[David Ellis]

Most of my work on this is complete.  The crossover design is done and I am quite pleased with it.  Please feel free to ask me questions about the changes here.  I managed to encompass a fair amount of the issues on my page over the past few days.  Please let me know if there are further questons you would like answered.  I would rather answer them here than via individual email messages.  I am obviously not afraid to share information publicly and this should save some of my time at the keyboard.

Please read the remarks on my page before posting questions here.  There are comments found in the "1801b" tab on the sidebar and in the "choose your values" option adjacent "resistors" in the kit and completed speakers sections.

I should also share some kind of adverising hype about the new crossover.  After all, it is NEW AND IMPROVED!!!  Such self aggrandizement would help me sell speakers, but... you folks know that I generally won't share opinions about my own product.  Sorry, no advertising hype.   This is why I ask my customers to share their opinions about the my products on this forum and at www.audioreview.com .

Dave

[jackman]

Dave,
Holy smokes!  You mention me by name on your site in the 1801b section.  I'm officially famous.  My mom and dad will be very proud...as wil my parole officer.   But seriously, the new change looks very interesting.  I will be more than happy to make the swap and post my experiences on this site.  I will invite some of my trusted friends like Audiojerry, Randy, Neil, Jeff, over to listen to the speakers.  This will be tough because I don't know how I can do an A/B between the A and B version, but several people (like Jerry, Randy and Neil) have listened to the 1801's and they know how they sound.  

If I can figure it out, I'll try to put together an external crossover box for both (for purposes of more scientific evaluation) that will allow for easy A/B testing between the two crossovers.  This would be for other people's benefit because I am VERY familiar with the sound of my speakers.  That's part of the reason I haven't posted a lot lately.  I've been listening to a lot of music.  

Thanks for everything and for being one of the most refreshing and honest people I have ever met, in audio and in general.  Dispite my suggestions (mostly bad ones), you have remained true to your non-hype principals and anti-marketing approach to business that I respect so dearly.  

Jack

Edit: added Randy's name.

[Rob Babcock]

Any chance of some picture before long?  Or maybe you've already got some on your website?

The 1801's sound pretty interesting, and a floorstander more interesting yet.  Too bad I live so far from the "AC action"

[EProvenzano]

Hi Dave,
How would these mods differ from slapping a 1ohm resistor in series with the tweet?
Reason I ask is because I like the flexibility of adding a resistor depending on the quality of the music I'm listening to. Crappy, harsh, rock/pop I'll often add the resistor and for most of my Classical and Jazz collection I take the resistor out. I'm adding the resistor at the tweeter's +ve binding post.
Is the modified XO a superior way to reduce the tweet output?

Thanks,
EP

[randog]

Dave,

Thanks for taking the time to explain the changes in detail on your website.

I found the section about the resistors both informative and perplexing. Perplexing in that I'm now unsure of what I should use. If you have already shipped my kit to Darren, what resistors did you send?

Perhaps you can help me decide based on my 'stuff'. I will be using the Odyssey Stratos separate chassis monoblocks as well as the Odyssey Tempest preamp. I recently purchased these 2nd hand so I can only say what I've already heard about what to expect from them. I plan to play both cd's and vinyl and although I plan to feed the system some real good, modern recordings, I am also a huge fan of early american root music (blues, zydeco, bluegrass, swing, etc) and I think it's fair to say the speakers will need to digest less than optimal recordings without chasing me out of the room. Room size is roughly 15 X 30' with carpeting and lots of glass. Now, this may point to an obvious choice, but also be aware that I am a treble freak when it comes to accuracy on good recordings especially when it comes to stringed instruments (cake and eat it too remarks, I know).

Your feedback on this will surely be of general interest, yet make no mistake that my anticipation of your response is strictly selfish!  

Randy

[Brad]

Jackman,

Shhhhhh.
You don't want the parole guy tracking you down!!

[David Ellis]

Folks,

Jack,

I don't know that being mentioned on my page makes a guy famous.  I suppose it could make you mother proud, but little more.

I plan to send you a configuration of the 1801b crossover that won't be very viable for external mounting.  The will be configured for internal mounting.   Swapping them will likely take a minimum of 10 minutes.  You will have to do the quick a/b testing between the crossovers in mono.   I could send you an externally mountable iteration, but then you would have to swap your current crossover into an external configuration too.  This ordeal would consume the better part of a day (minimum) and would be very messy.  I think that listening to an internal crossover will do just fine in mono.  Dennis and I both do our intial evaluations this way.  It is quite effective.


Rob,

The picture is the same.  The only real change is black screws on the drivers.  Eventually I'll change the picture on my site to reflect this.  For now, the silver screw pictures are fine.

Also, you will be closer to me than anyone else as of July 1 2003.  I'll be living in Omaha (Bellevue) at this time.  My wife and I close on our first real new house on Jan 30th 2003.  Hopefully I'll have something for you to audition by the end of July.  This is my first move with a full house, wife, and two children.  It should be "interesting".  You really are more than welcome to visit.  Sharing my habit with other folks is much better in-person.  It is nice to have others validate my addiction.

Emilio,

"How would these mods differ from slapping a 1ohm resistor in series with the tweet? "

The small gauge inductors constitue a veeeery slihgtly different value that the older configuration with the inductor+resistor in series.  Also, somehow the woofer slightly sounded better??????

"Reason I ask is because I like the flexibility of adding a resistor depending on the quality of the music I'm listening to. Crappy, harsh, rock/pop I'll often add the resistor and for most of my Classical and Jazz collection I take the resistor out. I'm adding the resistor at the tweeter's +ve binding post. "

You resistor guesses/swaps are 100% superbly, prestinely, precisely, sublimely ACCURATE!  I wish there was a variable potentiometer that sounded as clean as a mills resistor, but such a potentiometer doesn't exist.

"Is the modified XO a superior way to reduce the tweet output? "

Nope, you can reduce the tweeter in the 1801a using the exact method you describe above.

The primary driver for the crossover change was the slightly lean mid-bass condition.  This is corrected with a larger inductors in series with the W18.  This obviously drove some additional crossover changes.

Randy,

"Perhaps you can help me decide based on my 'stuff'. "  My belief is that the recording is the #1 factor, the room is #2 and the equipment is #3 with respect to their significance.

Your room sounds very dead, until the remark about the glass.  I shold do some research on glass, but my Acoustics book is in storage before the move.  I can't get to that bugger.  I believe, however, that glass will resonate and creates strange anomalies in the tweeter response.  I believe these anomalies are generally peaks in the high frequency response due to the resonating glass.  I have also learned through some crossover design work that dips in response are much more tolerable that peaks.  Peaks sound forward.  Dips sound smooth.  The latter is obviously more tolerable.  Then there is the "treble freak" issue.  Hmmmm,

I have 3 kits going out on Monday.  I sent 8, 12.5 & 15 ohm resistors with these kits.  I will likely continue this until folks have further feedback for my site.  My hunch is that you will like the 7, 15 combination.

The difference between the 8, 15 and 8, 12.5 combination is presnent, but almost nuance.  The 8,15 will NOT chase anyone out of the room, but I believe the musical BALANCE is more correct with MOST recordings when using the 8, 12.5 in my system in my room.  The 8,12.5 isn't DEAD, and the 8, 15 isn't harsh.  The difference is very small, less than 1db.  The change is really just a balance issue.

Hopefully some of this helps.  Eventually folks will provide me with furter feedback about the resistors.  I will eagerly publish their remarks.  For now, Dennis and I are the only voting members.

[jackman]

Dave,
No worries, I would like to keep this as simple as possible.  Let's stick with the internal and I'll use the listening methods you describe.  Thank you for this opportunity.  I'll invite all of my audio-geek friends  (none as geeky as me!) for the evaluation.

Jack

[randog]

Dave,

Thanks for the thoughtful response. I should clarify what I meant by the treble freak comment. I was a musician during the first half of my life and when I hear reproduced music, I get most bothered by inaccuracies of instruments in the higher frequencies. Now, that's a much more professional description than 'treble freak', wouldn't you say?  

And, no, I didn't play the flute dammit!  

Randy

[randog]

Dave,

In layman's terms, can you describe what effect each paired ohm value has on the tweeter sound? i.e: if there's approx 1 db difference between 7/15, 8/15 and 8/12.5, what difference would you hear between, say an 7/12.5 and an 8/15? Again, I haven't a clue what I just asked (I'm a mechanical guy by nature) but having you try to answer it would educate me on the different values and how they relate to each other.

Darren informed me he has the 8/15 combo for my speakers and I'm leaning that way for a couple of reasons: a) My carpeted room is on my wife's remodel list to wood flooring, and b) the old recordings I like. It is my assumption that if the speakers are on the bright side (which I understand to be flat and accurate... much of what I prefer on good recordings per my previous message), that brightness will add to the harshness on the older, poorer recordings. Is this a fair assumption? If I were to play that stuff exclusively I would assume I would want the 8/12.5 combo... correct? (Then again, if I played that stuff exclusively, I'd probably be better off with a victrola!   )

Thanks again for your insights.
Randy

[David Ellis]

Your question is a very good one.  Thanks for asking this.  I'll add these comments to my web page.  Folks should understand how the resistors vary.

Presumably you have read the remarks on my page about resistor values.  If not, they are here:   http://www.ellisaudio.com/resistorvalueoptions.htm

There is no 7,12.5 resistor combination.

Please think of electricity like water. Flowing electricity is like flowing water. Adding resistance to electricity is very similar to placing your thumb over the end of a garden hose. Your thumb will resist the flow of water. Consider electrical PRESSURE in the same way as water PRESSURE. Consider electrical FLOW in the same way as water FLOW.

This paragraph will address the effect of the series resistor. The first number (i.e. 7 or 8 ) is the value of the series resistor. As this value becomes larger the spl of the tweeter decreases. This is because a larger resistor will absorb a greater amount of energy from the signal. A HUGE resistor would absorb all the energy. No energy/heat will remain for the tweeter and no sound will come out of the tweeter. NO resistor will soak up NO energy/heat. All of the sound will come out of the tweeter.

This paragraph will address the effect of the parallel resistor. This resistor is effectively placed across the terminals of the tweeter/driver. This is the second number (i.e. 12.5 or 15). As this number becomes larger the amount of electricity traveling through the tweeter will increase. As this number becomes smaller the amount of electricity traveling through the tweeter will decrease. This is because the voice coil in the tweeter will has roughly 6 ohms. If a straight wire, no resistance, is placed across the terminals of the tweeter then ALL of the electricity will go through that straight wire. Electricity applies pressure evenly to both the tweeter and the straight wire. There is no resistance in the straight wire, therefore all of the electricity will go through that straight wire.

There is a more complex reason that both of these resistors exist in the circuit.  Please don't read this if you want to "keep it simple".  I don't think there is a simple mechanical way to convey this. The purpose of having both the series and parallel resistors in the tweeter circuit is to obtain the proper level of impedance in that circuit. This way the impedance of the tweeter and the woofer will be the same at the crossover point. An even impedance transition makes the phase matching easier. This is because phase shift across a capacitor or inductor is determined by the inverse tangent of the AC versus DC resistance. The AC resistance is frequency dependent. The phase shift direction depends on whether a capacitor or inductor are providing the AC resistance. Capacitors shift phase forward and inductors delay the phase. The DC resistance is provide by the voice coils, resistors, and inductors in the circuit. Capacitors do provide some consistent DC resistance, but it is effectively negligible. Therefore, getting the phase relationship correct at the crossover point requires the even resistance at the crossover frequency.
You are welcome to question me on the information in this section, but my response will not be quick. I'll likely have to do some research. Also, I generally don't do any of the above calculations manually. I did this once and it was waaaay too much work. I allow my measurement jig to determine proper impedance and phase. It is significantly  easier. I thank God for my measurement jig - when it works. Sometimes, well, my jig gets a little frustrating.

Hopefully these remarks are helpful.

Whew,

[randog]

Hopefully some of these remarks are helpful.

Hell yes. This is fantastic stuff and that you took the time to explain it speaks volumes in itself... it's much appreciated. Thanks.

You have a lot of great little tidbits on your website in hidden corners that I often miss. Thanks for the link as I missed that one as well.

Randy

Edit: Oops. Right after posting this I went to that link and it's not one I missed after all. In fact, it's what prompted my original question about the resistor values.  

[JoshK]

Dave,

As always, I find your explanations easy to understand and very helpful in understanding it adds a lot to understanding how things work, which for me is the goal.  Thanks for taking the time to answer so beneficially.  Ever consider teaching?  Actually don't, we need you to stay in this industry but you have a knack for explaining things.

[David Ellis]

Actually yes,

I'd actually like to teach physics after retiring from the military.  I loved physics theory in high school and college.  I did quite well with it too.  Then... calculus hit - ouch!  I surrendered at Calc III.  I recently learned that teaching physics in high school doesn't require a MASS of mathematical backround.  I acually have enough math and will merely need to take a few additional physics/education undergraduate classes to obtain my physics teaching certificate.  After I finish my masters degree (almost done) in Learning Development, I might persue a physics teaching certificate after finishing with my masters degree.

But... in 6-7 years I might actually be making $ at this hobby.  I figure that if I can make $20-$30k/yr from my home then maybe I'll build speakers.  I am kinda' like Guideon in this regard.  I just keep asking God questions and throwing the wool-fleece into the environement for answers.  5 years ago I built my first pair of speakers... and then... and then... and then...   God only knows what I'll be doing in 10 years.

[JoshK]

I loved physics and would have majored in it but I thought math would be more applicable.  Turns out it didn't really matter, either would have worked.  Calc III was hard for me at first.  Only math course I didn't end up in the tops.  I later came to find it was pretty easy/doable but only after a lot of practice and other supporting courses.  Then when I finally got a handle on all of that along came measure theory and stochastic analysis....ouch that is some tough stuff.  

I'm still considering teaching at some point.  I may finish my doctorate in the next few years.  I would only want to teach at the college level and preferrable the graduate level so I am considering teaching in an MBA program.  Probably teach rigorous financial theory, derivative pricing and other finance courses that require a lot of math.

[OBF]

Hi Dave,

I'm sure you're sick of SPL questions, but after reading about the changes to the 1801b, I got to wondering if the 2db baffle step compensation reduction in the mid and highs also serves to protect the tweeter more than in the 1801a?

Also, regarding resistor options, if I'm thinking that either the 8,15 or the 8,12.5 would be the most appropriate......is the parallel resistor very easy to change?  Like is it physically attached to the driver, where one just unscrews it and makes the change?  Obviously I don't know much about crossovers!

[David Ellis]

I got to wondering if the 2db baffle step compensation reduction in the mid and highs also serves to protect the tweeter more than in the 1801a?

No, not really.  The sound is a little richer, but the lack of the 2db just requires slightly more turn of the volume knob on my super high power Jolida 302b.

[/quote]......is the parallel resistor very easy to change?

I wire the parallel resistor immediately behind the tweeter, between the tweeter leads, using spade terminals from Del-City.  These terminals clamp pretty hard, but allow the resistor to be swapped quite easily.  I supply these terminals with my kit/speakers.

The raw tweeter leads look like this before mounting:

Dave

[OBF]

Thanks for the explanation and picture.

Are you still looking at several weeks until you get more Excel drivers?

[David Ellis]

The drivers are scheduled to ship from Norway on the 3rd of April.  I should have them broke-in, measured, matched and ready to ship on the 15th.

Dave