Zoot Horn wrote:Well now that we have opened that can,,, could you pontificate on any other bang for the buck upgrades, such as?
Well it's kind of hard to pick for others what makes good bang for the buck. But I'd pull first for good caps. The best caps are no caps. But once you must have them, then first is ones right for the circuit they're in followed by the flavor of your choice.
Output DC blocking caps are them ones people tend to focus on first, but the cathode cap may be as or more important. We have both as candidates to change in this design. We've discussed them in places here, but I'll revisit them.
The output coupling cap should be about 3.3mfd. It should excede the voltage present on the B+, which is in this case 150vdc. So a 250 volt or higher is a good choice. Too high of a voltage some feel start to hurt sonics. Again, I'd think about lowering that output coupling cap value a bit if you're running vinyl and don't otherwise have a rumble filter. Maybe drop the 3.3 to a 2.2.
The cathode cap is a 220mfd at 100v. You can alter either value some ok. Lower end of voltage I'd want would be a 50v. But I'd be ok with a 65v and up. We'll have room hopefully to deal with about any physical size. Proper support for a cap is important. Some believe vibration prevention to be important as caps typically are microphonic. So raising voltage tends to increase size and increases challenge to keep them in a good mounting situation. I'd keep the cathode cap between about 150 and 470 or so.
After the caps, some folks will be looking at nice RCA's. Bang for the buck part gets tougher as the cost for a total of 12 chassis mount female connectors gets above cheap. But putting them in as you build sure would be less of a challenge than changing them later with everything in the way!
After that, I'd maybe look at a higher quality cathode resistor maybe. It's a 750 ohm, and I don't have figures in front of me, but the smallest size you'd want would be a 3 watt. I'm spec'ing a 5w Mills. So you'll have to top that for quality to improve there.
After that, places to look might be the volume attenuator or the source selector switch. I'm a believer in quality in both. I really like remote switching by HQ relays of audio but that's not an easy mod. Changing the pot is not terribly hard but what I'm putting in isn't too bad.
I'm thinking that we'll have enough room and the circuit complexity is simple enough that changing the caps and resistors and stuff might be something to do after you've gotten used to the unit and it's gotten familar with you too! The harder thing to change later would probably be the RCA's.
But as you heard it George, it wasn't really broken in and didn't yet have a few decent parts in it that even will be provided. And it was doing ok at that point. So not everyone needs to feel to bad about building as it is even. We all want an overachiever even if we can step it to a higher plain as we chose later.
PS...sure, good wire isn't going to hurt a thing! In a couple weeks, I could probably provide approx lengths and desirable colors.