Thanks for the info! Depending on how large the XO gets I have started from scratch and then mounted it behind the tweeter. My method is to glue a piece of 1/2" MFD to the inside back panel that has pre drilled mounting holes for the actual completed XO. Then I can install and remove the crossover as need. The Maestro is Jensen's version of the Advent 6003. Jensen reduced the cost and complexity of the XO along with making a more conventional speaker cabinet dimensions. From the Frequency Graph of my Maesto's, I am hesitant to jump into that design mental gymnastics as you have. The frequency graph of OEM Maestro crossover is not ideal with a variance of about 10 db between the low and the high. There is about a 6 db upward slope from 1.8K to 10K which may account for the tendancy to be a bit bright. With my old ears I can use the high frequency bump! :>) In my searching, I found an image of the original 6003 XO which I have attached for your reference. Hey, it did have Japanese electrolytic capacitors! :>)
I see.
So in order to make these speakers right I need to find a schematic of an advent 6003 and duplicate it, right?
So in order to make these speakers right I need to find a schematic of an advent 6003 and duplicate it, right?
My take on it is that the 6003 components needed resistors to adjust them to match the other components. This leads me to conclude that with the crossover in place the 6003 resulted in a reading at the terminal of 8 ohm which they were shooting for. Once the resistors are pulled out the ohm of the speaker are changed. My view is that when Jensen bought the company, they inherited the 6003 components so they designed the Maestro which could be manufactured at less cost by changing the complex cabinet of the 6003 to a box cabinet. They then simplified the XO and let the chip fall were they fell.
Where I want to put the speakers they will fit, but I'd have to remove a couple "subs" made out of a 3cu ft sealed box with a Cerwin Vega woofer in each one.
I haven't really used them since I got tired of connecting and disconnecting the Carver amp I used with them every time I needed it for speakers I use to DJ with.
I'm still on the fence about it though.
I do intend to remove one midrange and woofer so that I can get the parameters measured in order to calculate the necessary components for the zobel networks.
The speakers may then sound better.
I've got a Carver TFM-15 amp I'd use with them, however I do quite like the Adcom GFA series amplifiers since I've had a chance to listen to the GFA-545II for a bit. It doesn't seem to color the sound much if at all
I haven't really used them since I got tired of connecting and disconnecting the Carver amp I used with them every time I needed it for speakers I use to DJ with.
I'm still on the fence about it though.
I do intend to remove one midrange and woofer so that I can get the parameters measured in order to calculate the necessary components for the zobel networks.
The speakers may then sound better.
I've got a Carver TFM-15 amp I'd use with them, however I do quite like the Adcom GFA series amplifiers since I've had a chance to listen to the GFA-545II for a bit. It doesn't seem to color the sound much if at all
Finally had the chance to listen to the Maestros in an environment where I could turn them up and with little background noise.
I think the mids are too loud and the tweeter too quiet.
I might try an Advent 6003 crossover in these just to see if it improves the sound any.
I can get a pair for $25 with $13.08 shipping on eBay.
Here's the schematic someone drew of the crossover
If I do the calculations based on the impedances of the drivers I have, the caps are off based on the listed crossover frequencies.
The midrange driver would need to e 23 ohms and the tweeter would need to be 12 ohms in order for the caps to be correct, unless there's a reason to use lower value caps such as possibly making the drivers better at the crossover frequency.
To make the caps correct with the driver impedances the crossover frequency is then 10kHz midrange to tweeter and the woofer to midrange is 1.326kHz.
For the price I can always try the crossovers just to see and if I am not happy I can resell them or modify them.
I think the mids are too loud and the tweeter too quiet.
I might try an Advent 6003 crossover in these just to see if it improves the sound any.
I can get a pair for $25 with $13.08 shipping on eBay.
Here's the schematic someone drew of the crossover
If I do the calculations based on the impedances of the drivers I have, the caps are off based on the listed crossover frequencies.
The midrange driver would need to e 23 ohms and the tweeter would need to be 12 ohms in order for the caps to be correct, unless there's a reason to use lower value caps such as possibly making the drivers better at the crossover frequency.
To make the caps correct with the driver impedances the crossover frequency is then 10kHz midrange to tweeter and the woofer to midrange is 1.326kHz.
For the price I can always try the crossovers just to see and if I am not happy I can resell them or modify them.
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I'll post the link where I got it from when I get home from work as I cannot access that site at work.
Here's where I got the schematic from.
https://audiokarma.org/forums/index.php?threads/advent-6003-speaker-crossover.989043/
The temptation is to buy the 6003 crossovers and try them with these speakers just to see if they improve the sound.
If I do that I may order some T nuts and use them in place of the woofer screws so that I have easy access to the crossover without worrying about stripping the holes in the wood out. I'll also use some sort of gasket on the woofer that won't be damaged by removing it from the cabinet.
Work on these speakers is on hold for the foreseeable future as I needed to use them in the fellowship hall at church to temporarily replace the one powered speaker we had that failed Wednesday night.
In the mean time I'll do more research on these speakers so that I can be better informed when I work on them again.
https://audiokarma.org/forums/index.php?threads/advent-6003-speaker-crossover.989043/
The temptation is to buy the 6003 crossovers and try them with these speakers just to see if they improve the sound.
If I do that I may order some T nuts and use them in place of the woofer screws so that I have easy access to the crossover without worrying about stripping the holes in the wood out. I'll also use some sort of gasket on the woofer that won't be damaged by removing it from the cabinet.
Work on these speakers is on hold for the foreseeable future as I needed to use them in the fellowship hall at church to temporarily replace the one powered speaker we had that failed Wednesday night.
In the mean time I'll do more research on these speakers so that I can be better informed when I work on them again.
Thank you for the link! I would love to know what the air coils measure! Good luck with the project.
With the 6003 crossover there's 4 ohms in series with the midrange so the midrange is being attenuated by 3.67dB assuming my measurement of 7.6 ohms impedance is correct.
The tweeter is 5.3 ohms and has a 1 ohm series resistor so it is being attenuated by 1.5dB.
With my modified Maestro crossover the tweeter is attenuated by 4.2dB and the midrange is attenuated by .955dB.
To attenuate the midrange properly without altering the crossover I'd need a series resistor of 2.96 ohms and a parallel resistor of 16.36 ohms. I could use a 3 ohm ands 16 ohm resistor for an attenuation of 3.73dB which more than likely won't be an audible difference.
To attenuate the tweeter properly I'd need a 1 ohm resistor and the cap would need to be increased to 5.5uF which would require a 1.5uF cap in parallel with the 4uF cap.
Hmmmmmmm I found a discrepancy in the crossover calculator I used.
If I change the crossover frequency between the midrange and tweeter it also changes the value of the cap in series with the midrange.
Not sure that should be happening as the cap is the high pass for the midrange unless I'm missing something here.
The tweeter is 5.3 ohms and has a 1 ohm series resistor so it is being attenuated by 1.5dB.
With my modified Maestro crossover the tweeter is attenuated by 4.2dB and the midrange is attenuated by .955dB.
To attenuate the midrange properly without altering the crossover I'd need a series resistor of 2.96 ohms and a parallel resistor of 16.36 ohms. I could use a 3 ohm ands 16 ohm resistor for an attenuation of 3.73dB which more than likely won't be an audible difference.
To attenuate the tweeter properly I'd need a 1 ohm resistor and the cap would need to be increased to 5.5uF which would require a 1.5uF cap in parallel with the 4uF cap.
Hmmmmmmm I found a discrepancy in the crossover calculator I used.
If I change the crossover frequency between the midrange and tweeter it also changes the value of the cap in series with the midrange.
Not sure that should be happening as the cap is the high pass for the midrange unless I'm missing something here.
What's nice about having the Advent 6003 crossover schematic is that I know what components to use for the zobel networks without having to calculate them.
While dealing with a set of bookshelf speakers I was reminded about baffle step compensation.
Pretty sure that's what the foam on the baffle was for. Eliminated the need for baffle step compensation.
So I will replace the foam before trying to do anything else to the crossover.
Instead of a passive crossover, what do y'all think about using this active crossover and three amplifiers from the same series?
https://www.xkitz.com/collections/a...-way-active-crossover-fully-assembled-xover-3
If that is a good way to do it, what amplifiers should I get and if the amps do not have speaker protection circuitry should I place a film cap in series with the midrange and tweeter of a sufficiently large enough value to where it doesn't affect the drivers at the crossover frequencies?
Now I do know the Maestro speakers are not flat to 20Hz so when I'm ready to add a powered sub or several, I can add this crossover to the woofer output of the three way crossover and order it with a 60Hz crossover frequency.
https://www.xkitz.com/collections/a...-way-active-crossover-fully-assembled-xover-2
So what I could do for amps is find three Carver TFM-15 amps or three other 100 WPC amps of similar or better quality that have a speaker protection relay.
Pretty sure that's what the foam on the baffle was for. Eliminated the need for baffle step compensation.
So I will replace the foam before trying to do anything else to the crossover.
Instead of a passive crossover, what do y'all think about using this active crossover and three amplifiers from the same series?
https://www.xkitz.com/collections/a...-way-active-crossover-fully-assembled-xover-3
If that is a good way to do it, what amplifiers should I get and if the amps do not have speaker protection circuitry should I place a film cap in series with the midrange and tweeter of a sufficiently large enough value to where it doesn't affect the drivers at the crossover frequencies?
Now I do know the Maestro speakers are not flat to 20Hz so when I'm ready to add a powered sub or several, I can add this crossover to the woofer output of the three way crossover and order it with a 60Hz crossover frequency.
https://www.xkitz.com/collections/a...-way-active-crossover-fully-assembled-xover-2
So what I could do for amps is find three Carver TFM-15 amps or three other 100 WPC amps of similar or better quality that have a speaker protection relay.
So the plan is this.
I have a pair of DBX 234XS crossovers that I can use for these speakers.
Given I'll be using subs I have two options.
1. Set the crossovers for four way
2. Set one crossover for three way and the other for two way and connect the three way to the high output of the two way.
Which is the better way or does it really matter?
The speakers will be powered by:
1. Woofer GFA-545II
2. Midrange GFA 535II
3. Tweeter GFA-535II unless there's a smaller GFA amplifier
I'll also be adding speaker protection circuits given the GFA amplifiers do not have them stock.
I'm not so concerned about the woofers as they could likely handle a little DC offset, but the mids and tweeters cannot.
Doing it this way I don't have to figure out a crossover and I have none of the downfalls of using a passive crossover.
I have a pair of DBX 234XS crossovers that I can use for these speakers.
Given I'll be using subs I have two options.
1. Set the crossovers for four way
2. Set one crossover for three way and the other for two way and connect the three way to the high output of the two way.
Which is the better way or does it really matter?
The speakers will be powered by:
1. Woofer GFA-545II
2. Midrange GFA 535II
3. Tweeter GFA-535II unless there's a smaller GFA amplifier
I'll also be adding speaker protection circuits given the GFA amplifiers do not have them stock.
I'm not so concerned about the woofers as they could likely handle a little DC offset, but the mids and tweeters cannot.
Doing it this way I don't have to figure out a crossover and I have none of the downfalls of using a passive crossover.
I'm itching to get these speakers redone soon.
The fastest way I can think of doing it is to use my Carver TFM-25 on the woofer (need to recap the Carver though), my Adcom 535II on the midrange and a TFM-15 on the tweeter.
I then need an amp for the subs.
I do have a Carver TFM-35 and an Adcom 545II. Both need work before they are usable.
I then need to figure out what connectors to use on the speakers. I might use banana jacks and would install a new panel where the existing connector panel is.
I also need a four way active crossover.
That said how do I remove the woofers once the screws have been removed as I need them out so I can replace the foam on the speaker baffle. I once tried to pry them, but they must be glued in and I didn't want to force the plastic rings too much.
The fastest way I can think of doing it is to use my Carver TFM-25 on the woofer (need to recap the Carver though), my Adcom 535II on the midrange and a TFM-15 on the tweeter.
I then need an amp for the subs.
I do have a Carver TFM-35 and an Adcom 545II. Both need work before they are usable.
I then need to figure out what connectors to use on the speakers. I might use banana jacks and would install a new panel where the existing connector panel is.
I also need a four way active crossover.
That said how do I remove the woofers once the screws have been removed as I need them out so I can replace the foam on the speaker baffle. I once tried to pry them, but they must be glued in and I didn't want to force the plastic rings too much.
I just completed a three way open baffle speaker and found a good three way crossover calculator that provided excellent results.
Instead of going active amplification, I may use that crossover calculator and my DATS V3 speaker tester to design a proper three way crossover. I'll use the l-pad resistor values for the midrange and tweeter from the Advent 6003 speaker crossover schematic as from what I understand the 6003 used the same drivers. To be sure the l-pad resistors are right I may build a simple 6dB/octave crossover as a test using parts on hand.
Instead of going active amplification, I may use that crossover calculator and my DATS V3 speaker tester to design a proper three way crossover. I'll use the l-pad resistor values for the midrange and tweeter from the Advent 6003 speaker crossover schematic as from what I understand the 6003 used the same drivers. To be sure the l-pad resistors are right I may build a simple 6dB/octave crossover as a test using parts on hand.