[TV MAN]

Hey all! With winter rapidly approaching I'm getting set up to finish a few projects and start a few. While waiting on parts for the Emerson TV, I finished a Zenith radio and ended up with a bare spot on the bench. Then I saw it - my chi-fi amp kit. Yes, I have several different ones for different goals, but this one I bought mainly for the chassis and parts. It was cheap and gave me a lot of the parts I wanted to do something of my own creation. To buy the individual parts and have a chassis punched, etc etc would cost a lot more and this gives me a ready made chassis, power supply and all the little gizmos that add up quickly.

To begin with, the kit was an eBay find for about $150 +-. Just a simple single ended kit with a couple 6BQ5 (china versions) finals and double triode driver. Simple power trans with bridge. I havent been really happy with the past kit I built - it lacks something but not sure just what, so this one is getting scrapped and I'm building my own design. Will it work? Shoot, I don't know - if not, I'll yank the parts and try again with a different design, or trial and error until I get something decent. It's just a basic PP amp circuit and my goal is a 15  watt monoblock. I want to keep it simple. Probably the most complicated thing will be an adjustable bias supply so I can set it for the right current if I want to try some different bulbs. Honestly, there aren't many more parts if I'd do a cathode bias, but it's a little harder to adjust.

This is actually on my bucket list. To build my own design. This is JUST an experiment. I have several output trannys to try, and may even dabble with some sweep tubes, but for now, I axed the china tubes in favor of some 6V6s and a 6U8 or 6GH8. (I've seen quite a few 6GH8s be noisy), but seen 6U8s in organs and other musical instruments. Speaking of organs (organ donors?? ), I have a tranny from a Hammond organ I'm going to try (6V6), a couple cheap eBay finds and something from Musical Power Supplys I have coming. The latter are ultra linear and will probably be my final choice, but again, this is an experiment. Sure, there are numerous threads in DIY, Carma, and so on about this, but this is my compilation. I really couldn't find a diagram I really liked (I'm more traditional), so I drew something up using ideas from several diagrams.

Alright, so here's what I did and where I am. I'm using the power trans/supply from the kit. The trans "says" .2a on a 230v B+ with a bridge, 3A on the filament, couple 330 caps and 100 ohm resistor. Should be in the 300v B+ range to work with that. I'll send that to the output trans, come off that with a 5h choke and 47mf cap to supply the G2 and driver. If I use the ultra linear, then it'll only supply the driver. I had to enlarge 2 of the tube holes to accept the octal sockets. Forget a cheap big box store step bit, this baby is stainless, so that was a FAIL, ended up using a burr and die grinder. Got that done. Sure, I could have used the 6BQ5s, but this gives me more options to swap tubes around with anything from a 6F6 to a KT90 (well, maybe not that big, but more options anyway). 9 pins really limit. Need to get a good step bit for the future. The biggest problem was the vent holes around the tubes, but I found the sockets I used fit the holes already there perfectly, and gives me a lot of available positions for the sockets. I used the top mount sockets to cover my redneck engineering.

My goal with this? Well, I'm not really an audiophool, but I want something that sounds really good. I'm sick of those cheap bluetooth speakers, squeaky phones, and crappy radios you get nowdays. I want to try my own design, use new production, readily available, economical parts (unless something special is needed), and build up to something better. Oh, this isn't my 1st crack at this. I built an amp back when I was in junior high, using a schematic found in an old radio book and parts I had around. Once I got the bugs worked out, it really sounded pretty good, but it was just built on a flat piece of metal robbed from some old cable TV strip amps. Done a few kits, and sure, could get my Dynas out, but ... So now, I try again. At least this will be good for some entertainment. If it smokes, it smokes, if it blows something, it blows it, if it works, it works. If it fails, it fails. Stay tuned for the fireworks!