Duplex

[Ron Overs]

Ron N,

Great to hear from you so soon. Now I'm supposed to be in bed over 
here in Aus', its nearly 1.00 am here. See what happens when 
irresistible topics come up.
Give a dog a bone then . . .

>  > A front duplex which has been carefully
>>set to a harmonic length of the speaking length is a sure way to
>>build a lousy sounding note.
>
>I don't know, Ron. Some are less lousy sounding than others, so it's
>possibly not that dependable an approach.

Maybe so but the commonplace tuned lengths always manage to come up 
with at least some noise. I concede that bar radius and hardness is 
also an issue. And I certainly agree with you that the lengths must 
be short. We have found that the pianos we rebuilt over the past six 
years have been cleaner than the average factory fodder (and these 
were not detuned - remember the 1993 recording I sent to you? This 
piano was relatively quiet then, but its nearly as noisy as factory 
now, because the bars weren't hardened in those earlier days). I put 
the improvement prior to detuning down to the smaller radius harder 
bars. But I still believe that there's even more to be had when the 
lengths are detuned. The results of our piano no. 003 are far and 
away cleaner than any other piano, new or rebuilt, that we have done 
to date. It's a pity that no. 003 was so 'green' at Reno, it's a 
considerably better sounding piano now that its stable. While I'm 
relatively pleased with the tone we're getting thus far, I believe 
there's more clarity without 'junk noise' to be got yet.

>Of course, a lot of it depends on
>how noisy the duplex has to be to "compensate" for what the lousy
>soundboard isn't providing.

Sure, but I don't regard noisy pianos with 'concrete' boards as 
having tone just because there's a duplex screaming at me. And I'm 
sure you don't either. While I agree with what you say about the 
board, I'm assuming in this context that we are considering a piano 
where the board is working. The others, well I'd prefer to go pig 
shooting.

>I'll have to take exception that the front duplex lengths MUST be detuned
>to be quiet. Simply keeping them short, and the bearing angles somewhere in
>the 15° range will produce a very clean, quiet front duplex regardless of
>the duplex length proportion to the speaking length.

Maybe so, but are you talking 20-25 mm here? Certainly 33 mm is long 
enough to be extremely noisy - that much I have conclusively proven. 
When I modified C#53 on our piano No. 001, it produced more tone than 
our no. 003. I deliberately increased the bridge height in 003 to 
lengthen sustain and cut power. So the piano certainly didn't need 
duplex noise to fudge tone. I haven't done any experiments yet with 
really short lengths (but I need to do my own plate first). But its 
so easy to detune duplexs its just as easy to do the maths then build 
'em short as possible and detuned anyhow. That way all bases are 
covered.

>Absolutely. "Help Stamp Out Tuned Front Duplexes" bumper stickers are being
>printed, on fire resistant material, even as we speak.

Thanks for that Ron, I can sleep easy now. Looking forward to the 
next edition from Wichita. I'll expect that answer on 20mm when I get 
up in 6.5 hours hence. Gotta get horizontal for now.

Regards,

Ron O
-- 
Overs Pianos
Sydney Australia
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Web site: http://www.overspianos.com.au
Email:     mailto:ron@overspianos.com.au
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