Marantz 2245, AR3a and Thorens TD 125 MkII with SME 3009

[snorbans]

Has anyone worked on AR3a speakers or similar AR speakers

I just bought a new system that includes nice condition AR3a they sound, with a low level feed, like what would be heard out of 2 bean cans separated by a very long piece of string. The woofers need refoaming, straightforward, there has been some kind of calamity associated with the pots, blackened wire and stuffing. Corrosion leading to increased resistance and heat presumably. The pots seem salvageable. The drivers are working so all should be ok for a successful restoration.


As far as caps I'm tempted for cost to go down the alcap route 150, 50 and 6 uFd based on cost and the fact that the 50 and 150 are electrolytic and the sound might be closer to original, the 6uFd is in a waxy box 'industrial cond corp'

Advice and comment welcomed!

[hermit]

Lovely vintage system that you've bought. I've always wanted a pair of AR3s but none have come up within striking distance of home. I did buy a pair on spec on the bay but they had to go back due to having no original drivers and a butchered baffle. There's a guide to restoring the pots on AR speakers on Audiokarma (http://www.audiokarma.org/forums/showthread.php?t=306818&highlight=potentiometer) and a guide to restoring AR3s here (http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/restoring_the_ar-3a_full_pd.pdf) on classic speaker pages which is a great resource for AR. Good luck!

[DSJR]

Classic speaker pages has good articles on the AR3a. They're worth every penny to do up and PLEASE don't do it on the cheap.

P.S. The TD125 can sound very good, but check the main bearing for platter wobbles in the bushings, which may need a more heavily viscous oil than the turbine stuff Thorens fitted.

[snorbans]

Classic speaker pages has good articles on the AR3a. They're worth every penny to do up and PLEASE don't do it on the cheap.

P.S. The TD125 can sound very good, but check the main bearing for platter wobbles in the bushings, which may need a more heavily viscous oil than the turbine stuff Thorens fitted.

Ah Dave from Tring, I heard that name from Garry from Aylesbury. I'm all for not doing it on the cheap, though how high do you go. I would be glad of any advice. I will get them working with capacitors I have. Once assurred I have got a full heads up on all their issues, I will upgrade to PP's which I will get from Falcon. The woofers, I will get a refoam kit from the AR shop on ebay but there is also a foam/cone/ wire supplier so I will have to look at them more closely and determine whats needed. Testing to check for sag or mis alignment would be worthwhile either when finished or I could refer the speakers now to the professionals and lose out on the fun of getting them going. What do you think? I have started a pfm thread on their restoration, but I'm commited to doing them justice

As for the turntable, I may start a new thread here as I'm a newbie (ish) to turntables, and this is a complicated beast. It rotates, smoothly but with a little noise, suggesting a lube might be a good idea. I have the instruction book but will need to source some oil

[snorbans]

Thanks for your post hermit. Not quite the Ar3's but the Ar3a's but I have checked out both those links and the Ar3a pdf will be my bible. Is it the done thing to say I have a pfm thread going? probably not but I have already added some photos there. I'm new to both forums and I think I will post a turntable thread here and keep the Ar3a's going on pfm

[snorbans]

Could anyone help with guidance on this? The speakers showed evidence of some high temperatures inside round the pots

The AR3a restoration pdf from classicspeakers is a great guide but the heating is prompting me to wonder if I should go a little further with replacing components. I have to replace most of the internal wiring and I have ordered several colours of 17 AWG, 32/0.2 hook up wire to maintain the original colours and enable me to keep sense of the wiring. There was a post in one of the many Ar3a threads to suggest all wiring was 17 AWG though my original has 18AWG on the Woofer capacior and driver +ve side and something thinner everywhere else. Safe to go with 17AWG?

The inductors will sometimes be replaced on restorations. I've checked with a multimeter and resistance is low in all cases. The No.9 coil is close to the area that got fried. The 2.85 and 0.88 MH could be replaced with new air core inductors. 17AWG wire was used for the originals. Jentzen do 18AWG's with values of 0.82 (18AWG) 0.84/ 0.92 (17AWG) and 2.7mH (18AWG). This will be splitting hairs but I would be glad to hear some opinions.

The 0.51, 20W Nichrome wire would also have got a heating, but would resist that well - keep or replace?

I'm cobbling a XO together from bits to ensure there are no problems so far hidden but then will order re foam kit, new pots and capacitor (PP) sets from the great AR store on e bay.

[hermit]

Could anyone help with guidance on this? The speakers showed evidence of some high temperatures inside round the pots

The AR3a restoration pdf from classicspeakers is a great guide but the heating is prompting me to wonder if I should go a little further with replacing components. I have to replace most of the internal wiring and I have ordered several colours of 17 AWG, 32/0.2 hook up wire to maintain the original colours and enable me to keep sense of the wiring. There was a post in one of the many Ar3a threads to suggest all wiring was 17 AWG though my original has 18AWG on the Woofer capacior and driver +ve side and something thinner everywhere else. Safe to go with 17AWG?

The inductors will sometimes be replaced on restorations. I've checked with a multimeter and resistance is low in all cases. The No.9 coil is close to the area that got fried. The 2.85 and 0.88 MH could be replaced with new air core inductors. 17AWG wire was used for the originals. Jentzen do 18AWG's with values of 0.82 (18AWG) 0.84/ 0.92 (17AWG) and 2.7mH (18AWG). This will be splitting hairs but I would be glad to hear some opinions.

The 0.51, 20W Nichrome wire would also have got a heating, but would resist that well - keep or replace?

I'm cobbling a XO together from bits to ensure there are no problems so far hidden but then will order re foam kit, new pots and capacitor (PP) sets from the great AR store on e bay.

If you don't get any help on the forums, you could try calling Jerry at Falcon Acoustics. He's both knowledgeable and helpful. Also his is a good site to buy your crossover bits.

[snorbans]

I shall try him thanks!