The impedance curve for the horn suggests that it is damped (stuffed). Check the first minimum point (noticeably higher than Re) and the low height of the peaks (compared to an undamped TH). This suggests damping, which can also reduce Fb
I suspect this damping is somewhere between S2 and S3. Try modeling the effect HornResp.
That's actually a great theory, one that I can definitely buy in to with certain stipulations.
I did a quick sim as you suggested with a random TH in Hornresp and it took a metric ton of stuffing to shift Fb 5 hz (from 30 hz to 25 hz), stuffing the entire length from S2 to S3, a full 2/3 of the horn with fairly dense stuffing. That amount of stuffing also caused the spiky, undamped response of the TH to become very damped, I'd say overdamped with that amount of stuffing.
So while I like this theory much better than the others that were offered (like split paths and other things that were clearly not in the drawing we were looking at), I'm not sure stuffing alone was responsible for the entire discrepancy between the Fb of your sim vs the reported Fb of the commercial box. I don't remember, how many hz did we need to account for?
In my defense, if this theory is true, an accurate sim (including any applicable stuffing) absolutely would match the measurement, which was my point all along. (In case it's not obvious, I'm a major proponent of the resulting accuracy of well done accurately input simulations.) While I thought the Fb discrepancy was entirely due to path length error in the sim because I wasn't imaginative enough to envision the use of stuffing (especially since that's not where DSL would usually place stuffing), I still stand by my assertion that an accurate sim would match the measurement.
To your credit, if this theory is true, you would have correctly identified that a dimensionally accurate sim (without any applicable stuffing added, as stuffing was an unforeseen parameter at that point) would not match the measurement no matter what due to the missing parameter.
Either way, whether this theory turns out to be true or not (and to what degree - how much stuffing and how much if any path length error in the sim), it's definitely plausible (much more plausible than the other theories presented) and it's a great idea. It also takes a keen eye to notice differences in impedance in different tapped horns (height of stuffed vs unstuffed peaks and stuff like that), so good work.
It would be interesting to see how accurate your sim was and how much stuffing may be inside the box (and at what location) but I still don't have time to reverse engineer that thing.
I did a quick sim as you suggested with a random TH in Hornresp and it took a metric ton of stuffing to shift Fb 5 hz (from 30 hz to 25 hz), stuffing the entire length from S2 to S3, a full 2/3 of the horn with fairly dense stuffing. That amount of stuffing also caused the spiky, undamped response of the TH to become very damped, I'd say overdamped with that amount of stuffing.
So while I like this theory much better than the others that were offered (like split paths and other things that were clearly not in the drawing we were looking at), I'm not sure stuffing alone was responsible for the entire discrepancy between the Fb of your sim vs the reported Fb of the commercial box. I don't remember, how many hz did we need to account for?
In my defense, if this theory is true, an accurate sim (including any applicable stuffing) absolutely would match the measurement, which was my point all along. (In case it's not obvious, I'm a major proponent of the resulting accuracy of well done accurately input simulations.) While I thought the Fb discrepancy was entirely due to path length error in the sim because I wasn't imaginative enough to envision the use of stuffing (especially since that's not where DSL would usually place stuffing), I still stand by my assertion that an accurate sim would match the measurement.
To your credit, if this theory is true, you would have correctly identified that a dimensionally accurate sim (without any applicable stuffing added, as stuffing was an unforeseen parameter at that point) would not match the measurement no matter what due to the missing parameter.
Either way, whether this theory turns out to be true or not (and to what degree - how much stuffing and how much if any path length error in the sim), it's definitely plausible (much more plausible than the other theories presented) and it's a great idea. It also takes a keen eye to notice differences in impedance in different tapped horns (height of stuffed vs unstuffed peaks and stuff like that), so good work.
It would be interesting to see how accurate your sim was and how much stuffing may be inside the box (and at what location) but I still don't have time to reverse engineer that thing.
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Actually, Fb for the TH118 is about 28 Hz, according to the impedance chart from the website, so you shouldn't have to stuff it that much 🙂
The slight increase in volume @S2 and decease @S4 (due to the larger driver) could account for a small drop in Fb as well.
I hope to finish the new triangular cabinet today - weather permitting.
Then it will be off to the church to do some measurements.
Bach On
Then it will be off to the church to do some measurements.
Bach On
Brian I have photos of a Danley long tapped horn DTS20 is the current designation and it is stuffed over part of it's length.
It also has a few resonator tubes that no longer seem to be used.
So you are on the right track.
It's polyester batting, like the kind used to fill blankets. About 20mm thick or a hairy 3/4" thick. Yes inches can be hairy, and have whiskers! On construction sites they have other colourful addendums as well!
It also has a few resonator tubes that no longer seem to be used.
So you are on the right track.
It's polyester batting, like the kind used to fill blankets. About 20mm thick or a hairy 3/4" thick. Yes inches can be hairy, and have whiskers! On construction sites they have other colourful addendums as well!
Right. That's what "alignments" are all about... that's how the term came to be used in Thiele world of cone woofers.
But wrong too. You just don't want any resonances in the reproduction of music although avoiding them is hard in practice. All resonances introduce colourations not present in the source. I challenge anyone to make a coherent argument otherwise.
In this forum, nearly all the chat is about cabs which feature aspects of resonance as main determinants of their output. By contrast, the concept is hardly mentioned among ESL enthusiasts because of the inherent damping of such systems. It will be a happy day when ESLs can go lower than Dayton-Wrights (good down to about 40 Hz).
Likewise, I'd say OBs and IBs have resonances, but they are kind of inevitable by-products that unfortunately hang around the bottom end of their range. A true horn likewise does not use resonances as inherent in its design.
The cabs that are created with "alignments" are not invented to create better or cleaner sound. They are intended as practical comprises over other considerations.
Sure great to hear Bach On is moving on to the testing. Looking forward to that.
Ben
Any vibrating system that has mass also has a resonance. As you need to vibrate something to make sound, any device that makes sound has resonance.
If you're suggesting that the "perfect horn" has no resonance, then I can safely say that the perfect horn doesn't exist because to do so its moving parts would have to have no mass.
If you're suggesting that the "perfect horn" has no resonance, then I can safely say that the perfect horn doesn't exist because to do so its moving parts would have to have no mass.
Yes, of course.
But a key goal of good design is to avoid having these resonances pollute the sound. Ideally, by having them outside the range but also by damping.
Any doubts about that?
It itsn't necessarily a matter of having no mass (an obvious straw-man ploy). As with true horns and ESLs, reasonable impedance matching helps. And more interestingly, by motional feedback.
As for shaking heavy cones in resonant boxes.... makes no more sense than an IC engine to power a car.
Ben
I already made a very coherent argument. A resonance in itself is benign, it's not automatically a coloration. I strongly suggest you are confusing the sound of a bad design as a symptom of resonance. When you have huge, undamped resonances (like the Klipschhorn) or when you use resonances to keep the response curve boosted to low frequencies that don't match the room gain curve well (like typical max flat ported boxes), these designs will sound bad. But it's due to bad design, not because the design uses resonances.
Can you explain what exactly you mean by "coloration"? If the frequency response is the same (as a sealed box) and the group delay is the same (in the usable bandwidth portion, down to 20 hz or lower), and the distortion is no worse in the resonant box, where is this "coloration" you speak of? What is the scientific term?
What is your definition of a "true" horn? Are you suggesting there are fake horns? Or are you suggesting that all front loaded horns are "true" horns but tapped horns are not? Or maybe just Klipschhorns are true horns? Or maybe only full size flhs are "true" horns even though their usable bandwidth is loaded with resonances the same as all horns? It's really hard to have a scientific discussion when you use terms that have no meaning.
I can guarantee you that ALL horns of all types have a series of resonances all through their usable bandwidth. I challenge you to find ANY horn that has a ruler flat impedance curve. It just does not exist. If there are bumps in the impedance curve there are resonances, that is what resonances are. And since all horns DO have resonances, they definitely are inherent in the design.
I can also guarantee you that the Klipschhorn has a very bumpy impedance curve and it's full of resonances all through it's usable bandwidth.
At this point if you think there are horns that don't have any resonances I think it's pretty clear that you don't know how these things work, but maybe if you try to use some scientific terms instead of meaningless buzzwords and phrases like undefined "colorations" and "true horns" maybe I can make some kind of sense of what you are saying.
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I transported the new triangular speaker box to the church. Had to do the transport between rains. Got it in the nursery near the closet with the amps. Put the smaller top onto the larger bottom containing the speaker. The seal is nowhere near airtight. My plan is to seal that joint with PL Construction Adhesive once it is in place. But the joint has major leaks that started producing noise just as soon as things were connected. I’ve temporarily plugged the leaks using tissue and masking tape. I was FINALLY able to get a pretty good seal.
The circuit works like this. The Crown XLS1500 was connected using a Speakon Connector to the speaker. The Stereo Integrity HT18 has dual 2 ohm voice coils. I connected these in a series to come up with a 4 ohm circuit. The #16 gauge cable is about 18 feet in length.
I started by connecting a CD player to the XLS1500. The amp was set for Lowpass with a crossover at 112 Hertz. I played Bach’s Toccata and Fugue in D. I started with the gain control of the left channel at the half-way point (about 50%). The volume of the speaker was very low. Even raising it to 100% produced a very weak signal.
The HT18 driver is rated for 600 watts RMS and peaks up to 1,000 watts. At 4 ohms the XLS1500 should produce 525 watts. I knew this would be on the low side of the 600 watts continuous rating. My surmise is that it is probably too low. So I switched the amp to Bridged mode. The XLS1500 can produce 1,050 watts at 8 ohms in bridged mode. (I’m guessing that the 1,050 watts is somewhat higher into a 4 ohm speaker.) The SPL was still low with the gain set at 50%. It became a little more pronounced at 85-90%.
I connected my laptop to the amp using a box intended for this purpose. It communicates with the box via a USB connection. I connected it to the XLS1500 with ONE input channel. A limitation of the XLS series is that when the built-in crossover is utilized the amp only uses Input 1. Input 2 goes offline. Stereo or Bridged mode still utilizes the crossover circuit.
So the output of the amp was providing signals below 112 Hertz. I utilized the signal generator in REW to play tones through the speaker. I spent over 30 minutes plugging up the leaks at the previously mentioned joint.
I had REW produce sweeps from 100 Hertz down to 10 Hertz. I set the duration to 60 seconds. The maximum sound level was 3db. I also did sweeps from 64 Hertz down to 16 Hertz.
I did not have the mike connected to the computer. That will have to wait until tomorrow. So all I can give you is my aural impression.
The box easily produces 16 Hertz. It isn’t as loud as 44 Hertz, but it is pretty solid. Until I got the leaks temporarily plugged up, there was right much noise coming from them. With them plugged up, the port is creating right much velocity from 22 Hertz down to 14 Hertz. The sound level and port velocity falls off a lot below 14.
I sat in a chair about 8 feet in front of the speaker. Many room objects – such as windows and the air conditioner (which was turned off) produced sympathetic vibrations below 22 Hertz.
I had the amp in bridged mode with a Lowpass filter and the gain set to 85% to obtain this solid sound pressure level. Lowering the gain on the amp to 50 or 60% vastly reduced the speaker’s SPL.
So my initial take away is that the Crown XLS1500 may be under powered for this box. I really do not want to have to run the amp with the gain set at over 85%. I feel this may introduce too much distortion.
I switched the amp to Bypass mode and took it out of Bridged mode. This takes the crossover circuit offline. The speaker will play, but the volume still has to be at 100% to get any real sound.
I’ll use the mike tomorrow to obtain some measurements for posting. But it looks to me like we’re going to need a more powerful amp to run this driver in this box.
I’m open to all observations and suggestions.
Bach On
The circuit works like this. The Crown XLS1500 was connected using a Speakon Connector to the speaker. The Stereo Integrity HT18 has dual 2 ohm voice coils. I connected these in a series to come up with a 4 ohm circuit. The #16 gauge cable is about 18 feet in length.
I started by connecting a CD player to the XLS1500. The amp was set for Lowpass with a crossover at 112 Hertz. I played Bach’s Toccata and Fugue in D. I started with the gain control of the left channel at the half-way point (about 50%). The volume of the speaker was very low. Even raising it to 100% produced a very weak signal.
The HT18 driver is rated for 600 watts RMS and peaks up to 1,000 watts. At 4 ohms the XLS1500 should produce 525 watts. I knew this would be on the low side of the 600 watts continuous rating. My surmise is that it is probably too low. So I switched the amp to Bridged mode. The XLS1500 can produce 1,050 watts at 8 ohms in bridged mode. (I’m guessing that the 1,050 watts is somewhat higher into a 4 ohm speaker.) The SPL was still low with the gain set at 50%. It became a little more pronounced at 85-90%.
I connected my laptop to the amp using a box intended for this purpose. It communicates with the box via a USB connection. I connected it to the XLS1500 with ONE input channel. A limitation of the XLS series is that when the built-in crossover is utilized the amp only uses Input 1. Input 2 goes offline. Stereo or Bridged mode still utilizes the crossover circuit.
So the output of the amp was providing signals below 112 Hertz. I utilized the signal generator in REW to play tones through the speaker. I spent over 30 minutes plugging up the leaks at the previously mentioned joint.
I had REW produce sweeps from 100 Hertz down to 10 Hertz. I set the duration to 60 seconds. The maximum sound level was 3db. I also did sweeps from 64 Hertz down to 16 Hertz.
I did not have the mike connected to the computer. That will have to wait until tomorrow. So all I can give you is my aural impression.
The box easily produces 16 Hertz. It isn’t as loud as 44 Hertz, but it is pretty solid. Until I got the leaks temporarily plugged up, there was right much noise coming from them. With them plugged up, the port is creating right much velocity from 22 Hertz down to 14 Hertz. The sound level and port velocity falls off a lot below 14.
I sat in a chair about 8 feet in front of the speaker. Many room objects – such as windows and the air conditioner (which was turned off) produced sympathetic vibrations below 22 Hertz.
I had the amp in bridged mode with a Lowpass filter and the gain set to 85% to obtain this solid sound pressure level. Lowering the gain on the amp to 50 or 60% vastly reduced the speaker’s SPL.
So my initial take away is that the Crown XLS1500 may be under powered for this box. I really do not want to have to run the amp with the gain set at over 85%. I feel this may introduce too much distortion.
I switched the amp to Bypass mode and took it out of Bridged mode. This takes the crossover circuit offline. The speaker will play, but the volume still has to be at 100% to get any real sound.
I’ll use the mike tomorrow to obtain some measurements for posting. But it looks to me like we’re going to need a more powerful amp to run this driver in this box.
I’m open to all observations and suggestions.
Bach On
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You might need an impedance matching transformer.
ART CLEANBoxPro Stereo Balanced/Unbalanced Converter
Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR
Talent SXC Two-Way Balanced/Unbalanced Converter
It's not your subwoofer. It is the mismatch in signal strength from your CD player.
Pro-Sound amplifiers work on a much lower impedance on the inputs than consumer equipment. The consumer equipment just can't push enough current to get the Pro-amps to get enough signal to get them to full output.
Any one of those little boxes with the correct cables will be you friend.
You got just a little bit worried!
ART CLEANBoxPro Stereo Balanced/Unbalanced Converter
Rolls MB15b ProMatch Balanced/Unbalanced Converter 3.5mm/RCA/XLR
Talent SXC Two-Way Balanced/Unbalanced Converter
It's not your subwoofer. It is the mismatch in signal strength from your CD player.
Pro-Sound amplifiers work on a much lower impedance on the inputs than consumer equipment. The consumer equipment just can't push enough current to get the Pro-amps to get enough signal to get them to full output.
Any one of those little boxes with the correct cables will be you friend.
You got just a little bit worried!
That might be (probably is) the problem. Some pro amps can accept consumer level inputs low voltage without using an external preamp but not many, it should say right in the amp specs what voltage input it expects to see.
The problem with a lot of these DI boxes is that they are meant for pro audio - they roll off the low frequencies severely. This is the Art Cleanbox frequency response (before and after modification).
An externally hosted image should be here but it was not working when we last tested it.
So it's already rolling off at 100 hz and you lose about 6 db at 16 hz with the stock unit. You could eq it back if you have an eq, but ...
There's about a thousand threads about this issue on various forums, I could link a few dozen but just do a search. There's also mods to fix this issue, but modding brand new gear is not ideal. There are also some DI boxes that do flat frequency response right out of the box, but they are more expensive. There's also differences between models, new Cleanbox is different than old Cleanbox, which is different from Rolls, etc. There's a ton of info out there, it's best to look into this issue before buying.
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I don't think you are low on power, you simply don't have enough "gain". You've not mentioned clipping, so I don't think you're low on power, you just need to push it harder.
Signal Level & Filter
@ Bach On
Good to see you're on the way. I would be Extremely careful to NOT drive the driver hard without proper sealing of the box 🙁 So it's fortunate that you didn't have enough voltage going into the amp for the test.
What is this box exactly, make/model ?
Your laptop should be able to drive the amp quite well, & the CD player should have no propblems. Have you checked the gain settings via the Menu button on the amp to see if they are set too low ?
There seems to be a typo. To make sense it should say ( and Channel 2 ) In which case you CAN do it like that 😉
In the PDF it's corrected http://rdn.harmanpro.com/product_do...1_XLS3_MultilingualManual_041210_original.pdf
If you don't use bridged mode, then both CH1 & CH2 need to be fed the same signal.
@ Bach On
Good to see you're on the way. I would be Extremely careful to NOT drive the driver hard without proper sealing of the box 🙁 So it's fortunate that you didn't have enough voltage going into the amp for the test.
What is this box exactly, make/model ?
Your laptop should be able to drive the amp quite well, & the CD player should have no propblems. Have you checked the gain settings via the Menu button on the amp to see if they are set too low ?
There seems to be a typo. To make sense it should say ( and Channel 2 ) In which case you CAN do it like that 😉
In the PDF it's corrected http://rdn.harmanpro.com/product_do...1_XLS3_MultilingualManual_041210_original.pdf
If you don't use bridged mode, then both CH1 & CH2 need to be fed the same signal.
Likely you just aren't putting enough volts into your amp. Easy to fix with a pre-amp from the Salvation Army. Most any pre-amp (or amp or receiver, whatever you find at the Salvation Army) can drive the system, prolly using the "tape out" or "output" jack.
But you are missing a small and quick step. First you should run REW to see what signal is going into the speaker. Only trick is to be sure the amp ground is connected to the computer ground. Do not assume you know what is going into the speaker: test.
Your leak, as you say is just temporary. You know the old joke, "No problem too bad that it can't be fixed by silicone rubber".
Masking tape just won't do the trick. I'd use caulking stuff called "Draft Stop" which is essentially gooey rubber cement in a caulk tube (again, maybe from a Canadian source!). The special advantage is that you can strip it off immediately when done (or around windows, when spring comes to Canada in July) by just tugging the end and the whole fat strip comes away. Fat bead.
While the sim-lovers will scream, the truth in your setting is that a bit of leak and noise (at least during testing) is no big thing within a context of many other uncontrollable variables.
BTW, good to have these dry runs before the final installation, eh.
Ben
But you are missing a small and quick step. First you should run REW to see what signal is going into the speaker. Only trick is to be sure the amp ground is connected to the computer ground. Do not assume you know what is going into the speaker: test.
Your leak, as you say is just temporary. You know the old joke, "No problem too bad that it can't be fixed by silicone rubber".
Masking tape just won't do the trick. I'd use caulking stuff called "Draft Stop" which is essentially gooey rubber cement in a caulk tube (again, maybe from a Canadian source!). The special advantage is that you can strip it off immediately when done (or around windows, when spring comes to Canada in July) by just tugging the end and the whole fat strip comes away. Fat bead.
While the sim-lovers will scream, the truth in your setting is that a bit of leak and noise (at least during testing) is no big thing within a context of many other uncontrollable variables.
BTW, good to have these dry runs before the final installation, eh.
Ben
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I think I have the leaks plugged. Is it perfect? Not quite, but very close.
The interface box I'm using is the ART Phantom 2 Pro Dual Phantom Power Adapter
The Dayton calibrated mike requires Phantom Power. This unit can send a mono signal to the amp from the laptop on one channel AND accept input from the mike on another channel. Connection to the laptop is via USB.
The XLS manuals don't seem to be very clear about the crossover situation.
The confusion seems to be around Input, vs. Output channels.
I've was told by a service technician where I bought it that there is only one DSP chip to handle a single INPUT channel. He said that the amp can only process signals for Input Y.
But the manual which has now been updated seems to contradict that.
I've told hat Crown has developed a replacement amp for this series that can process on two input channels at the same time. But all this information may be bogus.
I have the Clipping Filter set to ON. But I saw no place in the amp software to adjust the gain.
I'm wondering if there might be different versions of the firmware loaded on these amps?
I did discover I did not have the speaker connected properly in Bridged mode. I'll experiment with that today.
Going back today to try some measurements. I have a small mixer that may allow me to increase the input.
Thanks to all!
Bach On
Just as a FYI - consumer electronics produce a maximum output of -10 dbm ie .707 V rms
Pro equipment (including the Crown Amps) require an input level of 1.4 V rms to drive them to full rated output. Even though the Crown amps provide consumer (unbalanced) RCA input jacks they still require an input level of 1.4 V rms to drive them to full rated output on these RCA input jacks.
Without using a matchbox/preamp(as mentioned previously) you will never be able to get to the full output of your Crown amp no matter what your gain on the Crown is set to, in fact with the Crown set to maximum gain you will just be amplifying a fair bit of the noise and distortion from the consumer gear
FYI - the ART Phantom 2 Pro Dual Phantom Power Adapter can't be used to provide Gain/impedance matching between consumer and Pro gear at line levels since it is designed for microphone usage.
Gain(voltage) matching between consumer and Pro gear is a must if you want things to work to your expectations.
Pro equipment (including the Crown Amps) require an input level of 1.4 V rms to drive them to full rated output. Even though the Crown amps provide consumer (unbalanced) RCA input jacks they still require an input level of 1.4 V rms to drive them to full rated output on these RCA input jacks.
Without using a matchbox/preamp(as mentioned previously) you will never be able to get to the full output of your Crown amp no matter what your gain on the Crown is set to, in fact with the Crown set to maximum gain you will just be amplifying a fair bit of the noise and distortion from the consumer gear
FYI - the ART Phantom 2 Pro Dual Phantom Power Adapter can't be used to provide Gain/impedance matching between consumer and Pro gear at line levels since it is designed for microphone usage.
Gain(voltage) matching between consumer and Pro gear is a must if you want things to work to your expectations.
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Most old junky stuff you will find at Salvation Army will roll off the bass like the Art Cleanbox graph I showed previously. Maybe not quite that bad, but MOST gear is not made to play below 20 hz and if you have a bunch of stuff rolling off the bass in your signal chain, by the time the signal gets to the sub sometimes there isn't much low bass left. A regular consumer level preamp probably won't be able to drive the voltage up high enough anyway.
Sim lovers are not going to scream, we might calmly suggest that this is a common sense issue. Pressure driven systems need pressure to operate properly. What do you think would happen if you blow a small hole in the engine of your car, is it going to operate properly?
Sure, the sub will still make noise with a small leak, but it won't operate the way it's supposed to. You will lose a lot of your low bass. Here's a recent thread showing the effect of a small leak.
http://www.diyaudio.com/forums/subwoofers/275969-when-things-dont-go-quite-planned.html
When the whole point of this design is to get a strong 16 hz, a loss like shown in the linked thread is pretty catastrophic. Sure it will still make noise, but it won't operate as designed and it won't do 16 hz as well as it could.
First you question the validity of sims, then you suggest that things that will guarantee the measurement won't match the sim are unimportant. It's absolutely necessary to accurately build what you simulated (including plugging up leaks) if you want a speaker to operate as designed.
I just ordered the Rolls unit from Amazon. It was out of stock at Parts Express. Customer complaints on the ART unit mentioned a loud POP in the speakers when it is first powered ON. No similar complaint was mentioned about the Rolls unit. I didn't get to the Talent unit.
And YES. I was a bit worried. A new Crown XLS2500 would cost right at $500. I'd rather not have to spend that. 😎
BTW, I did check. The XLS1500 will provide 1,550 watts into 4 ohms in Bridged Mono. But I didn't have the connection to the speaker correct yesterday. I'll correct that today.
But now I have a new question to ask Artisan. The sound module has eight 1/4 inch RCA female output sockets. I want to use the XLR inputs on the Crown amps. So I bought color coded patch cables with RCA male plugs on one end and XLR males on the other end. Now I have to find out more on the output from these 1/4 inch jacks on the Artisan Sound Engine. I don't want to have to buy or use the $65 Rolls converter boxes for these channels when we are finally connected.
As to the leaks, you can hear and feel the air from the leaks. I'm pretty sure I've got them temporarily plugged.
The good news is that there doesn't seem to be any rattles and mechanical noise coming from the cabinet and the driver. And the low frequencies are pretty solid. The air coming out of that port around 16 Hertz is probably fast enough to blow out a candle when the volume is turned up. But it really doesn't seem to be very noisy. Oliver's design seems very good. 🙂
But if I need to run this amp in Bridged mode, I may be looking at needing another amp for the other bass cabinet with the two 15 inch Dayton drivers. 😡
I'm going to temporarily move this new box into the Sanctuary today for testing. It's like moving a refrigerator. I need begin to find out if there are going to be sympathetic vibrations in that room at those low pitches.
I'll do my best to get some measurements today.
I'm working hard, but I'm still enjoying myself. 🙂
Bach On
http://www.crownaudio.com/media/pdf/amps/XLS_Datasheet_CRO137.pdf
Second page, left side half way down shows you the unbalanced input impedance. It is 10kohms. Normal impedance for consumer products is around 48kohms. Full power output for the amp is 1.4 volts. From the same data sheet.
Now for a little thinnin. Because most of you guys know that a CD player can push out 1.4 volts signal. What you will be getting is 1.4 of that signal because the signal amplifier within the CD player is not designed to produce enough current. The load they like to see is 4 times greater.
Now as for the potential problem mentioned by justaguy.
It usually requires changing the output capacitor to a larger value if you want a lower frequency response.
Something that I know Bach On has done already.
The ART Cleanbox - why you might need one, and how to modify it for subwoofer usage.
Good advice is here.
Second page, left side half way down shows you the unbalanced input impedance. It is 10kohms. Normal impedance for consumer products is around 48kohms. Full power output for the amp is 1.4 volts. From the same data sheet.
Now for a little thinnin. Because most of you guys know that a CD player can push out 1.4 volts signal. What you will be getting is 1.4 of that signal because the signal amplifier within the CD player is not designed to produce enough current. The load they like to see is 4 times greater.
Now as for the potential problem mentioned by justaguy.
It usually requires changing the output capacitor to a larger value if you want a lower frequency response.
Something that I know Bach On has done already.
The ART Cleanbox - why you might need one, and how to modify it for subwoofer usage.
Good advice is here.
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