juniper Posted December 9, 2015 Share Posted December 9, 2015 Just bought some 4002's and they are 16ohms, read on the Tad site that is how they come. then I read that Radian makes an 8 ohm fram for these drivers. Are most using 16ohm 4002's with their jub setups? Thanks Quote Link to comment Share on other sites More sharing options...
Chris A Posted December 9, 2015 Share Posted December 9, 2015 The TADs that I believe everyone is using on Jubs are "16 ohm". They have a minimum impedance of about 11 ohms at 600 Hz and from 4-10 kHz, and a maximum of about 35 ohms at 1100 Hz while mounted on a K-402 horn. They are easy for even high output impedance tube/valve amplifiers to drive without having to worry about re-EQing the output due to load coupling. I've read not much that is positive about the replacement Radian diaphragms, I'm afraid. They'll work, but they won't sound anywhere near the same--according to everything I've read. Chris Quote Link to comment Share on other sites More sharing options...
juniper Posted December 9, 2015 Author Share Posted December 9, 2015 (edited) Thanks Chris I used the radian as an example of my confusion, being they make an 8ohm fram for this driver. Just had the seller measure up a few with a meter to match a pair, the numbers seem low for a 16ohm unit. Most are between 7.1 and 7.8 in matched pairs.. Is 7.1 to 7.8 normal readings for this setup? Edited December 9, 2015 by juniper Quote Link to comment Share on other sites More sharing options...
babadono Posted December 9, 2015 Share Posted December 9, 2015 DC resistance(measured with a meter) and AC impedance are/can be different. All the meter is telling you is the voice coil is not open(blown). Quote Link to comment Share on other sites More sharing options...
mark1101 Posted December 9, 2015 Share Posted December 9, 2015 I just checked and mine are 16 ohms. Quote Link to comment Share on other sites More sharing options...
juniper Posted December 9, 2015 Author Share Posted December 9, 2015 DC resistance(measured with a meter) and AC impedance are/can be different. All the meter is telling you is the voice coil is not open(blown). Thanks Babadono, I just read that companies spec their ohm readings all over the map as far as "what they should read" Quote Link to comment Share on other sites More sharing options...
juniper Posted December 9, 2015 Author Share Posted December 9, 2015 I just checked and mine are 16 ohms. Thanks Mark1101!!!! Quote Link to comment Share on other sites More sharing options...
whatever55 Posted December 10, 2015 Share Posted December 10, 2015 How critical is using the correct settings for a crossover ? Say I have a crossover designed for the k69, I have a 7 band EQ in my pre amp. Will that give enough adjustment range ? Thank you. Quote Link to comment Share on other sites More sharing options...
Chris A Posted December 10, 2015 Share Posted December 10, 2015 I've not tried that before. If you look at the active crossover settings for a K-69-A and a TAD TD-4002, you might notice how many fewer PEQ filters are needed for the TAD. If you have a passive crossover that has been designed with that many reactive elements to approximate the settings for a K-69-A active crossover, then it will have a fair amount of both frequency-based amplitude and phase shifts associated with it. You can certainly try it. The worst that it may come to is that you might later wind up removing some elements in the passive crossovers to simplify their operation for the TADs, and use your EQ for the rest. The impedance of the TADs are higher than the K-69-As, so the crossover filter to the bass bin might need to be readjusted. Chris Quote Link to comment Share on other sites More sharing options...
mark1101 Posted December 10, 2015 Share Posted December 10, 2015 How critical is using the correct settings for a crossover ? Say I have a crossover designed for the k69, I have a 7 band EQ in my pre amp. Will that give enough adjustment range ? Thank you. I use ALK ESNs with no EQ in the network. I have a DBX 1231 EQ that takes care of all EQ. This setup has been a dream for many years as I can change drivers to my hearts content and it is very easy to re-EQ. Highly recommended. This solution was tested by Roy at Klipsch and while it is not exactly as accurate as his specific settings in a programmable digital active crossover.........its very close. My recommendation is to get networks with no EQ and use outboard EQ as I have described........for an passive analog solution. When I A/B vs. my active digital setup there is virtually no difference whatsoever. Quote Link to comment Share on other sites More sharing options...
Fjd Posted December 10, 2015 Share Posted December 10, 2015 (edited) Thanks Chris I used the radian as an example of my confusion, being they make an 8ohm fram for this driver. Just had the seller measure up a few with a meter to match a pair, the numbers seem low for a 16ohm unit. Most are between 7.1 and 7.8 in matched pairs.. Is 7.1 to 7.8 normal readings for this setup? DC resistance(measured with a meter) and AC impedance are/can be different. All the meter is telling you is the voice coil is not open(blown). I'll try to expand on babadono's post since I ran across this conundrum when I first started messing with compression drivers wondering why my measurements were approximately half the published rating. In general, I believe that many confuse the typical relationship of the nominal impedance of cone drivers such as woofers used as direct radiators that has basically been a rule-of-thumb of 1.25x the direct current (DC) resistance (~ 6 Ohm DC resistance for an 8 Ohm nominal impedance woofer). Whereas, the nominal impedance of compression drivers used on horns has traditionally been about 2x the DC resistance (~ 8 Ohm DC resistance for a 16 Ohm nominal impedance driver). I fully realize that there are exceptions to the 2x rule-of-thumb as I have certain compression drivers that are 16 Ohm nominal impedance that measure 11 Ohms DC resistance. My TAD compression drivers and all of my JBL compression drivers have typically measured a direct current resistance (DCR) of approximately one-half the ‘nominal impedance’ of the compression driver, with the TAD TD-4001 and TD-4002 being approximately 7.8 Ohms DCR with a rated nominal impedance of 16 Ohms. I generally think of nominal impedance somewhat like an “average” value over a range of frequencies, since the impedance of a speaker driver can vary greatly by frequency as demonstrated in various impedance curves. From all of the above, the important aspect that I now remind myself is that the impedance (Z) of a compression driver is not identical to DCR measurement. When measuring DCR with a simple Ohm meter we are basically measuring the DC resistance of the wire used in the voice coil. Essentially, we are measuring the voice coil resistance at a resting state without a music signal and no other components attached. I find that DCR measurements are good for verifying continuity of the voice coil and for comparing speaker drivers when initially trying to match pairs. When measuring impedance think of this as alternating current (AC) resistance instead of DC resistance. Generally, I believe that the term impedance is used when the voice coil starts moving as an AC music signal is applied. The AC resistance measurement will vary with frequency (and other factors such as inductance and capacitance; along with any motor force and mechanical losses in the driver assembly) in what becomes the impedance curve of the speaker driver. Here are a couple of examples and links to the full spec sheets, which also include impedance curves for a specific compression driver / horn combination; from a time period when JBL used to publish nominal impedance, minimum impedance (measured at 5 kHz) and DC resistance for compression drivers. JBL 2447 compression driver DC resistance of 4.3 Ohms (8 Ohm nominal impedance driver) and DC resistance of 8.5 Ohms (16 Ohm nominal impedance driver) http://www2.jblpro.com/pub/components/2447.pdf JBL 2426 compression driver DC resistance of 3.3 Ohms (8 Ohm nominal impedance driver) and DC resistance of 6.5 Ohms (16 Ohm nominal impedance driver) http://www2.jblpro.com/pub/components/2426.pdf . Edited December 10, 2015 by Fjd Quote Link to comment Share on other sites More sharing options...
juniper Posted December 11, 2015 Author Share Posted December 11, 2015 Thanks FJD!!! That info explains a lot!!!! Thanks again all for the help!!!! Cant wait to hear the 4002's..... Quote Link to comment Share on other sites More sharing options...
jorjen Posted December 11, 2015 Share Posted December 11, 2015 Thanks FJD!!! That info explains a lot!!!! Thanks again all for the help!!!! Cant wait to hear the 4002's..... You are in for a treat! I LOVE the TD-4001's in my Jube Clones. TAD drivers are exceptional. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted December 17, 2015 Share Posted December 17, 2015 So how are the TAD drivers? have you tried them yet? Quote Link to comment Share on other sites More sharing options...
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