[David Ellis]

Many folks inquire about crossover component upgrades for the 1801.  The query is generally:

I WANTED TO KNOW ABOUT UPGRADE OPTIONS AND COST. I AM PARTICULARLY INTERESTED  IN CROSSOVER CAP OPTIONS AND COST. DO YOU RECOMMEND THE THETA?

Since this query is recurring, I thought some open discussion on this matter might be fruitful.

I no longer sell speakers/kits with Solen grade crossover components.  About 2 years ago I sold 2 crossover quality grades.  One of them was Solen.  The Solen stuff was lesser/cheaper.  While this stiff is indeed found in relatively expensive loudspeakers (up to $15k at least), it's nothing special.  Even so, this grade of crossover componet remains an excellent commercial value and was OEM in my Anthem CD player ($1k used).  

Given the good value of Solen components they are a very smart choice for commercial manufacturers of hifi gear.  The Solens are dirt cheap, and perform nicely.  However, after about 18 months of purveying 2 crossover grades, 90% of customers wanted the the better grade of crossover.  I subsequently stopped selling the Solen crossover with my speakers/kits.  This saves me a few overhead $.

I think the Theta is indeed the best, but the SoniCap is only a scosh behind and much cheaper.  If you have normal hifi gear, the SoniCap is more than a good match for your source equipment.  If you have $30k+  in esoteric source gear then spending another $100 on Audio Cap Theta's is smart.

Also, I have learned that capacitor quality improvements in the signal path have FAR more impact in source gear than behind tweeters in a loudspeaker filter   The impact on a good capacitor in a coupling circuit is immense IME.  Others have told me this.  I have experimented.  I am complete believer!  The reason for this is ALL of the signal traveling to your speakers travels through that coupling capacitor in your preamp/CD player/amp.  This same very good capacitor implemented in a loudspeaker filter will only transfer the tweeter signal.

There is also the subject of capacitor differences.  In this arena I must admit some subjective preference.  I really like the SoniCap.  It has very good detail and quite low noise.  I think it's the best capacitor for many applications and I use SoniCaps in my home stereo in many places.  I must admit having two Theta's in my amplifier coupling circuit.  This is only because I had some Theta leftovers from bypass experimenation.  I do think the Audio Cap Theta is an upgrade from the SoniCap in the 1801s, but certainly not worth $100.  The SoniCap is already an excellent performer and I believe the best value in among "better" audiophile capacitors.

Any questions on this matter are very welcome.

[Al Garay]

Hi Dave,

What about resistors, Mills, and inductors, Alphacore? Can you comment about them?

Thanks,

Al

[David Ellis]

Inductors are somewhat of a mystery to me.  The transition towards flat wire makes good sense, but seems to have less impact with inductors and more impact with speaker wire.  I must admit hearing significant impact with Goertz speaker wire, but very little impact with Goertz inductors.  My understanding of this material is tertiary only.  I don't have a degree in materials science.

The basic principle of wire is that electrons flow initially on the surface, then work their way towards the middle.  Since flat wire has more surface, less electrons will be pressed towards the middle.  Also, a smart guy told me that the inductive characteristic of a single wire is determined by the distance from the center of the wire to the outside.  Given this perspective, it's easy to see how flat wire is less inductive.  Hence, the flat wire is clearly better!  Well, almost  

While I do hear a significant impact with Goertz speaker wire, I don't hear a significant improvement of Goertz inductors.  Sure, they sound a little cleaner than their Solen  counterpart, but the difference is NOT significant.  The audible difference between these inductors is very slight.  Nonetheless, the difference is present, and now the Goertz inductors are less expensive than the Solen inductors.  This wasn't always true.  The choice for Goertz is a no brainer

It's getting late.  I'll comment on resistors in a few days.  I'll be at a wedding this weekend.

[David Ellis]

I have done some subjective comparisons going from Dayton caps and the newer dayton audiophile resistors over to sonicap/mills. I only changed things in the tweeter circuit.

I am sure that I hear a difference. I was not able to measure any difference. I am 90% sure that I like the sonicap/mills better.

The audibility of the difference was without question. I am going to try swapping back and forth a few more times just to make sure I am sane.

-Paul Hilgeman

I've tried a number of combinations, but Sonicaps/Mills gets my vote. That's all I'll buy these days.

- Jim Salk

These are a couple of quotes from guys on the Madisound discussion page.  Their results bear what I agree is the truth on such matters.  Further, Dave Elledge mentioned something about the purity of the material in Mills resistors.  The improvement in material quality in the Mills resistors was significant.  I think the audible impact of these resistors is significant, but not equal to capacitors.  Mills resistors are good, and worth $3 IMO.

[pem]

Dear Dave,

have you ever tried to use bypass capacitors in parallel to other
capacitors of the crossover?
Do you thing this could have a positive impact?

  kind regards,
  Pierre-Etienne

[Rocket]

Hi Dave,

What do you think of axon capacitors used in xovers?

Regards

Rod

[David Ellis]

have you ever tried to use bypass capacitors in parallel to other
capacitors of the crossover?

Yes.

Do you think this could have a positive impact?

I thought there would be some impact, but coudn't hear it - no matter how much I TRIED to hear the impact.

I have found significant & positve impact using bypass capacitors in power supplies, and coupling circuits.  Unfortunately I found no impact using bypass capacitors behind my tweeter.

I believe the reason for this is the environment of application.  

Given a power supply electrolytic the smaller metallized poly bypass will reduce ESR siginificantly.  This helps drain the grunge present in the power lines.  It also helps drain the ringing/ripple from the diodes.  Better diodes will generaly have less ripple, but there is still some ripple.  I was skeptical about the impact of bypassing in power supplies BEFORE trying this experiment.  After the experiment, this changed.  Using smaller "high quality" bypass capacitors around bigger electrolytics works very well.

Given a coupling application, the circuit impedance is very high.  This high impedance exacerbates the importance of Time Constant.  Time constant - the rate a capacitor fully "drains", is dependent upon the size of the capacitor, and the impedance of the circuit.  Bigger capacitors drain slower.  Higher impedance circuits drain slower.  Hence the importance of using a smaller capacitor in high impedance circuits becomes very important when considering time constant.  

I do realize there is a plethora of discussion about Time Constant online.  I believe much of this discussion among laymen is based on hear-say and liberally applied generalities.  I find this somewhat irritatating.  Formally, the AuriCap site conveyed that bypassing in the signal path is wrong http://www.jacmusic.com/auricap/htm/auricap_application_notes.htm  I obviously disagree.  I have tried this and openly disagree with their statement.

In contrast George Short ( NorthCreekMusic ) conveys affirmation for bypassing in loudspeaker crossovers.

I am in the middle on these issues.  I fully understand time constant issues as addressed by Horowitz in the Art of Electronics.  This issue is very simple.  Beyond this... can I hear it.?  In loudspeaker crossovers using quality capacitors the answer is "no".  In high impedance circuits (i.e. bypassing) and when bypassing power supply electrolitcs the answer is affirmatively "yes".

What do you think of axon capacitors used in xovers?

I think they sound on par with Solen capacitors, but I prefer the stiff/solid lead of the Axon.  Most of the Axon capacitors seem to have a stiff/solid lead.  Most of the Solen capacitors have a stranded lead with insulation.  I think either of these capacitors are better than Bennic capacitors.  I think Axon and Solen capacitors are a very wise budget capacitor and found in commercial products up to $15k.  I'd easily use an Axon capacitor in a parallel circuit behind a woofer.