Frankdorn

iTrader: (7)

I have two sets of Polk DB 6.5" components for my 2GS...one set is missing the tweeters, though. So I picked up some MB Quart QM 13 HX 1” tweeters in the classifieds, from what I gather these come from the DSE216 component set.

Which tweeters would sound better so I know to put those in front?

I think the impedance is different (6 ohms for the MB Quart vs. 2 ohms for the db's ??) so I'm not sure if I can even use the MB Quarts... Any knowledge here would help!

Percy

Quart tweeters are always bright, even with the most padded setting on their dedicated xover. This is due to the ringing effects of the titanium dome. Hard dome tweeters have this nasty problem. I've had the HX25, 218.03s, 160.03, 150.02, etc etc and sold them all for Dynaudio products.

They (MB Quart) sound good at first, but they get tiring very quickly.

If they have Dynaudio tweeters, you'll be very happy, that's if you're after accuracy.

Frankdorn

iTrader: (7)

I really wanted Focals, Rainbows, or Dynaudios, but work cut hours this year so...

Will it hurt anything to hook up the MB Quart tweets to the Polk crossovers to try 'em out?

scooter58

iTrader: (2)

u can hook them up to polk crossover,

why would the mb quartz tweeter be 6 ohm?

GSteg

iTrader: (15)

The tweeter is 6ohm just because the design eventually landed it that way. There is no rule that they have to be 2 or 4ohm, just like the JL Audio W7s

Hooking the MBQ tweeters to the Polk crossover will change the crossover frequency. Usually it wont sound good because the points were specifically picked for the polk tweeters.

lev00221

iTrader: (28)

Frankdorn,
You should keep the Polk tweeters, crossovers and woofers together as a set. That is what will give you the best sound. Whether or not the MB Quart tweeters are better or not is not the question. The question should be what will blend better and give you a more seamless transition at the crossover point. The answer to that is the Polk tweeters since they were designed with the crossovers and the woofers in mind. It would be hard to improve upon what many engineers spent many hours working on.
Good luck!

Stormforge

+1, absolutely correct.

mitsuguy

iTrader: (2)

one other note no one picked up on... part of a crossover design takes into account the impedance of the speaker to be used with said crossover... if the Polks were 2 or 4 ohm, then that crossover was designed for 2 or 4 ohm speakers... being the Quarts are 6 ohm, not only will the crossover frequency be wrong for the Quart tweeters (because the crossover was not designed for them), but the impedance change would also screw with the crossover frequency...

Big Mack

iTrader: (1)

Looks to me like 2 other people picked up on it and gave a good reason for not using a different impedance tweet with the crossover...

These two sentences mean almost exactly the same thing, but it doesn't make it any less correct. Essentially, when you use a different impedance it will raise or lower the crossover frequency. For example, if you go from a 4 ohm tweet to an 8 ohm tweet but want to keep the same value for crossover, you would halve the capacitor value (for 1st order). If you use a 6 ohm tweet, you've effectively raised the crossover point by a half octave. This is not necessarily bad if it's standalone. In a component set, though, it means there may be a hole in the response since the woofer's crossover point hasn't changed, and that might lead to sounding worse. Lev covered that in his post, too, and he's dead on.

Big Mack

mitsuguy

iTrader: (2)

I hate to be as picky as you when reading posts, but I can be... no one except me mentioned the impedance difference... Many times, a tweeter of the correct impedance can be substituted on a different component set, so long as that tweeter has a frequency response range that covers what it will be asked to reproduce. However, when you go changing impedances, you change the original crossover frequency altogether...

I'll give you a "for instance"

Lets assume Brand X has a crossover frequency of 4000 hz and runs an impedance of 4 ohms... If Brand Y's tweeter has a frequency response of 2500 hz to 20khz and is 4 ohms, then there is a good chance you can substitute the tweeter and it sound just fine... However, if Brand Y's tweeter is a different ohm load, then it changes the crossover frequency completely... I'll be a little more specific than what everyone else said (cause everyone basically said "it wont work well because it wasn't designed for it), which is correct, but not specific... The real info is that if a crossover was designed as mentioned at 4000 hz, that the woofer will cross over at 4000 hz because its at 4 ohms, where the crossover was designed at, but, because the impedance has been raised to, say 8 ohms, then it will act like a higher frequency crossover, leaving, as Big Mack mentioned, a hole in the frequency response....

Big Mack

iTrader: (1)

No worries, mang. No harm intended, either.

I liked your example, too. Reinforces the point quite nicely.

Big Mack

GSteg

iTrader: (15)

...And thus why I like my active crossover I use to swap tweeters and drivers all the time and I'd have to build new crossover networks to accommodate the changes in impedance, xover freq, octave etc.