do a search here on the term "K-12G" and you'll get lots of ideas. But in essence it will build and play fine stock - once you have it going and know what it sounds like, you can tweak away to your heart's content - its not a complicated circuit and if you have to ditch the pcb at some point cos stuff doesn't fit (or the tracks get damaged), its only an hour's work to rewire it point to point.
I chose to build the K502 and am still happy with my choice. The ability to try out other schematics available for the 11BM8 ( 6BM8 ) is the main reason. I haven't heard how the other versions sound but think they would all be mainly limited soundwise by the output transformers used.
My amp has been extensively modded but the biggest sonic difference IMHO was in upgrading the output transformers. S5 must review their choice of components from time to time so things can change, hopefully for the better particullarly if they listen to our feedback. (I believe psu's have been beefed up and better coupling caps used.)
If you go down the modding route then you will be hooked!
As Aardvarkash10 says,
Klipsch is > 90dB
Look for Klipsch RB-51, RB-61 (or RB-81 for a bit more money and wall-shaking bass) or their poor cousins B-2 and B-3. All of these are bookshelf speakers with 92dB and more and are generally a very good match for low-powered amps (I use F-2 95dB floorstanders in a 60sqm open-concept area powered by 2*3W amp and the volume seldom gets turned over 1/2.
Look for Klipsch RB-51, RB-61 (or RB-81 for a bit more money and wall-shaking bass) or their poor cousins B-2 and B-3. All of these are bookshelf speakers with 92dB and more and are generally a very good match for low-powered amps (I use F-2 95dB floorstanders in a 60sqm open-concept area powered by 2*3W amp and the volume seldom gets turned over 1/2.
Milsman: A couple of rough rules of thumb.......smaller diameter drivers are usually less sensitive (efficient) than larger diameter drivers, and sealed enclosures yield a less sensitive system then vented enclosures. Small drivers in small (bookshelf) enclosures tend to have low sensitivity, especially sealed box designs. Thats why most small bookshelf systems are vented.
Large drivers in large vented or horn loaded enclosures have relatively high sensitivity.
Front loading a driver with a horn (very popular with tweeters), increases the sensitivity by increasing the coupling of the driver with air (impedance matching).
Many folks here running small flea powered SE amps have large, horn loaded full range drivers for speakers. Check out the full range speaker forum to get an idea of the above. These systems typically have around 94db-100db+ of sensitivity, which can rock the house with a couple of watts.
As mentioned, depending on your listening habits, 8W may be plenty with 90db speakers.
Large drivers in large vented or horn loaded enclosures have relatively high sensitivity.
Front loading a driver with a horn (very popular with tweeters), increases the sensitivity by increasing the coupling of the driver with air (impedance matching).
Many folks here running small flea powered SE amps have large, horn loaded full range drivers for speakers. Check out the full range speaker forum to get an idea of the above. These systems typically have around 94db-100db+ of sensitivity, which can rock the house with a couple of watts.
As mentioned, depending on your listening habits, 8W may be plenty with 90db speakers.
K-502 isn't produced anymore , but used a popular tube used in very low power amps. Maybe they quit making it as that tube is not in production and getting hard to find.
I think the K-12G will distort at higher power (like one in test), and really is only okay at low level listening unless you can afford the efficient bulky speakers needed. I listen to vintage EL84 PP amps now and you can't beat the sound for the $ from those tubes and 15W/CH will work nicely with a lot of more affordable speakers. Believe me you will really appreciate that extra power! Most popular tube in lower power vintage and new production big $ tube PP amps. JJ EL84's can be had for $10 ea and a great bang for the buck.
I think the K-12G will distort at higher power (like one in test), and really is only okay at low level listening unless you can afford the efficient bulky speakers needed. I listen to vintage EL84 PP amps now and you can't beat the sound for the $ from those tubes and 15W/CH will work nicely with a lot of more affordable speakers. Believe me you will really appreciate that extra power! Most popular tube in lower power vintage and new production big $ tube PP amps. JJ EL84's can be had for $10 ea and a great bang for the buck.
Well be that as it may, I really like the idea that the K-12G comes with all of the parts, albeit a few caps and other bits that will be upgraded. That being said, I realize the level of power that is coming out but the Klipsch RG-61's are 95dB which realistically IMHO would provide plenty for a small apartment bedroom. The 8 W will probably never be pushed to full power (in fact I really doubt they ever will be) so I think this is a fine choice, especially for this kit. I know that more headroom could be attained and there are lots of options, but the K-12G seems really solid and easily built and/or customized for a beginner's build. Thoughts?
K502 here
Antique Electronic Supply
Click on kits in the menu and then click on "audio", for details.
I listen to " Baby Huey "..........
They are selling 11BM8 tubes for $6.20 and 10GV8 tubes for only $2!
Antique Electronic Supply
Click on kits in the menu and then click on "audio", for details.
I listen to " Baby Huey "..........
They are selling 11BM8 tubes for $6.20 and 10GV8 tubes for only $2!
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As mentioned the 6BM8 was a popular tube in low power production amps back in the day. Then proven good sonics would be in favor of K-502. Too bad you couldn't at least opt for better output transformers. Since this is diy you could build a point to point one which would be very simple (driver is in the same tube) with better transformers for not much more money. The schematics are out there from diy amps built by others. Lots of help here. You would learn a lot. I think all the uprading done is to improve the quality of the parts!
If you like small tube PP amps which could be built from a kit of parts another nice amp is El Cheapo. More complicated but sonics will be a reward for your work.
Audiophiletalk - Bargain Basement
http://www.mcshanedesign.net/elcheapo.htm
Latest schematic is on pg. 22 and Jim is a great guy to buy parts and well tested NOS & new tubes from.
You could also use the in production 6V6 tube too with different sockets. One would have to build a chassis and buy transformers. Dynaclone Z-565 is a very nice OPT for EL-84 /6V6 amps. Will give 20-20KHZ at full power (17W) too with very low distortion. It also has 25% UL taps if desired or needed.
If you like small tube PP amps which could be built from a kit of parts another nice amp is El Cheapo. More complicated but sonics will be a reward for your work.
Audiophiletalk - Bargain Basement
http://www.mcshanedesign.net/elcheapo.htm
Latest schematic is on pg. 22 and Jim is a great guy to buy parts and well tested NOS & new tubes from.
You could also use the in production 6V6 tube too with different sockets. One would have to build a chassis and buy transformers. Dynaclone Z-565 is a very nice OPT for EL-84 /6V6 amps. Will give 20-20KHZ at full power (17W) too with very low distortion. It also has 25% UL taps if desired or needed.
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I don't want to bother building P2P for now. I really just want my first real kit built and powered up to some good speakers . I am totally down to order the K-502 for the better sonics. Do you have any suggestions for OPT replacements? I am also okay with opting for that, sorry about the mix up, I just didn't want to go down that dark and slippery slope and end up dumping an extra $200 into a $200 kit . I hear good things about the Hammond 1609 for this kit.
. I am totally down to order the K-502 for the better sonics. Do you have any suggestions for OPT replacements? I am also okay with opting for that, sorry about the mix up, I just didn't want to go down that dark and slippery slope and end up dumping an extra $200 into a $200 kit . I hear good things about the Hammond 1609 for this kit.
I used the Hammond 1609 ( raa10k) in my K502, well pleased. 1608 ( raa8k ) has been used to great effect as well I believe. The 1609 is currently doing great service in my " Baby Huey". The 1608 and 1609 can be used in other future builds using the ECL86 and EL84 tubes amongst others
Edcor iron is also very well respected
Neither did I but I did it any way, just the price of learning I suppose....
Edcor iron is also very well respected
Neither did I but I did it any way, just the price of learning I suppose....
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Looks like 10K or better is recommended primary impedence for output transformer. Too bad that kit is all low cost parts probably worth a lot less than $200. I see your point about throwing most out to upgrade! That's why I also don't like that kit.
http://www.diyaudio.com/forums/tubes-valves/147313-k-502-upgrading-opts-hammonds.html
Could you afford these as they may be what your looking for too? If so maybe look at parts of triode electonics version of ST-35 in kit form. Maybe save money by making your own chassis. They sell the board and parts kits, transformers etc.. Has nice output trans I mentioned. I think you could add a volume control. diytube.com has lots of info! Say $230 for all transformers and choke and $125 for PC board and parts. Tubes about $70. Just over $400 @ $425. Worth adding the EFB mod mentioned in the diytube form.
diytube.com :: View Forum - stereo 35
DIYTube Dynaco ST35 Tube DIY Amp Kit Great for iPod
Product Detail: ST-35 KIT (120 VAC)
Is another one to look at the same way is the exact Dynaco ST-35 copy which you could save a bit by omitting the chassis, but you would probably need a preamp.
audioregenisis sells built boards too for the ST-35 for $70.
http://www.audioregenesis.com/
In the end if you upgrade the K-502 you will probably spend close to the cost of the above kits without chassis.
This would be the correct output transformer if you wanted to save about $44 for the pair, but you may have to wait 4-6 weeks to get them. Don't know if they are sonically as good, but Edcor is well liked on forms.
http://www.edcorusa.com/products/799-cxpp25-ms-8k-23.aspx
http://www.diyaudio.com/forums/tubes-valves/147313-k-502-upgrading-opts-hammonds.html
Could you afford these as they may be what your looking for too? If so maybe look at parts of triode electonics version of ST-35 in kit form. Maybe save money by making your own chassis. They sell the board and parts kits, transformers etc.. Has nice output trans I mentioned. I think you could add a volume control. diytube.com has lots of info! Say $230 for all transformers and choke and $125 for PC board and parts. Tubes about $70. Just over $400 @ $425. Worth adding the EFB mod mentioned in the diytube form.
diytube.com :: View Forum - stereo 35
DIYTube Dynaco ST35 Tube DIY Amp Kit Great for iPod
Product Detail: ST-35 KIT (120 VAC)
Is another one to look at the same way is the exact Dynaco ST-35 copy which you could save a bit by omitting the chassis, but you would probably need a preamp.
audioregenisis sells built boards too for the ST-35 for $70.
http://www.audioregenesis.com/
In the end if you upgrade the K-502 you will probably spend close to the cost of the above kits without chassis.
This would be the correct output transformer if you wanted to save about $44 for the pair, but you may have to wait 4-6 weeks to get them. Don't know if they are sonically as good, but Edcor is well liked on forms.
http://www.edcorusa.com/products/799-cxpp25-ms-8k-23.aspx
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