I'm in the bedding-in stage for the Duelund-Corona 832A Project. I'm only about 15 hours in of the 100 hours or so needed for bedding-in of the breadboard phase of the crossovers, but the overall sound quality, tonality, and level of emotional engagement is already really shaping up impressively.

Altec Corona 832A loudspeaker with Duelund CAST copper breadboard crossover.

There's a couple of things about the Duelund CAST copper breadboard crossovers that have really impressed me, the first being how much more information is coming through compared to the stock Altec N800E crossovers. 

Altec 803A low-frequency driver - the king of Altec 15-inch LF drivers - is an earlier version of the 803B.

In particular, the Duelund CAST copper breadboard crossovers are revealing that the lighter and more rigid cones of the earlier Altec 803A low-frequency drivers (compared to the 803Bs), are more agile, more resolving, and have more clarity than I've ever heard in the low-frequencies from Altec 15-inch low-frequency drivers.

When I bought my Corona 832A loudspeakers I had a choice of a buying a pair with either the 803A or the 803B low-frequency drivers (both had the 802D compression drivers up top).

Based on Keith Aschenbrenner's (Auditorium 23) praise to me of the 803A LF drivers additional resolution and agility in the low-frequencies, I went with the 803A drivers. 

Altec 803B low-frequency driver in my "Stokowski" Altecs, which is an earlier version of the 416.

The 803Bs are terrific drivers in my Stokowski Altecs, but as much as I love them, there's no denying the 803As deliver more agile, more detailed, and more nuanced bass response. 

The overall clarity of the 803A drivers is impressive, and I can hear an abundance of beautiful overtones and harmonics that were completely missing with the stock N800E crossovers of my Coronas.

Now I understand a lot better Keith Aschenbrenner's praise of the Altec 803A LF drivers, they really are something special, and the Duelund CAST copper magic has set them free to perform as they were intended to. 

Closeup of a Duelund CAST pure copper 10.5uF capacitor.

Closeup of a Duelund CAST 12AWG pure copper inductor.

It's impressing the heck out me to hear what a huge difference the Duelund CAST copper capacitors & inductors made in the circuit. 

The second thing that is impressing me is how utterly natural the tonality is with the Duelund CAST copper capacitors and inductors in an N800E circuit. 

Leben CS-300F integrated amplifier.

When I first fired up the Duelund CAST crossovers with the ultra-revealing Leben CS-300F integrated amplifier providing the juice, I could hear that I had some fresh tinned-copper cables in the circuit, with their typically "rough" sound quality as they're settling down.

That initial roughness quickly faded away and was replaced with a rich, detailed, and utterly natural-sounding presentation that is simply breathtaking with its live-like presence and spaciousness. 

N800E crossover with L-pad replacing the resistance network.

That same sort of transformation was taking place in the high-frequencies with the Altec 802D compression driver & Altec 811B HF horn, with that pairing sounding very detailed and with a beautifully rich "live-like" tonal balance. 

Altec 802D compression driver & Altec 811B HF horn.

However, the additional clarity & resolution I was hearing in the low-frequencies with the 803A drivers, was somewhat diminished in the high-frequencies with the 802D compression driver & Altec 811B HF horn combo by comparison.  

Both the high-frequency & low-frequency circuits of the crossovers have one Duelund CAST copper 3.5 mH inductor & one Duelund CAST copper 10.5 uF capacitor each in the circuits, and the only real difference component-wise is the 16 Ohm L-pads in the high-frequency circuits, which I think are responsible for reducing clarity & resolution a touch.  

I should mention that the high-frequency part of the circuit with the L-pads is settling down quite a bit, with much of the "resistance roughness" of the L-pad disappearing, and with only a touch remaining. As a result, I've been able to use less attenuation over time to get the overall LF to HF balance better dialed-in. 

I think transformer attenuators might make a meaningful difference in the HF part of the circuit compared to the L-pads. There's no other way to say it, while the L-pads still sound very good overall in the breadboard crossovers, I can hear their limitations in the HF circuit.

The L-pads cut down the amount of information coming through the high-frequency part of the circuit relative to the low-frequency circuit, and they are less smooth & liquid sounding, they reduce clarity a touch, and are just less nuanced sounding overall compared to just the Duelund CAST copper capacitors & inductors on their own as in the LF circuit.  

Luxman AS-10 transformer constant impedance attenuators.

So I need to think about whether to go with the Luxman AS-10 transformer constant impedance attenuators that are so popular with Japanese audio hobbyists, but are hard to find these days due to being out of production for a long time, or something like Dave Slagle's transformer based attenuators. 

Dave Slagle's "Speakerformers".

I'm still thinking about if I should try different wiring in the crossovers, and different wiring to connect to the drivers to the crossovers.

Pure copper or silver might do really well in this particular application, but that experiment is off a ways somewhere in the future. 

Yazaki-san's hot-rodded Douk Audio U4.

I installed Yazaki-san's hot-rodded U4 into the system and have been using it for bedding-in the crossovers & wires.

Not only does the U4 sound great in this system, it really is handy just to leave it running to get bedding-in time accumulated. 

I've also been using an inexpensive upsampling Sony Blu-ray player to play CDs and DVDs, and it sounds better than it has any right to in this system.

Massenet's Thais opera recorded in Paris in 1961.

Did I mention the Coronas are in my bedroom system? They are.

Last night as I was laying on the bed, reading a book and relaxing, I decided to play the Massenet Thais opera that was recorded in 1961, featuring Renée Doria, Robert Massard, Michel Sénéchal, Françoise Louvay, Gérard Serkoyan, et al. (Accord 149 179 2 CD box set).

This performance of Thais was truly exceptional, and the recording quality was superb. I just melted away in reverie as Thais filled my room and my heart. Literally a goosebumps producing listening experience.

So far I've played jazz, classical, and opera albums, with each album impressing the heck out of me through my vintage Altec Corona 832A loudspeakers with their Duelund CAST copper crossovers. 

So while I'm nitpicking at the L-pads performance, still overall the performance of my Coronas with their Duelund CAST copper breadboard crossovers easily produced a goosebumps response, and are really impressing me.  

Over the 100 hours of bedding-in time I have planned for the crossovers & wiring, I expect everything to open up even more in terms of clarity, openness, and tone.  

After I get a little further along with the bedding-in time, I'll then give more consideration to the crossovers & loudspeakers wiring, and transformer attenuators.  

I've decided external crossovers are a better way to go for this project, so I'm thinking about options for that.

The Wood Doctor Professional Quality Furniture Polish.

A tip to my fellow vintage Altec loudspeaker enthusiasts: The Wood Doctor Professional Quality Wood Polish is the best out there for keeping your wood cabinets in good shape and looking great. 

It features "An 18th century cabinetmakers' formula of beeswax, lemon oil, and other natural oils. Preserves, protects, and enriches the beauty of fine furniture."  

Or at least it was the best out there. I contacted Van Dyke's and they no longer sell it. Apparently the original gentleman furniture restorer who developed it and provided it to Van Dyke's was no longer in business. I was crushed.

Williamsville Wax.

However, I found a similar product offered by Williamsville Wax that is available through H. F. Staples & Co and arrived just as I was writing this article. It's inexpensive as far as specialty products go, and I was able to buy 3 8 oz bottles of it for $18 USD.

I've given my Coronas a coat of the Wood Doctor furniture polish and it was predictably excellent. I still have two of the back panels on one Corona that need some furniture polish applied, so I'll give it a try and report back. 

A huge "Thank you!" Frederik at Duelund Coherent Audio for partnering with me on the Duelund-Corona 832A Project - you're the best! 

Previous articles in the Duelund-Corona 832A series:

• A New Audio DIY Project Announcement: The Duelund-Corona 832A Project! HERE
• The Duelund-Corona 832A Project: The resistance network! HERE
• Jeff Checking In: The Duelund-Corona 832A Project (go to the second page) HERE

To find all seven feature articles about Duelund Coherent Audio products at Positive Feedback, enter "Duelund" in the search function on the Positive Feedback homepage HERE.

To find all four-hundred and fifty-two references mentioning Duelund Coherent Audio products in Jeff's Place articles, enter "Duelund" in the Jeff's Place search function. 

Ok, that's all for now. As always, thanks for stopping by, and may the tone be with you!