henry4841 Posted January 30, 2022 Share Posted January 30, 2022 I think you may be heading in the right direction considering making an outstanding SE amplifier at a reasonable price rather then trying to hit a low price point. Especially when considering the cost of the iron and chassis being the most expensive part of any tube build. An excellent, well designed, with decent parts SET amplifier less then $1000. would be a hit on this forum in my humble opinion. I have a number of Nelson Pass' SE SS amplifier and the cost to build one of them can surpass the $1000 mark or at the very least start towards that figure. Most novice builders are going to require a board to build on not building point to point and designing and producing a board is the job you seem to be more then able to accomplish. Link to comment Share on other sites More sharing options...
CWelsh Posted January 30, 2022 Share Posted January 30, 2022 2 hours ago, henry4841 said: I think you may be heading in the right direction considering making an outstanding SE amplifier at a reasonable price rather then trying to hit a low price point. Especially when considering the cost of the iron and chassis being the most expensive part of any tube build. An excellent, well designed, with decent parts SET amplifier less then $1000. would be a hit on this forum in my humble opinion. Shhhhh, he's been talking under $500. Don't give him ideas. 😄 Link to comment Share on other sites More sharing options...
captainbeefheart Posted January 30, 2022 Share Posted January 30, 2022 14 minutes ago, CWelsh said: Shhhhh, he's been talking under $500. Don't give him ideas. 😄 That's funny!!! I am pretty certain we can do the single ended KT88 amp, Class A2 for $500 with a nice chassis and shipped. 2 hours ago, henry4841 said: Most novice builders are going to require a board to build on not building point to point and designing and producing a board is the job you seem to be more then able to accomplish. This is what I have been doing a lot of thinking about. I may just go with turret style boards as they are more rugged for modifications and certainly have a cool factor to them. I have epoxy board and turrets plus all the tools already here. I can send the boards out populated with the kits with instructions to wire them up. Most likely two boards, one for the front end and one for the power supply, the power tubes do not need a board. I guess I will just ask everyone now. What do all the guys interested in building themselves prefer, point to point with detailed instructions? Populated turret boards ready to just be installed and wired up? Or lastly printed circuit boards? Link to comment Share on other sites More sharing options...
CWelsh Posted January 31, 2022 Share Posted January 31, 2022 7 minutes ago, captainbeefheart said: What do all the guys interested in building themselves prefer, point to point with detailed instructions? Populated turret boards ready to just be installed and wired up? Or lastly printed circuit boards? I can only speak for myself. I have decent soldering skills, but I'm not an engineer and would have no ability to make decisions about proper configuration. In other words, I can handle some assembly, but that is the limit of my comfort level. Does that help? Link to comment Share on other sites More sharing options...
Shakeydeal Posted January 31, 2022 Share Posted January 31, 2022 I’m in for a point to point wired amp with some Jupiter caps in a nice chassis. Where do I sign up? Link to comment Share on other sites More sharing options...
henry4841 Posted January 31, 2022 Share Posted January 31, 2022 Circuit boards are the best option to put more SE tube amps into more peoples homes. I know it is asking a lot from Captain but lets hope he has the time to spare. All of the tube amps I have built are point to point working from a schematic but then I have an electronic background. The majority of members that visit this site do not or care to go done that road just like I would not know how or want to do the field they are in. But many of those members know how or have the ability learn to solder. Not much to it actually. Hold the iron on both parts you wish to connect until the parts melt the solder and not the other way around. They are the ones that might want to assemble their own amplifier. In a way the project would be a forum effort, as it has become a little bit now, contributing to Captain ideas for a somewhat joint effort with Captain doing all the heavy lifting. It will be fun seeing how this continues. A Klipsch Forum SET Amplifier. 2 Link to comment Share on other sites More sharing options...
Racer X Posted January 31, 2022 Share Posted January 31, 2022 While all the various construction variations sound interesting, I have to be realistic in my solder abilities have only been recently developed to allow crossover modifications. I enjoy rolling my own wires, and am just starting to try to solder up interconnects. Plug and play assembly is a no brainer, but possibly someday getting to the point of assembling an amp point to point is something to aspire to. Starting with a Chinese amp chassis assembled and making some mods sounds like a good interim step. Link to comment Share on other sites More sharing options...
captainbeefheart Posted January 31, 2022 Share Posted January 31, 2022 There is another option that I am very surprised someone hasn't marketed already, especially Klipsch. PWK was a really big fan of the Brook 12a amplifier, I even heard rumors of a specific Klipsch model where it had a 'K' in the model number like 'Brook 12a k-1' or something along those lines where Paul had influenced the design, lower bandwidth I believe was the only difference but I have never seen one. There is also the rumor where that was really just Paul's own personal version of the Brook amplifier that he kept working for him for a very long time. The problem is this is push pull, well I guess not a problem really just a different direction. I also don't think PWK himself would object to a really good 15 watt single ended amplifier either. I guess I am just curious how many Klipsch fans out there would want the amplifier that the big guy himself PWK admired so much when paired with his beloved speakers. IF this went that route I may to keep the price down use 6AV5GA in triode mode instead of actual 2A3's. I have made this amplifier before and measurements were the same between the two and I personally didn't hear a difference either. The circuit is to thank for that. The 6J5 drivers will be replaced with a single 6SN7 which is electrically identical just two triodes in one bottle unlike the 6J5 single triode per bottle. Due to the rich history this would almost be a perfect 'forum' amplifier as it was Paul's favorite amp with his speakers. That says a lot. 2 Link to comment Share on other sites More sharing options...
CWelsh Posted January 31, 2022 Share Posted January 31, 2022 @captainbeefheart A lot of the most active people on the forum seem to have multiple amplifiers. This little project could easily turn into something ongoing with a number of "Forum" amps as long as there are willing designers. It just has to start somewhere. Since this is your idea, Captain, I think you should start with something that appeals to you and let's see where it goes. Link to comment Share on other sites More sharing options...
Curious_George Posted January 31, 2022 Share Posted January 31, 2022 51 minutes ago, captainbeefheart said: I may to keep the price down use 6AV5GA in triode mode instead of actual 2A3's. I have made this amplifier before and measurements were the same between the two and I personally didn't hear a difference either. The circuit is to thank for that. The 6J5 drivers will be replaced with a single 6SN7 which is electrically identical just two triodes in one bottle unlike the 6J5 single triode per bottle. Due to the rich history this would almost be a perfect 'forum' amplifier as it was Paul's favorite amp with his speakers. That says a lot. I recently bought a small stash of 12AV5GA’s on eBay for use in 2A3 “type” amps. They are a little cheaper than 6AV5GA’s. Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 1, 2022 Share Posted February 1, 2022 Here is a stripped down schematic, just the signal circuit excluding the variable damping control. 12 watts 1% THD it will push more power out but at higher distortion. I conservatively rate my amplifiers. Fixed resistors in the bias scheme will be changed to a pot for adjustment in the build. The 1 ohm cathode resistor will either have tip jacks going external for bias readings, or I will install a current meter in the cathode circuit so nobody needs a digital volt meter to change bias. Whichever people feel is best and if I can add the analog current meters for decent cost. There are no compensation networks at this time, I do that after it's built. 6SN7 may be changed to 12AU7 or 12BH7, anything similar. Same for 6AU6A, will try different small signal pentodes once built. Thoughts? Ideas? Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 1, 2022 Share Posted February 1, 2022 12 watts output 1.19% THD Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 1, 2022 Share Posted February 1, 2022 Typical output distortion profile I aim for in a single ended amplifier, second harmonic dominant and then the cascading 'waterfall' look of diminishing harmonics. I'll post at 1 watt. Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 1, 2022 Share Posted February 1, 2022 1 watt output .19% THD Clean and accurate but with a little second harmonic dominant distortion and blip of third. This or even lower is where most of us Klipsch users will be running on average listening. 1 Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 2, 2022 Share Posted February 2, 2022 I have thick skin.........don't worry my feelings will not be hurt lol. Should I submit a couple different ideas along with this? That's no issue at all, I am more than happy to model several ideas before I start building. I have lots of parts to whip up a channel and test it as soon as we get a design approval from the committee, that's you Or do people not really give a crap about details and have me make an amp, take some measurements and pictures and put it up as the first prototype? I like an organic process, no need to be confined to strict protocols. Link to comment Share on other sites More sharing options...
Curious_George Posted February 2, 2022 Share Posted February 2, 2022 Looks great! Nice and clean, no fat. Link to comment Share on other sites More sharing options...
Curious_George Posted February 2, 2022 Share Posted February 2, 2022 How much current can the 6SN7 sink in your design? I know it’s not too much, but just enough to get some A2. Link to comment Share on other sites More sharing options...
CWelsh Posted February 2, 2022 Share Posted February 2, 2022 11 minutes ago, captainbeefheart said: I have thick skin.........don't worry my feelings will not be hurt lol. Should I submit a couple different ideas along with this? That's no issue at all, I am more than happy to model several ideas before I start building. I have lots of parts to whip up a channel and test it as soon as we get a design approval from the committee, that's you Or do people not really give a crap about details and have me make the just bang out an amp, take some measurements and pictures and put it up as the first prototype? I like an organic process, no need to be confined to strict protocols. I'm qualified to say you've chosen a nice shade of blue for the schematic and that your lines are straight. Beyond that...well, I'm not worth much. 1 Link to comment Share on other sites More sharing options...
grindstone Posted February 2, 2022 Share Posted February 2, 2022 I think commentary is witheld to not pollute your process and to allow it to happen. You are giving freely and we were all raised well :). Link to comment Share on other sites More sharing options...
captainbeefheart Posted February 2, 2022 Share Posted February 2, 2022 31 minutes ago, Curious_George said: How much current can the 6SN7 sink in your design? I know it’s not too much, but just enough to get some A2. It depends what value R6 is, the design is tolerant to 4.7k-82k. The lower the value the more current it can deliver, it will maintain signal integrity better past 0v so more power out. For someone that will not push the amplifier at all I'd install a 47k-56k for long life. Real world testing I'll decide which gives best performance at as low a value as I can get, might be 22k-39k my guess but if 56k (1.6mA) works well enough I'll leave it. For someone that wants ultimate full power performance to squeak every bit out of it 10k will do well (8mA) or possibly lower, maximum I would run idle is 12mA. Link to comment Share on other sites More sharing options...
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