is this a dull forum... [message #11351] Tue, 14 November 2006 17:32 Go to next message
SteveBrown is currently offline  SteveBrown
Messages: 330
Registered: May 2009
Grand Master
Okay, now that I caught some attention I'll say, well, it is kind of dull. Where are the posts? What are you all working on? What's on the bench? Ideas? I wish I'd built.. ? what's up?
But also, I have a question. On another forum I read a review of caps. I have long believed that no caps are good caps, but lets face it, sometimes they're needed. So how many, if any, folks have tried V-Caps? They were second rated in that review only to AN Silver caps. I ordered a (very expensive) pair, but have not received them yet. I'll let you know what I think, but in the mean time, anyone else with some experience?

Re: Boy, is this a dull forum... [message #11352 is a reply to message #11351] Wed, 15 November 2006 08:23 Go to previous messageGo to next message
gfederys is currently offline  gfederys
Messages: 46
Registered: May 2009
Baron
Well, In response to your first question, after 2 years I'm FINALLY in the process of putting together my 2A3/300B SE amp science project. I did all the machining and woodworking on it and it's been sitting boxed up. Hopefully by Christmas, (can I say that here?), it'll be completed. Being more mechanically then electronically oriented, it's being more of a challenge then I expected. Luckily I have some freinds that are way better @ this then I am to help out. In response to your 2nd question, I've only listened to Solens and Hovlands in my PP amp and prefer the Hovlands by a long shot. I undestand there are way better out there for a lot more money. OK, time for a snooze.

Re: Boy, is this a dull forum... [message #11353 is a reply to message #11352] Wed, 15 November 2006 10:04 Go to previous messageGo to next message
SteveBrown is currently offline  SteveBrown
Messages: 330
Registered: May 2009
Grand Master
So you're building an amp where you can switch the filiments and cathode R to allow swapping 2A3 and 300B? Sounds interesting. What kind of driver are you using?

Re: Boy, is this a dull forum... [message #11354 is a reply to message #11353] Wed, 15 November 2006 10:21 Go to previous messageGo to next message
gfederys is currently offline  gfederys
Messages: 46
Registered: May 2009
Baron
WHAT, HUH, Hmmmm.... Sorry, musta dosed off. I decided to build the Angela/JE Labs 2A3 Simple. Then one engineer friend of mine looked @ the schematic and thought I should be able to run 300B's off of it by adding a Tamura filament transformer and a switch to go between parallel and series which indeed does change the filament voltage between 2.5v and 5v. It's starting out stock running the recommended 6SL7's but another friend suggests reworking it to use 6W6's. Don't forget, it should be able to play 45's, (NOT the early 60's discs), as well. I'm just an innocent pawn in their games.

Re: Boy, is this a dull forum... [message #11355 is a reply to message #11354] Thu, 16 November 2006 07:27 Go to previous messageGo to next message
SteveBrown is currently offline  SteveBrown
Messages: 330
Registered: May 2009
Grand Master
Sounds interesting. And as you likely know, the 2A3 is a 15w tube, and the 300b is a 40w tube, so it isn't just heaters that need to change. If you slap a 300B in the 2A3 circuit, without altering the operating point for the 300b, you'll hear a difference (due to the diff tube), but you'll not really get any more power out. Also, the 300b, borrowing the 2A3's bias R may or may not be at a good operating point, you'd have to look at the plate curves to figure that out. I suspect it will run just fine, but may not be the best representation of what a 300B can do. Overall, sounds like you'll have fun. Keep us informed on the progress!

Re: Boy, is this a dull forum... [message #11356 is a reply to message #11355] Thu, 16 November 2006 08:26 Go to previous messageGo to next message
gfederys is currently offline  gfederys
Messages: 46
Registered: May 2009
Baron
I kinda knew that. The main idea flash @ the time was to be able to run and listen to some 300B's I bought cheap. From everything I've been reading, most people prefer the 2A3 tube. If it sounds like the 300B will be a clear winner, I'll change parts to adjust for the 300B's. If I had a place to post some pictures, I would. I'll have to look into that. Thanx for the encouragement.

Another Way [message #11357 is a reply to message #11351] Fri, 17 November 2006 12:31 Go to previous messageGo to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
About six weeks ago I put Magnequest EXO-45 transformers and BCP-15
extralinear chokes (all M6 cores) in my standard Bottlehead Sex Amp.
I also replaced the .1 ufd. interstage coupling cap with V-caps. I
think I've got enough hours on it now, and it sounds wonderful on
my Lowther Medallion IIs (15 ohm PM2Cs). Richer mids and some real
bass, though it naturally doesn't go deep. My combination of mods
made the cap change largely unobservable, of course, but the total
result is sure there.

I'm not about to spend the bucks it would take to replace the parafeed
cap (1 ufd.) with a V-cap. I'll try and Auricap or a motor run (if I
can find a 1 ufd. motor run) there in a few months.

Skip

Subject should be: About the V-Caps [message #11358 is a reply to message #11357] Fri, 17 November 2006 12:33 Go to previous messageGo to next message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor



Re: Subject should be: About the V-Caps [message #11359 is a reply to message #11358] Fri, 17 November 2006 14:34 Go to previous messageGo to next message
SteveBrown is currently offline  SteveBrown
Messages: 330
Registered: May 2009
Grand Master
Not sure why the 45 would not have bass. Mine sure does. Are you driving efficent speakers? On the parafeed cap, having heard the DIY Audio "Obligato's", I think that's a great way to go. I'd also suggest more like 3 -10uf for that cap.

Subject should be: About the V-Caps [message #11360 is a reply to message #11359] Fri, 17 November 2006 15:02 Go to previous messageGo to previous message
Skip is currently offline  Skip
Messages: 27
Registered: May 2009
Chancellor
I'm fairly sure the amp has good bass, it does through phones.
The Lowther Medallions run out around 60-70 hz or so with hints
below that. Might need a transconductance amp to push those drivers
much lower. I'll work on something with more watts as well. 2 watts
with a baffle step correction (line level before the amp) pushing up
the lows has its limits.

Skip

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