Tuning a pair of JBL ATX 60

[gabrielbecheanu]

Hello
I would like to try this summer to make a pair of Andromeda speakers Tony Gee project (hope to find his contact address) but until to start this project I want to tune up my speakers a pair of JBL ATX 60. A friend told me that JBL use in this speakers, cheap Audax drivers specially made for JBL.
Have anyone some idea how to do this, what kind of drivers to use? I would like to change only the 4” midranges and tweeters driver, I want to keep the woofer and I don’t want to modify the drivers hole. If I don’t like the changes I would like to put back the original drivers.. How to modify the crossover?

Thanks.

[justblair]

I'm no expert on this, but I a learning.

I think that your first port of call is to map your crossover. Find out what components you have in there and then you can research your choices.

Capacitors, inductors and resitors can all be replaced with better quality items. How much improvement that makes I cant make you any guarantees. I just replaced the electrolytic caps in mine with higher quality ones only to find it made a difference to the sound, though It wasn't the most cost effective mod I have done.

On the smaller cap values you can replace with polyester items. Companies market "audio" grade replacements for a lot of these. I am waiting on a couple of these which should be here any day. I will report my results in this thread...

My mission 753 thread

Other crossover recomendations (non speaker specific) are to replace the inductors with good quality air core items. Of course you need to know the values of the origional probably iron/ferrite core inductors. Meters can be bought pretty cheaply now to determine these values. Something that you might find handy in later projects.

The other mod that I have found to work on my missions, and know is well reckoned for other brands of speakers is to dampen the speaker baskets. There are various methods of doing this some reversible some not that use modeling clay, "no more nails" (what I used) or other materials. I like this one a lot. Metal pressed baskets add colouration to the output of the speakers, greater clarity can be achieved for a very modest outlay.

If you are thinking about replacing the drivers anyway I would try this mod first. You might just find you like them enough to keep them. And finding replacement drivers is not just about finding one that fits the whole. All sorts of other factors must be taken into account. Your speaker is built around the drivers properties. Finding another with exactly the same properties is not easy.

I found that for £3 in no more nails I made far more improvement than spending 10 times that in caps. I may feel differently when my sonicaps arrive.

I know my advice is not specific to your speakers, but it might give you some ideas

Blair

[gabrielbecheanu]

Justblair Thanks for the replay. What you told me it was in my mind also, For the beginning it will be the first thing to do, replace the capacitors and other stuff on the crossover, but if I don’t se any improvements I would like to replace the driver or maybe to keep the existing driver and made another crossover. The problem is that I don’t know the specs for this drivers. The speaker cabinets have 66l after I made some calculation These are the dimensions (H-950, W-286, D-315mm ant the material have 16mm) . If someone knows more about the driver use in this speakers I would like to send me the specifications to made a better crossover.

[gabrielbecheanu]

Hello
This is the crossover schematic diagram. The drivers of these speakers have this impedance, woofer 6ohmi midrange 6ohmi and tweeter 8ohmi. Crossover frequency 800/3500Hz. I will try to make another crossover to see the difference. if is one. I will waiting for suggestion.