Capacitors for Guitar

[monradon]

Hobbit here and the meter is a Extech MN26 and it does almost everything and its very reasonable , the cap checker is very accurate. By the way the caps I got from a guitar place got home and checked them they were so far off I would have to put three in parallel to get a 22uf cap. Went down to Radio Shack and bought some and checked them and right on the money better made and guess what they were cheaper .

[ChrisK]

Ceramic capacitors come in different types which have different tolerances.

COG/NPO Ultra-low value drift over temperature. Typically +/- 5% or better. Cost is about $0.20 to $0.75. Typically only available under 300 pF or so.

X7R (Semi)suitable for analog circuits. Some are good, some are not. Typically +/- 20%. Cost is about $0.20 to $0.75.

Z5U/Y5U Power supply bypass. Significant leakage. Horrid for analog circuits. +80/-20%. Cheapest type, probably what you actually get for your $3 cap.

BTW, these are about $0.15 to $0.30 in quantity of 10.


I like polypropylene caps, they're quite good. And dang are they expensive. In extremely high quantities for a 0.022 uF/50 volt unit (uh, like 1 each), they cost between $0.24 to $0.61 EACH. I told you that these were expensive. And the tolerance is so shoddy that you'll have to live with +/-1% to +/- 2%.
www.digikey.com/scripts/DkSearch/dksus.dll?Filter

Thank God that they invented the ceramics to save the world money.

If you are unable to qualify for the loan for the polypropylene caps, but still want something better than ceramic, you may have to settle for the pedestrian polyester film. But be warned, even if you buy 10 of these, they're still over $0.07 EACH.
www.digikey.com/scripts/DkSearch/dksus.dll?Filter


In comparison, the $40 units simply are a bargain not to be missed.


(Holy C(r)aps Batman, you mean that the regular plain human types can buy good parts also.)

(Hmmm, perchance these $40 vintage caps just may have been the pedestrian caps of their day?)

[JohnH]

pmccook1 said:

www.vacuumtube.com/VTV%20Ultratonecaps.htm

Vacuum Tube Valley web site.....

Phillip

It says they include:

".....high grade Kraft paper dielectric and newer dielectric mineral oil with a higher temperature rating. The caps are hermetically sealed... "

That explains the high price of those caps. They are made from rolled up slices of processed cheese! Plus they have to pay all those hermits to seal them....

John

[toddw]

I get such a kick out of this type of discussion. I'd agree with ChrisK that for audio, the cap quality is important, and I also like polys. But $40?? you guys are talking about guitar frequencies here, often through tube amps with inaccurate drivers . . .

Just to add possible sources, I like to peak at: www.apexjr.com/capacitorA.html and www.allelectronics.com/cgi-bin/category/140/Capacitors.html

every once in a while. Especially when I'm buying a lot of caps to build an amp. But for a guitar, I'll usually go to ratshack and save P&H. As long as the voltage on them is low, I figure they'll be close enough for my purposes, and if the cap is reasonable, good shielding and layout is more important to me.

The first post in this thread linked to Angela's, and while I love them as a source of Hammond transformers, and they are great to deal with, what they charge for some of those Caps leaves me ROFLMAO.

For filtering the B+ at amp voltages, I'll take a metalized poly cap over old time mojo any time. That's what I used in the first two stages of my kids amps because I'm of the opinion every 5 and 7 year old kid should have a boutique style tube amp to play through (granted only if they're 3 watts or less! ;D )

I'm a newbie here, but would put in a plug to save your money for nice PUPS, new strings, and to get cap job and improved grounding layout for your old tube amps.

Todd

[bobtec]

Fender used Cornell Duprive (spelling wrong) .05mfd@150 v.d.c. and a .01 150mfd for Telecasters 1950-58.Stratocasters Used a .01 mfd 150 (C-D) znw1p1 Square Cap.Remember a Guitar Tone Cap only takes away Highs it does Do anything else.Like someone said before Do Not Confuse Amp Caps with a Guitar Tone Cap If you want something that "looks"very cool.www.deluxe.com

[dd842]

bobtec said:

Fender used Cornell Duprive (spelling wrong) .05mfd@150 v.d.c. and a .01 150mfd for Telecasters 1950-58.Stratocasters Used a .01 mfd 150 (C-D) znw1p1 Square Cap.Remember a Guitar Tone Cap only takes away Highs it does Do anything else.Like someone said before Do Not Confuse Amp Caps with a Guitar Tone Cap If you want something that "looks"very cool.www.deluxe.com

Hi bobtec - good to see you actively posting again ...

Are you sure deluxe.com is the correct URL? It appears to be a personal cheque manufacturer ...

... although they do have some cheques that look very cool

Dan

[ChrisK]

www.deluxe.com is a site for deluxe checks. I know, we used to own Clark American, the other large check publishing house.

Cornell Dublier

[dd842]

chrisk said:

www.deluxe.com is a site for deluxe checks. I know, we used to own Clark American, the other large check publishing house.

Cornell Dublier

Cornell Dublier ... www.cde.com/

Cheque! Cheque! ... ;D

Dan

P.S. For those outside of North America, I'm having a bit of fun with Chris' spelling of check because Canada and USA occasionally use different spellings for the same werd.

[ltb]

About 2 years ago A guy on an Internet Forum tested several types of caps and using an Oscilloscope and other instruments He showed and told how each type responded to a particular audio signal. According to his tests the old Oil Foil type tubular capacitors had the best response closely followed by Polystyrene then polyprophylene then Polyester I believe.
While the Oil Foil type cap was clearly supperior there was not even $15 difference in cost/value from the Oil Foil to the next type down which I believe was Polystyrene.
The Ultra's show to go for aprox. $56 on the site link at the top of this post and not $37. There was a type just below the Ultra that went for $30+
Would I like to have an Ultra Cap, you bet but not at any $56+ and knowing the fact that the old Oil caps tend to dry out over a period of time (accellerated by heat) I know I don't wish to pay that!

[UnklMickey]

ltb said:

About 2 years ago A guy on an Internet Forum tested several types of caps and using an Oscilloscope and other instruments He showed and told how each type responded to a particular audio signal. ...

before that, Steve Bench did this:

members.aol.com/sbench102/caps.html

[ltb]

Concerning the paper oil capacitors, I was doing research to find if the "Oxygen Free" copper paper oil capacitors were any better than the substantually lower priced Aluminum case Paper oil caps. What I found on two different sites was this:

Oxygen Free Copper only makes it purer copper and not significantly more conductive as some claim. In refining copper they shoot oxygen into it to remove impurities. It causes water and hydrogen to attract near the surface. It can make the copper slightly more brittle but only .1 percent less conductive than oxygen free copper.
Another site stated they looked it up in an Engineering book. It was not mentioned 3 times, 2 times, or 1 time but ZERO times.

Now that I got that out of the way, what cap do you guys think would make the best tone cap for Gibson Classic 57 Humbuckers in an EPI Les Paul Classic?

Please, I need help with the hype
We have Paper Oil
We have Vitamin Q
We have Mallory 150's (which sounded awesome in a 73 Fender Pro Reverb amp used as coupling caps)
We have Orange Drops which I think are too high fi'ish.

I have not tried any of the above mentioned caps for tone caps in a guitar before except for the Orange Drops and I did not care much for them. I like a smooth chimey clean tone with good Distinctive low end and smooth highs with some decent mid chimeyness. So far I have found the Poly chicklets from guess who (Radio Shack of all places) are ok but I would like to know if there are better choices.

[ChrisK]

guitarnuts2.proboards45.com/index.cgi?board=wiring&action=display&thread=1173993060

[ltb]

Chris, thanks for the info. I decided to just buy an inexpensive Polyester film .022mfd capacitor. I installed it and really like the results.

[ltb]

Update. I did a comparison between the "Green Chicklet " style Radio Shack capactor and a Mallory 150. In the A/B comparison the Mallory 150 won hands down. Funny how something sounds decent to you until you actually try something else. The same thing happened with my pickups. Epi Alnico V's sounded good until I tried a Gibson Classic 57 Humbucker in my Epi LP Studio.

[duosonicboy]

I have a rule to keep me from obsessing - any bit of gear that makes less of a difference in tone then room humidity I simply don't worry about. That being said, I can hear the difference between ceramic and everything else, with ceramic sounding much more trashy and trebly. I usually use ceramics in fuzz circuits when normal caps sound too polite - it helps for getting that sixties garage-band sound. Other then that, most of my stuff just gets the green candy : )

[drummer]

So what happens if you do somthing daft like put an insanely high MF cap in a guitar?

[ChrisK]

It depends on where you put it and how you define "insanely high" (regarding capacitor values that is).

If you put it across the signal chain it will attenuate most/all frequencies.

If you put it in series with the signal chain it will pass most/all frequencies.

If you put it in the wiring compartment without attaching it to anything, it will do little except rattle aboot and randomly short to things.


It's sort of like comparing a peach.

[ranchtooth]

I'm searching high and low for a 33 uf capacitor with a 450 V minimum rating.... I figured this is the proper thread to ask if anyone knows where I might locate one. Anyone???

BTW this is a filter cap for a clone of a matchless spitfire I'm building

[sumgai]

rt,

You're looking for an electrolytic, which is polarized. This is the predominant player in the filter capacitor department, the few other players in this game are much more expensive than necessary.

In general, you can't go lower in the voltage rating, but higher is OK. You also shouldn't go lower in the capacitance value, but if you go too much higher, then you start to get results that go against the intent. IOW, if you were to put in a 100µf cap instead of that 33µf, you'd tighten up the power supply so much that it would rarely, if ever, sag. In turn, this will keep the output stage from compressing the signal, and that's not what you want.

A 40µf unit would be fine, possibly even a 50µf, if necessary. I wouldn't go any higher than that though, unless I wanted a bit more power, at the expense of less "sweet singing tone" from the output stage.

BTW, any thread is the right thread in which to ask your question, but you should do your shopping from here:

THE LINKS PAGE - sort of......

HTH


sumgai

[toddw]

Sumgai,

Guess a spitfire uses a tube rectifier. But if ranchtooth only has larger caps, then increasing the value after the power transformer would decrease power supply hum (as long as he limits the max initial current with a low value high watt resistor. . . ) and, couldn't he simply put a 100 ohm resistor after that first cap to simulate sag?

Todd

[drummer]

chrisk said:

It depends on where you put it and how you define "insanely high" (regarding capacitor values that is).

If you put it across the signal chain it will attenuate most/all frequencies.

If you put it in series with the signal chain it will pass most/all frequencies.

If you put it in the wiring compartment without attaching it to anything, it will do little except rattle aboot and randomly short to things.


It's sort of like comparing a peach.

The reason i asked is because I've got a 220 uF (microfarads), 10V cap sat in front of me and I'm curious as to whether it'll kill me if i put in the place of the cap already in my guitar. ;D

[ranchtooth]

I'm trying to go as close to the original specs as possible (if it ain't broke, don't fix it mentality).

I might try two 16 uf caps in parallel.... That would get about 32, if i remember first year electronics

EDIT: scratch that, I just found what I'm looking for. God bless the links page.

[sumgai]

Todd,

Sumgai,

Guess a spitfire uses a tube rectifier. But if ranchtooth only has larger caps, then increasing the value after the power transformer would decrease power supply hum (as long as he limits the max initial current with a low value high watt resistor. . . ) and, couldn't he simply put a 100 ohm resistor after that first cap to simulate sag?

Todd

Yes, as the capacitance goes up, the hum should go down. That means that we have a trade off between how much we can make the power supply "sing", and how quiet it needs to be. These are design parameters, and both ideals can be met, with some careful planning or some experimenting. (Hands-on is...... )

The part about an initial current limiter isn't a concern for us, particularly in tube amps. In point of fact, a simple resistor can not distinguish between current that first hit it, and current that continues to hit it. What that means is that we would be limiting the current at all times, not just the moment of initial power-up. That's detrimental to our purposes, I'm sure you can see.

I have to say, I can see no way to imitate sag with a simple resistor in series between a power supply and a load, that one escapes me, sorry. Sag occurs because at some point in time, the maximum current that can be delivered was indeed delivered, and the capacitor filter stages, having delivered their stored charge at the maximum voltage, begin delivering that charge at a lower voltage. This is the nature of capacitor, to deliver the largest amount of current possible. It is the nature of a resistor to divide volts by amps, because the resistance is "cast in stone", so to speak.

If you'll look at the schematics for most tube guitar amplifers, you'll find that there's no resistor in series between the first filter cap and the output transformer. (There may be two filter caps in series, with a resistor across each of them, but they aren't in series with the load - they are in series to ground.) What you will find is a nice big, fat, output transformer, in series with the tubes. While the transformer itself is presenting merely an aggregate of the loads from the tube(s) and the speaker(s), it's also a critical point wherein sag is developed, due to magnetics, etc.

Additionally, there may also be a filter choke in series with the output transformer, that's an option taken by some circuit designers. I'll leave it up to you and the other readers to determine if such a choke actually helps or hinders the production of sag.

One must consider the circuit interactions of all the parts of a circuit before one can start to appreciate the phenomemon of sag. That would include, but not be limited to, the output transformer, the filter cap(s), possibly a filter choke, and the rectifier.

HTH


sumgai

[ChrisK]

I'm searching high and low for a 33 uf capacitor with a 450 V minimum rating....

These work up to 85C;
www.digikey.com/scripts/DkSearch/dksus.dll

This is nice;
www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=P7421-ND

These work up to 105C;
www.digikey.com/scripts/DkSearch/dksus.dll

FWIW since you found what you needed.

The reason i asked is because I've got a 220 uF (microfarads), 10V cap sat in front of me

Well, this is likely a unipolar cap so it shouldn't generally be used on AC signals, and it's aboot 10,000 times the value normally used in a tone control so it will have 1/10,000th of the normal impedance used (this qualifies as a short).

Although way large for a passive guitar circuit, it's not anywhere near insanely large for a cap.
www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=ESHSP-5000C0-002R7-ND
Yep, that there's 5,000 FARADS (5,000,000,000 uF).

22,727,272 times larger than that there dinky little thing that's sittin' aboot in front of you.

It's interesting that they quote the price to a 1/10th of a mil ($254.99750.)

and I'm curious as to whether it'll kill me if i put in the place of the cap already in my guitar.

Let us know if it works out............


It's sort of like comparing an apple.

[toddw]

The part about an initial current limiter isn't a concern for us, particularly in tube amps. In point of fact, a simple resistor can not distinguish between current that first hit it, and current that continues to hit it. What that means is that we would be limiting the current at all times, not just the moment of initial power-up. That's detrimental to our purposes, I'm sure you can see.

The initial resistor was intended to protect the rectifier tube. I thought if the first cap was really large, it would allow a lot of current initially. But I will believe you if you tell me that a tube rectifier won't be harmed by a current spike on power up. Maybe I read about it being used to protect solid state rectifiers from excessive initial current flow, although I really thought it was for tubes. Anyway, I think it was a 10 ohms, 5 watt resistor that was rec'd and I'll try to find the source.

I have to say, I can see no way to imitate sag with a simple resistor in series between a power supply and a load, that one escapes me, sorry. Sag occurs because at some point in time, the maximum current that can be delivered was indeed delivered, and the capacitor filter stages, having delivered their stored charge at the maximum voltage, begin delivering that charge at a lower voltage. This is the nature of capacitor, to deliver the largest amount of current possible. It is the nature of a resistor to divide volts by amps, because the resistance is "cast in stone", so to speak.

Well, if the PT/tube rectifier is capable of supplying sufficient current, you won't ever get sag, right. . . So it's really a result of not supplying the cap with sufficient current. If you draw a lot of current, the cap gets depleted and voltage drops.

If you put a small resistor, say 100ohms, between the output cap and the OT, the voltage drop across the resistor will increase as current draw goes up. Obviously it won't be a dramatic drop at that occurs only during high current draw, but it seems like it would drop the voltage on the output tubes the most during high current draw, similar to what occurs when the power supply "sags".

I can't claim any credit for that idea. I think it's in one of Kevin O'Connors books discussing how to simulate Sag, or at least make it an amp sound less sterile when using a solid state rectifier.

Todd

[ChrisK]

Folks make tube rectifier emulators. I think that Weber has one.
Tube rectifiers are fairly lousy rectifiers in that they have significant internal dynamic resistance.

This is used to good effect to limit the peak B+ voltage developed (and as a side effect in adding "sag"). One should be careful since a higher value cap will increase the equivalent RMS current draw thru a rectifier (higher current for a shorter time) thus perhaps over-stressing the rectifier, and it will increase the average B+ voltage developed, possibly over-stressing the output (and other) tubes.

The problem with tube amp designs is that they tend to be minimalistic in nature, with every thing depending on everything else.

[drummer]

ChrisK - Didn't work, probably too high or somthing, cut out all noise... I'm going to experiment with some caps which are silly cheap from 'Maplin' anyone in the UK could do well to look there, loads of caps at about 12 pence each. not just the ceramics ones either, the most expensive I found was about £5, that was a large one though.

So is the differance in caps very noticable?

I noticed my brother's new bass had the same caps as my guitar, [and the bass is actually shielded!]

[ChrisK]

I see that you've decided to follow my advice below.
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[toddw]

Chris,

That Weber tube rectifier emulator looks cool, but it's to replace a tube rectifier, not to make a couple of silicone diodes sound like a tube rectifier. Do you think it uses a thermister for the soft start?

Regarding your comment on overstressing the tube recifier with a large cap. Would a 10ohm resistor before the first cap be sufficient to prevent this?

Lastly, regarding sag. The spitfire is biased pretty hot. Matchless says it is in class A, although I think that is only true at low output levels. Regardless, is sag in any way relevent to building a Spitfire clone? If it isn't, then bumping up the first cap size (with or without a small resistor right after it), seems like it'd be an obvious improvement. Well, at least to me. I hate 120hz hum!

Todd

[ChrisK]

I would recommend a good few reads of the RCA Receiving Tube Handbook (mine's a recent one from 1970). I would then recommend getting/reading The Tube Amp Book by Aspen Pittman (the Groove Tube guy).

For me to correctly answer these questions without concern for inadvertent equipment destruction would require me to spend a few hours or more reacquainting myself with the sins of my past. I don't have the time now.

While I pay some attention to tube circuits, it's only from the perspective of the few amps that I consider/am modifying. Currently that's an Allen Encore kit.


Or ask sumgai