Acoustic Zen Crescendo speaker crossover capacitors ... who makes them?

I own the MKl version of the Crescendo and see the crossover uses all Acoustic Zen branded capacitors. Most are blue in color with the smallest values bring black. Does anyone know what company makes these for AZ? I did email the builder, but no answer. Love any information the community may have on this topic. 

How do you like these speakers and what else are you driving them with? Jeff
Loved the 40.1’s! We moved to Franklin, TN and downsized. I lost my dedicaded music room and now share a space in our main living area. The home is new with cool tone colors like white kitchen, light gray walls, black granite etc... and my wife felt the Harbeth’s just didn’t work in the space aesthetically. I also agree though hard to admit:)

The good news is I have always loved the Crescendo speakers and was lucky enough to get a used set in gloss black that my wife also loves. (Great price also)Turns out I like the Crescendo even more 😊

I looked inside the speakers for the first time and like most $10,000 - $20,000 speakers I have taken apart I saw sand cast resistors and other obvious places that could be improved. Still blows my mind that a speaker of this expense uses 89 cent sand cast resistors that any good DIY guy knows sound just ok, and a tad harsh in the highs compared to a Mills MRA for example.

I love the speakers and will leave most of it alone except for the resistors and caps on the tweeter and mids. All else will remain the same. I assume the film caps used are middle of the road at best based on the resistors and inductor quality used. I am not certain, thus my question.
Forgot to answer the question about what I drive them with. Well here is something I could talk about for hours. We could not have a bunch of gear in our living room so I had to search for a downsized, yet wonderful solution. I listened to many integrated amps including the Devialet. I ended up talking to Neal over at Sound Science who sold off $30,000 worth of separates for this Lyngdorf 2170. Well I decided to try one and my goodness was this piece special. It is a preamp, amp, room correction, dac all in one box. It actually sounded as good and in some ways better then my wonderful separates including the TRL Dude preamp, Luxman DA06 dac, expensive cabling, and Von Gaylord Triode Lengend monoblock tube amps.

The room correction in this Lyngdorf is amazing and the diffference maker. It is 100% digital from beginning to end with the signal going to analog just before powering the speakers. So the internal dac is really not a dac in the conventional sense.

I also have have a very highly modified Cary Rocket 88r that I also use with the Lyngdorf at times as I must always own a tube also. It is so highly modified that you would not recognize it as a Cary any longer with the expansion chassis and all I did.

Enjoying the new home and system and looking to get the very most out of these already very good speakers.

Hi Bill,

On the one hand you certainly have to admire the talent of Robert Lee using very low cost passive parts and getting such truly high quality sound. A quite talented builder with excellent design and execution of the Cresendo.

However I do see your point and agree that the wise selection and placement of high quality resistors and capacitors will yield more from this fine speaker. Those passive parts do sonically matter. No harm in making something "very" good even better with thoughtful part upgrades.


Yes Robert’s design is not in question as the speaker is awesome. The crossover is very complex with many parts. 15 resistors and 13 capacitors per speaker with many additional inductors. Easy to see why one could not use Duelund level parts!

That speaker with Duelund quality parts would retail for 35 K easily. Bill that is quite a complex crossover.


Ha! Yes indeed. I putting a game plan together. Most of the caps are polyester types (MET).  Better MPT caps are used on the mids and tweeter. 
Seems nobody knows? Well I have decided to go with Duelund CAST resistors and deciding between Jupiter HT flat stacked caps or perhaps Jupiter VT round caps. 
Bill, I look forward to following your progress with this project. 
Curious to see how much improvement you'll extract from an already excellent speaker.  This will be illuminating. 
I will report back. Using the very good Jupiter flat stacked HT caps on the tweeter and midrange drivers. Using a mix of Duelund and Mills MRA resistors also. I will remove the crossover board behind the top woofer and do the best I can to fit these much larger parts. 

The caps are huge. For example the 6.8uf cap has a 4x4  inch cross section!  I am replacing a 4.7uf, 6.8uf, and 12 Uf caps. 

I am am not changing out the caps on the woofers as I simply don't have the funds 🙂
I suspect that in terms of sonic impact the tweeter and midrange capacitors are the sites to address compared to the woofer location.  Knowing how well the AZ Crescendos sound I'm eager to learn what these presumably superior parts do with these speakers. 

In my speakers merely changing the single Solen tweeter capacitor to a Duelund CAST reaped undeniable improvement,  just one capacitor in each speaker was all it took.
Hope this question is not intrusive but didn't you live in Minnesota? How did you find yourself in Tennessee? Any culture shock?

Well my wife and I are now empty nesters and we wanted to move to warmer climate and an area vital musically and economically. We did a ton of research and Williamson Country (Franklin, TN) just south of Nashville seemed ideal. We visited a couple of times and loved it. No state income tax, reasonable real estate tax, wonderful live music all around, great climate, nicest people I have encountered in any geographic area I have lived...

There is a spirit of creativity and entrepreneurialism that is wonderful here. Folks are happy and so much to do.

We love it here!

No wonder it is one of the fastest growing areas in the country and real estate prices are going through the roof! 
Another Bill (Brownsfan) did the same several years ago moving from Indiana to TENN. He and his wife love it there and say the people are as friendly and nice as can be. I’m happy for both you Bills.
Thanks Charles! 

For you Crescendo owners this is not an upgrade for the timid. Getting the crossover board out is tight and requires patience. Not enough extra length or slack on the driver connections makes it difficult. Tight space!

Once it was out I realized I needed to buy more caps! All the parts are matched precisely thus I had to pay extra to do the same. 

I should be be able to finished the job next weekend once all the parts are in. I will take pictures and post also. So much easier to do this up front😬
Need to purchase 5.6uf and 22uf caps for each speaker in addition to the 12uf, 6.8uf, and 4.7uf caps mentioned above. I will now have to devise a way to load these much larger parts on a board that fits....
That Cresendo crossover has a lot of big value (capacitance) capacitors. It’s actually somewhat surprising how well this speaker sounds given all of those capacitors in the signal path. Quite a complex crossover, but the bottom line is how does it sound? Very darn good.
I haven't even mentioned the 8 other caps in each speaker! Values up to 68uf and 100 uf.  Well then there are the 14 resistors. Dont even talk about the scores of inductors.

I agree Charles it is amazing how good they sound with all these parts. Robert knows what he is doing and is very talented. 
Big kudos for Robert of Acoustic Zen who has responded to my email questions and helped me. Nice man willing to help a DIY pain in the rear like me:)

Ok, I finished the upgraded crossover board and just installed them. A ton of work. Imagine replacing caps that are 1/2 inch in diameter and 2.5 inches long with caps almost 6 inches long and 4.5 inch diameter! Had to get it all to fit into the same space. Initial results seem most excellent. The thing I noticed within 20 seconds was the absence of noise, music flowing out of a dead quiet backdrop. The difference over the standard crossover is astounding in this regard. Already I hear more resolution combined with greater space, body, texture and improved natural tone. I also hear a greater sense of ease and natural flow. Only 2 hours thus far. I will report back after 24 hours.

i will try and post pics in a link as you have to see the before and after.
There is also an additional board on the very bottom of the speaker that I have not touched as yet. It is for the bass drivers. Unfortunately it contains two 1000uf electrolytic caps! The two resistors on the bass board are sand cast and will be replaced with Mills MRA 12. As for those 1000 uf caps I will think on my plan of action. I cannot believe how many parts are in this crossover. This is not your simply first order type.

I believe it is a 3rd order Linkwitz/Riley design. 
This is the amp I am using to drive them right now. It started its life as a Cary Rocket 88r. I modified it to the hilt with....

- all high quality film caps in the power supply (Clarity TC, ASC, Obbligato)  and increased the capacitance. Needed to add a wooden expansion chassis to fit the film caps in the power supply. A double decker build. 
- Arizona capacitor blue cactus coupling caps
- Western electric NOS hook up wire
- Mills MRA resistors
- Moved the RCA jacks right next to the input tube and also made more direct connection in addition to shortening the signal path
- removed all electrolytics caps and replaced with Clarity and Theta caps.
- removed binding posts and use Teflon posts to "clamp" the output transformer leads directly to the nude speaker cable.
- direct soldered high quality power cord

There is more, but you get the idea....

Here are some pics.

Outstanding and can't wait to hear your report after 300+ hours; those caps should be at their best by then...

Wow that's some ambitious work Grannyring. I've recently been using clarity TC caps and have had very good results. Enjoy!
Hi Bill,
I can appreciate the time and effort you put in accomplishing this project,  very nice work. You are right,  this is not a simple crossover by any means.. I know how well the stock Crescendos sound.  With the improvement via better parts it must be quite heavenly. 
Jet, those TC caps are the best I have heard in a power supply! Hard to fit because they are so large however. The Arizona Blue Cactus caps are wonderful for coupling. Wonderful tone.  
Charles, thus far the improvement is so gratifying. My wife commented last night that the system sounded beautiful and the presence of the performers was an obvious improvement. 
Granny you remind me of my DIY friend Tony Ho. He solders all connections directly without any rca or speaker jacks. He even makes his own High purity all silver wire that he hand braids with cotton. I think you need to do this next. I would not recommend soldering direct for AC sorry that is too dangerous and not worth it my friend.
Jwm, I have built and owned all manner of soft annealed silver speaker, IC, and hook up wire for signal path in amps. I have always used cotton also with this silver. This is very subjective and just my preference, but silver has always caused my tinnitus to flare up due to what I describe as tipped up upper mids. Just could never really smile with silver in cotton. Although using a little bit of it in my mods does add some nice resolution. I do make all my own cables out of Duelund stranded copper that is tinned in oil impregnated cotton. It sounds fantastic to my ears. Jeff Day and Jim Smith both have had the same experience even though, they like myself, have listened to all manner of wire.  

If if not for my uber sensitivity to upper mids I would certainly enjoy silver wire far more! I certainly hear what it does so very well. I have not listened to every kind of wire produced, who can, but thus far the new Duelund wire is my favorite. 
Granny my mistake he uses copper not silver. He also thought the silver was too lean. I think you would have to add gold or Pl to the silver to make it sound more natural. He does hand braid his own cotton insulation.
Owners of this fine speaker I have some news for you. After only 24 hours of consistent playing with the upgrades I can hardly believe what I am hearing. As music lovers and audiophiles every once in a while we experience an upgrade that just causes you to rest deeply into recordings you know very well hearing them seemingly for the first time. This is happening as I type.

It’s as if someone placed a monster tube amp with the finesse of the finest SET amp and the scale, control, and swelling stage of the best tube amp beast in my system without me knowing. I keep looking at my rack thinking something must have awakened and changed my Crescendo speaker. No, no changes other than the crossover. The change is nothing short of extraordinary. Here are some short thoughts running through my mind based on this afternoons listening session.

- never heard the music grow and swell with this kind of beauty and control as I turn it up.
- wonderful layering and waves of musical experience with the speakers being lost, meaning the sound is not coming from drivers here or there...
- new levels of impact and dynamic impact
- where is the noise I thought was never there in the first place? No kidding. I think those old sand cast resistors were causing the less refined sound I never knew was less refined.
- Improved resolution is easy to hear, but it is served up in a completely natural and meaty way. I love the beauty of the mids and highs.

The problem is is I can’t tell you what exactly is causing this remarkable improvement. Is it the new caps? Which ones? The new resistors? The aggregate of all the improvements? Most likely.

l replace the forest of sand cast resistors with a mix of these;

- All 20 watt sand cast replaced by two Mills MRA 12 in parallel.
- All 10 watt sand cast replaced by both Duelund standard and Duelund CAST.

Each of these resistors has has its own strengths and a mix seems to work very well indeed. I matched all part values within 1%

I am sure the original metalized poly caps do not sound as good as the paper, foil, and wax caps now in place.

I spent about $800 on the upgrade and improved the speaker in very real and important ways for me.

Keep in mind mine are MKl, not MKll. I am not sure if the newer version has any real changes in the crossover. If you see a sea of white sand cast resistors and AZ labeled poly caps, then you have opportunity.

So so why not build these with better parts upfront and change for a plus version? They should. It is a job to do it after, but possible.

Ok, I will keep posting as the hours build.

I purchased the Duelund resistors at Parts Connextion over 50% off the retail price. The caps were also on sale. I saved a good amount of money for this job.

I suppose the price for the Crescendo with upgraded crossover parts would be pretty high with additional builder and dealer margins etc... Perhaps $2500? Maybe more.

Anyway, I will report back middle of the week. I suppose the burn in process could take things south for a season. 

Hi Bill,

It was great that Robert Lee replied to your emails. What insight did he give for upgrading the crossover?

Can you give an executive summary of the sonic differences between: Harbeth 40.1, stock AZ Cresendo and the modified AZ Crescendo?

Congratulations on your sucessful Cresendo modification project. I know that you have much experience doing numerous upgrade modifications over the years but I can tell you are especially pleased with this particular one.

There are certain speaker brands that offer upgraded/superior parts as a package. Daedalus and Kaiser (Kawero model) are 2 that come to mind, certainly there are others.

There’s no question that better quality parts can and do improve sound quality, I don’t know why some people are so resistant to this fact. My background isn’t as extensive and hands on as yours. In my experience capacitors, resistors, wire,fuses, etc. They all make a difference and I’ve heard it as plain as day.

Bill, you’ve taken a very fine speaker and have improved it to your satisfaction.


Robert answered one question I had as an inductor and resistor were on the board and not soldered in the circuit. I wanted to confirm he meant to leave them out of the circuit. He did make a change and decided the speaker sounded better without these parts in play. He also offered to help to should I have any other questions. That is the extent of what he helped me with.

The 40.1 speakers are amazing and every bit as good as the Crescendo speaker. I sold them for aesthetic reasons in our new home and shared living/listening space. I would say the Crescendos go deeper and more powerful in the bass while the 40.1s seem to play all types of music and poor recordings well. They are so smooth and easy to like while the AZ speakers are more dynamic and resolving.

The upgraded AZ speakers just widen the gap in improved resolution, dynamics, and refinement.

Congrats on your upgrade... its really satisfying to make these changes and really hear the results of your effort...
I've built many a speakers, so just a couple of comments from the thread...
The parts quality does matter incredibly much so, I don't want to take away from that,  but when it comes to really improving soundstage and placement.... hand matching quality parts in the crossover to 1% or less makes more difference than the Ultra Uber expensive parts.
Linkwitz Riley 3rd order:  Joe D'Appolito is the innovator of the MTM design, he originally used and still always suggest a 3rd order butterworth for MTM.... I have used Linkwitz Riley Alignment with great success in MTM also, but LR does not offer a 3rd order alignment.
You have modded with what are most likely the best sounding parts available... Enjoy my Audiophile brother,  Nicely done.
Enjoying  my music again tonight. Cassandra Wilson night. So wonderfully beautiful as she is in the room with me. 
Tonight we have an additional 70 or so hours of burn in. The sound has changed a bit. Even more relaxed, in a good way, and even more natural sounding. The sound has opened up a tad and is just wonderful. I find myself listening to recordings that in the past sounded marginal at best. I find I can now enjoy these less than ideal recordings like never before. 

What I love most is how real my music sounds. Real and engaging in a special way. Instruments and voices do not sound recorded, but real in my space. 
When terms such as "ralaxed",  "natural", "real " and "engaging" are used to describe what you hear, you're on the right path . The truly excellent audio products always seem to improve in this direction.