Originally Posted by andy497
Back on topic, I just finished breaking in my D4s. 20 hours straight of 17 hz sine wave at roughly xmax in free air. I was pretty nervous leaving things running when I went to bed, but there they were in the morning pumping happily and silently with everything cool to the touch. When I got home from work that day, I stretched them out a bit. At somewhere just past the 3 inch peak to peak range (estimating), one woofer started tapping but the other stayed quiet. I backed it off 0.5 db and both were quiet. You hear some chuffing from all the VC venting going on, but there is amazingly little mechanical noise. I have never *ever* gotten my existing sealed D4s out into that excursion range, but now I know they won't tear apart.
Thank you very much for your observations above
Josh Ricci noted similar on the DB test, IIRC, but it's good to have the fact that there is minimal mechanical noise confirmed! I'm hoping to do a PPSL design, which would mean one cone magnet-out, so mechanical noise is one of my concerns that I can't really test until it is all up and running.
Originally Posted by Anthony_Gomez
4 cu ft and 1000 watts puts the 15-25 hz cone excursion at 20-19 mm.
For possible usefulness(?) I've got a couple of graphs of 4 SI18s in 15cuft total with a CV5000 in my build thread (n.b. - graphs are hosted elsewhere):
They pretty much model as staying within XMax the whole time, even without a LT, and I am hopeful that if the modelling is correct, it will be pretty much impossible to bottom them out. The posts in this thread increase my confidence that all will be fine (thank you, all!
) even with, potentially, 1250wRMS into each driver. They should only be sucking over their 600wRMS rating under about 28Hz, possibly low-20s Hz if I use a LT, and full amplifier power is only really approached under 10Hz (with no LT).
Takng CV5000 roll off into consideration (-3dB at 5Hz, I believe) I think they should only be getting full amplifier power between 5Hz and 10Hz, although I will have to wait until they are built and in-room to see if I need to add a boost down low, which may reduce upper end headroom (which should be fine as they model at something like 130dB+, which is way more than Reference calibration needs!)
I can't wait to get them built, I just need my box-building guy to start!Edited by MemX - 2/24/14 at 6:09am