Non-electrolytic replacement caps, Orange Drops, etc - Your thoughts please?

[olddawg]

Dammit, I typoed my whole response away.

There is no wrong part to use. And who knows who made those caps for NTE anyway?

Modern film caps will all work fine in this amp, and differences will be subtle tonal ones. It will make less difference than brand of guitar string. Can you listen to a recording and hear D'addarios from Fenders? When you get the golden ears, then worry about brand.

REstoring the amp to original specs is a myth. Back then 20% tolerance parts were common. Leo Fender was not going to spend extra for 5% parts when 20% was good enough. That means your 100k plate resistor could be anything from 80k to 120k and be within spec. ecaps were spec'd at +80/-20% most of the time. Your coupling caps were no more precise. Today 5% parts are expected, and 2% parts are quite common too. Not so back when your amp was made.


SO to try to "match" the original sound with some particular brand, is to me wasted effort. Two amps side by side off the line didn't sound the same. There is nothing to match. SOme guys have their favorites, and involved rationalizations for every choice. But not everyone prefers the same tone, so the guy who likes shrill amps will chose different parts from the guy who is after smooth sound.

Thank you Enzo. Now that's what I wanted to hear and more in line to my original post. So most of this cap mojo is hype in your opinion? Like I said earlier, I understand tolerance and the fact that any modern cap will be superior to ancient failing technology. Personally I would prefer smooth over shrill. And you are right, the NTE sub could be any brand mylar film cap they contracted with. I would still be interested in hearing what serious restoration techs use as their favorites and their rationalizations.

[Enzo]

You'll have to read between the lines. What one man calls shrill, another calls bright and well defined. ANd what someone calls smooth or mellow, someone else calls dull.

[soundmasterg]

I would still be interested in hearing what serious restoration techs use as their favorites and their rationalizations.

From what I've seen cruising around the boards over the years, it seems that there are a lot of people using Mallory 150's to replicate the sound of the older paper caps. Some others use the Orange Drops, and still some others use Sozo, Xicon, etc. I used some Mallory 150's in a 1958 GA-20T Gibson amp and they sounded great. I used some of the generic yellow polyester caps that AES sells in a 1959 GA-20T Gibson amp and they sounded just about the same. I've used Orange Drops 715P, 716P, 225P, and 6PS in some Sunn and Silvertone rebuilds and they sound different, but also fine. I've used Solens in some Sunns too and they also sound fine but different. They all sound different from each other, but the differences are very minor and subtle, and some people don't even hear them. Its not something that you point to when hearing an amp on stage and say "yah, that one has Solen caps in it...I can tell by the way it sounds." If you're subbing parts in one after the other on a test bench and playing, then you might be able to hear some differences, but they are subtle. There's really no substitute to experimenting yourself and coming up with your own impression of what works for you.

For old amps, aside from the electrolytics, I try to only replace what is necessary usually due to the cap leaking DC. The old yellow and red Astrons, bumblebees, black cats, and green Cornell Dublier's almost always leak too much DC and need to be replaced from what I've seen. I still check them for leakage though before replacing. The brown turd caps that Fender used in the first silverface stuff and Sunn used in some stuff don't usually leak, but don't sound very good and have a high ESR. I usually replace these as any new cap will be better than them. The later silverface used some blue caps and they usually are fine...I usually don't have to replace these. The blue "molded" Mallories almost never leak from what I've seen and sound fabulous so I almost never replace them. If I have to, then I use a Mallory 150 unless someone requests something else. Some unscrupulous techs will change all of the blue "molded" caps out, then turn around and sell them on ebay to the higest bidder. Thats not the way to be in my eyes.

Greg

[Steve Conner]

I believe that all the "sound of capacitor brands" thing is just pure hype. The brand shouldn't make any difference, as long as they are the same value and don't leak!

Enzo, you make an interesting point, does this mean that after rebuilding an old amp with new components, or cloning an old design, we should expect to have to tune it to taste?

On a similar note, I heard that transformer iron has improved a great deal over the years. Modern stuff has a higher permeability and saturation flux density, but a much squarer B-H loop. In other words, old iron saturated gently, but the new stuff really saturates hard when it eventually does. This could make all the difference between fattening bass and just making it fart out.

So, how long before people like Mercury Magnetics can't actually get transformer iron of low enough quality to make accurate clones? (Of course the cynic in me would say that they never bothered in the first place...) Issues like this worry me a lot more than capacitors.

[Enzo]

If you wanted to clone a particular old Deluxe or something, you would indeed need to measure all the components to capture the nuance of the particular unit. On average, parts in an amp ought to come out more or less similar, but just luck of the draw will make some amps tend more towards higher val;ues and other amps trend towards lower values. Yes most amps will have both. Just because the schematic says it, doesn't mean that was hte value of your part. But that in part explains why amps of a given model sounded different, one from another. And we have no shortage of folks here on a daily basis fretting (pun intended) over the value of the cathode resistor here, and the plate load there.

+80/-20% blew my mind the first time I saw that on a cap.

Who was it - Mesa? Matchless? - that had their people take speakers and whack the magnets with mallets before installing the speakers? It was intended to give the speaker a old worn-in tone, the tone of a fading magnet.

[Paul P]

If the differences in sound between similar amps is due to the variations in
tolerance of their components then it should be possible to start with
a good approximation built from precision components and then vary these
in small steps to creep up on the best sound (to whoever is listening).

For example, if you build an amp with a 1% cathode resistor you could then
vary the value of that resistor slightly, without changing anything else, and
see what the effect is on the sound. By doing this to every component in
the amp it should be possible to come up with a more precise specification
that could then be used to produce copies that would vary less amongst
themselves.

I imagine that there is an enormous number of variations possible considering
all the interactions between components in an amp making it difficult to try
them all.

I read somewhere about old amps with "the" tone being disassembled and
measured to enable cloning them. Did it work ?

Paul P

[Enzo]

Such disassembly and measuring was exactly what I described in the post above.

Rather than mess with 1% types and increment, if you really want to get the exact sweet values, just mount small trimer pots. Dial in the optimum sound then pull the trimmer out and measure it. THEN order 1% in those values. I actually did that for a customer on an old SIlvertone. Each attempt to tweak made something else less desirable, so I mounted a half dozen little trimmers so now the customer can second guess til his heart's content. Plate loads, tone slope, etc.

I have another customer who comes by every now and then and pays me for a "lesson," to help him learn about amps. He is going through a basic Fender design and adjusting every single part in it for "best" sound. "Enzo, where can I buy 496 ohm resistors?" He is now extremely happy with his amp, although it has some really odd circuits. There is a bleeder across every filter cap for example. And other extraneous parts. They work, it is just not real parts-efficient.

[stokes]

Way too much hype out there.One of my favorites is the "balanced" PI tube being better in a guitar amp.Might be useful in Hi-Fi applications,but if all the other components are +/- 10-20% that "balanced" tube aint balanced any more,is it?I like Enzo's "trimmer pot solution".That guy gotta be losing his mind,tweaking his brains out.

[imo]

That said, balancing the caps and resistors around the PI tube in my Vibrolux made a pretty noticeable difference, not subtle at all. Louder and cleaner.
It seems that a lot can be improved with a couple of hours and a few bucks in parts. I don't ascribe to, or have the money for, the high end parts market, but i have been pretty impressed at the cumulative effects of changing a few resistors and caps in an amp.
Ian

[jrfrond]

When doing restorations, what is actually more important than component TYPE (within reason), is component VALUE. Caps drift DOWN in value. Resistors drift UP. What needs to be determined is: do you want the amp to sound as it did NEW, or aged? This is particularly important if you are dealing with clients. Recap a vintage amp with all new caps of the correct value, even if they are the same original type, and you will most likely have an amp that sounds different than it did before the cap job. Ditto for plate resistors, cathode resistors, etc. This counts for filter caps too. Hence, it helps to measure what you are replacing first to help "pre-age" the replacement components, THEN decide on type.

It is for this reason that I stock replacement caps and resistors that are about 10% below and above standard values, respectively.

Enzo,

In all due respect, you are both nuts AND have the patience of a saint!

[capnjuan]

... Personally I would prefer smooth over shrill....I would still be interested in hearing what serious restoration techs use as their favorites and their rationalizations.

Hi olddawg; agree with earlier comment re/ Orange Drops; made to extreme tolerances and rugged but to my ear a little bright up top and tubby on the bottom. Again, just my opinion but I like the Sprague 150s for interstage coupling; very smooth, uniform top to bottom, and moderately priced. CJ

[Bruce / Mission Amps]

Hi olddawg; agree with earlier comment re/ Orange Drops; made to extreme tolerances and rugged but to my ear a little bright up top and tubby on the bottom. Again, just my opinion but I like the Sprague 150s for interstage coupling; very smooth, uniform top to bottom, and moderately priced. CJ

We will assume you meant, Mallory 150s...

[capnjuan]

We will assume you meant, Mallory 150s...

Thank you Bruce; in fact I did. CJ

[soundmasterg]

When doing restorations, what is actually more important than component TYPE (within reason), is component VALUE. Caps drift DOWN in value. Resistors drift UP. What needs to be determined is: do you want the amp to sound as it did NEW, or aged? This is particularly important if you are dealing with clients. Recap a vintage amp with all new caps of the correct value, even if they are the same original type, and you will most likely have an amp that sounds different than it did before the cap job. Ditto for plate resistors, cathode resistors, etc. This counts for filter caps too. Hence, it helps to measure what you are replacing first to help "pre-age" the replacement components, THEN decide on type.

I agree with you to a certain extent, but keep in mind that if you are trying to measure a cap to find out what value it is now, a leaky cap with throw off the meter's reading. Also, if you measured an amp all out and replace parts accordingly being 10% one way or the other for example, it kind of confuses things later on when the amp needs work again. The person working on it will have to figure out what your intent was with the part substitutions, especially if things have drifted again.

Greg

[jrfrond]

I agree with you to a certain extent, but keep in mind that if you are trying to measure a cap to find out what value it is now, a leaky cap with throw off the meter's reading. Also, if you measured an amp all out and replace parts accordingly being 10% one way or the other for example, it kind of confuses things later on when the amp needs work again. The person working on it will have to figure out what your intent was with the part substitutions, especially if things have drifted again.

Greg

Yes, you are correct on both accounts, but a good cap tester can get pretty close. In addition, I NEVER do component value mods without getting an OK from the client first, and I ALWAYS supply an updated, marked-up schematic later.

I offer this as an option. Most customers keep it original, but a few of those subsequently complained about sonic changes, which is WHY it is an option.