[David Ellis]

These comments will cover a recent experiment I performed with .1uf bypass capacitors in the 1801C.  I do realize this commentary may be controversial, and I certainly do accept there will be some naysayer's.  I was certainly a member of this group until this test was accomplished.  Hence, I am compelled to offer my comments.  The first point that needs to be addressed is the 1801C.  I will then describe the testing arrangement, provide a summary of the results, and specific comments regarding the capacitors.

The 1801C is a 2-way speaker in development using the Accuton C95 and the OW1.  The initial results are very favorable, and this product will eventually be found on my web page.  The typology of the crossover is similar to the 1801 and several other designs using a 7" stiff cone midwoofer.  The crossover components included Goertz 14ga Inductors (in series), plain air-core inductors in parallel, Sonicap Gen I capacitors, and Mills Resistors.  The test box for the 1801C used in the bypass experiment was & is quite crude.  It's simple plywood with an MDF baffle.  It doesn't have significant mass, and the cabinet was placed on a non-spiked stand during testing.  Nonetheless, the 1801C performed admirably when compared to the 1801B and the ACI Jaguar in the system used for testing.  Despite the humble cabinet, the 1801C sounded very good.  After completion, the 1801C will easily displace the 1801B in my home.

The source gear used was extremely good.  The amplifier was a 60wpc Atma-Sphere unit, and the other associated pieces were commensurate.  This is Ralph's system, and Ralph was the test-subject. 

I presented 4 pairs of .1uf bypass capacitors for testing.  Each capacitor was covered with Blue Masking tape to conceal it's identity.  Ralph isn't keen on the various flavors of capacitors, and did NOT know what flavor capacitor was being tested.

Ralph preferred a slightly older female vocal track for testing.  He was very familiar with this track.

I installed/inserted the coupling capacitors into the circuit using copper alligator clips.  I clamped the bypass and primary capacitor wires together to make a connection. 

I was very careful not to prompt Ralph or create any bias. He didn't touch or handle the capacitors prior to testing.  He didn't know what capacitors were being tested.  I did not present the capacitors in hierarchical manner.  Hence, the most expensive capacitor was not tested last, and the least expensive capacitor was not tested first.  I did my very best to ensure that Ralph didn't know what was being tested.  I was only interested in his comments.

There were 4 bypass capacitors tested.  I will first provide a summary of the findings, and then describe their individual sonic character.

Overall, I was extremely surprised at the impact of the .1uf bypass capacitors.  I really thought the impact would be very mild and that Ralph would have to spend hours with the capacitors to discern a very mild difference.  This wasn't the case.  The impact was immediate and obvious.  Subjectively, the impact was less significant than bypass capacitors in coupling circuits, but only because the region of impact for this test was the tweeter.  In this regard, the sonic impact was prevalent.  I didn't expect this, but it did happen.

Sonicap Gen1 – I don't recommend this.  The impact was extremely detailed, but quite harsh and not very pleasant.  As a bypass capacitor it provided a very clear example of why folks don't like using bypass capacitors in the signal path.  It just sounded wrong.

Sonicap Gen2 – This was quite pleasant, and much better overall.  The impact was slightly more detailed, while remaining reasonable harmonic character in the tweeter.  However, it created a sonic separation between the tweeter and woofer, that some folks may not deem desirable.  The cost of these capacitors is very minimal.  As such, experimentation purchasing them for experimentation is very worthwhile IMO.  I sincerely hope others test these capacitors and provide feedback herein.

Sonicap Gen5 (prototype) – This capacitor is obviously not available for open purchase, but did sound fairly decent behind the tweeter.  The impact was slightly more detailed, but a slight edge was also present.  Overall, Ralph and I preferred the character of the Sonicap Gen 2 and the next capacitor.

Sonicap Platinum – Darn!  Darn!  Darn!  Why does the best performer also have to be the most expensive?!!  The Sonicap Platinum had wonderful separation, and a very pleasant tonal character without any nasty edge.  I can't explain why this happened, but it did.  For the guy willing to spend solid money $$ on a product that is the very best, using Sonicap Platinum bypass capacitors is wise.  Their quality is commensurate with this cost.  I will be using them in my home speakers. 

I also performed a test using a .1uf bypass capacitor in the trap circuit in the crossover.  Much to my chagrin, there was audible impact here too.  Although the impact was slightly different (and lesser) than bypassing the tweeter capacitors, the impact was audible.

My short summary is the Sonicap Platinum (yes, again) proved superior and the Sonicap Gen 5 came in 2nd place.  The Sonicap Gen 1 and Sonicap Gen 2 were not desirable in this component location.  I really don't know why, but this is how we heard it.

Oh, I almost forgot, we also tried a .22uf Audio Note capacitor in the trap circuit.  It sounded inferior to the Sonicap Platinum and Gen 5.

Unfortunately, the .1uf Sonicap Platinum is temporarily out of stock.  When more arrive, I will complete the prototype of the 1801C.  While these capacitors add about $185 to the cost of the speaker, I believe they are fully essential when offering the best possible product.

A question that is will likely be asked is… what about other capacitors.  Well, in other areas in my source gear I used Mundorf Gold and Mundorf Silver and Oil.  I have also experimented with Auricap.  I do intend to accomplish some further experiments in the realm of bypass capacitors, but I have learned over the years to trust Jeff Glowacki at Soniccraft.  While his public press might lag behind more popular capacitors, his honest and product quality do not.  Jeff has sold me a very competitive product for many years.  Some experiments will follow, but I won't be testing every .1uf capacitor available.  Solen and Bennic need not apply.  However, if anyone is willing to share a pair of .1uf capacitors, I will gladly entertain them.  Heck, you can even send them with blue masking tape and your initials covering the seal/seam. 

Update - Nov 07.  I implemented .1uf Sonicap bypass capacitors in the 1801B (using the Seas W18 driver) at the Rocky Mountain Audio Fest on Friday evening of the show without telling Hugh Dean (AKSA) that I planned to accomplish this.  The next morning Hugh Dean entered our listening room and within 1 minute of listening he affirmatively commented, "you installed the Sonicap Platinum's... didn't you?".  Hugh is familiar with the positive impact of the Sonicap Platinum and was able to easily discern the change.

So, the impact of installing Sonicap Plaintum bypass capacitors in the 1801B and 1801C is the same.  In this case there aren't any issues of driver and capacitor synergy affecting a disparity.  Both speaker's responded in the same fashion.  I suspect this would not be true in other situations.

My general hunch is that a very lush sounding capacitor (i.e. Audio Cap Theta or any Paper/Oil) would sound very good behind a harsh metal come or planar tweeter.  I actually read a very good example of this last week.  The designer used an Audio Cap Theta behind a HiVi planar tweeter.  This is a very wise decision - IMO.

[David Ellis]

I don't have a scientific explanation for the post above, but I would like to offer the following comments.  I feel compelled to mention that I fully disagree with this comment:

Bypassing

Do not use bypass capacitors in the signal path. A single capacitor for DC blocking/AC coupling creates a simple path with one time constant. The signal quality will be compromised if a bypass or multiple bypass capacitors are added to a signal path capacitor. Bypass capacitors were used in the past to bypass low quality film capacitors or electrolytic capacitors. The bypass was the lesser of two evils. With the advent of better quality film capacitors the need for a bypass capacitor was eliminated. Bypass capacitors create multiple signal paths with multiple time constants. These time constants are very short but they can still be heard as a smear or overall loss of focus.

It can be viewed in on the original web page here:

http://www.jacmusic.com/auricap/htm/auricap_application_notes.htm

Candidly I believe the words time-constant are abused and eschewed by many folks, and it really makes me wonder if there is an understanding of this very simple issue.  Time constant is the measure of how completely a capacitor will discharge in a given impedance circuit.  Smaller value (i.e. uf) capacitors discharge faster.  Lower impedance circuits also create a faster discharge.  Small capacitors in low impedance circuits discharge faster.  Large capacitors in high impedance circuits tend to discharge slowly. 

A while ago I bypassed a Sonicap Gen I with a smaller Sonicap Gen I in my CD player.  It worked well, and the results were positive. I believe this is because the more "faithful" smaller bypass capacitor restored some of the information lost by the larger capacitor.

Also important is the assumption in the Auricap note concerning the better quality film capacitors. They seem to infer that ALL better quality metalized capacitors are identical.  Hence the comment, "With the advent of better quality film capacitors" .

For the record, I do not believe all better quality film capacitors are the same. There are differences in film composition, thickness, porosity, winding tension, and tension.  I also believe there are differences in the metal chemistry, and how the crystallization process happens after the metal is deposited.  Oh, and the end spray also varies.  Please understand these are guesses from an capacitor outsider.  I have not spent the $30k + necessary to have a capacitor constructed, and don't intimately understand the process.

Dave

[jeffreybehr]

Mr. Ellis--
1.  'Ralph' is the Wonder Dog?  Or?
2.  What's the value of the original tweeter cap?

[David Ellis]

1.  'Ralph' is the Wonder Dog?[/

Nope. Ralph is a local hifi nut living here in Bellevue (Omaha) Nebraska.  This test was accomplished in his listenging room with his system.

2.  What's the value of the original tweeter cap?

Both of the tweeters capacitors were between 4uf and 7uf. 

Dave

[David Ellis]

Also, Ralph provided these slighlty more specific comments about the comparative character of the 1801B and 1801C.  At the bottom of these comments is his system information:

Dave,

1801B - I found to be extremely detailed with a soundstage on plane or slightly forward of the speakers. It was excellent from the upper midrange though the mid-bass. It became slightly less distinct in the dilineation of bass notes as it moved lower in the scale of the bass range. Decay is superb, particularly notable when hearing the dying resonances of instruments in the fade out at the end of songs.  In some music coherence of the overall presentation is lessened due to the sharp relief of the detail presented. Instruments can seem more forward from the whole of the music than usual because of an aggressive attack. It walks very close to "edgy" but never gets there.  Realistic and accurate reproduction of the input signal with minimal colorations are the hallmarks of this speaker.

1801C - This version sounds very natural in its delivery of musical tones sacrificing only the smallest bit of detail to the 1801B. I was more impressed with the smooth presentation of difficult to reproduce piano  notes and female vocals with the "C" than the 1801B. Again superb through the upper mids, mids and upper bass and having a better tonal quality in the lower bass region though not going much deeper. The decay is wonderful like the 1801B revealing instrument and vocal nuance. The attack is much smoother. The layering and texture of music is better to my ear than the 1801B because it suits my preference of coherence and musicality in speakers. There is accuracy in the presentation a more refined delivery.

Associated gear:
Meridian 508.24 CD player
Reference Line 1A Passive Preamp
Atma-Sphere M60MkII.3 OTL amps
JPS labs Superconductor FX interconnects and speaker wire

Ralph

[DSK]

Interesting experiment, David. I've been thinking about bypassing the Sonicap Gen I's in my own XO's with the Platinums for a while but haven't gotten around to it.

Most people seem to bypass tweeter caps with a smaller 0.01uF cap. Do you feel there is any benefit or downside to using the larger 0.1uF cap instead (other than being more expensive)?

Also, where multiple smaller caps are used to make up the required uF value, do you advocate bypassing each cap with its own bypass cap, or just one bypass cap for the group of caps?

[rez]

Hi Dave,
Any advantage to retrofitting the XO components in the 1801b with the ones listed for the 1801c?  What is the cost of 2 Accuton C95's if one was to upgrade an existing 1801b?
Thanks
Roman

pacific beach last summer

[David Ellis]

Interesting experiment, David. I've been thinking about bypassing the Sonicap Gen I's in my own XO's with the Platinum's for a while but haven't gotten around to it.

And unfortunately, it's fairly expensive  .

Most people seem to bypass tweeter caps with a smaller 0.01uF cap. Do you feel there is any benefit or downside to using the larger 0.1uF cap instead (other than being more expensive)?

This is very new territory for me.  Jeff told me that .1uf is what I should try.  Since he makes a living providing the best possible sonic impact from his products, this advice came with a very good base of testing.  However, from an impedance and time constant perspective, a .47 should work better.  Years ago I tried a .47uf capacitor around a 5uf sonicap and couldn't hear any impact.  However, my source gear back then was unmodified Stereopile grade "B" stuff.  The gear used in the current test is much better.  There are probably other issues extant that I don't understand.  The 10% step-down cascade bypass seems to make the most sense objectively, and is certainly present in better source gear power supplies.

Also, where multiple smaller caps are used to make up the required uF value, do you advocate bypassing each cap with its own bypass cap, or just one bypass cap for the group of caps?

This is a bag of worms having many possible outcomes and explanations. I have never experimented with this, but suggest using a cascade setup and bypassing the smallest capacitor with the .1uf.  Aside from this, the multiple capacitors (if the same size) should be electrically "one".  As such, they are effectively a multi-cap.  As such, using a single bypass should be fine.  However, this advice is a could be a "mixed bag".  There is probably some shard of truth to time constant smear when using various size capacitors in the signal path.  I really don't have a good answer for you.  Based on my experiment, I can easily suggest using a single .1uf bypass around the correct size larger capacitor. 

Any advantage to retrofitting the XO components in the 1801b with the ones listed for the 1801c?  What is the cost of 2 Accuton C95's if one was to upgrade an existing 1801b?

I stilll have some prototype work to accomplish before the 1801C arrives on my web page.  The initial answer regarding the Accuton C95s is... they are expensive.  I don't have any sneaky/special way to buy them cheap.  Additionally, most of the crossover is different, but there are a few salvageable parts.  The 1801B inductors could easily be unwound in my workshop.

But..., the cost to upgrade the 1801B to 1801C is much more than the sonic impact warrants IMO.  The drivers ($550) plus crossover (perhaps $100 if the inductors are re-used), and Platinum Bypass (if desired - about $185) make this a very painful proposition.

If you have an itch, I highly suggest installing 4 very inexpensive Sonicap Gen 2 (not Gen 1) capacitors around the tweeter capacitors in the 1801B.  If you like what you hear, and still have an itch, take the plunge for 6 Sonicap Platinums and bypass all the capacitors in the 1801B crossover.  Please let me know what you find/hear if you do this experiment.

Guys, I really have to admit that suggesting the purchase of $185 in bypass capacitors is very difficult for me.  It's uncomfortable!  This is because 2 weeks ago I would have thought it completely ludicrous.  Spending $185 on 6 small value capacitors seems absolutely insane. It makes minimal objective sense and I have very little explanation for the phenomena.  Those little capacitors really shouldn't have any impact, and they really should be so darn expensive.  But, I don't understand the issues.  I am still emotionally adjusting to this illogical reality.     

I also fully understand these comments may be considered snake-oil by many.  However, so was the initial introduction to the Audio Cap Theta loudspeaker capacitor using a Walkman-type CD player at Dennis Murphy's house (I think?).  Many folks heard the test, and testified regarding it's validity and impact.  Following the test, many others dismissed the results citing the scientific method used.  However, regardless of what many people thought, this was the test inspiring Parts Express to purchase a huge quantity of Audio Cap Theta capacitors.  From my perspective, folks need a good reason to spend considerable $$.   I heard the impact and I will be installing Platinum bypass capacitors in my home speakers.  If other folks don't, that's okay.

Dave

[DSK]

Thanks Dave.

These positive results were before any break-in of the Platinums? Did they improve much/any with additional hours on them?

If I understand correctly, you are suggesting using a 0.1uF Platinum bypass cap on the midwoofer cap as well? What is the original midwoofer cap ....Solen?

[David Ellis]

These positive results were before any break-in of the Platinums?

Yes.

Did they improve much/any with additional hours on them?

According to Jeff, the Platinum shouldn't change during break-in.  The dielectric is good and has no "healing" properties. 

However, a very fine gentlemen ( a wire/cable nut) told me a few years ago that all of the old analog telephone lines were placed on a break-in signal for a few days and that some change was audible and measurable due to changes in the solder connections and minor changes in the wire itself.  As such there may be a very slightly change after break-in.

If I understand correctly, you are suggesting using a 0.1uF Platinum bypass cap on the midwoofer cap as well?

Unfortunately ($$), yes.

What is the original midwoofer cap ....Solen?

Sonicap Gen 1.

Dave

[Danny Richie]

Dave, my listening test revealed similar results.

I use the .1uF Sonicap Gen.2's by-passing the Erse poly caps in the standard crossover of our A/V series kits. The Gen.2 by-pass cap certainly takes it up a notch over the standard poly caps and does so with little added cost. They are only $2.70 each. This is a highly recommend low cost tweak.

I just hope the next batch is available soon (it should be here late next week) I have 1000 of them on order. I use a lot of them.

I have also found that the Sonicap Platinum's as by-pass caps are really outstanding and without equal. I usually by-pass standard Gen.1 Sonicap with them. I have found them to be very noticeable in loudspeaker crossovers and electronics.

Anything really serious that I build gets Platinum by-pass caps. My D/A converter has them in it and so does my pre-amp. In fact my pre-amp comes with them from the manufacturer.

I am having a new set of tube mono-blocks custom built for me right now. Each amp has three .33uF Platinum's and six 1.0uF Platinum's in the circuit. Retail on just those caps is $1,494. Is it worth it. You beat it is !

My stock is pretty low on Platinum's right now too. I am down to about 30 pieces of .1uF. The only value I am out of right now is 1.0uF. If you need some let me know.

[Christof]

I wonder how many people overlook the bypass caps?  Thanks for sharing this info, Dave

-c.

[JoshK]

FWIW,

I have always read that bypass caps are best at 1/100'th the value for the least "spectral overlap".  No idea, myself, as I've not tested this, so take it FWIW. The .1uf is closer to 1/100'th than 1/10th...maybe this is why he chose this value?? 

[David Ellis]

I wonder how many people overlook the bypass caps?

I bet most folks overlook bypass caps.  Heck, most folks believe all metalized poly caps are the same.  Overcoming the mental barrier regarding differences in capacitors is probably an easier step to take.  Overcoming the mental barrier that a very good Sonicap in a loudspeaker filter will actually benefit from a bypass capacitor is something that still causes me mental consternation.

I tested .1uf because that is what Jeff recommended I test.  Jeff has spent many nights puttering with this stuff, and understands the "why".   All of this is new to me in loudspeaker filters.  I have bypassed in the signal path of my source gear, but the impedance here is MUCH higher and the time-constant issues are commensurately significant.  This situation isn't present (relatively speaking) in the tweeter circuit of a loudspeaker.  I really didn't expect this to happen.

Dave

[Guilhermejs]

Hello Dave,


          Thanks for being always imporving your awesome loudspeakers! So I need two 0,1uF capacitors per speaker, one for the tweeter and another for the midbass?

Regards,

Guilherme

[David Ellis]

The number desired will be different depending on what capacitor you choose.  Strangely, the Sonicap Platinum had a positive impact on the woofer shunt capacitor too.  The Sonicap Gen 2 impact was not audible in this position.  I don't have an intellectual explanation for this  .

So, my reccommendation is... if you are willing to buy the Sonicap Platinums, buy 6 of them for bypassing - one for each primary capacitor.  If wish to have a less expensive experiment, buy 4 Sonicap Gen 2 capacitors for the tweeter only.

Yes, I know the Sonicap Platinum capacitors are expensive , but for those wishing for the very best sound quality - the Sonicap Platinums are "all that".

Dave

[Kris]

If one out of five caps have a "positive change" on SQ, then i think that cap is defective. Especially a 100nf cap.

[David Ellis]

If one out of five caps have a "positive change" on SQ, then i think that cap is defective. Especially a 100nf cap.

Where did you read/infer "1 of 5" ?

[jipper]

Dave, will the 1801C go into production in the near future? and what sort of sensitivity and ohm rating will you target with this model?  Are you looking to increase sensitivity or are you satisfied with this is the 1801b?

As you can see I have not yet decided on my speaker purchase.  The 1801b looks to be a great match for something like the st70 but if/when I want to move towards an SET design with low power, I am not sure the 1801b can still be used.  And of course (some sarcasm here) I would like to try to make my purchases as practical as possible (future potential and what not).

thank you,
JP

[David Ellis]

Dave, will the 1801C go into production in the near future? and what sort of sensitivity and ohm rating will you target with this model?

Yes.  The hold for the past 4 weeks has been availability of the .1uf Sonicap Platinum capacitors.  Jeff has been sold-out, but more should arrive in the next 1-2 weeks.  I needed more capacitors to complete a fully assembled pair of 1801C speakers including the

The 1801C will have roughly the same impedance as the 1801B.  It will dip to a low of about 6 ohms in the bass region.

The 1801C will be about 2db more sensitive.  This is commensurate with the raw sensitivity of the woofer.  The C95 is about 2db more sensitive than the W18.  However, I DON'T think 87-88db will be enough sensitivity for the average 8wpc 300b SET.  The Cary 572 SET (I have one) has enough juice, but it's a 20wpc amp. 

Also, I admire your apparent desire to reduce the amplifier complexity.  This is something I have tried too.  I have realized that quality parts are far more important than the size of the amplifier.  My stock Cary 572 is not a very good amplifier - IMO.

Dave