Pass Labs Rushmore

[jotom750]

I am just collecting bits for a 3 or 4 way PHL based speaker. (Passive or active)
Could I suppose be regarded as a bit of a Rushmore clone, though will probably use multi dome tweeters.
Could anybody point me to an, in english review of the Rushmore ?
Or any technical info ?
Thanks in advance.
Richard.

[asbjbo]

I'm in progress with a similar project, but with a Beyma TPL-150 on top. It seems like the only magazine reviews of the Rushmore were done in the Far East, according to this list. I did find the Rushmore manual interesting.

[jotom750]

Hi.
That Beyma looks very interesting, can't quite make out the polar resp though.
Great sensitivity ! Have you used it before ?
I was hoping to use PHL's 2540 mid, 6030 bass, and 3420 mid-bass.
Just getting the box design sorted out. Never done a 4 way x over though.
How are you getting on ?
Regards.
Richard.

[asbjbo]

I have not used the TPL150 before, but Stig Erik (look for his dipole thread here) has quite a bit of experience with it. The vertical response of the TPL150 collapses above 3 kHz. I will use a conventional, rear-firing tweeter angled upwards to fill in above that. The midrange and midbass are PHL 1130 and 3440, both 16 ohm drivers with 96-98 dB sensitivities. The bottom end will be dual Beyma 12SW1300Nd front and back in a push-push-configuration. This also gives some ability to fight the cancellation from the wall behind the speakers. All drivers will be in closed cabinets.

To begin with, I'll run this "semi-actively" using a DEQX HDP3 digital crossover together with six Hypex UcD monoblocks I already have, three amplifier channels per speaker with two drivers per amplifier channel. The digital crossovers will go between the basses and the midbass, and between the midrange and the tweeters. I'll use a passive first order crossover to protect the rear tweeter, and probably a second order Butterworth between midbass and midrange. The two 12" basses will run in tandem with no passive crossover. That means that both 12" basses and the pleated diaphragm tweeter will be connected directly to an amplifier with no passive components between. The other drivers will see one or two passive components between them and the amplifiers. I can then fine-tune the frequency and phase response in the DEQX. I would really not want to make a passive crossover for these speakers!

Later on, I hope to move to separate amplifier channels for each driver, along the lines of the Rushmore itself, since these speakers really do not need a kilowatt of power per side. I'll still keep the amplifiers separate from the loudspeakers for flexibility, and will still have (at least one) DEQX HDP3 as the brains of the act.

As for progress, I'm done with the paper design and calculations, the drivers have arrived, and I'll start cutting wood shortly. Attached a preliminary rendering - we will see if I'm able to translate it into actual wood...

[jotom750]

Great picture.
I will probably go for something like this, each driver in it's own box. More work but can help to reduce interactions.
Major part just for bass/woofer, around 140 ltrs, mid /bass around 20ltrs.
Cabinet made from 25mm mdf, well braced. I suppose not really a Rushmore clone, more a
3 or 4 way using PHL drivers.

[SunRa]

This is the closest speaker design to Rushmore I am aware of. It uses PHL drivers, same as the original: Humble Homemade Hifi



The difference is in the cabinet and in the crossover. Galactica is passive, Rushmore is active, with build in amplifiers.

THe cabinet is a different story. Galactica is more conventional, the cabinet is built to be acoustically inert. Rushmore's side curved walls are build out of thin plywood, fixed between a heavy, granit front baffle and the rear baffle which is a solid piece of aluminium and also functions as heatsink for the amps.

[56oval]

Hi
This is my take on a similar speaker to the Rushmore .I have heard PHL drivers in 2 ways,3ways & 4ways active & passuve ,two with Raven ribbons and the 4 way with out I liked the sound very much . My will be active but the drivers will be driven by 300B SET amps I'm building .I'm looking at using a F5 amp on the 15" PHL 5021 bass driver .
The drivers I'm using
Raven R1
6.5" PHL1120 ,very nice match the the R1
10" PHL3020 ,mid/bass
15" PHL5021 ,bass





15" alloy baffle & driver


One of the mono300B SET amps I built ,the xover values are part of the amps signal circuit.


Cheers

[asbjbo]

That is a very impressive project!

I'm building the cabinets in Baltic ply with constrained layer damping and internal bracing, BTW. The baffle will be a alu-ply-alu sandwich. I looked closely at the Galacticas, but decided to go for a more compact format for good driver integration at shorter listening distances. I spent quite some time trying to figure out how the speakers would interact with the floor bounce and front wall reflection.