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..
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,
A couple of notes on that: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.
Ah, with them being so close I wondered if it was an offshoot or breakaway. Just a different arm then.
Okay, that's good to know. MJK's paper suggests the resonance lowers in frequency quite considerably.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.
By some kind of duping presumably?It's worth noting that simply adding mass to a cone will decrease Fs and raise Qts, which might open up some options.
How would you rate the PD drivers to the Beymas say Steve? Guessing you preferred the Beymas as that's what you have?
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.
To be the honest the PD drivers sounded dreadful in their test room.
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...
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.