Loudspeakers in Lockdown

Part 1

[Loudspeakers in Lockdown]
[Italian version here]

Product: DIY Loudspeakers in Lockdown
Reviewer: Chris Templer - TNT South Africa
Reviewed: June, 2021

The last year has been a bit tumultuous for all of us, some a lot worse than others. I stay on a small holding some 25 km from the nearest town and the closest house to me is about 300 meters away and I have been lucky to have avoided Corona. As far as I'm aware nobody in our community of some 350 small holdings has been infected. This has left me with time on my hands and my woodworking friend Rob, who stays 3 km or so from me, had no option but to keep working (no work = no food), so I was able to indulge a bit in speaker projects. In addition some of my audio friends likewise needed diversion, so what follows is a description of some of the projects. Most of these loudspeakers used second hand drivers and in my case only one pair of Celestion HF pressure drivers needed to be sourced from a vendor. The point of all this is to show that DIY is a viable alternative to the “chequebook audiophile” and as each of these loudspeakers turned out better than commercial ones at many times the cost, there is no reason why anyone can not do something similar especially as there are far more second hand drivers to be found in Europe, the UK and the US than here in our small pond.

[Phase Onken]

Rob Barresi, the man who builds all these things, is on the left - chap on the right, Alan F, is the proud new owner of the 15" Onken cabinets with the replica Iwata horns. For interest, the horn driver is a JBL 2455 HPL, the 15" main speaker is a Beyma. The smaller horn in the left hand picture was going to be used until Alan found the 2455, which go up to 20 kHz. Onken has a Walnut veneer and the horns a painted on burl finish. Cabinet walls are in total 36 mm thick and are on casters. The bigger horns weigh 25 kg each! Due to lock down I've not been to listen to them, but those who have are very impressed.

The next set of cabinets was an attempt to take Altec A7 cabinets and to resize them to something with better WAF. The internal volume is close to the original, they have been squeezed sideways and lengthend and section to hold the Altec 511 horn was added. The A7 could be described as “Early Industrial Monolithic” and these tried to improve them visually. Didn't really work as friend Jorge G wanted them grey in colour and you can just imagine the reception his wife gave them.

Altec 416 main speaker, Altec 511 horn with 802B HF drivers. The sound wasn't compromised much, perhaps a bit less slam. The original wooden cabinet horns were cut out and rotated 90 degrees. I got them back from Jorge and had them re-sprayed - the finish here is all paint! Not shown here is that they have again been modified, the section that holds the horn has been removed. Jorge is planning to try Tannoy 15" Dual Concentrics in them next.

[Mod A7][Mod A7]

The next “rinse and repeat” was to custom make another set of these cabinets paying attention to his wife............! These were destined for use with Altec 604 speakers so the cabinet had to be enlarged front to back as the 604 magnet is very long, and large. And heavy. Plus the two 604's he had were of different vintages and the small multicells were different. Plus the cones were shot. The cones were replaced with the nearest in shape and new surrounds fitted. While that was happening wooden Manta Ray type horns were made up and at the last moment a pair of eliptical horns were 3D printed. The Manta Ray type are a bit more efficient (louder) but the eliptical much smoother and the crossover has a gain control so in they went. A bit startling having the blue horn.

[Altec 604 speakers][Altec 604 speakers]

Right. Stacked Axiom 80's in Coral based horns. Top Axiom has had a surround fitted. The modified Altec A7 cabinet with a bit more volume works very well and the 604's now sound the same. That strange Lens on top of the cabinets was there for show. I'm using that in a forthcoming project.

Some other projects. On the left are replica Voigt Domestic Horns. The smaller set have just been finished - not listened to them yet but if they sound anything like the bigger ones then a job well done. The horns are crafted in Plater of Paris - a very big job! Klipsch La Scala replicas and these are built with more modern drivers and horns - the ultimate bedroom system? Due to lock down there are a lot of systems i need to catch up with! Also made were a two cabinet design (original drawings) for 12" Bozac speakers with the mid range and tweeters in separate cabinets.



[Fast forward to Part II]

DISCLAIMER. TNT-Audio is a 100% independent magazine that neither accepts advertising from companies nor requires readers to register or pay for subscriptions. After publication of reviews, the authors do not retain samples other than on long-term loan for further evaluation or comparison with later-received gear. Hence, all contents are written free of any “editorial” or “advertising” influence, and all reviews in this publication, positive or negative, reflect the independent opinions of their respective authors. TNT-Audio will publish all manufacturer responses, subject to the reviewer's right to reply in turn.

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Copyright © 2021 Chris Templer - chris@tnt-audio.com - www.tnt-audio.com