Dayton RS270P-8A - Lockdown project.

[georgepapa]

I did a boredom purchase of these 10" paper cone drivers during our now long term lockdown from The Loudspeaker Kit

I'm going to fast forward through the significant stages of this build, which took around a month working at a very casual pace, and which I completed some two weeks ago

Couldn't find many projects on the net regarding this driver so I would hope that some of the information and findings will be of help to people.

I had previously purchased a pair of 18mm mdf ,52 litre, second hand boxes which I have repurposed for the project.

I also have on hand one of the earlier Proac Super Tablet models which were to be used for the new systems mid and tweeter modules.

As this is a three way active project, using the Behringer 2496 and six channel Hypex amplifier, I bypassed the crossover in the Proacs and installed an extra two terminals for biamping of the mid tweeter module.

I did it all the lazy and silly way by repurposing an unused enclosure of approximately 52litres and then scouring the net for a compatible driver.

You really are far better off buying the best driver you can afford which meets your needs and then build, or have someone else build the optimal enclosures.

The RS270P came up as the best value option as a large driver which is optimal at around the 50 litre mark. 

I added extra mass and rigidity to the box with cross bracing, 16mm sheets of mdf and 2mm sound deadening material from Jaycar.

I was careful not to reduce the volume of the enclosure too much, otherwise the port length would be too long and too close to the back wall. 

I cannot say that I saved any time or money in modifying the old boxes, however they are already veneered and in reasonable condition.

Not really into the cosmetic side of loudspeaker building.

 

 

As the bass drivers are intended to operate below 550hz i did not flush mount the drivers.

I believe that in this operating range any diffraction effect from surface mounting would be negligible, or probably occur at a higher frequency where the driver is already rolling of at LR24db. This also allows a full 18mm of baffle thickness in which to securely screw the drivers into.

 

So here is the finished product with and without grills.

Pretty easy really, and not terrible looking.

 

Due

The Proac's use the Seas CA11RCY 9.5cm bass mid and the Scanspeak D2008/851100.

The Seas demonstrates good linearity, though not that extended in the top end for such a small driver.

The Scans seem to be happier crossed over above 4khz and can sound very thin below 3.5khz.

At 4khz whilst the Seas does the job I am aware of some of axis audio anomalies near the crossover frequency due to beaming issues in the mid at high frequencies.

Ideally i would like to see a replacement tweeter crossing over somewhat under 3khz

Here are the full range test results from 10cm. Seas in red, Scans in blue.. The Proac enclosure is 5litres BR.

 

 

The Dayton woofers exhibit flat and extended bass and mid bass response.

There is a nasty dip in the response at around 650hz which in my view underline the limits of the drivers use. Not that I intended crossing them over that high. A dedicated come midrange will always deliver improved performance in this range as subjective listening confirmed.

This measurement below demonstrates the dramatic effect an enclosure has on the response compared to the free air measurement. Green is free air.

The enclosure affects the response right up to 600hz.

The spreadsheet below which I regularly use allows some modelling based on box volume and various port diameters.

I packed out the boxes to a 50l volume with only a thin layer of hollow-fill dampening on internal surfaces, most likely pushing the volume up to 51 to 53 litres.

You'll notice that the driver is also very well suited for sealed enclosures as well.

Phase alignment between bass and midrange was a breeze.

With excellent spl matching from 200 to 2000hz ,at 00:40ms delay  on the mids, these drivers are phase aligned for a full 1.5 octaves , from 300hz to 900hz.

I've always liked the large scale sound of a big woofer working up 500 hz, giving the driver the breadth to cover most of the bass instrument spectrum and adding a larger scale to voice, rock and orchestral works.

The same can not be said for the mid and tweeter where the position of the RTA microphone significantly affected the phase plots, leading to considerable confusion regarding positioning. Theres not much choice there really. They need to be crossed over above 4khz and no higher than 4.5khz, otherwise the mids are rendering quite average HF reproduction.

And now here's the full range measurement, nominally at 400hz and 4khz at approximately 100cm distance, single speaker only.

Regardless of the mid tweeter crossover points or phase alignment, I am consistently getting a broad  but acceptable dip at around 3.8khz.

The Proac's with the original crossovers produced the same dip, maybe as a result of baffle diffraction loss with the very narrow front baffle.

So what do they sound like?

These speakers fill my ample listening  room with with a large, solid soundstage, very powerful deep bass and excellent imaging .

A linear response of +/- 5db from 35hz to 20000Hhz allows faithful reproduction and suitability to all musical styles.

I can strongly recommend the Dayton's to anybody wishing to use them up to 550hz in a 3way system.

I've heard that people have used them in two way designs but really they don't sound great above 800hz.

Other tweaks included, spikes, rubber feet on the Proac's, covering the rear firing Proac ports and of course messing around with placement and tilt in.

Thanks guys.

 

 

 

 

Edited July 18, 2020 by georgepapa
Image removal