Guest pbda Posted June 26, 2005 Report Share Posted June 26, 2005 Were all AR-3 woofer surrounds made of cloth, or were there some foam surrounds as well? Link to comment Share on other sites More sharing options...
tysontom Posted June 26, 2005 Report Share Posted June 26, 2005 >Were all AR-3 woofer surrounds made of cloth, or were there>some foam surrounds as well?All AR-3 woofers were the PN 3700 Alnico woofer with cloth surrounds. There were some variations in the cone configurations, but all had treated cloth surrounds. See examples below:http://www.classicspeakerpages.net/dc/user_files/514.jpg(Fig. 1) Earliest-style (1959) AR-3 woofer, Alnico version with cloth surround, no ribbing ("corrugation") or damping rings. This woofer was a carry-over from the AR-1 woofer.http://www.classicspeakerpages.net/dc/user_files/515.jpg(Fig. 2) Later (1960) AR-3 woofer, Alnico with cloth surround, ribbing and damping rings. This woofer also had damping rings on the apex as well as the edge of the cone, but the rings are deteriorated and missing on this example.http://www.classicspeakerpages.net/dc/user_files/516.jpg(Fig. 3) Latest (1963-1968) AR-3 woofer Alnico with lamp-black cloth surround and apex damping ring, but cone-edge damping ring was eliminated. Note: this is also the earliest (1967-1968) AR-3a woofer. These are rough examples, but most AR-3s fall somewhere in these categories. There were variations in cone foam-damping rings and so forth, but the basic woofer was pretty much the same. Some minor internal changes were made in the skiver stiffness as time went on, but it was very minor. The motor circuit, as well as voice coils, remained basically unchanged throughout the series. All woofers had cloth (linen) surrounds treated with a butyl-latex material to help seal the cloth and improved higher-frequency response of the woofer (along with the damping rings). Later surrounds had lamp black die added to the butyl-latex material covering the surrounds. --Tom Tyson Link to comment Share on other sites More sharing options...
Guest Ed Ruane Posted June 27, 2005 Report Share Posted June 27, 2005 Tom I have a set of AR2's and AR3's and they have the cloth surrounds like you show in fig 2. They are cloth but they are shot,worn out,they are very limp and have no tension left in them.I have replaced a lot of cones and foam surrounds in other speakers can I use foam on these to rebuild them as I have not seen replacement cloth surrounds for these AR speakers. Is the spider giving the cone the tension on these cloth surrounds?Ed Link to comment Share on other sites More sharing options...
Guest pbda Posted June 27, 2005 Report Share Posted June 27, 2005 Tom, many thanks for your prompt and helpful response! Link to comment Share on other sites More sharing options...
ninohernes Posted June 27, 2005 Report Share Posted June 27, 2005 >Tom I have a set of AR2's and AR3's and they have the cloth>surrounds like you show in fig 2. They are cloth but they are>shot,worn out,they are very limp and have no tension left in>them.I have replaced a lot of cones and foam surrounds in>other speakers can I use foam on these to rebuild them as I>have not seen replacement cloth surrounds for these AR>speakers. Is the spider giving the cone the tension on these>cloth surrounds?>EdIf the woofer is out of the cabinet, it will be limp and it will bounce freely up and down. Once installed in their proper sealed cabinet they will become stiff. That is how the Acoustic Suspension system works. The air cushion behind the cone is what supplies the restoring force. When the cone is stimulated by a signal and moves out, since the cabinet is airtight, the pressure drops inside sucking the cone back in.However, I have come across AR drivers that do have damaged cloth surrounds. If they can't be repaired, they can be replaced with foam. But be warned, they will not sound the same. The cone will be thicker, and the foam will absorb different frequencies than the cloth did. Link to comment Share on other sites More sharing options...
tysontom Posted June 27, 2005 Report Share Posted June 27, 2005 >Tom I have a set of AR2's and AR3's and they have the cloth>surrounds like you show in fig 2. They are cloth but they are>shot,worn out,they are very limp and have no tension left in>them.I have replaced a lot of cones and foam surrounds in>other speakers can I use foam on these to rebuild them as I>have not seen replacement cloth surrounds for these AR>speakers. Is the spider giving the cone the tension on these>cloth surrounds?>EdEd, when you say that they are "shot, worn out... no tension left in them," do you mean that the cones will not return to center position? Do the voice coils rub when you push the cone from the center? Are the spiders stretched away from the center position? Observe the spider to see if it is relatively straight across and not badly sagging. If the cones settles, at rest, way below the center position, the spiders may be stretched. Test the speakers by placing them on a flat surface, magnet down, and observe the cones at rest. Remember that the early AR-1, AR-2 and AR-3 woofers were extremely compliant and loose, and would seem to be very "floppy" out of the cabinet. This was normal. Once installed in the sealed AR cabinets, the woofers regain springiness by virtue of the trapped air in the enclosure. The mechanical springs (spider and surround) of these early AR woofers account for approximately 10% of the restoring force -- just enough for voice-coil centering -- and the trapped air in the AR cabinet accounts for the rest. If the surrounds are flattened, collapsed or torn, you could replace them with the newer-style foam surround kit if you can find the size to match. So far as I know, these newer foam kits will work perfectly fine on the earlier AR woofers, as several people have done this. I have never done this, but I've seen examples of these surrounds on the earlier woofers. Before you do it, however, be sure that your woofer really needs surround replacement. If the cloth surround is still intact but very porous and deteriorated, it will leak air badly and may need to be coated with a butyl-rubber compound (such as the Lord Corporation, Chemical Products Division, BL-100 butyl-rubber) liquid or similar substance. This is the white, milky liquid substance that can be applied to an old cloth surround to help seal it, but maintain pliability. Lord does not sell consumer products to my knowledge, but someone may have something similar to this product. There are other similar products as well, but I don't know the source. --Tom Tyson Link to comment Share on other sites More sharing options...
Guest Ed Ruane Posted June 27, 2005 Report Share Posted June 27, 2005 Tom and Joe thanks for all the info on the AR speakers.I may have been a little hard on my speakers.Let me give you a little history on these two sets of speakers.I have built several sets of very large high end speakers for myself and others 25 years ago.I have rebuilt many jukebox speakers but they are a very different speakers than the AR's.Two years ago I started to buy vintage high end audio equipment.I didn't buy many speakers as most that I came across were junk.About three months ago at a Antique Wireless meet a gut next to me unloads three speakers covered in straw and dirt,very very ugly.I saw that they were AR's and I bought the three for $30.He said the tweeter were not working.When I got home I found he was correct,no sound from the mids or tweets.The grills had been re glued back on by someone so I cut the grill cloth and worked the frames out.Some one had tried to get the mids and the tweets working and had done a butcher job on them.I removed all drivers and repaired the lead wiring and got two tweets and one midrange working.I believe I can rebuild the one midrange if I can get the voice coil rewound.They are very crudely built and It's hard to believe that any are still working after all these years. The third speaker was a AR2 and I did nothing with it thinking I would never find another one.Well last week I found another AR2 for$10 and it is in good shape. After I read what you both wrote to me I took a better look at the AR3's.The surrounds are in poor shape,they have flat spots in them and they are out of shape,not a half round but flat and then pointed in places.They look like they have been re coated at some time.The voice coil doesn't rub and I can put a lot off power to them but they don't have the AR3 sound.I have all the drivers out at this time and I am going to refinish the cabinets and replace the caps.They are dated 1963.I will put them back in the cabinets when they are finished and try them again and be sure the they are air tight.If they need it I will replace the surrounds at that time.Also I may have located some clothe surrounds for them.Now the good news.I brought the AR2 inside the house from my shop where I only have a Pioneer Sa6700 and connected them to my Carver PM900 amp.I pushed them to -3db,that is around 250 wpc and they took it with no problems.The low end was clean with no cracking or strange sounds, just super clean base.I was very surprised at how well they punched the low end.Because the surround are so soft compared to the foam one I thought they were bad.The 5 inch mid tweets need to be replaced but that is very simple to correct with something more up to date.I took a couple of picture off the surrounds but the defects do not show up in them.Thanks again for the help.Ed Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.