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06-26-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 1
Post ID: 4671
Reply to: 4671
Additive capacitance: mixing oils and films?

heres a question for the lot of you-

due to general lack of many available capacitors in my shop-- i recently mixed both film AND oil caps to pull together a necessary value for a passive crossover. 

the GOOD of it, is that it takes away some of the overaccentuated "speed" of the film caps, which is a nice touch.  to boot-- it sounds like a better FR fit, too.  the lesser glareyness in the upper mids is nice as well, but could be either a function of a less strained driver due to the raised XO frequency (it is a small 2 way system), or the oil cap--  but its too early to tell.

the BAD of it... it is noisy..  but sonically-- not enough time to tell yet.

beyond this-  its so recent, i cant speak as to its merit (or not)-- but i wonder if the mixing of such radically different capacitors is bound for sonic disaster time wise, or otherwise?  any input or experiences would be appreciated on "proper capacitor etiquette" in passive crossover construction!


thanks all--

dan
06-27-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004
Post #: 2
Post ID: 4677
Reply to: 4671
I tend do not bypass or mix the caps…

Dan

it is a slippery subject and I do not think that anything could be “right” or “wrong” in there.  I generally do not “voice” drivers with section of capacitors. However, but it is not mean that I do not see difference between the capacitors sound. Juts as I said before any good caps inflict only “static” coloration that is not really important. Bad caps do “dynamic coloration” it is bad but we do not use bad caps, do we?

I can tall only about my personal experience and I did in the past combine oil and film. As many others I have a very large box with speakers-type-value capacitors the box has all imaginable caps, staring from exotic Teflon and cupper foils and ending with many hundreds uF polypropylenes or huge and expensive cupper Jensons…

My personal observations I my surmise in following:

1) For larger values 10uF and up the electrolytic with active bias do the best. Among many caps the I tried in this application the Nichikon was preferable (not even Muse but the cheapest KZ line)

2) For smaller values I like Sprague Vitamin Q from 50s. They are available 1uF and you can pile them up as much as you wish. Vitamin sounds horrible for the first 5-6 days: no HF, very noise and very dirty. Then it clean itself up

I tend do not bypass or mix the caps, thought I admit that the Vitamins are at a very slight soft side…It kind of never heard to save a lightly soft cap where the S2 sitting somewhere down the line…

The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-27-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 3
Post ID: 4678
Reply to: 4677
vitamin q and a hovland, to be precise!

mixing those two seems to bring out  some of the best of both, so far!

the capacitor (or two, as the case may be) is an 8uF combo- 2 4uF caps-- one VQ, one hovland musicap.  i HAVE 8uF of vitamin q, but unfortunately, one 4uF is a 400VAC, the other 4uF is a monstrous 1000v..  which i've used.. but it's VERY noisy..  i'm not certain why, other than the fact that it's probably never going to fully charge under home listening!  that's the reason i mixed them in the first place-- as i have 9uF of hovlands- 1 too many...  which was putting a nasty bump in the middle that made violins sound like they were made of bell brass...

i'll scavenge the rest of my VQ's together (i have a few 1 mics around..) and see what i come up with!  thanks romy-

yrs

d
06-27-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004
Post #: 4
Post ID: 4679
Reply to: 4678
You had to tell that they’re undervoltaged
Dan, those 1000V caps must not be used under any circumstances, even they are with Vitamin Q impregnation. Even the 400V cap is too bad for speaker level and you need to go for 100V caps. The film caps with excessive voltage are not good but they sound more or less OK, however the oil caps with excessive voltage are horrible. In fact the old cap should be use at very max of their voltage, even with a near excessive voltage. The cap will be fine as the oil will self-heal the conductor. The Hovlands are very zippy caps and it is why the Morons love them in audio. It is possible that within very dull sounding undervoltaged Vitamins the present of the Hovlands you found beneficial…. But why do not use a normally sounding cap in the first place?

Rgs, Romy

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
06-27-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 5
Post ID: 4680
Reply to: 4679
that's why they're out!
yep-- i could tell from the minute i stuck them in they were a no go... the foil is WAY too thick.


i've used what i've been able to track down via ebay, and other nefarious means-- so those came in a lot of other lower voltage caps-- all in the 1-200v range.    finding some of the larger value, lower voltage caps (or 16 of them!), would require more patience and time than i have currently!  i know.. i know..    but the music's got to play!   refining is one thing.. but NO music.. that's not a good option!

the hovlands were an experiment as well- but they have a lot less self noise than the big VQ... for very obvious reasons!

i'd be very glad to take any spares you may have adding up to 16uF though if youve got 'em!

d.
06-27-2007 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006
Post #: 6
Post ID: 4681
Reply to: 4680
Mix, match & settle
Dan, it is funny that the Hovland is one of only a few caps I have specifically ruled out for crossovers.

I do not like but merely settle for black Solens for larger values, mostly because I just don't like to solder together great wads of smaller values.

I like the expensive Mundorfs OK for some things, but have never liked the oilers for crossovers because their sound seems to change around in that application.

OTOH, if you mix oilers and film caps in a speaker crossover then your experience of this willl be new to me.

I like to use as low a voltage as I can get away with for pretty much everything; it's just hard sometimes to find exactly what I'm looking for with respect to both capacitance value and voltage rating.

Perhaps you will pony up and try some Duelund coppers, let us know what you think...

Best regards,
Paul S
06-27-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 7
Post ID: 4682
Reply to: 4681
yargh.. solens...
hmm..

well.. duelunds.. they ARE mortgage lifters!  i think i'd be more likely to hunt down old vitamin q's for a few months while settling though...

i did try solens-- and while they were a revelation by comparison to absurdly overrated voltage oils... they shrieked so badly in the upper mids.. i gave them up for the hovlands!  and they weren't an altogether convincing solution either-- a little better--  but not quite the ticket.   in messing about with rp302's-- vitamin q's have always been the best of the lot..  so maybe sticking with a surefire is my best bet.  unfortunately.. the values i have on hand reflect the use of them for that application.. not midrange!

argh.. such a dance trying to demand 6 octaves from a driver..  it definitely shows WHY, despite the integration hassles, more drivers and horns thoughtfully congregated, is a better way to go.  at this point-- i think your advice to 'settle' is going to have to be my best bet!  but i'm definitely trying to do 'due diligence', as this is my first effort at horns.

in the meantime.. off to ebay..

thanks paul!

d
07-01-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 8
Post ID: 4692
Reply to: 4682
a nice passel of vitamin q-
it must've been my time-- i just tripped across a batch of 20 1uF vitamin q 100vdc caps for $4!

it's a lot of soldering...  but for $4?  i bit...

thanks all!

d.
07-01-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,160
Joined on 05-28-2004
Post #: 9
Post ID: 4693
Reply to: 4692
The Vitamins Q short survival guide

Yes, it is a common deal and it is possible very frequently to get a bunch of the Vitamins Q for very little money. Thanks God that no one from Sprague pay (paid) to market-makers to drool about the Vitamins’s sound and therefore the wide majority of Morons do not know about the Vitamins Q’s sound. Also, what keeps the Vitamins Q in shadow is the fact that they sound extremely horrible for a first 5-6 days…

There are two type of low voltage Vitamins: withy chasses connected and chasses lifted. I prefer the chasses (the body of the cap lifted). Also the 1uF Vitamins are not 1uF but very slightly less. If you put 8 of them together then you will not have 8uF but more likely somewhere like 7.5uF. Have a few small values Vitamins ready to parallel them with the rest bundle in order to get the exact value you need.

Another very interesting idiosyncrasy of the Vitamins is that they most likely love current. The Vitamins do very fine in speaker-level crossover but when they use in line–level as coupling caps then do not do well. Listen many Shindo units and you will hear what I mean.

Also you will see some sealers advertise this caps as “Vitamins Q” but they are not the Vitamins Q. They have a very similar contrition and identical “vintage” look but they have no letter “Q” on them. There were a number of companies that did them (I have a many of them) but those caps have no Sprague “Vitamins Q” impregnation. Therefore always ask for a picture of the caps you buy or a conformation that it has the “Q” written on them. I anticipate that if the Vitamins’ popularity will go up then we will see some counterfeited caps with Vitamins Q making….

Rgs, Romy the caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-01-2007 Post does not mapped to Knowledge Tree
stuck.wilson
Hyattsville, MD, US
Posts 21
Joined on 09-04-2006
Post #: 10
Post ID: 4694
Reply to: 4693
couldn't be more chuffed...
yep-- i always measure first to get as close as i can get to a matched set (within a % or 2 at least!).  luckily, for this application, i got 4 extras.. so i should be able to get close, and for all the sub- 1uF caps i have around for all the other experimenting, i oughta be able to dial in just right.

these appear to be the NON glass lined caps-- but the voltage is right, and the price sure was-- so i'm in a better position than i was with bad voltage and hovlands!  no worries about line level usage at this point-- i'm still operating my amp full range, and probably will be for a while!  so current they'll get..

i have actually written several advertisers of 'vitamin q capacitors' that were gudemans or west caps or pyramids or the like, and i asked them to advertise truthfully.  most were relatively polite, but went back to their bullshit..  no surprise.  having listened to quite a few of the 'vitamin q type' caps-- they do sound differently that i can tell.. but all of those that i use (except for breadboarding something new if i don't have the right values...) are the real deal spragues.   that said-- a few of the crap peddlers on ebay'll just use that term to sell them-- but you can usually tell when they're face down in their pictures...  luckily-- i've seen this format before, and i've also purchased from the same gent before as well, so i think i'm in good shape.  thanks for the warning though!

4 bucks!  sure beats the hell outa paying for something like jensens..  which i've never heard, and for the cost of them, probably won't.  mebbe some day i'll be a rich guy in a rich guys game!

d.
08-16-2009 Post does not mapped to Knowledge Tree
Axel
South Africa
Posts 80
Joined on 07-18-2009
Post #: 11
Post ID: 11426
Reply to: 4671
Re: Additive capacitance: mixing oils and films?
fiogf49gjkf0d
well, to add my bit of mustard to this here oldie thread.

I HAVE mixed film and oils successfully in e.g. a tweeter x-over of a Burmester 961. The tweeter is an AMT (air-motion-transformer) and very revealing.

The original C's are two sets of 1uF 630V || 3.3uF 400V + 1uF || 3.3uF (same voltages i.e. physically close in size). In between the two parallel C's is the 'tap-off' for an RCL. All caps are Mundorf MCaps. I have now added to each parallel set 1 Mundorf silver-oil of 0.01uF and it is quite amazing how much it cleared-up the tweeter. (If I remove the by-pass it seems to haze-over the treble!)

So this worked fine, BUT having tried some other by-passes with a 5.6uF C, parallel to signal path in the mids x-over, using e.g. 0.1uF tin foil, or also 0.01uF silver oil all produced a very incoherent sound.

Lastly, by-passing big value electrolytic (220uF and 47uF) with a 1uF tin foil worked very well, -- using a 0.68uF tin foil didn't, causing incoherence also.

Long story short: it is pretty much a case by case trial and error situation and much depends on the particular circuit.

My own rules:
- Do not mix cap brands the chance for incoherence will be greater

- Stay below 1% of base value for 3rd (cascaded by-pass cap)

- Tin foil caps actually can sound tinny in tweeter circuit, avoid it.

- Tin foil in mid circuit are fine and seem to work OK to 'clean up' electrolytic caps both, smooth and rough caps.

- By passing electrolytic caps in woofer circuit will very likely produce some 'glare' in the upper mid. A 180Hz xo point will still have enough energy with 2nd order (4th acoustic) to mess noticeably in the upper midrange!

- Reduce electrolytic 'rough' value and make it up with electrolytic 'smooth' in woofer circuit. This can yield some unexpectely good results in an improved upper bass performance.

- Same applies to mids circuit but one added foil by-pass cap can further improve things (note < 1% of base value)

- One more mid alternative for ~> 10uF electrolytic is to replace 1 value of a 'rough' (etched) cap, with ~ 2 'smooth' smaller values and making up the final value with e.g. polyprop foil cap of not more then ~ 10% of total value.

- Do not mix caps to of very different physical dimensions (incoherence!), use lower voltage for base value and go up with voltage for smaller values.

Axel
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