Dchristie

Hi Vern, thanks for your response. As the A-25XL came out in the mid 70s, I assume that they are more scarce compared to the original A-25. I do not see that many for sale on the used market. Great for you that you have been able to secure a couple of nice pairs.

I actually bought this pair thinking I was buying an A-25 only to find out it was the XL model once I saw the actual speakers - the owner also mistakenly thought they were A-25s. It is interesting to see the renewed interest in these old speakers today. When I was in college, I did not know a single person with Dynaco speakers. It is amazing to me how many were sold but I also lived in a more remote area and did not have access to a lot of dealers. I do remember them being available in all of the mail order centers however. When I was buying speakers back then, I had my sights on the KLH 5s, AR 3as, or ADS 810s. I did consider buying Dynaco A-50s but finally settled on the KLH 5s and then moved on to the ADS 810s.

This pair of A-25 XLs appeared to be OK upon buying them ( quick inspection showed no damage to the drivers) but they actually had some major issues which I discovered after I got them home. In addition to the broken coil in the xover, both had sat in water for an extended amount of time and the cabinets were severely compromised as a result. The miter seams had separated significantly at the joints from the water exposure to both speakers. Of course the veneer on the lower parts of the speakers was also severely discolored as well. In addition, once I got into the speakers, I noticed that someone had broken one of the woofer leads (positive lead from the voice coil attachment to the solder joint on the woofer basket)at the positive terminal. They had just tied picture frame wire to the broken lead and then wrapped it around the solder terminal on the woofer basket - it was a wonder it even worked at all! Also, the positive solder connection for the voice coil lead on the other speaker had broken loose from the woofer basket and was just dangling loose on the basket. I am grateful the voice coil did not short out on the metal woofer basket.

Well, I was able to splice a piece of wire lead from another damaged speaker to the broken lead of the woofer and resolder it back on the terminal. I was also able to epoxy the loose solder terminal back onto the woofer basket of the other speaker and I then reinforced all of the other 3 solder lead terminals with a little epoxy as I have read that these terninals often fail over time and become dislodged as mine did.

I have also resanded both speakers and glued the open joints back together (as well as I could without doing a major cabinetry rebuild) and have reoiled both cabinets with 2 coats of clear danish oil. Once the oiled cabinets are dried, I will add a topcoat finish. And finally, I rebuilt the crossovers with Mundorf oil capacitors and noninductive resistors. Hope to have them up and running within the next week or so.

I also have a review of the Dynaco A-25 XL from the 1976 edition of High Fidelity Test Reports and they concluded that the XL model sounded very similar to the original A-25 with just a little more extension in the highs and perhaps a shade more bass definition. Intersting to read different opinions from owners of both speakers on the different web sites. There seem to be supporters for both models - which is fine. Some prefer the originals and some prefer the XLs. I only listened to my pair breifly before I dismantled them, but I thought they sounded pretty good in spite of their problems at the time. Since I have updated the xovers, I will be listening to a non-original A-25 XL but I look forward to hearing what they can do. For me, the fun is in fixing up these old speakers and hearing them again after 40 years .

Hi Vern, thanks for posting the A-25 XL crossover photos.

 

I now have a question for the Dynaco folks regarding the actual crossover components.

 

Does anyone have access to an actual schematic of the A-25 XL crossover? The caps and resistors are fairly evident as is the layout but to date, I have not been able to find any information about the small air core inductor in the circuit.

 

I recently picked up a pair of A-25 XL speakers and noticed the very small inductor leads are both broken right at the coil and may not be able to be repaired. Since it looks like the inductor is part of the 2nd order crossover for the tweeter, I would like to replace it if I can't fix the originals.

 

Thanks

 

Dean

If you are asking about voice coil height when you refoam the NLA woofers, it is automatically corrected once the new foam diaphragms are attached. You do not need to do anything else.

Sendigitall,

 

I have bought all of my refoam  diaphragms for my speaker projects from Looney Tunes ( I have refoamed 8 drivers in the past year including 2 pairs of large Advents with the metal baskets and 1 pair of Smaller Advents ) and have never had a problem with any of them. The 30 hz tone works well and of course, the advantage is that you do not have to cut away the dust cap. If you are comfortable with using shims, it probably is more accurate but as I said, all 3 of my Advent refoam projects came out just fine. You just need to be diligent and work patiently and carefully read the instructions ahead of time to get a feel what will need to be done.

 

As Kent said above, there are strong opinions for both the 30 hz tone method and the shim method. The 30 hz tone method is relatively straight forward and has worked well for me as the shim method has also worked well for others.

 

Good luck with whichever method you decide upon!

 

Regarding the freely moving cones and their tendency to allow the voice coils to hit if you tilt the baskets, this is normal if the foam diaphragms are not intact. Without the intact foam diaphragms in place , the cones will move very easily as only the flexible spider is holding them in place. Once you get your new foams attached, they will be alright and align properly. And, yes, the Advent cones are relatively thick (being a traditional acoustic suspension driver).

 

Dean

Correct, they are not "classic"  A-25 speakers.

 

As per my response above, they are A-25 Classics.

 

Please see the attached PDF s for more information.

 

 A-25 Classic.pdf   689.89K   39 downloads

 A-25 Classic Specs .pdf   1.08MB   35 downloads