Author Topic: Teflon Bypass  (Read 18751 times)

Offline BobM

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Teflon Bypass
« on: September 10, 2012, 12:23:21 PM »
I've got 2 left over V-Cap .1uF's and 2 Russian .1 UF Teflons that I want to use on my speakers tweeter crossover. I have Apogee's, so this crossover schematic might look a little strange to some of you. My question is, where shold I put the teflon bypasses?

I figured, put the best cap (V-Cap) at the earliest part in the circuit (C5) and the Russian Teflon at the next closest point (C1). Anyone disagree with me, or have a bettter suggestion (short of buying more V-Caps or replacing them all with $20K worth of Duelands  :duh)?

Thanks

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Offline BobM

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Re: Teflon Bypass
« Reply #1 on: September 10, 2012, 12:36:51 PM »
Similar question about the resistors.  I plan on using Mills, but I am wondering if I can use the MRA5's (5 watt power handling with 25 watt peaks) or should I step up to the MRA 12's (12 watt power rating with 120 watt peaks)? I am using a high powered McCormack amp that could push 1000 watts into 2 ohms.

Are the MRA 12's overkill or necessary? In a normal speaker I would say 5 watts is plenty, but I'm not sure about these.


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Re: Teflon Bypass
« Reply #2 on: September 10, 2012, 12:37:05 PM »

I figured, put the best cap (V-Cap) at the earliest part in the circuit (C5) and the Russian Teflon at the next closest point (C1). Anyone disagree with me, or have a bettter suggestion (short of buying more V-Caps or replacing them all with $20K worth of Duelands  :duh)?

Thanks


That's what I'd do... C1 and 3 could be replaced by film caps if they are currently electrolytics... C5 could too but it would be very large.

The resistors and inductors might be a good upgrade too depending on what's in there now...

edit... I like Mills resistors, they are very clean and neutral sounding to me. I'd go with the 12s if there's any doubt, they aren't that big or much more expensive.
« Last Edit: September 10, 2012, 12:38:36 PM by DaveC »

Offline BobM

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Re: Teflon Bypass
« Reply #3 on: September 10, 2012, 12:52:00 PM »
All the caps are films (old Spragues originally, but now a combo of Auricaps, Sonicaps, Multicaps and a few leftover Spragues). I've found that mixing and matching cap brands delivers better sound overall than sticking to just one brand, especially when the values are large (like 70uF) and you need multiple caps in parallel to get the value right.

I'll probably get a .1uF Sonical Gen II bypass for that last C3 position just to be a completest.
« Last Edit: September 10, 2012, 12:53:55 PM by BobM »
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Offline Face

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Re: Teflon Bypass
« Reply #4 on: September 10, 2012, 02:15:35 PM »
I've never liked the sound of bypass caps in a speaker crossover.  Either replace the large caps with caps of better quality or leave them alone. 

Claritycap has all the values you need among their misc. lines. 

DaveC

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Re: Teflon Bypass
« Reply #5 on: September 10, 2012, 05:50:34 PM »
All the caps are films (old Spragues originally, but now a combo of Auricaps, Sonicaps, Multicaps and a few leftover Spragues). I've found that mixing and matching cap brands delivers better sound overall than sticking to just one brand, especially when the values are large (like 70uF) and you need multiple caps in parallel to get the value right.

I'll probably get a .1uF Sonical Gen II bypass for that last C3 position just to be a completest.

I'd guess bypassing or replacing caps is only going to make for a small difference and not really better unless you spend big $ on them... I also agree that bypassing might be worse, especially at .1 uF, the combination might not work out so well. Partsconnexion is having a big sale on Duelund  :D

Offline Response Audio

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Re: Teflon Bypass
« Reply #6 on: September 10, 2012, 08:13:26 PM »
My recommendation is to replace the 70uF cap with whatever you prefer and can afford. Try to use the best polypropylene cap(s) possible.  This is the place where a decent bypass would be most effective. The problem is you will have to use a decent quality and larger value cap to notice a difference.
The second two caps are small enough that they can be replaced with good quality capacitors of your choice.
I would. Ertainly replace the resistors with Mills 12 watt units and if possible, replace the inductors since everything is in series.
Not sure how far your skills go but I would measure the DCR of the inductors and try to come close with the replacements. If the replacement inductors have a lower resistance, you always place a small value resistors in series with the inductor to equal that of the original.

These circuits are critical as they help control dips and peaks in the ribbon tweeter. If your values are off, it can really effect how the ribbon performs and sounds. Something to consider before taking the Inge into crossover tweaking with this type of speaker.
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DaveC

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Re: Teflon Bypass
« Reply #7 on: September 10, 2012, 11:35:14 PM »
For the inductors, partsconnexion will custom tailor their foil inductors to your specs for a very small charge, you just buy the next largest value and they will unwind it for you. They would also supply you with the new DCR spec so you can match the old ones.

Offline BobM

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Re: Teflon Bypass
« Reply #8 on: September 11, 2012, 05:50:06 AM »
BTW - I started the same thread over at AC. An interesting reply over there states that due to the low effeciency of these speakers, a bypass of .1uF will have little effect and I should use larger values. Don;t know about that because I definitely hear a difference in my initial tests.

C5 is actually 7 x 10uF foil caps in parallel. This is where I am using 2 Sonicaps, 3 Auricaps, and 2 leftover Spragues. I have bypassed this with my .1uF V-Cap.

C1 is a 10uF Sprague. I have bypassed this with the .1uF Russian teflon.

C3 is a 5uF Sprague.

The initial result I heard last night was a definite increase in top end extension. Perhaps too much so, because it became a little hard (all these teflons have been used before and should be fully broken in, but I am not ruling out that more break-in could smooth this out a bit).

My next thought is to replace the (C3) 5uF Sprague with a 1uF Russian K40Y paper and oil + a 4uF Sonicap. I'm thinking this will give me some additional midrange warmth and bloom.

I might also remove the .1uF Russian teflon from C1 and replace it with a .1uF Sonicap Gen II, depending on how the K40Y changes the sound. Or perhaps just replace it completely with a 10uF Sonicap.

Thanks
« Last Edit: September 11, 2012, 06:24:43 AM by BobM »
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Offline rollo

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Re: Teflon Bypass
« Reply #9 on: September 11, 2012, 09:29:56 AM »
 Bob would it feasible to leave the internal crossover build an outboard crossover and disconnect the internal to directly compare to internal ?
   This way you could do direct comparisons. The beauty of the Apogee crossover is it warmish character. The Maggie antithesis.
   Actually what areas are you looking to improve or change. Topend, bottom, mids, all of the above.
    BTW V-caps when sitting for a while will require break in again. I would recco the copper versions over the tin version. More detailed without the Teflon sound. If you could swing Dueland for the top alone I would do so. Even if just the Cast resistors. I would not bypass, especially the top. Look at Northcreek inductors if Dueland is out of reach. The Northcreeks will tighten up any bass.
   Have fun trying.


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Offline BobM

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Re: Teflon Bypass
« Reply #10 on: September 11, 2012, 11:34:27 AM »
I've actually removed the crossover from the speaker and put them in outboard boxes. This makes changing components far easier than otherwise.

Yes, I think I've lost that warmish character with too many bypasses to open things up on the top end and better caps to tighten them up on the bottom. Maybe re-break-in will resolve this, and one of the reasons I'm contemplating including a Russian K40Y PIO in there somewhere.

Another good idea from the other forum - Connect the bypass cap at one end only and play some white/pink noise , then touch the loose end of the bypass cap and see if I can hear the effect/difference and whether I like it or not.

Duelands of any kind are out. So are any additional V-Cap purchases. The original house wound inductors have all been potted and seem to be doing a decent job (tight tuneful bass with the cap changes), so I am not inclined to replace them.
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Offline Face

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Re: Teflon Bypass
« Reply #11 on: September 11, 2012, 03:04:30 PM »
Claritycap ESA have a warmish character and will improve spacial info(imaging/soundstage).  As for resistors, Mills have a warmish character too. 

http://www.partsconnexion.com/capacitor_film_claritycap_esa.html

http://www.madisoundspeakerstore.com/esa-cap-630vdc/

IMO, a single cap always sounded better to me than multiples.  But if you must split a value, always split evenly. 

Offline BobM

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Re: Teflon Bypass
« Reply #12 on: September 12, 2012, 09:17:40 AM »
Well I tried lifting the .1 Russian teflon bypass on C1 while playing pink noise. No discernable difference that I could detect with my ear right next to the tweeter ribbon. So I'm going to pull that off and replace the old Spragues in C1 and C3 as follows. In fact, here are the components of the reworked crossover in their entirety (once they arrive):

C5 (70uF) =
~ 1 x 20uF Sonicap
~ 2 x 10uF Sprague (original caps)
~ 3 x 10uF Auricaps
~ 1 x .1 uF V-Cap Teflon (bypass)

C1 (10uF) =
~ 1 x 1.0uF K40Y (Russian PIO)
~ 1 x 4.0uF Sonicap
~ 1 x 5.0uF Sprague (or maybe a Multicap I have lying around unused)

C3 (5uF) =
~ 1 x 1.0uF K40Y (Russian PIO)
~ 1 x 4.0 Sonicap

I'm hoping to get some additional bloom and midrange PIO warmth by using the Russian K40Y PIO's, but if they don't work out I have either 1.0 Sonicaps, Multicaps or Obbligato Coppers I could use instead.

All resistors are being replaced with Mills MRA12's. The inductors I am leaving alone (for now).
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Offline Response Audio

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Re: Teflon Bypass
« Reply #13 on: September 12, 2012, 07:36:26 PM »
Hey Bob
SoniCaps are the last capacitor to have in a crossover if warmth is what you are looking for. In my opinion, the best choice for this would be the largest value Mundorf Silver/Oil you could afford to put in. The down side is that you will not experience the warmth and smoothness of this cap for many hours (200 or so).
An exceptional capacitor for smoothing out a tweeter or even an aggressive analog circuit.
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Offline BobM

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Re: Teflon Bypass
« Reply #14 on: September 13, 2012, 06:04:24 AM »
Bill,

I've heard a lot of good, and bad, about the Mundorfs. I can't say that I've tried them myself. Basically, people seem to like them initially, and then don't after a while once they are fully broken in. They seem to have a bi-polar reputation.

The Apogees are still very smooth and not aggressive in the least. I'm trying to improve the openness and bloom while still retaining their overall tonally even character. I think I might have gone a bit far one way and want to see if I can bring it back a notch with the PIO's as I move into the "second half" of the crossover.

The Auricaps were recommended to me by several Apogee owners who have upgraded their crossovers, so I used them in my original mod of the Calipers. They are clean and open and transparent and fast, but I also tend to find them a bit dry with maybe a bit of a loss of harmonic richness and a bit of plastic sheen. Anyway, I've got them and I used them. They may be the real culprit in what I am hearing now.

I've found Sonicaps to be one of the most balanced caps around for a crossover, with a very even character - not overly warm and not shrill in any way. Yes, they are open and fast too, but they retain that harmonic stuff that makes the magic. They work very well on the bass too, being extended and tight. They are my "go-to" cap when I want to keep things on an even keel, and allow me to tune things with the other outlying caps.

I know I will get where I want eventually, but it is fun to learn new things as I play a bit. :mrgreen: After all, I'm not in any rush and have all winter to experiment (that's typically my audio play time).
« Last Edit: September 13, 2012, 06:15:13 AM by BobM »
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