Anyone have expereince with Tantalum Resistors?

[goldear]

No, I'm NOT asking about tantalum capacitors, which are possibly the worst sounding caps ever made.

I'm asking about those super fancy tantalum resistors which cost a fortune. I never paid much attention to these, believing that the Metal film resistors that I usually use sounded very good. That was until I heard an amp that used tantalum resistors a few days ago; and boy did it ever sound fantastic!

Now there are a million other variables in the sound; not the least of which are an amps topology, and the power supply. However, I can say that I know that these resistors sounded fantastic in that particular amp.

Has anybody out these ever experiment with these megabuck resistors? I'm considering trying a few when I rebuild my Eico HF-89. I was thinking that the plate resistors would probably be the place where they would make the most difference. I wouldn't think that biasing resistors would make nearly as much difference though.

I'd love to hear from somebody who has actually tried these, and hear what they liked, or disliked about them.

[jcmjrt]

I haven't ever tried anything other than basic metal film type. I've read in a few places when people talk about upgrades that upgrade resistors like Mills, etc will provide some improvement but that it's pretty minor compared to good caps....so I guess that has kind of kept me from playing too much in that direction. I'll be very interested to hear comparisons from you if you try it.

[Billfort]

I've used them in a few SET amps and was very happy with the results. A friend who has built over 50 tube amps and who's opinion I respect immensely based on how good his stuff sounds swears by them.

I've never A-B'ed them with something else in the same positions but I like em and will use them again.

[PakProtector]

I've used them in a few SET amps and was very happy with the results. A friend who has built over 50 tube amps and who's opinion I respect immensely based on how good his stuff sounds swears by them.

I've never A-B'ed them with something else in the same positions but I like em and will use them again.

If only they were cheaper, it would be so simple to acquire enough of them to play with and write an eval. I know folks who use them, and their analysis leaves them looking for the best in a particular job. It isn't always a Tantalum.
cheers,
Douglas

[Billfort]

No, I wouldn't think using them everywhere would be the optimum and never have heard anyone say it would be.

[goldear]

If only they were cheaper, it would be so simple to acquire enough of them to play with and write an eval. I know folks who use them, and their analysis leaves them looking for the best in a particular job. It isn't always a Tantalum.
cheers,
Douglas
This is how I was thinking of using them. Please tell me if you where you would agree or disagree:

-All plate resistors for amplifying tubes.
-All Cathode resistor for differential amps, or splitters.
-Probably for cathode resistors on input amps. But if they are capacitor bypassed, then probaly not.
-Proabaly not for any biasing resistors.
-Definitely not for the cathode resistors on power tubes.
-Not sure about series resistors connected to grids inside the signal path which pass essentially no current though :scratch2: I lean towards replacing these, but I suspect that these are much less critical than the plate resistors.

[PakProtector]

This is how I was thinking of using them. Please tell me if you where you would agree or disagree:

-All plate resistors for amplifying tubes.

me: I agree, assuming that the 'Tantalum Sound' is what you want. Plate resistors do flavour the sound.
-All Cathode resistor for differential amps, or splitters.

me: if it is not bypassed, it is probably a location where you'll be able to hear a difference.
-Probably for cathode resistors on input amps. But if they are capacitor bypassed, then probaly not.

me: Agreed
-Proabaly not for any biasing resistors.

me: here I must disagree, the grid resistor is a large fraction of the load being driven, and I have found this one quite important. It is usually a fairly large resistance, but for some reason it often makes a difference, even on power stages.
-Definitely not for the cathode resistors on power tubes.

me: Agreed
-Not sure about series resistors connected to grids inside the signal path which pass essentially no current though :scratch2: I lean towards replacing these, but I suspect that these are much less critical than the plate resistors.

me: not sure how you've differentiated these from biasing resistors. Grid reference, either fixed bias, or for a self-bias scheme all fall into the 'important' category for me. Their behaviour is afterall being introduced *BEFORE* the amplifying stage.


Just so we're aware that I am throwing an opinion around like a fan at a sewage discharge....:)
cheers,
Douglas

[goldear]

Thanks for the input! I figured not on the cathodes of th power tubes simply because the occasional cherry incident can fry them so easily. :eek: Do your comments hold for fixed bias supplies?

And to clarify: what I meant by biasing resistors is resistors that connect from the grid to ground, or from the grid to a negative bias supply. I fully realize that cathode resistors are an integral part of biasing, but I was simply attempting to distinguish between them.

Let me ask you this: You had an interesting comment on using these on the plates. What is the less desirable quality that you sort-of implied in your answer? I figured that these would be most audible in that location, so that was my fist choice. Is it just too much of a good thing, or something?

The amps that I'm considering upgrading are all warm, and lush sounding tube amps that I would like to get to sound just a little more transparent and detailed, without killing the lush, liquid mids, and sweet highs.

[PakProtector]

Hey!!!,

in lieu of quoting the whole thing:Let me ask you this: You had an interesting comment on using these on the plates. What is the less desirable quality that you sort-of implied in your answer? I figured that these would be most audible in that location, so that was my fist choice. Is it just too much of a good thing, or something?

I have found that the plate load resistor contirbutes a lot to the sound. Since this overall signature may or may not match one's personal taste, I tried to cover this position. I have gotten all sorts of counter intuitive results with my experiments with different sorts of plate load resistors. Some of it must be real, some of it must be Psycho-...or perhaps it's me who'se psycho...:)

Since the bias resistor( and these judgements pertain to fixed and cathode grid referencing ), is part of the load driven, and at an upstream point of amplification, I've found that to be an important position sonically. In the extreme case with finals, I've gotten my best results from grid chokes. This leaves me to believe part of it is value induced, and part of it is 'type/construction/flavour' induced. It has not been difficult with the same type of resistor to try reducing the grid ref. resistor value and see the sound become clear/clean and more focused.

But then I built my last amp with carbon film plate loads and PIO coupling caps and found it anything but warm and fuzzy, so other stuff is clearly at work sometimes...this sort of thing can be remarkably hard to fix upon a single-cause/single-cure.
cheers,
Douglas

[lndm]

I have found that the plate load resistor contirbutes a lot to the sound.
By way of the large V swings on a plate resistor, it stands to reason that any voltage coefficient induced warmth (read: second harmonic distortion) would be more significant in this position.

The question I have is do the tantalums produce more or less warmth than carbons. I can only find conflicting accounts.

[goldear]

The question I have is do the tantalums produce more or less warmth than carbons. I can only find conflicting accounts.
I'd like to know the answer to this too. :yes:

[PakProtector]

By way of the large V swings on a plate resistor, it stands to reason that any voltage coefficient induced warmth (read: second harmonic distortion) would be more significant in this position.

The question I have is do the tantalums produce more or less warmth than carbons. I can only find conflicting accounts.

Hey!!!,
I'd like some insight as to how you came to this conclusion. The thermal mass at even 20 cps should be huge compared to any AC asymetric thermal effects. Now if it was symetric, we'd be talking odd HD...

Even at 25 cps, lights don't flicker, and that is one thin piece of tungsten. Ears are integrators, with the same sort of software as the eyes. I would suspect we'd notice this thermal effect with smaller resistors first, especially ones run to dissipation limits or perhaps near.

I don't even have a small idea on how to quantify 'warmth' in order to see what causes it. It is likely that warmth means different things to different sets of ears, further complicating things...:)
cheers,
Douglas

[lndm]

I'd like some insight as to how you came to this conclusion. The thermal mass at even 20 cps should be huge compared to any AC asymetric thermal effects. Now if it was symetric, we'd be talking odd HD...
I am not sure that Voltage coefficient and temperature coefficient are the same thing.

It does stand to reason that the effect of voltage coefficient will produce odd order harmonic distortion where there is no DC present on the resistor so naturally this is one criterion that makes a plate resistor a good candidate.

For this reason I also suspect that grid resistors and grid stoppers etc. etc. should (probably) use a good and linear resistor, especially if 2ndH is what you want.

Insight here http://www.geofex.com/Article_Folders/carbon_comp/carboncomp.htm
enjoy.

[Kegger]

Very cool bit of info banter here. :smoke:

Ecspecially for someone who is gathering parts to build an amp.
I'm watching with interest here, sorry I have no info on this subject. :D