Tizman

Thanks again. I’ll try them out and report back.

Thanks again for all the replies. I picked the JBLs up today.

Are you referring to the JBLs or the Altecs? The Altecs have a dropping HF tesponse, and will require a passive that helps to correct this. There are a couple of crossovers schematics available online that will do this. If you are referring to the JBLs, I honestly don’t have a clue how to go about correcting for this passively.

As in silly to worry about it? I'm a bit obsessive-compulsive, and I worry. (For example, ODS123 has me thinking about rebuilding my La Scalas in MDF.) Also, a pair of Altec 806-8a CDs has come up for just a bit more money locally, so now there is also competition for my hard earned money. I think I need to drink more...

This is certainly true. That said, I am mostly a tube amp builder, and I am out of my element with speaker building. This explains the dumb questions. That said, I am looking at buying a pair of used CDs, that will not be returnable, and that have been measured by the vendor for DCR. They don’t measure closely, so I was hoping to get a quick answer as they are being offered for sale locally and I would like to get them quickly, before they are sold to someone else, assuming the DCR difference on its own is not a concern. Matching DCR seems to be a selling point online, and these don’t match well...

babadono and pzannucci: Thanks for clarifying this for me!

babadono: There is almost no info whatsoever (that is searchable with Google) on the matching of compression drivers. It appears that your last post is intended to be sarcastic, so do you have different information or experience with this topic? If so, please share, as I have been unable to find anything else on the subject. Thanks!

Thanks for the reply. I am supposed to be picking up a pair of JBL 2425J drivers tomorrow that measure 6.8 and 7.5 Ohms. These are 16 Ohm drivers, so both numbers seem a bit low, and there is a .7 Ohm difference between them. This is much more than 5%. They are a good deal, but if I need to replace diaphragms, they won’t be. I have this question posted on DIYAudio as well, and this was the response... “DCR doesn't help except to tell you if you have an open or dead short. DCR is not useful at all in matching drivers otherwise. I think it's probably also true you could use DCR as a very rough guage of having a good or bad driver. Like, if it's 0 ohms, send it back, if it's infinite send it back. If it's 4 Ohms +- 0.5 Ohm it's probably worth more rigorous testing. When drivers are matched, you want the acoustic output and impedance chart. Not a lot of hobbyists do this, especially since they usually can't afford enough drivers to find pairs that match better than others. If you buy 200 drivers however, you measure each one and use a computer to find the one's that are closest. Of course, some manufacturers have tighter tolerances than others, so you may discover after measuring a few that matched pairs is too much effort. As a hobbyist, you buy 2 drivers, and hope for the best, but!! What you can do is measure each driver and attempt to design a custom crossover for it. You can use something like XSim to show you how each driver would work, and compare to see if there is enough of a difference to tweak the crossover in each speaker. It sounds like this could be fun. I have read of some manufacturers claim they do this for every single speaker. “

Hi All. How important is DCR matching, the type done with an average DMM, in pairs of mid/high compression drivers? Pairs of compression drivers are sold online all the time that are measured this way and presented as matched for sale. Is this sort of measurement any indication of actual matching with respect to frequency response and SPL matching? If it is, how close do two compression drivers have to be in this DCR measurement in order to be considered matched? Also, if the drivers are mismatched, how do you go about matching them? Thanks in advance for your replies!

Thanks YK Thom.

Hi All. I’m about to pick up a pair of JBL 2425J compression drivers, and was wondering if anyone has any experience with them with respect to SQ. The seller doesn’t know if they contain aluminum or titanium diaphragms. Any information or opinions you may have would be much appreciated.

Okay, I’m done for real this time. Counter-trolling isn’t that interesting after all. Time to start building stuff. I’ll see you all in the other threads, where I’ll be asking questions and learning from the many of you that know more than I do, rather than telling anyone what’s what. Bye ODS123! Congratulations on this monster thread. It’s been fun, kind of...

It's more like a traffic jam. Lots of honking and wasted energy, but no one is going anywhere.

Sounds like a monologue waiting to happen.

If not, the OP might want to moderate.

Most generous of you! Will you also police spelling and grammar?

Good idea.

How about a crossover resistor shootout? I don’t think anyone has done one of those yet. ABX tested of course, but this time with a proper all horn speaker.

Good luck getting an answer from ODS123. Maybe if you intentionally misspell something?

Here’s a comprehensive capacitor comparison... http://www.humblehomemadehifi.com/Cap.html

Boring, annoying, and repetitive. Did I spell everything correctly? ODS123, please feel free to correct my spelling and grammar if you see any errors. A speaker capacitor shoot out would be interesting. Any thoughts OSD123?

Because they don’t sound the same. Thanks for proving my point.

In real world applications, amplifiers don’t all sound the same. Deb is right.

Glens: ODS123 is all about conclusions looking for supporting evidence. The point is that the “Challenge” equalizes differences between amps before allowing participants to take the test. That means, irrefutably, that the amps tested don’t sound the same in the real world. The Guadalajara test used speakers that were not designed for the way they were used in the test. Conclusions looking for supporting evidence, unsuccessfully. Not very scientific either.

Sure, lots of people brought their Klipschorns, La Scalas and Klipsch Pro gear with them in their cars to do the test. All horns and no DRs, remember? HaHa! The Guadalajara test used a low sensitivity, all DR, nearfield monitor for the test but, incorrectly, not in the nearfield. Wrong again! Haha.