Resistor types ??? (carbon or metal film)

[Apogee]

Greetings all,

I need some help with resistors.

I recently acquired a Harman Kardon Citation V power amplifier. It was supposed to have been completely rebuilt and in proper working order. However, when I attempted to set the AC and DC balance, it became apparent that something was not correct.

All caps have been changed and the work was done very well.

I started measuring resistors and found several that are far out of spec.

Hence, I've decided to go through it and replace all of the resistors.

My question is, I have no idea what type to choose - i.e. carbon comp, carbon film, metal film, wire-wound, etc. that would sound the best.

I am toying with trying the 1 watt versions of these: TAKMAN - REX 1 Watt Carbon Film Resistor

From what I've read, metal films tend to sound "harder." I really don't want to do this twice if I choose incorrectly. Also, I'm concerned that resistor working voltages might be an issue since this is a tube amp.

I do know Jim McShane offers resistor kits for these amps, but wants $89 for them. I figured that I'd either save some $$ or spend the same amount and get better components for that kind of money. The unit has primarily .5 watt and some 2w units and has about 50 resistors total.

My thought process on using the carbon film was that if the original design also used carbon, it might stay truer to the original sound. I don't know if this thought process is sound, so I decided to ask for some help.

Also, please note the same company also builds a metal film that is non-magnetic. Not married to them specifically, just found them interesting:

TAKMAN - REY 1 Watt Metal Film Resistor

I've also considered using Dales, Mills, Holcos, Yageos or even Rikens. I don't want to toss money down the drain, and am not partial to any particular brand, but would like the amp to sound the best possible. I was tending to lean to non-magnetic types if possible.

Any help/thoughts would be appreciated!

Thanks,

Steve

[Eli Duttman]

JMO, pay McShane the money and you are certain to get parts proven to work well. What Jim has forgotten about in "the care and feeding" of vintage H/K Cit. tubed gear, the rest of us are likely never to learn.

BTW, does your specimen have Jim's choke tweak for the O/P tube screen grid supply? That change goes a fair way in improving performance. A stable g2 B+ supply is well known for making full pentode mode "finals" work well.

[Richard Ellis]

Looking up your TAKMAN brand resistors, I am dismayed at the words used, like "bright","detailed","warmth","natural sounding"...........these 'definitions' are purely marketing ploys for you to drop dollars when you should be spending quarters for your resistors.
Stick with so-called 'common' metal films & you'll be fine. 1% tolerance & packs of two to five will allow you to measure & nail your values.
They used carbon comps purely for cost concerns in the old gear...films will get you less noise especially at the front end.

__________________________________________________ ________Rick......

[TheGimp]

Step up one size in all resistors to help reduce noise. If the circuit is dissipating .6W and you would choose a 1W MF resistor, go with a 2W one instead. This will help reduce noise. This helps in two ways. (1) it reduces thermal shift of the resistor value (minor effect) and (2) it reduces noise by using a larger cross section of resistive element. It won't address noise that is related to resistor value.

Wire wound tend to be the quietest, but you will only get wire wound in low ohmic values. Metal film is next, then carbon film and carbon comp last. I quit using carbon comp in anything but low end guitar amps (<10W) where some guitar players insist they sound better.

[wakibaki]

Given the doubts you are experiencing regarding the selection of the resistor types, ratings and the problems in sourcing them (you may be forced to resort to more than one supplier), a kit of parts tailored to your requirements, even at $89, may prove the best solution.

While quarter watt resistors may cost only cents, higher wattage are more expensive, and prices vary from source to source. Simply listing the values, ratings, types, description, manufacturers part number, suppliers part number, number of items, price each and total price is quite a task, without trawling through to discover which part is cheapest where and whether it's in stock.

w

[bluelobster]

50 resistors for $1.78 ea.on average? I would think that a bargain considering all the choosing and ordering is done. Not only that your getting proven parts as Eli says. Follow Eli's tip on the choke mod as well.

[Apogee]

Just to be clear, in NO way did I mean to sound negative at all regarding the offerings from Jim McShane. I've bought multiple items from him the past and he's extremely responsive and knowledgeable. I was simply exploring options as $89 for 50 resistors seemed a bit pricey to me.

I also know ZERO regarding tube gear, so I figured I'd ask.

Eli - I don't know about the choke mod. I'll look into it. I was just on Jim's page and wasn't able to find what you're referring to but I'll keep digging. Thank you for the tip!

I paid top dollar for the Citation V because my time is extremely limited right now and I didn't want to have to work on it. In the seller's defense, he did show me the problem with the meter "displaying incorrectly" on one channel once at his home when I was purchasing the amp. He claimed that it'd been that way since he purchased it off eBay. I am simply not comfortable running it as it is because I have no way of knowing how much current the tubes are running at on that channel.

I also have two Citation II's needing rebuild that I was also planning on going through top to bottom. Hence, I thought that I'd see if there was a way to reduce the overall cost a bit. When I start looking at $300 in just resistors between all three from Jim, then add cap kits for the Citation II's at several hundred dollars each, then new tubes for all three, the total cost makes me cringe a bit, as it adds up very quickly.

That having been said, I know this hobby isn't cheap. I was simply trying to see if there was a more economical solution and that started with choosing the best sounding type of resistor for this application.

I'm not new to the DIY audio world and am more than comfortable modding and repairing the amps. I just know next to nothing about tube amps and would rather ask first than make dumb mistakes.

Thanks to each of you for the tips thus far!

Regards,

Steve

[Eli Duttman]

Steve,

Cit. 2s and Cit. 5s are worth the big bucks you spend in overhauling. See how much buying equivalent "iron" in today's climate costs. That's truly frightening. Top notch magnetics deserve serving in units whose state of repair leaves nothing to be desired.

Your heirs and assigns, generations removed, will thank you for passing these GEMS on to them.

[Apogee]

Originally Posted by Eli Duttman

Your heirs and assigns, generations removed, will thank you for passing these GEMS on to them.

Eli,

All I can do is hope!

I can only imagine them being sold at a garage sale because they don't fit with the current fad of flush-mount, in-wall, 50 channel surround sound systems because "they're old."

But, perhaps the person who ultimately finds them at that garage sale, or on the eBay of the future, will love and appreciate them!

I'm still holding out hope for a niece or nephew to get bitten by the audio bug, but we'll see.

I'd take them with me when I go if I could... LOL!

For the record, it does appear that the choke on the V has been changed. I haven't drawn out a schematic of exactly what has been done, but the choke value is the same as Jim lists on his power supply page and that is different from the original Citation schematic. All diodes and power supply caps have also been changed. I don't know if the parts were purchased from Jim but very easily could have been as the mods drilled no new holes. As I mentioned, the completed work is top-notch.

:-]

[wakibaki]

I have to agree, I'd expect to better these prices, with the input of some effort. The fact that you want 3 sets changes the balance of effort.

Film resistors have a maximum rating independent of their wattage, due to the potential for arcing between coils of the helix. For this reason film resistors must have their voltage rating checked if used as the anode load of a valve.

Just pick modern, cheap resistors of an appropriate wattage and suitable form factor (film in the smaller values) and you'll be constrained in your choice largely to wirewound in the higher wattages anyway. Wirewound types > 10k generally have negligible inductance.

w