JPW Sonatas

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Helen Bach
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JPW Sonatas

Unread post by Helen Bach »

Hello,

just arrived (I'll intro myself a little later) but I have come here to garner opinion about JPW Sonatas. I have been looking for some drive units so that I can put together what may be my last pair of 'speakers. At present, I have some Usher floorstanders, and they perform quite well, but are very tall, especially with some extra ribbon supertweets I've put on top.

I have found it difficult to source decent and relatively inexpensive drive units, and be sure of the sonic qualities (frequency response graphs don't tell the whole story, of course) which would work in closed boxes, with little in the way of crossover components. So I decided to buy a pair (actually two pairs) of JPW Sonata 'speakers, and work on them to my satisfaction. The intended final design will use just the main drivers without the tweeters, but in their boxes, with a Fountek CD3 on top, and an EPOS 10inch bass unit, also in a closed box. Each Sonata box will have it's own amplifier, as will the bass 'speaker.

Now the question.

What do you think is the reason for taking out the BAF wadding?

On the suggestion of a friend, I have removed the token damping in one of the speaker boxes, and initially it sound less congested and better balanced. But on further listening, I felt that although it sounded more lively, this was not what I wanted. I must confess to being a music lover, not an audiophile, so the music is all important to me. I listen mostly to classical (well Baroque) music, with forages into the 20th century from time to time. I also listen to some jazz, folk and rock, but the needs of Baroque are foremost in my design criteria.

Today, I have stuffed a Sonata box with a fibre used for roof insulation (can't remember the material, but it is NOT fibre glass). The results are very encouraging (to my ears), and although the 'speaker needs a little more power, the sound is much more to my liking, which doesn't appear to get muddled when passages in the music get 'heavy', as was the case sans wadding.

Any ideas?

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Dr Bunsen Honeydew
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Re: JPW Sonatas

Unread post by Dr Bunsen Honeydew »

If you take out the stuffing you have to finish the boxes by lining them with extra mass to stop them playing. My way is 4 to 6mm steel plate as much as you can stick in over as much surface area as you can.

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Helen Bach
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Re: JPW Sonatas

Unread post by Helen Bach »

thanks, Doc. The steel will add mass, obviously, but that will also increase bending stiffness, that will increase resonance fequencies, and push them more into the mid range. And as steel and mdf have little damping, where is all the energy dissipated?

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Re: JPW Sonatas

Unread post by Dr Bunsen Honeydew »

No, don't make presumptions, too many people do that. That is my advice do it or not it is up to you. Many people here have done it so they will comment.

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Helen Bach
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Re: JPW Sonatas

Unread post by Helen Bach »

not making presumptions, it's basic physics, Doc.

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Dr Bunsen Honeydew
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Re: JPW Sonatas

Unread post by Dr Bunsen Honeydew »

No its not - my troll warning lights are flashing.

Mass is one thing stiffness is another now look at the physics. Anyway you don't want my help so I will leave you to others.

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Helen Bach
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Re: JPW Sonatas

Unread post by Helen Bach »

yes it is! Bending stiffness is proportional to Young's Modulus and the second moment of inertia, resonance frequencies are related to bending stiffness and (surface) mass. So when you add steel (of considerable mass compared to the box wood) then the resonance frequencies will go up. Basic physics, as I said. If damping is not applied, those boxes are going to move for a considerable time!

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Re: JPW Sonatas

Unread post by Dr Bunsen Honeydew »

You want the physics http://www.systemplus.co.jp/support/dat ... ech/31.pdf

Have fun :lol: :lol:

Troll lights now on full red!

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Re: JPW Sonatas

Unread post by savvypaul »

Helen Bach wrote: Wed Nov 08, 2017 3:52 pm yes it is! Bending stiffness is proportional to Young's Modulus and the second moment of inertia, resonance frequencies are related to bending stiffness and (surface) mass. So when you add steel (of considerable mass compared to the box wood) then the resonance frequencies will go up. Basic physics, as I said. If damping is not applied, those boxes are going to move for a considerable time!
Would you like to buy the Harbeths that I don't bother with any more?

:lol: :lol: :lol: :lol:
I am in the hi-fi trade
Status: Manufacturer
Company Name: NVA Hi-Fi
https://nvahifi.co.uk/

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Helen Bach
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Re: JPW Sonatas

Unread post by Helen Bach »

thanks for the offer, Paul, but I like the Sonatas, but I think I need to do some remedial damping on those boxes. Acrylic seems to work very well.

Shame you are running away, Richard, I thought you might be able to throw some light on the reasons why you have chosen to incorporate certain aspects in your designs. Always useful to have other peopel's input.

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