Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: XYZGnomon on February 26, 2024, 09:07:43 pm
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A month or so ago, I decided to strip out my pandemic project StewMac 5F1 Champ, and start over. After spending some time looking at gut shots here and there and googling, I have noticed that there are a few distinct aesthetic schools. There are the vintage-at-all-costs people, the keep-nothing-replace-everything people, the pretend-this-is-an-airplane people, and so on. I don't have skin in that game, but I think I like the Hoffman aesthetic, with black G10 boards, and I really don't like the look of orange drop capacitors for some reason.
I recently discovered that there are resistors without colored lines, and instead have the value printed as text. Some are brown or tan, others are green and some are blue (https://el34world.com/Forum/index.php?topic=29364). I REALLY like this look.
I spent a fair amount of time on Digikey trying to make a list of all of the resistors in the 5F1 in the same series (such as Vishay Dale RN65), but no matter what, there doesn't seem to be a way to get the entire list of resistors all from the same series, for a uniform look. Tube Depot seems to have a decent list, and only slightly more expensive than Digikey, but they don't have them in the 470Ω-1W & 10kΩ-2W size the kit came with, so they would look different. Before I pinch my nose and go that route, I'd just thought I'd ask here if there's a better way.
StewMac specified 1/2W for all (100Ω, 1.5k, 22k, 68k, 220k, 100k & 1M) but the 470Ω cathode resistor (1W), and the 10kΩ voltage dropping resistor (2W). Is it okay to go bigger? Are there consequences of using 2W or 3W for everything, for the sake of aesthetics?
Metal film seems to be the fancy choice, but I've seen several instances of the cathode resistor being wirewound. As long as it looks nice, I see that as worth making an exception, except I like the white ceramic block look even less than the orange drop capacitor look. I am no expert!
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That's fine that you like your resistors to match, it's good to take pride in neatness etc and I have seen some really impressive tube amp builds where they take the time to make all of the wires bend at 90 degree angles and such. I don't know what to tell you to do to remedy the situation though, I guess I am just used to working on 30's and 40's radios but I just go point to point like an old Valco and I would just change out of spec or faulty components. My first builds I even used scavenged parts(the shame). I just take whatever components I have on hand that are the right value throw in some terminal strips where needed and call it a day. I am trying to play through them asap too. I guess that's why I never post pictures because I felt everyone would laugh at how they look under the hood, but truth be told my amps sound great and don't have noise problems whatsoever. I guess if I was doing a commission for someone, I might try to make resistors and caps match so it looks pro, But I mostly build amps for myself to play with and have a ton of components on hand purchased from multiple places over the last 10 years. I guess it's all what makes you feel good just like someone who washes and waxes his car every week.
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There's nothing wrong with upping resistor ratings, it just makes the parts larger and cooler-running. When you make the jump to wire wound parts, inductance comes into play unless they are purposely non-inductive parts. But as ever, at audio frequencies, this isn't much of an issue.. and may even provide some benefit in resistance to HF oscillation when used in the plate curcuit.
In theory, higher rated parts should be quieter due to lower current density.. though I doubt this is detectable in a gitamp.
The audiophile types think that the 2W carbon-comp Allen Bradley parts hold some sort of magic. I wouldn't know.
My last employer, a hi-end outfit, used the Roderstein Resista series as standard parts for decades. Later they switched to a Dale / Vishay part, cant recall the series but they have green bodies. The premium resistors were the Caddock MM215.. Big money stuff, printed values on each part.
If you need a 23.86K 0.05% 1.2W resistor, Caddock will make one for you, for probably around $35/ea. This is the stuff used in satellites, ICBMs, etc.