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K-69 vs K-69-A vs K-691


CANT
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I've done a good bit of research on these drivers but have yet to find what I was looking for...

 

What I know...

 

K69 = B&C DE75-8 P.Audio BMD750

K69A = P.Audio BMD750 *It would appear the "A" is a revision and was meant to replace the K69 fit/form/function. Driver may or may not have been modified? Driver was modified.

K691 = B&C DE75-? *Again it would appear the "1" is another revision. Driver is a new version of the DE75 and is definitely modded to some extent? This driver was at one point sold as an upgrade for the K69A but is now the std driver where applicable.

 

*At some point in the mix, the standard B&C DE75-8 driver appears to have been used without K69X/Klipsch badging per numerous images/eBay listings.

 

What I am curious about...

 

I have seen at least one person state that the B&C driver does sound slightly better than the P.Audio but this was in reference to a 2way setup. I have recently acquired a pair of 3way KPT-335 and was wondering if this driver might be an upgrade in my setup as well? The 2 drivers really appear to be very similar and this may just boil down to a personal preference but I would like to know what other people think. I am also curious if any one knows anything about crossover changes that might coincide with the K69 revisions. I have physically seen 2 iterations of the KPT-335 crossover (116663 Rev ? and Rev B) and the only difference I saw was board layout.

 

Thanks

Edited by CANT
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The K-69-A has good performance if crossed below 8-10 kHz, thus avoiding the ~13.8 kHz chattering.  I used this driver for a long time in my tri-amped JuBelle and the K-402-MEH. 

 

The K-69 was always a better-listening driver if using it full-range in the 10-20 kHz than the K-69-A...significantly better.  It was also significantly more expensive, IIRC.

 

The K-691 is slightly better than the K-69 it seems (both  the former reportedly B&C DE75 rebranded driver), but I've not had a K-69 to test directly against the K-691 to see and hear the differences. 

 

The issue with any 3-way design is the tweeter driver that is used and how it is crossed/EQed and most importantly time aligned into the loudspeaker.  Using higher order crossover filters, i.e., 12 dB/octave or higher, introduces negative (leading) phase shifts on the high frequencies relative to midrange that are audible.  Using lower order crossover networks between midrange and tweeter can result in a more seamless transition to HF without audible phase shifts due to the electrical crossover network or mismatched time delays due to physical misalignment of the apparent acoustic centers of the midrange to tweeter. 

 

I don't have any KPT-335 passive crossover networks to be able to answer your questions in that area.  I can tell you that the K-703 tweeter horn with unknown driver is not time aligned to the K-510 midrange horn with unknown driver--just by looking at how it's mounted.  There needs to be a step back of the tweeter horn/driver of probably 1.9+ inches or so plus the difference in depth of the K-510 and the K-703 horns (assuming 24 dB/oct passive crossover filters are used) relative to the K-510 and its driver to time align the horns/drivers.  The woofer-midrange looks like it is close to being time aligned within 90-180 degrees of phase.

 

Chris

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I don’t have time right now to transcribe it but the crossover is effectively...

 

LF input - 2nd order LP - Driver

MF input - 2nd order LP, 11ohm pad, LCR, 3rd order HP - Driver

HF input - 2ohm pad, 4th order HP - Driver

 

VC on the K70G/K703 and the K69A/K510 appear to be offset by only 1/4-3/8” which seems like at least a good start?

 

I did give these a shot in a 2way arrangement with just the K69A/K510 but it didn’t look anywhere near as flat as the 3way... 

 

 

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29 minutes ago, CANT said:

VC on the K70G/K703 and the K69A/K510 appear to be offset by only 1/4-3/8” which seems like at least a good start?

 

The alignment currently is probably "phase-aligned" at the crossover frequency, i.e., multiples of one full wavelength offset at 7 kHz. The wavelength at 7 kHz is 1.9" at room temp and std. pressure. Listen for dramatic changes in the apparent soundstage when moving the tweeter horn/driver backwards when they are aligned.

 

Chris

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I guess I’m kind of lost on the 1.9” cause I feel like final alignment would have more to do with the destination than the point of origin? I mean aren’t we mechanically talking about triangles and then acoustically talking adjusting that with phase? IDK, maybe I’ve had too many beers to be responding right now? I will say this sh!t can be fickle because I just changed the toe-in on the head and it has dramatically changed perception!

 

Center to center my speakers are rather close together at 80” I sit about 160” away... I previously had the heads toed in about 1.5” measuring from the edge of the cab back to the edge of the TM motorboard and have adjusted that, only slightly, to roughly 1.25”.

 

I guess my tought would be that you can only use any given theory to a logical mean but can’t really control the inevitable outcome... room/positioning

 

I feel like this has wondered off into left field...

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In the past, Klipsch tweeter-midrange designs have been phase aligned--like the Cornwall, Belle, etc.  I'm assuming that is also true for your current KPT-335s.  That's how I assume that the misalignment is probably 1.9 inches--or one wavelength at the crossover frequency.

 

Chris

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  • 4 weeks later...

I recently replaced the K-69-A drivers in my 402 JubScala IIs with new K-691 drivers, and noticed an immediate improvement in the sound, particularly in the higher frequencies.  The next day, they sounded even better, with cymbals sounding more realistic, but even the midrange sounds better now.  I'm glad I made the upgrade.

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12 minutes ago, Chief bonehead said:

...The k69a has an phaseplug diap spacing...

Were saying that the K-69-A has an increased phase plug spacing...?

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9 hours ago, Chief bonehead said:

K69 was a paudio driver. The k69a has a slightly decreased phaseplug diap spacing. K691 is the bnc 75 with a slight mod to the diap. 

 

Does that boost the HF response like the changes to the solder-terminal K-55-V?   How does that work?

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On 4/18/2019 at 10:46 AM, Chief bonehead said:

K69 was a paudio driver. The k69a has a slightly decreased phaseplug diap spacing. K691 is the bnc 75 with a slight mod to the diap. 

 

On 4/18/2019 at 10:47 AM, Chief bonehead said:

K69 and k69a are 2.75” diaps. K691 is a 3” diap. 

 

Thank you for the info

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For my part I will say that I did end up buying a preowned pair of B&C DE75s. I now know that they aren't exactly K691s but they were cheap and I was really only using them for testing purposes, so they are close enough.

 

Switching back and forth was a HUGE hassle and I really wanted to enjoy my new speakers so I only did so much testing but here are my notes:

 

*The K69A had significantly more energy/output above, we'll say, 5K... I don't remember the exact #. This would absolutely affect the crossover design so right off the bat I would say that the K691 isn't a plug and play replacement in this application. This increase in output/energy had a definite impact on the driver assessment in a 2way setting.

 

*I didn't much care for the K69A in the 2way test. It needed a lot of EQ for the response to flatten out and to start sounding ok.

 

*The DE75 absolutely looked/sounded better than the K69A in the 2way test but after all was said and done, I preferred the 3way... 

 

*I did try the DE75 out in the 3way but didn't like it as much as the K69A but that is to be expected since the crossover network was designed for use with the K69A. With a corrected network it would likely work fantastically but I'm not going to get into all that at this time.

 

*KPT-335 with stock drivers was my preference at the end of the day. Though I did make one change... I'm guessing that because this speaker was designed to be place behind a screen the tweeter was left a bit on the hot side, so I replaced the 2ohm pad resistor in the tweeter circuit with a 4.5ohm I had lying around.

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20 hours ago, rockhound said:

What about the DE75  vs the K691 in a 2 way test? What do you mean by "close enough"?

 

Per the Chief, the K691 is a DE75 with a slight mod to the diaphragm... though not confirmed, what I’ve heard is that the diaphragm is hardened? I’m not sure exactly how that affects the output/response of the driver but the DE75 is a fairly well regarded driver in its own right so for my purposes I considered it close enough.

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Something else I forgot to mention... while I was playing around with the 2way setups I did also test out a few different crossover configurations/points... again, the stock 800-900ish Hz won out. I absolutely did not care for the output when either driver was pushed to the horns 500Hz limit.

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