Ab763 rebuild from pcb - Which type of resistors are favourites these days?

[Twangisgood]

I’ve purchased a turret board from Modulus Amplification here in the UK and am planning on gutting my 68 deluxe reverb and rebuilding it with some nice new hand-wired components.
As I’m pretty new to this, I’d like some recommendations regarding what type of resistors are best to use? Ideally (and purely for cosmetic reasons!) I’d like to use carbon comps, but having done a fair bit of research on this, I was wondering what peoples thoughts were on using them? If you do, use them, where would you put them, why and what wattage would you recommend?

I also understand that a lot of builders would regard the old Alan Bradley resistors (or similar) as noisy etc. I love the look of them, but don’t wanna spend ages hunting down resistors if they’re going to end up just making the whole amp more noisy than it already is! And certainly if there’s no sonic advantage in using them.

I’ve already ordered some PRP metal films (1w) and some Takman’s (also 1w) just to see how they are.

I guess the main question is, if you were to use all modern components to rebuild an amp like this, which wattage and what brands will not only sound good, but look the part on a turret board?! Yes, no one will see it, but it’ll make me feel good to not be using tiny components with legs that probably won’t even reach across the turrets!

Sorry for so many questions.

Many thanks.

 

[ps_electrik]

I can't talk to specific manufacturers, but I am currently building the "BlackVibe" (RobRob single channel AB763) and am using metal film (and metal oxide) resistors almost everywhere, except for the coupling into the phase converter which I am using a 1W 220K carbon comp to add just a touch of flavor.

From what I have found there are limited values available for the carbon comps so that may drive things a bit. You also probably don't want them in the lower signal strength areas of the circuit, which is why I went with my approach.

Most other resistors are 1/2W except for certain ones in the power supply area. I have tightened up on the turret board spacing as I am stuffing this into a tweed deluxe style chassis which has fairly limited room. If anything, I may need to add some strain relief bends on some components.

 

[Twangisgood]

I can't talk to specific manufacturers, but I am currently building the "BlackVibe" (RobRob single channel AB763) and am using metal film (and metal oxide) resistors almost everywhere, except for the coupling into the phase converter which I am using a 1W 220K carbon comp to add just a touch of flavor.

From what I have found there are limited values available for the carbon comps so that may drive things a bit. You also probably don't want them in the lower signal strength areas of the circuit, which is why I went with my approach.

Most other resistors are 1/2W except for certain ones in the power supply area. I have tightened up on the turret board spacing as I am stuffing this into a tweed deluxe style chassis which has fairly limited room. If anything, I may need to add some strain relief bends on some components.

Cool. Be good to see some photos of your progress!

 

[11 Gauge]

I really only use carbon comps for the plate resistors, where it's kind of been loosely determined that they might have a positive sonic benefit.

And while metal films may really be possibly the best way to go noise-wise, with a high gain circuit, I've found that just regular carbon films are more than sufficient with BF/SF Fenders. I've also got them in my 2204'ish build, and they're fine in that, too.

I just tend to buy resistors in bulk, in the necessary resistances and wattages, and have never really paid much attention to who the actual manufacturer has been.

 

[dan40]

Because modern 1/2 watt resistors are so small these days, I typically use 1 watt carbon films for signal voltage because they look correct in size and larger resistors are naturally quieter than smaller resistors. I generally use these Xicon carbon films for most build but I do like metal films for the grid leak and grid stoppers on the input stage. Using metal films in these key areas will cut down on hiss considerably. In higher gain circuits, I like the PRP and Vishay 1 watt resistors throughout the entire circuit. For power resistors I generally stick with 2-3 watt metal oxides.

https://www.tubesandmore.com/products/resistors-1-watt-carbon-film-5-tolerance

Resistors - 2 Watt, Metal Oxide, Power | Antique Electronic Supply

Metal Oxide resistors are for applications where stability under high temperature conditions is required. Sold in multiples of 5. 2 watt. ±5% tolerance

www.tubesandmore.com

 

[Wayne Alexander]

I've built Marshall, Matchless, Vox, Tweed and Brownface type circuits (I have no affinity for Blackface type tones). I use 1-watt carbon films everywhere except the plate resistors (because Aiken) https://www.aikenamps.com/index.php/resistor-types-does-it-matter and 1 watt carbon comps as plate resistors. The amps I've built have all been quiet enough for their types, and sound good.

 

[Paul G.]

1-Watt carbon films most signal-carrying resistors, including plate resistors. 3-Watt Vishay-dale metal film for 470R screen resistors. Metal oxide or metal film 2-watt for power dropping resistors. 1-watt metal film most everyplace else.

 

[schmee]

I use Metal Oxide mostly now. They are dead nuts on value. Carbon comp quality is terrible, and let's face it CC resistors are the noisiest of the types over time. I have some brand new CC 100K from AES that are 40-100% the value they are supposed to be. Does anyone really care if a resistor is brown or grey?

 

[Twangisgood]

Because modern 1/2 watt resistors are so small these days, I typically use 1 watt carbon films for signal voltage because they look correct in size and larger resistors are naturally quieter than smaller resistors. I generally use these Xicon carbon films for most build but I do like metal films for the grid leak and grid stoppers on the input stage. Using metal films in these key areas will cut down on hiss considerably. In higher gain circuits, I like the PRP and Vishay 1 watt resistors throughout the entire circuit. For power resistors I generally stick with 2-3 watt metal oxides.

https://www.tubesandmore.com/products/resistors-1-watt-carbon-film-5-tolerance

Resistors - 2 Watt, Metal Oxide, Power | Antique Electronic Supply

Metal Oxide resistors are for applications where stability under high temperature conditions is required. Sold in multiples of 5. 2 watt. ±5% tolerance

www.tubesandmore.com

That’s great info, thanks!

 

[Nicko_Lps]

if you were to use all modern components to rebuild an amp like this, which wattage and what brands

There is a big on going fight on the internet about carbon comb vs metal film.. The magic "mojo" tone quest..

Personally i would go metal film on the 3 input resistors 2x68kohm and 1x1Mohm because those resistors produce the most noise in your signal.
2 watt carbon film plate resistors, when a preamp tube fails it should draw around 1.3watt. By using 2 watt plate resistors, you make sure you wont have to open and repair anything if a preamp tube fails and "maybe" lower thermal noise.

Carbon film or metal film in the signal path, its a good idea to use a 1 watt metal film in between preamp and power amp and the last reverb resistor fender uses that 470k, 5 watt ceramics in the screens(if you fuse HV, otherwise 1-2 watt metal oxide), 2 watt metal oxide flameproof power supply dropping resistors or 5 watt ceramics again.

I cant imagine myself buying and installing a carbon comp resistor in 2022+ but you never know what the future can bring