I have a question about passive crossovers.
I have a very good fullrange speeaker (Ported box with a Mark Audio 10.3M driver), but sometimes it lacks sub. I'm building a sub that fits it crossed over at about 150Hz with a 1st order passive crossover with a zorbel network on both drivers. I would love to have a bypass switch for that crossover because for a lot of music the fullrange is perfect. It's only when low subbass is required it lacks a bit.
The question is, how do i do that. I made a scheme where i use a dual DPST switch to switch between the network (on both sides) and the straight cable between the amp and the speaker, with an 16R resistor as bypass between + and - on the amp side (i use a tube amp that always need a load when on). Is that the right way to do it. Or should i do it otherwise?
I have a very good fullrange speeaker (Ported box with a Mark Audio 10.3M driver), but sometimes it lacks sub. I'm building a sub that fits it crossed over at about 150Hz with a 1st order passive crossover with a zorbel network on both drivers. I would love to have a bypass switch for that crossover because for a lot of music the fullrange is perfect. It's only when low subbass is required it lacks a bit.
The question is, how do i do that. I made a scheme where i use a dual DPST switch to switch between the network (on both sides) and the straight cable between the amp and the speaker, with an 16R resistor as bypass between + and - on the amp side (i use a tube amp that always need a load when on). Is that the right way to do it. Or should i do it otherwise?
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This is a good start.
The second switch might be optional. I would also consider changing the satellite Zobel to RLC over the mid/woofer resonance. You will also have room position based adjustments and crossover adjustments for ensuring the two blend.
The second switch might be optional. I would also consider changing the satellite Zobel to RLC over the mid/woofer resonance. You will also have room position based adjustments and crossover adjustments for ensuring the two blend.
This is a raw id of the crossover based on official specs of the drivers (that's why i erased the values of the components). I need to measure the speakers when build before i can design and build the real crossover as the published specs are not always right. But thank you for the confirmation of the bypass switch id. I just received the subwoofer drivers so now i can start... 😉
Since you have a tube amp, make sure the switch is a shorting-type. That will keep the connection. I also would not advise switching the mode while running sound to the drivers.
The 16 ohm resistor across your amplifier is not a good idea. There will be a lot of current going through there, and full-bandwidth at that. As long as you use a shorting switch, the load will be present and the resistor is not required.
Later,
Wolf
The 16 ohm resistor across your amplifier is not a good idea. There will be a lot of current going through there, and full-bandwidth at that. As long as you use a shorting switch, the load will be present and the resistor is not required.
Later,
Wolf
Your right, but i can't find a shorting switch like that. I need at least 60V (peak to peak) and 500mA handling, and no shop has those in stock... Are there no other ways than ordering a switch and wait half a year (thats the lead time to get one) to get this working? Would a higher value resistor accros the amp work (like 100R or more) as load?
But then you still got the short "no load" time while switching, wich can destroy a tube amp. So i need an impendance protection in the form of a load on the amp that is independent of what is behind the switch.
The higher resistance will just resist more and burn off more as heat. I would not advise it. If you want a load across the amp, I would recommend more of an amp zobel. 0.047-0.1uF and a 12 ohm/15W resistor. This will keep the amp loaded, and keep the bass range out of that resistor, as well as not siphoning current and becoming a small furnace turn fire-hazard. However, I'm not as knowledgeable as to whether this is a decent load to keep a tube-amp happy. I know it would be fine for some SS amps.
I'm questioning why you need a 120VAC switch when most music is less than half that at moderate levels. Like I said- don't switch while playing music. You'll run into other issues if you do- ESPECIALLY if you are running as much power as you say you are.
Later,
Wolf
I'm questioning why you need a 120VAC switch when most music is less than half that at moderate levels. Like I said- don't switch while playing music. You'll run into other issues if you do- ESPECIALLY if you are running as much power as you say you are.
Later,
Wolf
If he were using a 1st order xover, then I would agree with you. He has to eliminate the ground path as well back through the CR shunt.
Placing a switch at the aft end and bypassing as you state will make the 12dB HP seen as an CCR across it, and in the fore position will place the LR across it. The ground node has to be made incomplete to rule out the xover's effects both acoustically and electrically, as well as stop the feed to the woofer in the process as he wants.
Later,
Wolf
It makes sense what you say. A zorbel on the amp may be the solution. The amp gets a load, and the majority of the current is blocked due to the filtering cap. And i need a 60v switch to handle the +/- 28V RMS output (=56V voltage swing) as the speaker system is rated 50W in 8R.
And i need that protection as not everybody who uses this system knows about that the amp should be off while switching and i want to avoid accicdents. I rather overbuild and protect to much than to burn my expensive tube amp...
No, i want to avoid that i have to disconnect cables all the time. I want to make a crossover filter that i can switch off so the woofer and the filtering circuit is bypassed and the signal goes straigt to the fullrange speaker like i do it now.
The FR speaker like it is without sub or any electronic filtering at all is good for classical and jazz type of music, while for dub, reggae, hiphop or other bass-heavy music, the speaker is missing some sub frequencies and those that are there are to weak (due to the roll off). I listen to both so for that music i want to have the possiblity to switch on the subwoofer from the (external) passive crossover when needed. The top is an Alpair 10.3M based ported box going to just below 40hz flat and with an fs of 29hz (measured), the sub with a scanspeak driver will cover the 25hz-150hz flat (within 3dB) with an fs of 21hz (from calculations). Especially for (modern) dub 30hz flat is needed so then i'm covered.
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If you love your tube-amp, I would not advise doing this at all. I did not really mean the amp off, but music stopped flowing. Stop the source first.
If the speaker is rated 50W, does not mean it will pull 50W. This is a thermal rating capacity, and not really useful. The amp is capable of +/-28VAC RMS? That also does not mean that you will be using ALL of that +/-28VAC RMS as that is likely peak output approaching the rail voltage. Normal listening with ~84dB speakers at a moderately loud level involves that voltage only for transient peaks, which will not be a majority of your output level all the time. You'll find if you do the test in Pano's 'how loud do you really listen' thread, that you will only use a fraction of that voltage a majority of the time.
Later,
Wolf
If the speaker is rated 50W, does not mean it will pull 50W. This is a thermal rating capacity, and not really useful. The amp is capable of +/-28VAC RMS? That also does not mean that you will be using ALL of that +/-28VAC RMS as that is likely peak output approaching the rail voltage. Normal listening with ~84dB speakers at a moderately loud level involves that voltage only for transient peaks, which will not be a majority of your output level all the time. You'll find if you do the test in Pano's 'how loud do you really listen' thread, that you will only use a fraction of that voltage a majority of the time.
Later,
Wolf
If you really want a good switch, by the way, I recommend eliminating the toggle/push-button type altogether and going with a relay based solution with better compensation circuitry.
Later,
Wolf
Later,
Wolf
Ok, I understand what you're saying. But, there is a lot of low frequency content in both classical and jazz, to be honest I don't see much point not using the sub for all music, but then, I'm of the opinion that WAW is far better than so called fullrange 🙂
Based on what waxx says the integration is a challenge. I also find that doing this normally makes for worse sound at first, but with a lot of work it will be better.
This is a problem I have seen solved in a home cinema centre speaker. It used a biwire on the bass to choose fullrange, or limited bass response. Maybe a centre speaker doesn't need much bass, maybe you are adding a sub. A biwire looks like this:
The only difference between the two inputs was one switched in a cheap NP capacitor around 60uF. It's better than a ropey old switch. Default, the speaker came with some copper shorting connectors fitted, which leave the speaker in centre or light bass mode. 4 terminal biwire connectors are easy to buy. The inputs connect to either side of the capacitor. I won't bother drawing it, it all being so simple.
The only difference between the two inputs was one switched in a cheap NP capacitor around 60uF. It's better than a ropey old switch. Default, the speaker came with some copper shorting connectors fitted, which leave the speaker in centre or light bass mode. 4 terminal biwire connectors are easy to buy. The inputs connect to either side of the capacitor. I won't bother drawing it, it all being so simple.
This is a problem I have seen solved in a home cinema centre speaker. It used a biwire on the bass to choose fullrange, or limited bass response. Maybe a centre speaker doesn't need much bass, maybe you are adding a sub. A biwire looks like this:
The only difference between the two inputs was one switched in a cheap NP capacitor around 60uF. It's better than a ropey old switch. Default, the speaker came with some copper shorting connectors fitted, which leave the speaker in centre or light bass mode. 4 terminal biwire connectors are easy to buy. The inputs connect to either side of the capacitor. I won't bother drawing it, it all being so simple.
But then again, i need to switch cables. That is just what i try to avoid.
Also the crossover network is outside the speakers, in a seperate box (for various reasons) and the top and sub are seperate speakerboxes.
You are needlessly quoting the previous post. The forum discourages that, flattered as I am by how often I get quoted,
Switch or wires ends up in the same place. The wiring solution is higher quality IMO.
One thing I would take into consideration is that valve amps don't like open circuit usually. Preferring flat and defined impedance to match the chosen 4-8-16 ohm taps for maximum efficiency.
But not my problem since I use solid state. 🙂
Switch or wires ends up in the same place. The wiring solution is higher quality IMO.
One thing I would take into consideration is that valve amps don't like open circuit usually. Preferring flat and defined impedance to match the chosen 4-8-16 ohm taps for maximum efficiency.
But not my problem since I use solid state. 🙂
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