Another speaker thread

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steve s
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#166 Re: Another speaker thread

Post by steve s »

simon wrote: Fri Feb 05, 2021 7:24 pm

Not exactly cheap. I'd never heard of Precision Devices until I started this, but it turns out they're located about half a mile from my office. Fane are located about 100m from PD.
Simon, they are the same company, I had a tour around the factory a few years ago and heard a sample of the PD drivers, an interesting couple of hours. I heard the pd 21 & 24" drivers,
I decided twin 18s where more up my street at the time..
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#167 Re: Another speaker thread

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simon wrote: Fri Feb 05, 2021 7:24 pm So I'm thinking the way forward, initially at least, is to try a large pro driver to see how it works in my room and how low it goes. On the basis that bigger is better for OB I looked for drivers with Fs below 40Hz and Qts above 0.5. The intention is to use them in a H frame, and according to Martin King's paper on OB, U and H frames the H frame usefully lowers the Fs.
A couple of notes on that:

- According to Hornresp, the resonance shift is minimal - it's only the extra mass of air that's closely coupled to the cone. When I ran the sims, it was of the order of a few percent, which makes sense: the air mass is small compared to the moving mass of the driver.
- Qts can always be modified, either via series R or an amplifier that heads towards a current source.

It's worth noting that simply adding mass to a cone will decrease Fs and raise Qts, which might open up some options.

Chris
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#168 Re: Another speaker thread

Post by simon »

steve s wrote: Sat Feb 06, 2021 1:47 am Simon, they are the same company, I had a tour around the factory a few years ago and heard a sample of the PD drivers, an interesting couple of hours. I heard the pd 21 & 24" drivers,
I decided twin 18s where more up my street at the time..
Ah, with them being so close I wondered if it was an offshoot or breakaway. Just a different arm then.
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#169 Re: Another speaker thread

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chris661 wrote: Sat Feb 06, 2021 9:35 am A couple of notes on that:

- According to Hornresp, the resonance shift is minimal - it's only the extra mass of air that's closely coupled to the cone. When I ran the sims, it was of the order of a few percent, which makes sense: the air mass is small compared to the moving mass of the driver.
- Qts can always be modified, either via series R or an amplifier that heads towards a current source.
Okay, that's good to know. MJK's paper suggests the resonance lowers in frequency quite considerably.

One of my plans is to use MoFo amps, and the pro drivers also win here as they're much more efficient than the SBs and close to my Supravox and Fostex drivers.
It's worth noting that simply adding mass to a cone will decrease Fs and raise Qts, which might open up some options.
By some kind of duping presumably?
Last edited by simon on Sat Feb 06, 2021 10:03 am, edited 1 time in total.
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#170 Re: Another speaker thread

Post by simon »

steve s wrote: Sat Feb 06, 2021 1:47 am Simon, they are the same company, I had a tour around the factory a few years ago and heard a sample of the PD drivers, an interesting couple of hours. I heard the pd 21 & 24" drivers,
I decided twin 18s where more up my street at the time..
How would you rate the PD drivers to the Beymas say Steve? Guessing you preferred the Beymas as that's what you have?

Twin 18s is some thought :-)
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Ali Tait
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#171 Re: Another speaker thread

Post by Ali Tait »

How about a Z array inside an H? Would make them a bit less imposing if you go for twin 18’s.
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#172 Re: Another speaker thread

Post by simon »

Could do Ali, and it's tempting to do it just because I can :-D. But my room is only 3.3m x 3.6m and I don't need the volume, it may overpower the room even? Still, it's bloody tempting :lol:
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#173 Re: Another speaker thread

Post by chris661 »

simon wrote: Sat Feb 06, 2021 9:57 am
By some kind of duping presumably?
Well, when I did it, I just put a load of blu-tak on the join between dustcap and cone. Worked well enough, and was removable. For permanent installation, I'd think about silicon sealant or similar.

If it was mine, though, I'd reach for EQ before messing with the drivers. Low-Q drivers have their advantages.

Chris
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#174 Re: Another speaker thread

Post by steve s »

simon wrote: Sat Feb 06, 2021 10:00 am
steve s wrote: Sat Feb 06, 2021 1:47 am Simon, they are the same company, I had a tour around the factory a few years ago and heard a sample of the PD drivers, an interesting couple of hours. I heard the pd 21 & 24" drivers,
I decided twin 18s where more up my street at the time..
How would you rate the PD drivers to the Beymas say Steve? Guessing you preferred the Beymas as that's what you have?

Twin 18s is some thought :-)
To be the honest the PD drivers sounded dreadful in their test room.
He played the <200 hz through them and I thought the amplification ruined the sound, the pd 21" was only good for up to 80hz or so, but the low end was good, taking into account their amplification. They where on large baffle boards as it was their test facility come demo room
In the end I bought one pair of castleford made fane 18 xb then about 6 months later bought a Chinese built pair of the same, when I was there the guy was telling me had just come back from china as they where transferring fane production there.
I decided after my px4 ran out of puff driving 2 per side to revert to one 18 per side and started to look at other ways to improve the bass.. I tried H frames and 1930s style curtain damping, but I like where I am now.

To be fair Ed's had an effect on my opinion of how bass should sound.
And its an easy thing to ruin...
As that day in the pd/fane factory showed, even the pros dont know what they are doing when it comes to sound quality.
The engineer that demo'd them and showed me around the factory thought I was nutty when I talked about how much better they would sound with 5 watts of clean amplification.. but I was not wrong.

Knowing what I know now.. maybe the pd 21 would have been better bet, But they operate over a very narrow band, and one which is difficult to work with passively, which is my preference

I spent months agonising over what to buy if it's any consulation.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#175 Re: Another speaker thread

Post by steve s »

chris661 wrote: Sat Feb 06, 2021 11:27 am
simon wrote: Sat Feb 06, 2021 9:57 am


If it was mine, though, I'd reach for EQ before messing with the drivers. Low-Q drivers have their advantages.

Chris

That's my opinion too chris, I know when I walk around the wam show, there are many rooms with impressive bass, but all I can hear is what's missing in the bass on tracks I know... and what i know is there, replaced with an impressive thump
Last edited by steve s on Sat Feb 06, 2021 1:23 pm, edited 2 times in total.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#176 Re: Another speaker thread

Post by simon »

chris661 wrote: Sat Feb 06, 2021 11:27 am If it was mine, though, I'd reach for EQ before messing with the drivers. Low-Q drivers have their advantages.
Well, I do think it likely that the inescapable truth is that OB needs EQ down low. There are lots and lots of good speaker designers that have gone this way, why should a novice like me be able to come up with a magic solution they couldn't...

Can you summarise the advantages of low Qts?
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#177 Re: Another speaker thread

Post by simon »

steve s wrote: Sat Feb 06, 2021 12:15 pm To be fair Ed's had an effect on my opinion of how bass should sound.

...

I spent months agonising over what to buy if it's any consulation.
And in turn you mine Steve. I can listen to the big H frames and really enjoy them, but at times I can hear the problems with them too.

Really interesting feedback, thanks Steve. And yes, it's tricky to know what to do. Different drivers suit different types of speaker, so shelling out for a couple will likely still only let me try a particular flavour of speaker. What you've done fascinates me but scares me as I don't know how it works, or how to calculate it really I suppose. But it's probably the best compromise I've heard I think. But I suspect OB with EQ is easier.
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#178 Re: Another speaker thread

Post by steve s »

As you know you can borrow my spare 18xb, the other one is in my daughters bass cab
If there are any bridge visits this way..
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
steve s
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#179 Re: Another speaker thread

Post by steve s »

Slightly off topic, but questions I ask myself ..

Q... does it not stand for quality

Perfect Q... is that not a comprimise or an easy to implemented balance of the quality compromises?

Is there such thing as perfect transient ability when it come to loud speakers ? And how does that relate to Q..

I hope the young uns will chime in .
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number
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#180 Re: Another speaker thread

Post by Nick »

Yes it does. But quality in terms of a resonant system. No other implied meaning.
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