Design Acoustics PS-10

[JKent]

Nice (but little known) little speakers. I think Glenn has had some experience with them. They have "wood-grain vinyl" cabinets--the curse of the 80s. Woofer is downward firing and the surrounds needed to be replaced.

Ordered new 10" foams from SpeakerWorks. The foam attaches to the back of the cone (like Advents). I'm sure it doesn't matter but in the interest of authentic appearance I did likewise. A bit more difficult but not too bad using white glue.

The dustcap is a "spitwad" style, also like Advent (the Smaller Advent). As I understand it the spitwad is essential to the sound of the woofer, so I kept it, in this case following the instructions from SpeakerWorks on how to center the VC. I prefer shimming, but this seemed to work.

I've been told I don't need all those clamps but what the heck. Sort of a "belt and suspenders" approach ?

-Kent

[ra.ra]

Hi Kent. Before you wrap up this thread, please show us some additional pics and info about this speaker model. Also, exactly what are the SW recommendations for VC centering? Your re-foam looks very good done the "correct" way. Have never seen a spitwad cap that was not a Smaller Advent, and that woofer also has inner foam placed under the cone. And, is that a radial seam in the paper cone at 9 o'clock?

The DA speakers I'm working on (two pairs of D-4's) are from the early original series (D-2, D-4, D-6, D-8, D-12), when the company was located on Oregon Court in Torrance, CA. At that time, all speaker design (and marketing and purchasing.....) decisions were controlled by founder George Sioles, but I am not at all familiar with the PS series. 

 

[JKent]

Hey ra.ra

Here are more pics. I had previously worked on a pair of PS-6 speakers. The PS stands for "point source".  These are from Ohio, when DA was an Audio Technica company.

The 10s have 10" downward-firing woofers and come as mirrored pairs. I've read some positive comments about them but they certainly pale by comparison to my reference AR-91s ?. I'll have to compare them to the KLH Twenties I'm working on. Those are also 10" so maybe a fairer comparison.

Yes--the woofer cones do have a radial seam. SW's instructions say they do not recommend using shims (!). The method they describe pressing down of the cone and listening for scraping. Then "through trial and error, find the 'sweet spot' where you can move the woofer cone up and down without hearing any scraping."

I'm MUCH more comfortable with shims but I did not want to cut the spit wad (know many do this "hinge" method successfully).

-Kent

[ra.ra]

Those are stubby little fellas, ain't they? Almost cubic in dimensions. The drivers appear well constructed - - yes? - - but it took me a minute to realize that the tube is a separate enclosed chamber for the cone midrange. Crossover looks fairly robust, but a cap replacement could be a bit of a challenge unless that board is easily removable. I would guess there is at least one more cap we cannot yet see.

Interesting to see the little response curves which illustrate the crossover frequencies, and that Da logo does not show up anywhere on my D-4's, but yours do have nice binding posts. Two questions: What's going on with that black top grille that is held away from the vinyl top panel? And, did these woofers have a gasket between metal frame and bottom cabinet panel?   

[JKent]

Yes, the xo is robust. Looks like 4 NPEs sealed in ny-ties and hot melt. I'm not touching them!

Sorry about the mystery placement of the black grille. I just popped it off and set it on top to take the picture.

Woofers did have gaskets but they were so thin and compressed I replaced them with foam gasket tape from PE. There are also solid plastic rings on the outside.

[ra.ra]

11 minutes ago, JKent said:

Sorry about the mystery placement of the black grille. I just popped it off and set it on top to take the picture.

      .    Stoopid me......

12 minutes ago, JKent said:

...and hot melt. I'm not touching them!

Ugh.... I really despise working on hot melt glue schmoo assemblies.

[JKent]

On 4/29/2019 at 2:58 PM, JKent said:

they certainly pale by comparison to my reference AR-91s ?. I'll have to compare them to the KLH Twenties I'm working on. Those are also 10" so maybe a fairer comparison.

First impression: The KLH Twenties are much better. Definitely have better bass. I want to like the PS-10s but . . . meh.

These btw are PS-10A. I understand there were other iterations; 10B, 10C etc.

Julian Hirsch in SR 1983 was more impressed with these than I am.

[ra.ra]

Thanks for providing this write-up, Kent, but I could not see in your pics any designation of the "A" in the model number. It is often interesting to see a product (speaker or otherwise) go through these revisions and iterations (A, B, C, etc.) during its market run and then identify the specific changes and/or market strategies or justifications. In the case of the DA speakers I am currently working on, the later D-4a was a very different and far inferior speaker design than the original D-4 - - - it shared some similar proportions and vague visual identity, but had a different number of drivers which were all different from the original parts. 

A couple curious thoughts. That first sentence in the review in the Lab Measurements section: Isn't that sort of a redundant statement? Yet there appears to be no mention of a separate enclosure for the cone mid, as was found in your speakers. The oddest thing, however, IMO, about this speaker is its proportions, and the review does address this - - - the PS-10 clearly "looks" like it's meant to sit on the floor, but of course this puts all the HF delivery in the wrong place. Too deep for a bookshelf, and yet it's hard to imagine these fitting and looking good on a pedestal base. Now I'm getting a little curious to see what the rest of the PS line was all about.  

[JKent]

5 minutes ago, ra.ra said:

I could not see in your pics any designation of the "A" in the model number.

I'm assuming/deducing they are "A" because I read there were different iterations and the SNs of this pair are PS10A-78427 & PS10A-78428.

7 minutes ago, ra.ra said:

drivers which were all different from the original parts. 

The tweeter on this pair look a bit different from the ones in the review. Another thought--are you sure your 4s have original drivers? If you saw my AR TSW=410 write-up you know I recently had an unpleasant surprise with those (mismatched Rat Shack mids).

10 minutes ago, ra.ra said:

That first sentence in the review in the Lab Measurements section: Isn't that sort of a redundant statement?

Yes

11 minutes ago, ra.ra said:

the PS-10 clearly "looks" like it's meant to sit on the floor, but of course this puts all the HF delivery in the wrong place. Too deep for a bookshelf, and yet it's hard to imagine these fitting and looking good on a pedestal base.

Yes. A real challenge. As I mentioned above, there is very little on the interweb about these but there was some discussion on AK and our friend Glenn wrote about the ones he worked on. IIRC (always dicey) he mentioned stands. I don't know if they were from Design Acoustics or his own build.

[JKent]

 

1 hour ago, ra.ra said:

Now I'm getting a little curious to see what the rest of the PS line was all about.  

Here are a couple of reviews: http://www.hifi-classic.net/products/design-acoustics

Quite a bit on AK: https://www.google.com/search?q="Design+acoustics"+speakers+site:audiokarma.org&client=safari&rls=en&sa=X&ved=2ahUKEwixkczOp_3hAhUJd98KHUkuCsMQrQIoBDASegQIBxAN&biw=1113&bih=1046 and I see you've participated in those discussions.

 

On 4/29/2019 at 1:36 PM, ra.ra said:

The DA speakers I'm working on (two pairs of D-4's) are from the early original series (D-2, D-4, D-6, D-8, D-12), when the company was located on Oregon Court in Torrance, CA. At that time, all speaker design (and marketing and purchasing.....) decisions were controlled by founder George Sioles, but I am not at all familiar with the PS series. 

 

The PS series came after Audio Technica bought the company. AT is known for quality products but some have said DA went downhill after AT took over. I dunno.

Now a question for you: Did you test the old caps when you did the recap? I REALLY don't want to tear into that xo but if Glenn and others love the PS-10 and I'm underwhelmed, maybe there's an issue with the caps.

-Kent

[ra.ra]

Re: "A" designation, I suspected there was something you had discovered that we were unable to see, and I would tend to agree with your interpretation of the serial numbers. And yes, I think I recall reading a reasonably positive review from Glenn regarding the PS-10.

Even before I provided any supplemental pics, my well-informed DA source (located in CA) was able to describe and/or confirm that all of my D-4 drivers are indeed original. I have read the same overall diagnosis about DA after AT purchased the company, but the general decline may have begun even earlier, as described in the D-4 to D-4a transition.

About the caps, I'm not quite sure what to report, but like yourself, I would be real hesitant to dig into that tight mass of crossover assembly in the PS-10's. In my case, both pairs of D-4's have two caps per cabinet: a cheap tiny 4uF tweeter cap attached to the terminal panel, and a larger midrange cap (20uF in one pair; 33uF in the other) located deep inside the cabinet next to its driver. None have yet been removed and/or measured. The tweeter caps will be replaced without question because these panels need to be fully rebuilt due to broken switches and weak binding posts. The different values found in the mid caps are a bit of a mystery, but after some exchanges with my "source" regarding the particular drivers and the designer's basic philosophy, we've agreed that the 20uF with its higher x-o frequency is probably preferable. Nonetheless, due to their location in these cabinets, these will be a challenge to replace, as I'll be doing all of this without removing the iron-clad front grilles.   

[ra.ra]

Just wanted to post this comment found on the AK forum regarding DA PS-10's. Unfortch, there were no pics to show how he achieved the re-cap.

"BTW- I did a recap on a pair of PS-10 crossovers. Just for S's&G's I measured the capacitance and ESR values on the original caps. All the original caps measured within tolerance for capacitance and the ESR was well under .5 ohms also. The crossover capacitors may be the last place to do your troubleshooting based on my experience. Just FYI."

Also, starting on page 4 of this thread, you can see the stands that Glenn built for his PS-10's. https://www.audiokarma.org/forums/index.php?threads/lets-see-your-home-made-speaker-stands-im-going-to-build-some.457303/page-4

[BogBeat]

Hi, anyone have any idea where i can find speaker binding post for the PS-10?  One of them snapped... Is this even replaceable?