Everywhere I read "mojo" i feel like the discussion is turning into religion...
(& the price of these "magic" parts seems to surf on some kind of law according to which the imagination is more firm than will & knowledge)
Indeed music is an art, so it seems likely that hardly measurable(*) inconsistencies leaded to exceptional instruments, but this has little to do with technology.
Also not sure that big companies provide any warranty. They are producing so huge batch of parts that the mistakes are multiplied also, and when facing the choice of well... these billion parts out of tolerances, err... that is a lot of money...
(& the single consummer weights almost nothing in the equation.)
_
(*) the matter is subject to Heisenberg's uncertainty principle, after all
That's a good point. Modern caps run rings around their ancestors. They're smaller - dramatically! - for the same ratings, and have nearly no fluids in them to vent and dry out. Smaller means a lower ratio of interior volume to exterior surface, so heat gets out better. Smaller also means shorter distances through thin aluminum foils, so the distance between lead tabs and the working surface is smaller, and so the ESR is lower. Fewer turns of wound foil means lower ESL too. Finally, better foil management with extended foil or tabs means more and shorter paths to the working surface, again giving lower ESR and ESL.
Once again, the high volume manufacturers are the ones that can afford the latest in capacitor internal design. That makes them the go-to guys for good caps again.
It's true that they don't make 'em like they used to - and thank God for that!
Antique Electronics is remaking some twist lock cans for amps again, and I needed some of those cans in low voltages for fixes on old Thomas Vox amps. I tried to get them to sell me the empty twist lock cans, no filling at all, but they didn't want to do that. Sigh. Filling old twist lock cans with modern caps would be a real step forward for many amp repairs.
FourT6and2 wrote: ↑Thu Jun 15, 2017 12:27 am
For filter caps, I just go with whatever specs out the best. I don't look at the brand name, I look at the data sheet.
...you can't tell longevity or overall stability of a cap based upon a datasheet.
Oh, but you can by looking at the fancy brand name and price tag?
Specs are derived under specific conditions. And with that, you can compare like for like. If all else is equal, I'm going to pick the cap with the longer hour rating or ESR or ripple or temp stability and so on.
Or, you know... if the cap is purple. Because purple just sounds better and that's a fact.
I never said that... never even implied it. My implication was that experience beats a datasheet. Not 'marketing beats a datasheet' People are caught all the time doing hinkey tests that actually inflate numbers to make things seem better than they are. Look at Volvo with their recent major issues where their testing showed them as significantly better than they really were and they got in deep doo doo. If two datasheets were identical, but one was from a capacitor fresh from shenzen, and the other was one made in Japan or the US, does that mean they'll preform identically? maybe?
pompeiisneaks wrote: ↑Thu Jun 15, 2017 12:38 amThe only problem I could see with that is that you can't tell longevity or overall stability of a cap based upon a datasheet.
Life in hours at rated operating conditions is often quoted on data sheets.
That's their lab tested data, yes, and in theory all labs should follow strict conformity to expected standards, but just like my previous note about the scandal at Volvo due to their testing being a bit shaky, people usually don't just assume that all data on the datasheets are always 100% perfect, if they know a particular brand to be problematic, etc. Thus why I am indicating that more than just the datasheet should be considered. I don't discount them, I'm saying they're not always the perfect truth. On the other hand, my experience with datasheets for capacitors is pretty limited so I could be barking up a nonexistent tree.
...you can't tell longevity or overall stability of a cap based upon a datasheet.
Oh, but you can by looking at the fancy brand name and price tag?
Specs are derived under specific conditions. And with that, you can compare like for like. If all else is equal, I'm going to pick the cap with the longer hour rating or ESR or ripple or temp stability and so on.
Or, you know... if the cap is purple. Because purple just sounds better and that's a fact.
I never said that... never even implied it. My implication was that experience beats a datasheet. Not 'marketing beats a datasheet' People are caught all the time doing hinkey tests that actually inflate numbers to make things seem better than they are. Look at Volvo with their recent major issues where their testing showed them as significantly better than they really were and they got in deep doo doo. If two datasheets were identical, but one was from a capacitor fresh from shenzen, and the other was one made in Japan or the US, does that mean they'll preform identically? maybe?
If you're building an amp and need a capacitor, at some point you gotta bite the bullet, suspend your skepticism, and just buy the damn cap.
Absolutely, but I also know enough to ask around and find out from experienced builders what to avoid. I bought caps without asking on my first few builds, They sounded great to me, but they're only a year old, and could very well die in another year (illinois or nichicon I think). but then again, they may outlast me. I started moving to F&T due to the positive comments from others and have mostly used those or JJ since. I've done a few Sprague Atom but they're pretty pricey and I avoid them if I can. I'm still trying to learn from experience and am trying to learn from input from others as well.
I've stated my personal experience with general data/test data here, though and that's something I've encountered off and on throughout my life, and I'm no spring chicken
I'd just re-iterate that F&T make me feel the most confident. I do look at the data/spec sheets.
Then I measure every cap for tolerance & esr. Another handy trick is to use thermal imaging during burn in. Surprising what can show up. Little Flir camera plugged into my iphone.
In the end you pays your money & takes your chance.
Interesting thread.
R.G. wrote: ↑Thu Jun 15, 2017 3:09 pm
Antique Electronics is remaking some twist lock cans for amps again, and I needed some of those cans in low voltages for fixes on old Thomas Vox amps. I tried to get them to sell me the empty twist lock cans, no filling at all, but they didn't want to do that. Sigh. Filling old twist lock cans with modern caps would be a real step forward for many amp repairs.
Hayseed Hamfest make twist lock cans with modern innards to order.
Oh yes, I forgot: I also bought F&Ts, but the choice is rather obvious in Europe. Sprague Atoms seem to be overpriced,: close to ten times the price of their competitors...
R.G. wrote: ↑Thu Jun 15, 2017 3:09 pm
Modern caps run rings around their ancestors. They're smaller - dramatically! - for the same ratings, and have nearly no fluids in them to vent and dry out. Smaller means a lower ratio of interior volume to exterior surface, so heat gets out better. Smaller also means shorter distances through thin aluminum foils, so the distance between lead tabs and the working surface is smaller, and so the ESR is lower. Fewer turns of wound foil means lower ESL too. Finally, better foil management with extended foil or tabs means more and shorter paths to the working surface, again giving lower ESR and ESL.
That's interesting, thanks! I have always been puzzled by the size of the 25uF/50V sprague atoms, when compared to their 22uf/63V substitutes...
... now I feel better using the (much) smaller & cheaper alternatives.
chief mushroom cloud wrote: ↑Fri Jun 16, 2017 1:50 am
anyone know where I can get some Trump brand mojo caps?
Modern caps, that are made for industry, are definitely much better, and more affordable, than caps marketed for guitar amps. Look at any Epcos or Panasonic electrolytic compared to something like the antiquated ones for amps... The only downside is most modern caps are snap-in only. It's tough to find new multi-section e-caps, let alone ones with solder tags or eyelets. They're all snap-in these days. Not a bad thing, you can still solder leads to them and mount them in rings. But I haven't been able to find multi-section ones like a 50+50, 500v other than Ruby, JJ, F&T, ARS, etc. I'd prefer something NOT sold as a "guitar amp" cap.
I used these Panasonic ones for a build a while back. No complaints. But hey... they're filter caps.
Yeah I did a recap of a Bogner Shiva that was getting noisy and it had all nice nichicon caps similar to those you showed, all snap in so removal and replacement was super easy. It also sounded loads cleaner/nicer after the recap. I got picked on a bit for that one because some of them felt bubbled on the top and it was at 12 yrs (a 2004 amp). There was a noticeable difference in tone, cleaner tighter etc. But people were saying I'd wasted the customer's money, replacing good caps. Another one of those religious issues but whatever. I did really like the use of those style caps.
I select my caps by what color board I'm using this time.
Lot of silly internet talk regarding Illinois caps, I haven't seen a recall on commercially sold guitar amps that have been using Illinois caps for quite some time.
I have never had one go bad. I did have trouble with JJ axial caps 22uf/500v and 40uf/500v leads break off way too easy.
One of the major uses of the snap-in electros is in switching power supplies. These things are connected to the AC power line through a rectifier setup and sometimes an inrush surge limiting resistor, sometimes not. As you can imagine, cap failures can be unnecessarily exciting, especially if you're standing near the cap when it goes nova.
As a result, the industrial buyers of the high voltage snap in caps are serious about getting tough caps. Snap in cap manufacturers who ship bad batches don't get any more orders. These caps are generally suitable for really heavy use. Guitar amps don't generate anywhere near that level of abuse.
