Jim Posted December 26, 2015 Share Posted December 26, 2015 Mike, I don't know anything about the other amp you are speaking of, I only know how to listen to them. I've been listening to things from La Bouche, Beastie Boys, Metallica, James, Abba, Donna Summer, Linkin Park, Run DMC, and a bunch others on my hard drive in shuffle mode. What I can say is the sound stage is wider than the speakers placement, it's crisp, nice thumping bass (almost like a powered sub) with the forte II's, and also tamed the brightness I was getting with certain types of music. I'm listening to Rob Zombie while I am typing this and it's just fine as well. 1 Quote Link to comment Share on other sites More sharing options...
MyOwn Posted December 26, 2015 Share Posted December 26, 2015 You guys rock...Knowing why a circuit behaves the way it does is sooooooo far away for me... :blink: 1 Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 26, 2015 Author Share Posted December 26, 2015 I don't know anything about the other amp you are speaking of, I only know how to listen to them. There was a time before everyone called a triode strapped pentode, or beam tube in amplifier circuit SET. Single-ended triode. Yeah, technically a strapped pentode/beam tube is a triode with the tube's screen grid (G2) tied to the plate (anode) with fairly lower value resistor. But that's just me... I'm used to the name SET referring to a actual triode tube, like 45, 2A3, 300B, etc. The filament is the cathode in a triode tube. They can be directly heated with AC, or indirectly with DC. How said triode tubes are heated is an argument in itself. The 2A3 amplifier I have is AC heated. Quote Link to comment Share on other sites More sharing options...
Jim Posted December 26, 2015 Share Posted December 26, 2015 That's purdy Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 26, 2015 Author Share Posted December 26, 2015 It does need a paint job, but that beast will outlive me. It survived a good 4.5 foot fling to the floor from a burglary. Buckled the case a little, and knocked out a capacitor that I really didn't have affixed in the chassis well enough anyway. Also a few tubes fell out. Straightened the chassis, fixed the cap, tubes checked out fine, and all is well. I just hope that 40-45 pound amplifier caught a foot or a shin on the way to the floor. Quote Link to comment Share on other sites More sharing options...
xxJPMxx Posted December 27, 2015 Share Posted December 27, 2015 My opinion is that the driver is usually the weak link. Music has transients. We know the solid state guys just like to use huge wattage power amps. Tube amps, especially SET are low power so high power isn't really an option. The AC coupling from driver tube to power tube causes so many issues with these transients. Direct couple a Source follower to a power triode and oh baby!! . Old school amp designers that knew this used interstage transformers, but they are not as good as a source follower. Music with heavy low end transients are the problem so I advise you diyer's to try it, you won't go back. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 27, 2015 Author Share Posted December 27, 2015 I've been listening to things from La Bouche, Beastie Boys, Metallica, James, Abba, Donna Summer, Linkin Park, Run DMC, and a bunch others on my hard drive in shuffle mode. What I can say is the sound stage is wider than the speakers placement, it's crisp, nice thumping bass (almost like a powered sub) with the forte II's, and also tamed the brightness I was getting with certain types of music. I'm listening to Rob Zombie while I am typing this and it's just fine as well. I had forgot to ask. Have you used the "ear bleed" option that Maynard has built into the amplifier, and what is your opinion of the option if you happened to have used it? Mike Quote Link to comment Share on other sites More sharing options...
Jim Posted December 27, 2015 Share Posted December 27, 2015 Is that the option to tame the treble? If so, it's almost like a treble a knob and adjusts the brightness on the highs. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 27, 2015 Author Share Posted December 27, 2015 Yes. I was curious if you used it much while listening. Quote Link to comment Share on other sites More sharing options...
Jim Posted December 28, 2015 Share Posted December 28, 2015 I tried it with it on and off. I feel I don't need it on. I played with it and adjusted it and like it better off. The amp really matches up with the speakers and takes away the brightness I was getting with the new crossovers. The bass digs deeper than my Yaqin MC-10L when they are set at lower volumes. The Yaqin has more power so after a certain point it's moot. This also hits the mids and highs a little better. I've only been listening with the volume control between 9 and 11 o'clock. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 29, 2015 Author Share Posted December 29, 2015 (edited) Well I guess I'm committed now...I ordered a 17" X 10" X 2" aluminum chassis from Mouser. Two inches should be tall enough I would think. Working on the other side of the breadboard circuit, awaiting for the 6.3 volt filament transformer. I went with regular octal sockets for the 6SF5s, tied pins 1,2,3 together, and have the 10 meg grid resistor closer to the pin/pins. I also made a virtual center tap I suppose, with a 300 ohm resistor from each leg of the 6SF5's 6.3 volt heater winding to ground. These changes should help with the noise. A convenient way to do it is to tie pins 1 and 2 together, run a lead to the ground buss, and simply put the 10 meg resistor between pins 1 and 3 or 2 and 3 as close to the socket as possible. I tied pins 1, 2, 3 together, with the 10 meg resistor coming off pin 1 for convenience. Would that be okay to do? Or should run a lead from pins 1 and 2 to ground, untie pin 3, and ground with the 10 meg resistor separately? Edited December 29, 2015 by mike stehr Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted December 29, 2015 Share Posted December 29, 2015 Only pins 1 and 2 should be grounded to the buss. Pin 3 should be connected to the 10 meg resistor (the other end of which should be grounded to either pins 1/2, or the buss if close to the socket), and the coupling cap from the volume pot. Maynard Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 29, 2015 Author Share Posted December 29, 2015 Okay. Thanks for clarifying. I'll correct the error. I learned some new things from this project. Grid bias. Connecting output tubes in parallel, (never tried it before) and the series HP RC feedback network. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 29, 2015 Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted December 29, 2015 Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. what are the ingredients of the BWW Citrus Bowl? Quote Link to comment Share on other sites More sharing options...
Jim Posted December 29, 2015 Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. Had you said this yesterday, I may have asked about them. Just purchased a quad and pair. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 29, 2015 Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. what are the ingredients of the BWW Citrus Bowl? Wolverines and Gators Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 29, 2015 Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. Had you said this yesterday, I may have asked about them. Just purchased a quad and pair. If I was psychic, I would have posted this yesterday, but, alas, not... Quote Link to comment Share on other sites More sharing options...
mike stehr Posted December 29, 2015 Author Share Posted December 29, 2015 I saw the title of this thread a while back, and thought I should look in my stash for some of those tubes....(6AQ5/6005). If anyone needs some, let me know. I could use some, I'll give you a PM. Mike Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted December 30, 2015 Share Posted December 30, 2015 I tested a bunch tonight, several really nice pairs and quads. GE ribbed black plates and Sylvania smooth plates. I don't use them, so Mike has first crack. Quote Link to comment Share on other sites More sharing options...
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