Low volume on one of two speakers

[rprinkle]

What could cause one of my homemade three way loudspeakers to have reduced volume?
I'm pretty sure it is the speaker because when I swapped the pair out for another set of speakers there was no problem. I'm not sure when this happened. The speakers are 20 years old but worked fine at one time. When I built them I tested all the drivers with decibel meter and frequency generator.

 

[TLS Guy]

What could cause one of my homemade three way loudspeakers to have reduced volume?
I'm pretty sure it is the speaker because when I swapped the pair out for another set of speakers there was no problem. I'm not sure when this happened. The speakers are 20 years old but worked fine at one time. When I built them I tested all the drivers with decibel meter and frequency generator.

You need to find out which driver has the reduced output.

The most likely issue is that you have a non working driver or one with reduced output. The most common cause is over driving causing shorted turns in the driver voice coil.

If you find the driver, or driver with reduced output, then you need to remove that driver from BOTH speakers. Now compare the DC resistance of both drivers with an ohm meter. The damaged driver will have a lower DC resistance than the good one. The driver will then need reconing or replacement.

The other possibility is cap failure since your speakers are old. This would only affect the midrange or tweeter. These would be the only drivers with caps in series with the VC.

If the drivers check out OK, then this as almost certainly the problem. The DATS V2 loudspeaker tester can also check your drivers, caps, inductors and total speaker system.

Since you are into home speaker building then this is really an essential part of your tool kit.

Without the DATS V2 then you would just have to recap the crossover "blind" and hope for the best.

However with an ohm meter and DATS V2 you will be able to find the problem precisely and easily.

I am always plugging this, but almost all members here invest large sums in their gear but virtually nothing in test equipment.

However in this hobby investing in test gear and learning how to use it is actually part of the basics.

 

[rprinkle]

Thank you for your reply. Sadly, these were my first and last speaker builds so my equipment and expertise are now very limited. That being said I feel your info is spot on and will be working on your suggestions.

 

[rprinkle]

Solved it. With more help from a local audio guy. To see if it was the crossover or driver I switched each driver to the other speaker box. Thought the problem moved but still wasn't sure. I played a CD with some high frequencies, put my ear close to each driver. Thought it was the tweeter. Still not sure. Touched the cone. One was moving the other wasn't. I did try TLS Guy's suggestion measuring resistance but I did not try it on the tweeter. Should have done his test for on the tweeter.

 

[TLS Guy]

Solved it. With more help from a local audio guy. To see if it was the crossover or driver I switched each driver to the other speaker box. Thought the problem moved but still wasn't sure. I played a CD with some high frequencies, put my ear close to each driver. Thought it was the tweeter. Still not sure. Touched the cone. One was moving the other wasn't. I did try TLS Guy's suggestion measuring resistance but I did not try it on the tweeter. Should have done his test for on the tweeter.

I'm a little confused by your post, but I think you are trying to tell me that one of your tweeters has failed.

So test it with your ohm meter. If it is not working it will be open circuit and resistance will be infinite. You should confirm this.

What is the tweeter? It is likely NLA now.

Do you have the circuit for the crossovers? If not are you able to take one out, look at it and draw the circuit out?

If you, and the tweeter is NLA then another tweeter will need to be selected and the crossover modified. You will need to replace both tweeters and modify both crossovers. I can hopefully redesign the crossover for you and help select another tweeter. I will also need to know the other drivers in the speakers.

If this is not possible and your current tweeters are NLA then it is likely the end of the road for those speakers.

 

[rprinkle]

I checked the tweeter it's a gonner and no longer available. Dynaudio D-28/2 TH, Mid Eton 4-300 25s HDEXy, Woofer Seas Excel 8" W21 E002 E0012 8ohm. I've added a photo of the crossover with some of the values I could get. Don't remember inductor values.
Thanks for your help.

 

[TLS Guy]

I checked the tweeter it's a gonner and no longer available. Dynaudio D-28/2 TH, Mid Eton 4-300 25s HDEXy, Woofer Seas Excel 8" W21 E002 E0012 8ohm. I've added a photo of the crossover with some of the values I could get. Don't remember inductor values.
Thanks for your help.

That is interesting. May be those Dynaudio tweeters are starting to fail now. I had a Dynaudio D21 AF recently go open circuit.

Now you are in luck as there is a tweeter that is a direct replacement for your Dynaudio. You will though need to replace both tweeters. I have used this Scanspeak tweeter as a direct replacement for those 1" older Dynaudio domes. They were very good tweeters.

This Scanspeak has an almost identical acoustic response and above all impedance curve. Although the impedance of your tweeter is nominal 6 ohm and yours is 8 ohm, if you look at the impedance curves they are virtually identical. These tweeters were built at a time when the leadership of Dyanudio had a falling out and both Scanspeak and Morel came into being. I suspect your tweeter and the Scanspeak I recommend may well have had the same designer.

The sensitivity of the Scanspeak is 1 db less but you will not notice that.

Although that Scanspeak is pricey, so was the Dynaudio D28/2 in its day.

This is by far your cheapest solution as there will be a lot of expense reworking your speakers for a tweeter that is not in effect a direct replacement.

 

[rprinkle]

That looks like the way to go. Thanks again for your help. Greatly appreciated.