crossover help etc...

[Tristen]

So i'm looking at making a loudspeaker with a fullrange and a ribbon tweeter (these, to be exact (see below ))

https://www.madisound.com/store/product_info.php?cPath=45_229_236&products_id=8360

Fountek NeoCD3.0 ribbon tweeter
Impedance: 7 Ohm
Sensitivity: 95dB/M/W
Frequency response: 1,400~40,000Hz
Resonance frequency: 400Hz

https://www.madisound.com/store/product_info.php?cPath=45_241_307&products_id=8817

Fountek FR135EX 5" Full Range

EDIT:
I guess for a couple extra dollars i could put a fostex fullrange in it so it would be loud enough on 5wpc. then i could use the fostex design and throw my ribbon on top with an open baffle

FE206En 8" fullrange

I'm wondering where to put the crossover. I'm want to keep the crossover higher than vocal range, definitely, but i don't know what type of crossover to use or where to put it... or other things i might need to know about building my box before i start designing the enclosure and stuff.

also, to match sensitivity and make the tweeter 8 ohms (since it's 7) how would i attenuate it? would i add a 1ohm resistor and then put the attenuation before it?

any help would be greatly appreciated.

 

[elnaldo]

Hi,

It seems those are not a very good pair of drivers for a 2 ways... that full-range is designed to run up to 26000 Hz, higher than most of the tweeters around there, and more than what you will hear. Look at your amp specs, it's response is probably up to 20000 Hz, so it seems you don need a tweeter with this driver.

If you want to use it as a regular mid-woofer (freq response lets say up to 4000-5000 Hz), so the sensitivity is an issue. Your tweeter is 95dB and the woofer 85.1dB. there are 10dB difference. You'll need to attenuate the tweeter a lot to match the woofer. I would choose a more efficient woofer, to get a more efficient speaker. You need to calculate an "L-pad" or get one. you can use a 7 ohm tweeter with an 8 ohm woofer.

Regarding the xover point, 2500 Hz is a regular xover point for 2 ways (the tweeter manufacturer recommends this 2500Hz as xover point with 3rd order xover), but with this full-range driver you could go for a 3 ways xover point, and cross them at 4000-5000Hz or higher.

Anyway I think you don't need a tweeter here, You are crossing a tweeter capable to go down to 2500Hz with a full-range able to go up to 26000 Hz. I would add a sub-woofer instead.

with this budget, I would choose a DIY kit, already calculated and matched.

Of course, more knowledgeable people will give you some better advice.

Good luck

 

[MunkeyQ]

The fullrange + supertweeter combo is fairly well tried and tested - the aim is to keep one driver covering the majority of the vocal range whilst using the supertweeter to fill in the highest octaves. All but the most exotic fullrange drivers have trouble getting past about 13-15khz without getting beamy and sounding a tad "grainy" IMO.

I'd suggest trying a steep xover slope with an L-pad at about 10khz, allowing the all important vocal octaves to be well outside the xover slope and avoiding the breakup mode seen ~11khz on the FR plot. The supertweeter will seem to be doing very little, but you should notice it filling in the highest freq. information.

 

[Tristen]

So something like a LR2 would work, flipping one pole so the speakers are in phase?

 

[Tristen]

I guess I should mention that I have an rh84 tube amp to drive these (which is why I was wondering about the impedance of the tweeter since my output transformers are set up for 8 ohms)

 

[elnaldo]

All but the most exotic fullrange drivers have trouble getting past about 13-15khz without getting beamy and sounding a tad "grainy" IMO.

Good to know that. Perhaps some future DIY project

 

[bakes]

The fullrange + supertweeter combo is fairly well tried and tested - the aim is to keep one driver covering the majority of the vocal range whilst using the supertweeter to fill in the highest octaves. All but the most exotic fullrange drivers have trouble getting past about 13-15khz without getting beamy and sounding a tad "grainy" IMO.

I'd suggest trying a steep xover slope with an L-pad at about 10khz, allowing the all important vocal octaves to be well outside the xover slope and avoiding the breakup mode seen ~11khz on the FR plot. The supertweeter will seem to be doing very little, but you should notice it filling in the highest freq. information.

:tresbon: Good thoughts right there. You want to get the noted breakup node out of the way, so you could either notch it out or cross over the tweeter around 8khz, maybe w/ a 24 dB/oct L/R filter.

 

[bakes]

I guess I should mention that I have an rh84 tube amp to drive these (which is why I was wondering about the impedance of the tweeter since my output transformers are set up for 8 ohms)

No worries re the ribbons - they're almost a purely resistive load so your tubes will be happy with them set at 8 ohms.

 

[shelly_d]

Just ran some calculations for you. You will need a 10.5 dB pad on the tweeter to equalize the levels. The actual calculations work out to 10.48 so if the pad is not exact it may be better to err on the low side rather then the high. This should be designed as a 7 ohm pad, not an 8 ohm. Your amp will not be unhappy with a 7 ohm load on an 8 ohm tap for part of the frequency spectrum. Its when impedance falls much below the tap that it might become a concern.

These figures were worked out taking both the difference in impedance and the difference in sensitivity into account.

Hope this helps.

Shelly_D

 

[Tristen]

:tresbon: Good thoughts right there. You want to get the noted breakup node out of the way, so you could either notch it out or cross over the tweeter around 8khz, maybe w/ a 24 dB/oct L/R filter.

So a fourth order LR filter ^_^ somewhere around 8-10khz. sounds like a plan

Just ran some calculations for you. You will need a 10.5 dB pad on the tweeter to equalize the levels. The actual calculations work out to 10.48 so if the pad is not exact it may be better to err on the low side rather then the high. This should be designed as a 7 ohm pad, not an 8 ohm. Your amp will not be unhappy with a 7 ohm load on an 8 ohm tap for part of the frequency spectrum. Its when impedance falls much below the tap that it might become a concern.

These figures were worked out taking both the difference in impedance and the difference in sensitivity into account.

Hope this helps.

Shelly_D

sweet. I really appreciate the input.



to the internet... for more research, now that i got a good idea of what i'm doing now

 

[Tristen]

I guess for a couple extra dollars i could put a fostex fullrange in it so it would be loud enough on 5wpc. then i could use the fostex design and throw my ribbon on top with an open baffle

FE206En

 

[shelly_d]

I guess for a couple extra dollars i could put a fostex fullrange in it so it would be loud enough on 5wpc. then i could use the fostex design and throw my ribbon on top with an open baffle

FE206En

Blows my pad calcs to hell in a hand basket :stupid::sadwave:

 

[Tristen]

Blows my pad calcs to hell in a hand basket :stupid::sadwave:

:tears:

(p.s. i really appreciate the help... i'm one to waffle on ideas for a bit... a little ADHD in my own thought process, if you ask me.)

 

[shelly_d]

:tears:

(p.s. i really appreciate the help... i'm one to waffle on ideas for a bit... a little ADHD in my own thought process, if you ask me.)

Actually its ok. It inspired me to create a spreadsheet to do this sort of thing on a regular basis. I PM'd the caretaker of the Digital Docs archive to ask if they want to put it up there.

Shelly_D