Cjd mtm Abouriou

[steelervic]

hi, i have been listening to them for several months, they sound good but are just to bright for me. i built them with the silk rs28f tweeter using the rs28a crossover. any ideas on how to bring the tweeter level down a bit?
thanks


i don't know how to add the crossover diagram so here is the link

http://www.divine-audio.com/abouriou/150-28network/

[fbov]

I'm seeing two options
- use very low DCR coils for LM1 and LM2 to reduce parasitic losses from series elements on the RS150 side of the XO
- Increase RT1, the series resistor on the tweeter. Note that this will change overall tweeter load, and so the more you add, the more the FR curve will have unanticipated changes.

What gauge/DCR did you use for those inductors? There's a 4x difference in DCR between these two 1.2mH coils, and a 15 ga. is recommended. The 0.25mH coil offers much less reduction in DCR, so I'd ignore it.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=255-102

http://www.parts-express.com/pe/showdetl.cfm?partnumber=255-254

Short term, use your tone control. No effect for level between 28A and 28F, just a flatter top end. I've used both and the issue I find is sensitivity variation; perhaps you got a hot pair.

Have fun,
Frank

[steelervic]

thanks for the fast response. the 1.2 has .57 dcr. it looks like rt1 is the last component, can i add a resistor in the + line going to the tweeter? what ohms should i try? what effect will the fr curve change have? i used the 28f in my natp build and its great. when comparing them at the same volume using a/b the natps are not fatiguing at all, the abouriou make me wince.

[fbov]

$10/side isn't cheap, but it's the least invasive change and you lose 0.43 ohms of power dissipation on the woofer, about 10% or 0.5dB (I think). They get louder to match the tweeter.

I was advised to put a 20 ohm in parallel with my RS28 to bring it down 1dB, but I was working with a measurement system and saw the FR shape change in subtle ways in addition to tweeter level change. I'd suggest replacing the 1 ohm RT1 with a slightly higher value. Assuming you don't have a lot of extra parts, you can pull RT1 from one speaker and put it in series with resistor in the other to make a 2 ohm padding resistance and see how it sounds. Yes, from the positive of the tweeter to the positive of your XO will do just that.

Best of luck,
Frnak

PS the best idea may be to PM cjd...

[cjd]

It might work to add small series impedance in front of the tweeter network. That won't alter what the network sees so will be a little more benign. It's not super sensitive to changes after but I'd have to go back and verify to be confident though. It's been too long since I've done anything with that design.

[---k---]

Also, don't discount room positioning and stuffing. If you push them back towards the wall they will pick up more bass and may even out. Also, pointing them straight ahead instead of pointing at you will give you more off axis and roll the top off more. So, if you haven't make sure you play with that before you go making crossover changes.

Also, and I can't quite explain why but when I added stuffing to my Khans mid section which is a RS150mtm also, I found that it made it slightly harsh. So something else to try.

And, if you couldn't understand CJD above, what he said was to put a small resistor, probably like 0.5ohm to 2.0 ohm in front of CT1. And like Frank mentioned above, you could try increasing RT1 to like 2.0 to 4.0. Get several and experiment.

I don't know where you're at, but if you have a Fry's near you, it is a good place to get resistors cheap without paying shipping.

[steelervic]

ok, i removed the crossover, i am going to try a resistor in front of ct1. i am also going to remove some stuffing, and the next time i order parts i'll replace the inductors. i know neither my room placement or room are not ideal. i built them sealed with a rss265hf under each, while i have the crossover out should i make any changes to relieve the 150 of some of the bass?
you guys are great, thanks for the help!

[dlneubec]

Just a suggestion. Consider making one change at a time and evaluating each change individually. If you make multiple changes at once you may never learn what made the real difference and there is a better chance that it could negatively effect the balance of the speaker and make it hard to evaluate what to do next.

Better to change one factor at a time, in my experience, and take plenty of time to listen between changes.