Is this a good buy?

[Chienmortbb]

  On 14/03/2025 at 00:33, Stub Mandrel said:

 

Chromed plastic dust caps were very popular in crap audio equipment in the 80s.

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The Crescendo was aluminium, not coated. The drawback was that the dust cap would eventually crack. Mine were repaired with epoxy resin, no idea how that altered the sound. I could not hear it but it must have added mass to the dust cab. 
 

They sounded glorious to my ears but  in those days we had few reference points. I did put them plus the home made seals cabinets (my dad was a carpenter and they looked fantastic) kingside some big JBL cabs at an open air free concert in Slough. It was on the site of the Ice Rink at Montem for those that know the area. There were loads of bands playing but headlining were Slade. What a day! 

 

[Stub Mandrel]

  On 14/03/2025 at 09:09, Chienmortbb said:

The Crescendo was aluminium, not coated. The drawback was that the dust cap would eventually crack. Mine were repaired with epoxy resin, no idea how that altered the sound. I could not hear it but it must have added mass to the dust cab. 
 

They sounded glorious to my ears but  in those days we had few reference points. I did put them plus the home made seals cabinets (my dad was a carpenter and they looked fantastic) kingside some big JBL cabs at an open air free concert in Slough. It was on the site of the Ice Rink at Montem for those that know the area. There were loads of bands playing but headlining were Slade. What a day! 

 

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Ixm surebproper ones worked. I was just observing that many cheap speakers (e.g. in ghetto blasters and car shelf speakers) got tatty plastic domes. They may even have made a slight difference.

Edited March 14 by Stub Mandrel

[agedhorse]

  On 14/03/2025 at 00:33, Stub Mandrel said:

 

Chromed plastic dust caps were very popular in crap audio equipment in the 80s.

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That's a cosmetic treatment, unrelated to the real thing except in looks.

 

  On 14/03/2025 at 09:09, Chienmortbb said:

The Crescendo was aluminium, not coated. The drawback was that the dust cap would eventually crack. Mine were repaired with epoxy resin, no idea how that altered the sound. I could not hear it but it must have added mass to the dust cab. 
 

They sounded glorious to my ears but  in those days we had few reference points. I did put them plus the home made seals cabinets (my dad was a carpenter and they looked fantastic) kingside some big JBL cabs at an open air free concert in Slough. It was on the site of the Ice Rink at Montem for those that know the area. There were loads of bands playing but headlining were Slade. What a day! 

 

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Proper aluminum dust caps are formed then annealed so that they resist cracking/fracture. This is no different than how (quality) high frequency diaphragms are manufactured.

[Phil Starr]

  On 13/03/2025 at 22:20, bremen said:

Yes that's what mine look like.

 

When did you work for Tannoy? These, and their predecessors the Monitor Golds, were their flagship. They proved too expensive to manufacture (the hf driver fires through dozens of exponential holes in the magnet, then the cone continues the exponential curve so the hf from 1kHz up is horn loaded, very sensitive and thereby suffers less from thermal compression) so they dumbed down with the DC2000, still dual concentric but with separate hf unit. Then they did the Mercury and other bog standard boxes.

 

They recently(ie this century) reissued the hpds for staggering prices.

 

They have a unique sound that doesn't appeal to people who like Beats headphones, i think the average age of a tannoy hpd owner is similar to the Basdchat mean, but I wouldn't swap them for ordinary boom and tizz boxes.

 

Other fan boys here:

 

https://www.hilberink.nl/speaker.htm

 

 

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I'm loving the thread de-rail. Back in the 70's  I built a couple of cabs with the 15" Monitor Golds for a friend, at the time my memory is that they sounded as good as anything I'd ever heard. They also did duty as disco speakers so they would go quite loud by the standards of the day. Just the bare drivers with the crossovers cost several months wages though.

 

I also used some of the Fane Crescendos to build some two way speakers for a friend who was a sound engineer who worked on film sets. He wanted something to provide music for the dancers at Shepperton and Elstree studios, I pictured a good commission for something huge until he told me he needed a pair to fit in the boot of his Ford Cortina!. I built him some two way cabs with 12"Ccrescendos not unlike any common or garden modern PA speaker. Forgot all about them and went off to train as a teacher. I'd just started working at my first school and he came back with an order for 10 more pairs as apparently all the other freelance sound engineers wanted their own. One of those sliding doors had been crossed though and I'd given up my workshop, teaching was my life and speakers were just a hobby. I wonder what would have happened if he'd come back to me a couple of months earlier.

[Stub Mandrel]

  On 15/03/2025 at 23:57, agedhorse said:

  On 14/03/2025 at 00:33, Stub Mandrel said:

 

Chromed plastic dust caps were very popular in crap audio equipment in the 80s.

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That's a cosmetic treatment, unrelated to the real thing except in looks.

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My point!

[Stub Mandrel]

  On 15/03/2025 at 23:57, agedhorse said:

That's a cosmetic treatment, unrelated to the real thing except in looks.

 

Proper aluminum dust caps are formed then annealed so that they resist cracking/fracture. This is no different than how (quality) high frequency diaphragms are manufactured.

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Aluminium alloys generally age harden on a scale of time from hours to years. With the added stresses of being attached to a voice coil, stress cracking in anything thin enough to be practical  is always going yo be a possibility.

[stevie]

  On 13/03/2025 at 08:10, bremen said:

Excellent piece, Phil.

 

Here's how Tannoy attempt to reduce cone breakup:

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It's probably a similar idea to what Scan-Speak have done with their slit cones, where they slice the paper cones and glue them back together again to control cone resonance. Here's the reponse of one of their seven-inch drivers showing how they've controlled serious cone break up until about 5kHz. Notice how smooth the off-axis response is right up to 7kHz.

[stevie]

  On 10/03/2025 at 18:00, Chienmortbb said:

Aluminium dust cap was used in the late 60s by Fane on the original crescendo drivers and it did indeed extend the response considerably. 

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Are you sure it extended the frequency response, or could it have just induced peaking, which might have sounded like it did?

[agedhorse]

  On 16/03/2025 at 13:06, Stub Mandrel said:

 

Aluminium alloys generally age harden on a scale of time from hours to years. With the added stresses of being attached to a voice coil, stress cracking in anything thin enough to be practical  is always going yo be a possibility.

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That’s the reason for annealing and part of the reason for the dome shape (the other primary reason is to improve the HF radiation pattern). 
 

Work hardening and subsequent fatigue fracturing occurs when there is repeated flex in a material that is stiff in nature. 
 

As a practical example, JBL successfully perfected this process on their aluminum dust caps and high frequency diaphragms, they can last a lifetime if not abused. 

[Phil Starr]

  On 16/03/2025 at 14:09, stevie said:

 

It's probably a similar idea to what Scan-Speak have done with their slit cones, where they slice the paper cones and glue them back together again to control cone resonance. Here's the reponse of one of their seven-inch drivers showing how they've controlled serious cone break up until about 5kHz. Notice how smooth the off-axis response is right up to 7kHz.

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I hadn't seen that. Damn you, I feel a hi-fi design coming on. My current speakers; based on a 5" Focal driver and the Scan-Speak 2008 needs some attention to the crossover but that looks like a better mid/bass driver. If I hadn't seen this I wouldn't now have the itch 🤣

Edited March 17 by Phil Starr

[bremen]

  On 17/03/2025 at 08:01, Phil Starr said:

I hadn't seen that. Damn you, I feel a hi-fi design coming on. My current speakers; based on a 5" Focal driver and the Scan-Speak 2008 needs some attention to the crossover but that looks like a better mid/bass driver. If I hadn't seen this I wouldn't now have the itch 🤣

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It does look good. Should we start a new thread dedicated to non-bass amp and speaker builds?

[Chienmortbb]

  On 16/03/2025 at 14:25, stevie said:

 

Are you sure it extended the frequency response, or could it have just induced peaking, which might have sounded like it did?

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Sadly it was the late 60s so I had no knowledge of the complexities of speaker design of concepts. 
 

It was a heavy 12” 100 watt speaker with a quoted sensitivity of 100dB, at a time when most 12s were 25/30 watts so at least 3-4 time better innit. 😉

 

Honestly it did sound loud

[Phil Starr]

  On 17/03/2025 at 09:09, bremen said:

It does look good. Should we start a new thread dedicated to non-bass amp and speaker builds?

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My wife is going to love you

 

[bremen]

She'll hate this https://www.audiosciencereview.com/forum/index.php?threads/small-2-way-speakers-with-linear-on-axis-and-power-response-characteristics-scan-speak-and-sb-acoustics-drivers-h-v-off-axis-measurements-included.41757/

 

Is this too good to be true? All it needs is a pair of subs, or on its own as nearfield.

Edited March 17 by bremen

[stevie]

You can't go wrong with either SB Acoustics or Scan-Speak.

[BassmanPaul]

@Phil Starr being a teacher is a fine and noble occupation. My Mother and both of my sisters went to Bingley to become teachers. My cousin took my class at Grammar school for English. It's surprising I didn't follow in their footsteps! LOL