about monacor tweeter dt254

[beat dis]

i made my first project.it is TL bookshelf d appolito loudspeakers with 2 monacor sph-130 al and one dt254.suond is generaly ok.but frequency response after about 5khz is going down,so its about 7db
quiet on 17khz,measured on 2.5 m distance (on 1m is almost flat).so,my question is.is it normal and if it is,what can I do to make flatter response on bigger distance?hm,maybe removing protection grid from speaker will make diference?

 

[mcmahon48]

that is very difficult at the speaker end

you have to remember that
1 the cone does not move uniformly
2 the further away the more resistance in more direction
3 the speaker inefficencies at change to a different frequency
4 the crossover is affecting the electrical flow
the best way to overcome this is through bi or tri amping
and also using a equalizer in loop with your amp and hopefully a high current amp for each 3db bass increase watts x 2 to n(3db) and if you tweeters have a very low impedance at certain frequencies it will draw more current due to the low resistance

 

[Rudolf]

... bookshelf d appolito loudspeakers with 2 monacor sph-130 al and one dt254.suond is generaly ok.but frequency response after about 5khz is going down,so its about 7db quiet on 17khz, measured on 2.5 m distance (on 1m is almost flat).so,my question is.is it normal and if it is,what can I do to make flatter response on bigger distance?hm,maybe removing protection grid from speaker will make diference?

hifi-selbstbau looked into the DT 254 two years ago. They found that the frequency response of an old pair of those drivers fell earlier than the new ones they had bought for the test in early 2007. So you probably were sold drivers of pre 2006 production.
Another aspect: The DT 254 should be flush mounted and needs to be listened on-axis. Listening 30° off-axis SPL will be down 7 dB at 17 kHz even for the new drivers. hifi-selbstbau did not test the influence of the protection grid.

 

[beat dis]

Re: that is very difficult at the speaker end

you have to remember that
1 the cone does not move uniformly
2 the further away the more resistance in more direction
3 the speaker inefficencies at change to a different frequency
4 the crossover is affecting the electrical flow
the best way to overcome this is through bi or tri amping
and also using a equalizer in loop with your amp and hopefully a high current amp for each 3db bass increase watts x 2 to n(3db) and if you tweeters have a very low impedance at certain frequencies it will draw more current due to the low resistance

i m allredy using biamping mode of my digital receiver and i was thinking of using some active filter or equliser,but in that case i have to use clasic analog distribution from my audio sources to receiver.

 

[beat dis]

Re: Re: about monacor tweeter dt254

hifi-selbstbau looked into the DT 254 two years ago. They found that the frequency response of an old pair of those drivers fell earlier than the new ones they had bought for the test in early 2007. So you probably were sold drivers of pre 2006 production.
Another aspect: The DT 254 should be flush mounted and needs to be listened on-axis. Listening 30° off-axis SPL will be down 7 dB at 17 kHz even for the new drivers. hifi-selbstbau did not test the influence of the protection grid.

its bought mounth ago in local store,so i dont know.tweeter is flush mounted and i measure it on 0 degree of axis.maybe using zobel will solve the problem?

 

[Rudolf]

Well,
if the tweeter measures quite right at 1 m, but falls off at 2.5 m - how much experience do you have with measuring other tweeters in your room?
If you don´t measure an impulse or step response but some kind of noise without gating, you could easily get a power response measurement instead of direct response at 2.5 m - which will affect high frequencies most.

 

[beat dis]

Well,
if the tweeter measures quite right at 1 m, but falls off at 2.5 m - how much experience do you have with measuring other tweeters in your room?
If you don´t measure an impulse or step response but some kind of noise without gating, you could easily get a power response measurement instead of direct response at 2.5 m - which will affect high frequencies most.

it's my first project and it is my first measuring at all.it's measured in living room.I was using behringer b1 mic,calibrated by manufacturer's frequncy response list,with pink noise in RTA software.so,you telling me that it is posible to have flater high frequence response in some diffrent room?