Change LPF Rti-a7
First thanks to all who have helped on this forum. I have lurked over the years and learned much. I have the rti-a7's for 12 years now and I like them very much. I had to replace a Yamaha aventage 2020 to a aventage a6a. It powers 2 rti-a7's, csi-a6, 2 rti-a3's. I have SVS SB-4000.
As I was setting up the crossovers to the sub I started looking into current thoughts as it had been a while for me. I noted that if I set the a7 cross to the sub due to the lpf in the a7 at 125 Hz, the woofers in the a7 will only play from around 80 Hz to 125 Hz (I understand crossovers are not brick walls)
As has been pointed out on a previous thread the woofer/midrange has no hpf so the midrange is playing its full frequency range. This reduces the a7 to the a3 but with 2 woofers, a lpf, and a larger cabinet.
I read how some have upgrade the components of the crossovers and some have used active crossovers externally and triamped the r7's. I do not work in audio and have a limited understanding. Is it possible to upgrade the crossovers within the r7 AND change the frequency of the lpf and perhaps add a high pass filter?
My ultimate goal is an improved midrange by using the woofers to cover more than 80 to 125 Hz (again I understand the existence of slopes and the absence of brickwalls)
Thanks again to all that have provided me the little knowledge on the matter that I do have. However this is not my area of expertise or really much competence.
Brian
As I was setting up the crossovers to the sub I started looking into current thoughts as it had been a while for me. I noted that if I set the a7 cross to the sub due to the lpf in the a7 at 125 Hz, the woofers in the a7 will only play from around 80 Hz to 125 Hz (I understand crossovers are not brick walls)
As has been pointed out on a previous thread the woofer/midrange has no hpf so the midrange is playing its full frequency range. This reduces the a7 to the a3 but with 2 woofers, a lpf, and a larger cabinet.
I read how some have upgrade the components of the crossovers and some have used active crossovers externally and triamped the r7's. I do not work in audio and have a limited understanding. Is it possible to upgrade the crossovers within the r7 AND change the frequency of the lpf and perhaps add a high pass filter?
My ultimate goal is an improved midrange by using the woofers to cover more than 80 to 125 Hz (again I understand the existence of slopes and the absence of brickwalls)
Thanks again to all that have provided me the little knowledge on the matter that I do have. However this is not my area of expertise or really much competence.
Brian
Comments
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Just set the A7's to large in your AVR settings and they will play full range.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
@bgerm
Minus a different approach for subwoofer duty, we share the identical taste in speaker choices!
TonySamsung 60" UN60ES6100 LED, Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga: LCR mids “Foamed & Plugged**”, inside* & out
8 ga Powerline: LR woofers, inside* & out
*soldered **Rob the Man (Xschop) LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & Mids - 981, connected w/Monoprice Premiere ICs
Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s -
If I set the speakers to full range it would have the woofers play more but not the frequency I want more of. At full range the mid drivers will be getting even more signal that I don’t want them to have
The major genesis of my original post is I want to go the route some have taken here in upgrading the crossovers. But specifically change the crossover frequency of the woofer to the midrange. I don’t know if it is possible. Again I don’t want to go with external active crossovers. I want to change the speakers internal lpf crossover frequency
I really like the svs sub. I am happy that this post got the attention of the exact two people I hoped it would.
Thanks
Brian -
I surmise it is not possible to change the internal woofer/midrange crossover passively. I have searched many areas online and the only thing I see is upgrade of crossover components but not changing the crossover freq and/or external active crossovers.
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VR3 Authored this post in an RTi 10* thread:
“A long time ago... I believe we put a 100uf cap in front of the mid of the rtia7 and rti10 with decent success but I can't really remember the particulars or have pictures etc.”
…I’m sure its worth trying with, say, a Dayton 100uf cap. Many times better that nuthin’ for a few $s.
*same driver, inner chamber, and passive filtering** config as the ’7, but a rectangular shaped closure, slightly different XO specs and components.
TonySamsung 60" UN60ES6100 LED, Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga: LCR mids “Foamed & Plugged**”, inside* & out
8 ga Powerline: LR woofers, inside* & out
*soldered **Rob the Man (Xschop) LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & Mids - 981, connected w/Monoprice Premiere ICs
Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s -
Tony thank you for the reply. Correct me if I am wrong as I don't have much knowledge in the area. The 100 uf capacitor would high pass the midrange at some unspecified frequency. Currently my set up has the a7 crossed to the sb4000 at 80 Hz. So with the 100uf cap I could change it to 60 Hz and allow the woofer to play more without the midrange getting those lower signals.
If this is true would a different inductor change the low pass from the woofers to a different (higher frequency). This would allow the woofers to play more of the upper bass frequency.
If possible how do you determine the frequency crossover from a inductor or cap? And why did Polk have the low pass filter on the woofer set so low? Looking at other products 250 to 300 Hz seems more common. It seems like Polk wanted the woofers to act like subwoofers for 2 channel music, but the whole line is for HT. Most folks have a dedicated sub for HT.
Thanks,
Brian
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The 100 uf capacitor would high pass the midrange at some unspecified* frequency*.
per V3, AKA Trey:
”… I believe we put a 100uf cap in front of the [8ohm] mid” should result in 6dB/octave (1st order) slope, beginning w/-3dB ~100*hz
*I’m probably WRONG on the 1/2 power frequency, [PLEASE someone chime in; include the forumula] but I know I’m right on the slope.
yeah…Currently my set up has the a7 crossed to the sb4000 at 80 Hz. So with the 100uf cap I could change it [the HP setting to the ‘7s?] to 60 Hz and allow the woofer to play more without the midrange getting those lower signals.
Not exactly. Polk’s LP to the ‘7s woofers is second order: 12dB/octave. That uses more components, more complexity. Off the top of my head, a series inductor, parallel cap minimum - change the inductor demands changing the cap. I KNOW that filter has at one or more components. Now you understand why I went active?!If this is true would a different inductor change the low pass to the woofers to a different (higher frequency).
I wish I could recall the formula or website where you plug in a value and boom(!) but I don’t.If possible how do you determine the frequency crossover from a inductor or cap?
Google the “formula” for either “inductive reactance” and/or capacitive reactance. Either or both should help get you closer to your goal but take your time. Polk’s engineers has software to do what you’re considering “by hand.”
Then try this on one tower. Assuming your speaker wire is connected to the bottom pair of binding posts, sub one of jumpers to the top pair w/the [100uf*] cap and see/hear if you like it.
*or the cap value of your choice.
Why so low? You answered that below. No I disagree w/Polk too but…And why did Polk have the low pass filter on the woofer set so low? Looking at other products 250 to 300 Hz seems more common.
Yes a higher mid cutoff is more common.
check Polk’s ‘A7 & ‘A9 literature, you’ll see they call the woofers, subwoofers.It seems like Polk wanted the woofers to act like subwoofers for 2 channel music, but the whole line is for HT.
Tony
Samsung 60" UN60ES6100 LED, Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga: LCR mids “Foamed & Plugged**”, inside* & out
8 ga Powerline: LR woofers, inside* & out
*soldered **Rob the Man (Xschop) LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & Mids - 981, connected w/Monoprice Premiere ICs
Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s -
Thanks Tony, yes I see why you went with active crossovers for sure. Very much above my expertise. Considering that the places near me that could do this would be a bit of a drive. The only thing I should consider would be to just upgrade the components and keep everything else the same.
Interesting stuff. Thanks!
