capacitor recommendation

[aragorn723]

Hi,

I just built a Quickie, and really like the sound (its totally stock).  For the first mod, I was thinking about changing the 2.2 uf caps on the outputs.  Will that make a really big difference in the sound?  The sound i'm looking for is clear, open, liquid, and very smooth (especially with vocals).  What is the right capacitor to use?  Thanks,

Dave

 

[galyons]

I would suggest real paper in oil caps.  You can usually find nice old stock American PIO caps on eBay.  (Sprague Vitamin Q, Westcap, Micamold, CDE, Good-All & Aerovox are some of the vintage brands). Likely 2.0uf, won't make a difference.  You should be fine with 100v.  Not as much demand for these, so prices are more reasonable.

There are also Russian military, but in 2.2uF, K75's are probably your best bet. (They are mylar, paper and aluminum foil in oil similar to the new AudioNote tin foil/mylar caps at less than 10% of the cost!). K42's and K40's can be found in 1.0uF and paralleled.  KGB, PIO and MBG,  waxed paper and aluminum foil, are available in 2.0. The nice thing with the quickie is you do not need the higher voltages.  You should be fine with 100v. Not as much demand for these, so prices are more reasonable.

Rike-Audio S-caps are  probably my newly manufactured, high dollar favorites.  Jensen, Dueland also make PIO's.  All are pretty pricey.

Be aware that many caps marketed as paper in oil, are not.  They are really metalized polypropylene in oil.  Not the same, but many folks enjoy how they sound.

I have a nice pair of Aerovox's in my Quickie. Very smooth, wonderfully accurate timbre,  and imaging soundstage champions.  They are spectacular on female voice and smaller ensemble music.

Cheers,
Geary

 

[matthewmckay]

I put a pair of fully ran-in clarity cap ESAs (pulled from a FPIII build) in an otherwise stock quickie 1.1 and I am very happy with the result.  I haven't had any desire to put the PJCCS in the circuit, yet.

 

[2wo]

"The sound i'm looking for is clear, open, liquid, and very smooth (especially with vocals).  What is the right capacitor to use?  Thanks".

Geary has good advise.

I think you would be happy with one of the Russian caps. I urge you to try a pair or two. not much money and you can form your own opinion...John   

 

[aragorn723]

"The sound i'm looking for is clear, open, liquid, and very smooth (especially with vocals).  What is the right capacitor to use?  Thanks".

Geary has good advise.

I think you would be happy with one of the Russian caps. I urge you to try a pair or two. not much money and you can form your own opinion...John 

John,
That's just the issue, not knowing a lot of capacitor types and what they sound like.  The only basis for comparison I have are the metalized polypropylene ones from the Quickie (not sure what my old Audio Electronic Supply AE-3 preamp had).  The prices do look really good for the Russians, some of the capacitors out there are $70 a piece, so i'm a little gunshy about buying some only to find out that they weren't the right ones. 

Geary,

Are these the right caps?  These are 500V and almost 3" long!  There's a 250V that's about 2" long..  Will these fit in the Quickie?

http://rutubes.com/product/k75-10-2-2uf-500v-pio-capacitor/

Thanks,

Dave

 

[corndog71]

The Quickie runs on batteries so a 250V cap is more than adequate for the job.

 

[Grainger49]

Geary,

Are these the right caps?  These are 500V and almost 3" long!  There's a 250V that's about 2" long..  Will these fit in the Quickie?

Thanks,

Dave

Dave, 

The Quickie is almost empty.  So either the 3" or 2" long caps will fit. 

I am a fan of breaking in caps before use.  But the PIO caps are usually good when cold and don't go through an "awful" phase.

 

[aragorn723]

Geary,

Are these the right caps?  These are 500V and almost 3" long!  There's a 250V that's about 2" long..  Will these fit in the Quickie?

Thanks,

Dave

Dave, 

The Quickie is almost empty.  So either the 3" or 2" long caps will fit. 

I am a fan of breaking in caps before use.  But the PIO caps are usually good when cold and don't go through an "awful" phase.

Grainger,

I'm thinking more about the length of the leads in relation to the spot where it has to go-between terminal 1 and the output rca and between terminal 6 and the other rca (if I remember correctly).  There's about an inch of space, so the leads need to be long enough to bend around the caps and somehow fit into the terminal and rca.  How do you break in the caps?  Thanks,

Dave

 

[galyons]

The 250v caps are fine.  The Quickie B+ is =/- 36VDC so even 50v or 100v provide plenty of margin.

Many times you will have to put fly leads on caps for very reason that you state.  My process is:

-bend a small lop in the caps lead,
-put alligator clip heat sinks on the protruding ends, (sinks heat from the cap and helps keep the cap inplace while soldering)
-cut some good solid core wire to the required length,
-tin the ends of the wire,
-insert in loop and pull/squeeze the loop tight,
-solder very quickly.

Also some of the K75 have tabs, not wires, so you have to put on leads, all the same.

Some older caps came with steel leads, magnetic.  I check with a magnet and if they are steel,  I replace with copper leads, as above.

I would definitely burn in the caps.  Grainger has a good tutorial here:

I have a "Patented" burn in method:

How to break in the easy way

Buy yourself four Radio Shack 10W 10 Ohm resistors.  These are among the few parts they still sell.  You should always keep these on hand because you can use 10 ohms as a dummy 8 ohm load.  The value is close enough.

Determine the volume level for break in with a CD of your favorite music.  You want a loud but not distorted level for break in.  Determine the right volume level and remember this setting on your preamp or amp.  This is the break in level.

Wire each pair of resistors in parallel (see picture below), then put one capacitor in series with what is now a 5 ohm load (a good load for the amplifier). The first lead of the capacitor goes to one amplifier speaker terminal and the other lead goes to one of the the joined leads of the 10 ohm resistors.  The other joined leads of the 10 ohm resistors goes to the other amplifier speaker terminal.  You will end up with a pair of resistors and a capacitor on each of the amplifier speaker terminals.  (couldn't insert a picture in between the text so it is below)  I use a dual banana plugs because it is easier that way for me. 

Now, with only the resistors and capacitors on the amp output, no speakers, put your CD on repeat, set the volume level at the predetermined point and burn in the caps for 4 days, ~100 hours for polypropylene and polyethylene caps.  Burn in for 1-3 weeks if they are Teflon.

Using the pair of 10 ohm resistors in parallel feeds twice the current through the capacitor than a 10 ohm resistor and increases/speeds burn in.

That is it.  After 7 days, or 21 days for Teflon, you should have 90% burned in capacitors.  Any changes that happen after that will take many, many weeks anyway.  Break in is not a straight line but a curve.

(I got tired of soldering the capacitor leads so I have replaced the wires with alligator clip leads.)

The caps will burn-in in the Quickie, playing music, as well. 

Cheers,
Geary

 

[Paul Birkeland]

If you have a 5 Ohm resistor in series with a 0.1uF cap, you will provide an AC load above 320kHZ, otherwise the amp won't know that it's loaded, and there will be very little AC current traveling through the RC network.

I'd suggest trying a 1M resistor instead, as this should allow AC at nearly all frequencies.  Let us know what kind of changes you observe.

-PB

 

[Grainger49]

Paul,

Wouldn't a 1M resistor limit the current by itself?  Otherwise you would have to swing a lot of voltage to get current.

 

[aragorn723]

Do the K75's have polarity like an electrolytic, or can you install them either direction?  Also, will changing the stock electrolytics make a difference in sound?  Thanks

 

[Paul Birkeland]

Paul,

Wouldn't a 1M resistor limit the current by itself?  Otherwise you would have to swing a lot of voltage to get current.

It's more a matter of getting some instead of getting none with the available signal that's provided.  There's no "music" data at 320kHz, and below that the Zobel network is "open". 

For breaking in an electrolytic cap or a large film cap (47uF and up approximately), the 5 Ohm resistor will work nicely, otherwise you'll have to compensate a bit with the resistor value, or consider leaving it out all together.

 

[Grainger49]

@ Aragon...

They don't have a polarity.  Film caps are said to have a "preferred" orientation.  And I have seldom observed it.  What it does is gives a small additional noise rejection. 

I'm not on my desktop where I have the schematics.  I guess the electrolytics are from the cathode to circuit common.  Quickie doesn't really have a ground.  If those are the electrolytics, bypassing them is a good idea.

What is the value?

Paul,

I hadn't calculated the RC time constant.  I see your point.  I should modify the post.

 

[aragorn723]

@ Aragon...

They don't have a polarity.  Film caps are said to have a "preferred" orientation.  And I have seldom observed it.  What it does is gives a small additional noise rejection. 

I'm not on my desktop where I have the schematics.  I guess the electrolytics are from the cathode to circuit common.  Quickie doesn't really have a ground.  If those are the electrolytics, bypassing them is a good idea.

What is the value?

Paul,

I hadn't calculated the RC time constant.  I see your point.  I should modify the post.

The electrolytics are 150 uf

 

[Grainger49]

That might be a large capacitor, size wise.  I would go with a film bypass.  Get the lowest voltage you can find and go with say 10uF.

 

[aragorn723]

How about these for the 2.2 uf caps?

http://www.ebay.com/itm/Aerovox-AREM-Metalized-Polyester-Film-Capacitors-2-2uf-200v-x-4pcs-/230946005391?pt=LH_DefaultDomain_0&hash=item35c574618f

 

[Paul Birkeland]

Those are potentially much, much worse than what we include with the Quickie kit.

 

[galyons]

Those are potentially much, much worse than what we include with the Quickie kit.

NOOOoooooo! PB is, as usual, quite right.  Although Aerovox make good caps, those particular caps are metalized polyester. And  that material is way down the desirability/quality list for audio coupling or output caps.  The stock caps  are good metalized polypropylene, much better in this application than metalized polyester .  I know the caps alphabet soup is confusing...PIO...MPP...MKP...ad naseum. 

Happy Thanksgiving!

Geary

 

[aragorn723]

Happy Thanksgiving!  I should probably leave well-enough alone..  Yesterday I turned down my amp, and turned up the Quickie, (and changed the rca from the amp.  It was a monster cable, but is now Cardas Crosslink.  It sounds pretty amazing, just looking to push the envelope a little I guess 8)

Would it be better just to put in a PJCCS?