Why an "extra cone" on some versions of Philips AD5061/M4 midrange?

[oortone]

Hi!

I have Swedish active speakers Audio Pro 4-14 and since one of the midranges tends to get stuck from time to time I managed to find a replacement on eBay.
The elements are Philips AD5061/M4 but as shown on the picture, the replacement has an "extra cone" (looks older too).

Can anyone tell what the purpose of the extra one is and if it will color the sound differently than the original.

[Aadams]

On 10/13/2018 at 3:41 PM, oortone said:

Can anyone tell what the purpose of the extra one is and if it will color the sound differently than the original.

I thought someone more expert would have answered by now.   That looks like a whizzer cone ... One voice coil with two cones.  The small cone helps extend the high range of the larger speaker.  I always, perhaps incorrectly,  associated  whizzer cones with radios and cheap utility speakers.  IMO that is not a correct replacement even if it will fit but by now you should already know the answer.  How does it sound?

Adams

[ra.ra]

On 10/13/2018 at 3:41 PM, oortone said:

The elements are Philips AD5061/M4....

Greetings, oortone, and welcome to the CSP forum. I am not familiar with the specifics of the speaker model you are working on, but here's a little information on the earlier Philips drivers. It might be helpful to post pics of the backside of your two midrange drivers.

Some great pics of your speaker model are in this thread: http://forums.stevehoffman.tv/threads/vintage-audio-pro-a4-14-active-speakers-and-self-made-speaker-stands.761201/ 

As Aadams has already noted, many of these Philips drivers from this era included the whizzer cone. This AD5061 is a terrific small driver, and it was used in several US-made Rectilinear models from the mid-late 60's and early 70's. The foam at the octagonal perimeter suggests it was meant for rear-mounting, but even your speakers (and mine) suggest that it was not always installed that way. Also, the 5061 driver has an open back and was often installed in its own chamber to eliminate possible interference from the effects of a larger woofer in the same cabinet - - - but I am not sure if this issue applies to your speaker configuration.

Definitely your speaker features a more modern version of this driver, but you should be aware that the 5061 driver was available in both 4 and 8-ohm impedance values, and this might be an important determinant as to whether your 5061/M4 mid-driver can serve as a replacement in your Audio Pro 4-14 speakers. 

[oortone]

Thanks for the information. The elements in my speakers are definitely 4 ohms and as you can see from the rear shot (the top one is the original from the speaker) they are called "AD5061/M4 2422 257 35511. The only number different in the one I thought would be an exact replacement is as you can see the last one; 35501 instead of 35511. I find this very strange. Almost makes me wonder if the ones in the speaker have specially made cones.

Even stranger is that when I managed to get in touch with someone at Audio Pro support who know about these old speakers he said the correct component number should be AD5061-P4S. And this is an element I can't find at all, not even a datasheet.

However, the element I wanted to change is not really broken. Mostly it sounds nice but every now and then it will get stuck and I need to turn up the volume for a short period and then they will work again. Sometimes for months.

I can indeed certify theses speakres sounds great. The bass system is made of two elements, one facing up and the other facing down. I believe ACE has something to do with controlling the relation between acoustic and electric impedance to get a flat response.

[ra.ra]

Well, I'm not sure I can be much help here - - - all of these different permutations are indeed confusing - - - but I'll share what I've found anyway. 

Nothing truly revealing here, but the final post in this thread notes the same mid driver (AD 5061-P4S) that the company mentioned to you, even though your speakers show the 5061/M4 (does your second speaker have the same mid-driver?) http://audiokarma.org/forums/index.php?threads/cool-craigslist-obscure-speaker-find.219918/

Philip manufactured drivers in Belgium and Hungary, too, but the AD designation denotes it was built in the Netherlands, and on a Dutch audio forum, I was able to at least find an image of the P4S driver backside (see attached). Unless you think it is futile, you might have another contact with Audio Pro tech support to ask if there are any differences between the P4S and the mid-drivers that were installed in your speakers.

I'm not quite sure what you mean when you say the driver occasionally gets "stuck", but do these mids have foam surrounds? If so, is it possible that the foam surround might have failed and thereby create a situation where lack of full support for the cone sometimes throws the voice coil out of alignment......and then temporarily getting "stuck" in the gap? I'm just guessing here.....

[oortone]

Thanks ra.ra, will follow that link. Interesting to see that the P4S exists.
I have the save midrange in both speakers, but of course some one could have changed both at the same time from original.

I'm not sure what you mean by foam but there could be a slight alignment problem for sure. I've had headphones (Sennheiser HD540) doing the same thing.

[ra.ra]

59 minutes ago, oortone said:

I'm not sure what you mean by foam....

I am asking about the composition of the outer suspension material of the original driver, designated here by red arrows. Is it a thin profiled cellular foam material? For comparison, the earlier Philips mid has a treated cloth suspension material, shown here with blue arrows. This type of woven cloth material never requires replacement under normal use, whereas foam suspension surrounds have a limited lifespan and will require replacement if they have developed cracks or other deterioration.

[Aadams]

20 hours ago, oortone said:

I've had headphones (Sennheiser HD540) doing the same thing.

I recommend you do a swap of the drivers in question.  Just move each to the other box and see if the problem moves.  If it doesn't move the problem is not in the speaker driver.   JMO.

Adams

[oortone]

OK, no the foam is fine. Did have to replace it on the bass elements though.

A swap is a great idea. Will try that next time I'm in service mode (mood?).

 

[Larry D.]

I purchased new in 1970, a pair of Rectilinear 3 Highboys, then bought a used pair of Rec-3 Lowboys, then another pair of Rec-3 Highboys followed by a new pair of Rectilinear 7's, then later on, a new pair of Klipsch-Belle's.  All the Recs' 3's were equipped with the AD5061/M8 mids. Coupled with 12" Jensen Flexair woofers and simple paper cone alnico tweeters,  they sounded very lifelike!  The killers were the Philips midrange drivers used in all.  They made vocals sound as 'REAL' as can be...as though the voices were actually in the room in front of you, not just a speaker trying to reproduce vocals in front of you.  The Rec-7's also had a 7" Philips paper cone mid that was crap.  A car type speakers as far as I'm concerned. (I sold them in disgust).

The Belle's, played twice as loud as the Rec's were too 'Honky' for me, so I sold them also.

I also have a pair of NOS Philips AD5060/M8 raw drivers.  I feel IMO that they don't quite cut it in sound quality/realism as the 5061's.

[ChrisM]

Hi Larry,

Rectilinear III's are very different from most speakers. The main driver is the midrange. The 4 tweeters and Flex-Air woofer just fill in the very top and bottom . This way of designing a system require a really good, really wide range mid-range so Jon Dahquist used a full range driver.  No crossover, no phasing issues just a bit of help on the top and bottom. Spendor did the same thing in their classic series 3 ways.