Hello.
I am thinking of purchasing a Hivi RT1C-A. Admittedly because not only it has good specs and price, but because it looks cool. 😀
1. I would probably add it to supplement the high end of the W5-1611SAF I already have. Trouble is, at 5 Ohm and 94dB, it would be considerably louder. I'd like to add an adjustable L-pad, but most I saw were 4 and 8 ohms. It has a very flat impedance, almost completely linear. So if I add a non-inductive resistor in series to the tweeter, would it add up to 8 (or 7.8) ohms, and then would I be able to hook up an 8 ohm l-pad?
2. Upon researching I came across people wiring up 1st order HP to their tweeters, usually very high up at about 8-10kHz, and yet leave the full range unfiltered. How would the amp see this load at the tweeter frequency and beyond?
3. Another question (or a set of questions). My research had somehow made me come across the "ambiance tweeter" concept. Some say it works at adding a sense of open space, others say it's just muddy and artificial and ruins imaging. Rather than just reading what people have to say I'd like to try one out. Most probably with the RT1C as well. Who knows, maybe it's good for movies. I see some OB have them. I guess to compensate for the loss of HF at the rear, so they can be more dipole than they would normally be? Would this work with the aforementioned 1st order setup?
I am thinking of purchasing a Hivi RT1C-A. Admittedly because not only it has good specs and price, but because it looks cool. 😀
1. I would probably add it to supplement the high end of the W5-1611SAF I already have. Trouble is, at 5 Ohm and 94dB, it would be considerably louder. I'd like to add an adjustable L-pad, but most I saw were 4 and 8 ohms. It has a very flat impedance, almost completely linear. So if I add a non-inductive resistor in series to the tweeter, would it add up to 8 (or 7.8) ohms, and then would I be able to hook up an 8 ohm l-pad?
2. Upon researching I came across people wiring up 1st order HP to their tweeters, usually very high up at about 8-10kHz, and yet leave the full range unfiltered. How would the amp see this load at the tweeter frequency and beyond?
3. Another question (or a set of questions). My research had somehow made me come across the "ambiance tweeter" concept. Some say it works at adding a sense of open space, others say it's just muddy and artificial and ruins imaging. Rather than just reading what people have to say I'd like to try one out. Most probably with the RT1C as well. Who knows, maybe it's good for movies. I see some OB have them. I guess to compensate for the loss of HF at the rear, so they can be more dipole than they would normally be? Would this work with the aforementioned 1st order setup?
When you use an adjustable L-pad, the resulting impedance looks more and more like the nominal value the more you invoke it. In other words an 8 ohm L-pad will look like 8 ohms with higher levels of attenuation, even if the speaker is a 4 ohm or 16 ohm speaker.
As for your second question the impedance of a woofer rises at its top end so in combination with the tweeter crossover you may still achieve a smooth result with the impedance.
As for your second question the impedance of a woofer rises at its top end so in combination with the tweeter crossover you may still achieve a smooth result with the impedance.
So what happens when I needed much less attenuation? Say that I got a slightly more sensitive woofer to pair it with and I only needed to pad it down by 2-3dB?
No-one really uses adjustable attenuators except for fine adjustments more akin to brightness setting in designs.
You just set a resistor usually. Here Michael Chua uses a 10R in series with the filter.
"ORIOLE" (W5-704 + RT1C) Bookshelf by AmpsLab
Quite likely that whole setup will work with your Tang Band fullranger. They seem to follow a pattern in design. Low inductance, flat, underhung polycone.
You just set a resistor usually. Here Michael Chua uses a 10R in series with the filter.
"ORIOLE" (W5-704 + RT1C) Bookshelf by AmpsLab
Quite likely that whole setup will work with your Tang Band fullranger. They seem to follow a pattern in design. Low inductance, flat, underhung polycone.
The resistor before the XO doesn't affect the impedance it seems, from what I can see the Oriole. But, if it was just a cap in series to the tweeter as a filter, would the placement of the resistor matter in this case? I think for AC it wouldn't matter though so with only a cap as filter I would have to account for total resistance, I think, but I would probably be wrong.
Well I was planning on using the adjustable l-pad for experimentation purposes. I would like to make a quick box with another woofer and experiment with a rear-firing ambiance tweeter. I just want a thorough experiment so I would like to be able to dial in the loudness of the tweeter, without having to bi-amp.
Well I was planning on using the adjustable l-pad for experimentation purposes. I would like to make a quick box with another woofer and experiment with a rear-firing ambiance tweeter. I just want a thorough experiment so I would like to be able to dial in the loudness of the tweeter, without having to bi-amp.
You could certainly try the adjustable resistor followed by a 1.5uF capacitor here. Then the isodynamic tweeter which seems to be around 5 ohms. But you're going to need around 10 ohms anyway.
First order filters are truly Mickey Mouse in reality.They don't protect the tweeter enough from low frequencies, so they distort and even burn out. Some phase alignment is important too, so the drivers integrate.
So don't turn the volume up too high. You can't just add the output to the fullranger either. You should roll the bass off around 5kHz IMO. So to me, it says do a PROPER CROSSOVER! Like Michael Chua. 🙂
First order filters are truly Mickey Mouse in reality.They don't protect the tweeter enough from low frequencies, so they distort and even burn out. Some phase alignment is important too, so the drivers integrate.
So don't turn the volume up too high. You can't just add the output to the fullranger either. You should roll the bass off around 5kHz IMO. So to me, it says do a PROPER CROSSOVER! Like Michael Chua. 🙂
I see. Thanks for the pointers system7. 😀
I'll be doing the experiment nearfield, so I won't (or can't) go loud. I'll try higher order filters once I get to know the tweeter better in my experiments.
BTW I have much of what I need to get started but one last question, how would I calculate how much resistance I would need to pad down a certain dB?
I'll be doing the experiment nearfield, so I won't (or can't) go loud. I'll try higher order filters once I get to know the tweeter better in my experiments.
BTW I have much of what I need to get started but one last question, how would I calculate how much resistance I would need to pad down a certain dB?
Loudness in dB is a logarithmic scale. -3dB is half power. -6db is quarter power.
So put a 6R resistor in front of a a 6 ohm DC tweeter, and you have halved the voltage. Remember from ohms law that power is (voltage squared) / resistance.
So 6R added series resistance gives you quarter power, or -6dB. In other words, each ohm produces about roughly 1dB reduction.
I haven't really thought about it this way, but 10 ohms resistance must produce around 10dB reduction. Which makes sense in taking a 90dB tweeter to the 80dB levels of a 5" driver.
This assumes the impedance of the tweeter is a flat 6 ohms. It's not usually.
The resistance you add also interacts with the capacitor's RC time constant. You'd use around 3.3uF with 6 ohms usually for around 3kHz crossover. With 10 ohms added, you use a smaller capacitor to keep RC constant. Hence I suggested a smallish 1.5uF to start here.
So put a 6R resistor in front of a a 6 ohm DC tweeter, and you have halved the voltage. Remember from ohms law that power is (voltage squared) / resistance.
So 6R added series resistance gives you quarter power, or -6dB. In other words, each ohm produces about roughly 1dB reduction.
I haven't really thought about it this way, but 10 ohms resistance must produce around 10dB reduction. Which makes sense in taking a 90dB tweeter to the 80dB levels of a 5" driver.
This assumes the impedance of the tweeter is a flat 6 ohms. It's not usually.
The resistance you add also interacts with the capacitor's RC time constant. You'd use around 3.3uF with 6 ohms usually for around 3kHz crossover. With 10 ohms added, you use a smaller capacitor to keep RC constant. Hence I suggested a smallish 1.5uF to start here.
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