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Tarheel TJ
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Posts posted by Tarheel TJ
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This is a great idea. There are substantial gains to be made by playing with speaker positioning, but it becomes a major obstacle when you are talking about big horns. I keep my speakers on furniture sliders, but they are only ~100lbs each. I think wheels are a great choice for Jubs.
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19 hours ago, babadono said:
@Tarheel TJ I'm curious did you try putting your "skyline" diffusers on the back wall behind your listening position. I read or heard somewhere that's optimal place for such. I think it was on the "realtraps" website.
That may well be true for most rooms. My room is different from most. It is a large ~25x25 open basement room. Because of two columns and a staircase that break up the room, the stereo/home theater only occupies a little more than 1/4 of this space. So the back wall of my listening room is some 10-12 feet behind the couch. I don't think the panels would make a noticeable difference that far from both the speakers and listener.
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They are 25lbs or so per section. Definitely need a stud or very solid drywall anchor.
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A Dynaco tube amp will sound great with Heresies. I have used a similar setup in the past (Dynaco ST-70 w/ Heresy I). I'd add a sub if you like bass heavy music though. The Heresy doesn't dig too deep on its own.
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Ok. I think I got all that right. Take a look and let me know how you interpret this. Thanks
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Thanks again. Ok, here is what I get for the spectrogram. Can you help me decipher exactly what information this is giving? I only have a vague idea of what this is trying to show.
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Thank you for the explanation.
So it sounds like the phase growth in my setup (above 100hz) is mostly related to the inherent characteristics of the horn/driver combo. So potentially going to a different horn/driver could lead to improvements in that area?
Below 100hz, it seems there isn’t much that can be done besides using FIR filters.
So it sounds like I have made about as much of an improvement as I can with my current hardware. Would you agree?
I have one more question. How do you get REW to generate the spectrogram image? How about group delay and impulse response? I can do SPL and phase response easily enough, but the others just show a blank screen when I click on them. Thanks again.Lee
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I used Roxul Safe & Sound for the insulation, 4" thick for the walls and 2" thick for the ceiling. 1x4" pine frames. Acoustic fabric from Guilford of Maine. The wall panels are 2'x4'. The ceiling "clouds" are 4'x8'.
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Chris,
I'd love to get your thoughts on some more questions I have regarding phase growth. First, it looks like you achieve less than 90 degrees of phase growth from 100hz up with your Jubilee/TAD setup. So far, I have managed to reduce the phase growth in my setup (LaScala bass bins, B&C 2" CD on ZXPC horn) from ~700 degrees of phase growth above 100hz, down to about 240 degrees, by using your "fractional order" method. The improvement is great, but naturally, I'd like to go farther. To what do you attribute your lower phase growth? Is it a characteristic of the TAD drivers or the K-402? Or is there something in the crossover setup that is driving this? Is there something else I could be doing to farther reduce phase growth?
Second, It seems that in all of these measurements, phase grows considerably below 100hz, regardless of crossover settings. Why is this? Is there something about bass frequencies or drivers that fundamentally creates phase growth? Is there anything that can be done to reduce phase growth at lower frequencies?
Lee
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This thread on DIYaudio discusses another way to achieve low phase growth in a crossover. I don't speak French, so I can't make much of the original source material, but the OP seems to get very good phase behavior out of his speakers.
https://www.diyaudio.com/forums/multi-way/277691-harsch-xo.html
I may have to try this technique out. His phase measurements are impressive.
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Next up, I wanted to try Chris' "fractional order crossover" method, to see if I could further reduce phase growth. Unfortunately, it didn't seem to make much difference for me. The phase growth stayed about the same as where it was with the BW 6dB/octave setup (~240 degees from 90hz up). Any thoughts?
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Next up, I tried keeping the crossovers set where they are, but reducing the slope to a Butterworth 6dB/octave slope. This made a dramatic difference in phase behavior. I would agree with Chris that it is a difficult to describe effect, but not a subtle one. Everything sounds a lot more "together". The best way I can describe it is that it sounds less like a stereo system and a lot more like real life. Big step in the right direction.
The results show a clear difference. Huge reduction in phase growth, only about 240 degees of phase growth from 90hz-20khz. A nearly three fold reduction! This is very audible. It made me curious to go as far as possible with phase growth reduction.
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It sounds like blowing a compression driver is not much of a concern. I am running a 30 watt tube amp through compression drivers that are rated for 220 watts continuous, so I guess there is nothing to worry about there. That said, I'm not sure going to a fractional order crossover really makes much difference in my setup. I'd be interested to see what others have to say about my results.
For starters, here is how my system measured about a week ago. This is using Linkwitz Riley 24dB/octave crossover slopes for every driver and crossover point. As you can see, the frequency response is relatively flat (other than the sub), but the phase growth is considerable. Over 700 degrees of phase growth between 90hz and 20khz.
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Well I know one thing, you are in for a treat! Going fully active with DSP and treating my room with absorption/diffusion are unquestionably the two largest upgrades I have ever made to my system. Do both of those things and you will surely ascend to a higher plane of audio existence, haha.
My initial reaction is to say go active first, simply because it is such a powerful tool. You really can make your system sound exactly the way you want it to. You will have control over frequency response and phase in ways you never imagined possible. It truly puts you in the drivers' seat of your system. It also opens up a new world of upgrades and DIY tinkering. You can essentially swap individual speaker components at will, using the DSP to knit everything together. None of this is even remotely possible with passive components.
However, I think you actually have the right idea with doing panels first. There are two reasons for this. First, it is an immediate and very noticeable upgrade. Your system will sound much better as soon as you hang the panels, and you will gain the added enjoyment right away. Setting up a DSP crossover takes time. These systems are powerful and have impressive capability, but they are only as good as the person programming them. It took me well over a year just to figure out how to set up crossovers and properly EQ a system. Don't get me wrong, I had it up and running and sounding pretty good in a day or two, or so I thought. To really get it dialed in, you will have some learning to do. I am only now beginning to learn about how crossovers effect phase response, and some strategies to address this (see Subconscious auditory effects..... ). Additionally, having a well-treated room will help you make better measurements of your system's response, which is a critical part of optimizing a DSP crossover.
So, if I were you, I'd do some sound panels first. Do a mix of absorption and diffusion if you can, but do absorption for sure. Try to cover as much surface area as you can stand. One or two panels will probably not get the results you are looking for. Try behind the speakers, side wall first reflection points and if possible, ceiling. You will reduce the reverb time of your room and increase the proportion of direct sound. This will be a very noticeable improvement. Then, after you have enjoyed that for a while, take the leap and go active/DSP. You'll have a nice-sounding, low-reverb room in which to start measuring and tweaking.
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You house proud town mouse,
Haha, charade you are!
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Chris,
I read this thread a while back, but I was still trying to figure out how to use DSP to optimize SPL response, so I made a mental note to return to it. I came across it again over the weekend, and I decided to do an experiment. I simply changed my crossovers in my DSP from LR24 to BW6. Still using named crossovers, but dropping from 24dB/octave down to 6dB/octave. This made a HUGE improvement in clarity and intelligibility. Not subtle at all. To say the least, my curiosity was aroused.
Now I am trying to go all the way and eliminate named crossover slopes entirely, using your "fractional order" method. I think I understand how it works, but I have one question. Is there a risk to HF compression drivers by not using a crossover? My CD/horn combo drops like a stone below ~390hz. Assuming I throw a few PEQs cuts below this frequency, I can quickly kill output below my 400hz crossover frequency. However, below these PEQs (in the <150hz region) the input signal goes back up, as it is now outside of the PEQ's effective region. Does this signal represent a danger to my compression drivers? Am I going to shatter my CDs by hitting them with bass signals? Obviously they have no output down there, but does the signal move the voice coil anyway, or do the electrical properties of the voice coil reject signals at that low of a frequency?
Thanks
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Interesting. Thank you for your insight. I was hoping you would reply to this.
So, assuming the listener is always in the sweet spot, is limited vertical dispersion a significant drawback? Is vertical dispersion matching between the bass horn and HF horn worth pursuing?
I am debating going for TAD beryllium 2" drivers for the extended HF response. However, it seems one could go for an AMT-based HF section that would have a similar clean, extended response for much less money. The main drawback that I can figure is the limited vertical dispersion, as compared to a CD on a horn. I'm trying to decide if this is splitting hairs, or is it a significant issue.
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I would love to hear some experience from people who have used horns with different dispersion patterns in their system. I have been considering some upgrades to the HF section of my speakers and one of the main differences between the two potential upgrade paths is vertical dispersion (compression drivers in a horn vs. AMT drivers with wings). In what ways does this affect in-room performance?
On once hand, the very limited vertical dispersion of a AMT drivers would seem to be a benefit as it would keep excess sound off the floor and ceiling. On the other hand, it seems that it is good to match polar coverage of your HF and LF horns at the crossover point. Wouldn't a horn with somewhat wider vertical dispersion than an AMT (like a K-402) better match polars with a horn-loaded bass bin (like a La Scala)? Wouldn't that produce a more even power response? Or is this only important in the horizontal?
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7 minutes ago, Lbk said:
Have you run your horn's / speakers passive?
I have run these speakers in a number of configurations. At first, they were stock La Scalas with AL-3 crossovers. The only non-stock thing about them was that I removed the tweeter from the enclosure in order to time align it. I then ran this same configuration for a while with the K-400 horn replaced with the ZXPC horn (using stock K-55 with a 1"-2" adapter).
The real revelation, however, was going to a 2" exit driver (B&C De-75-TN) and a fully active DSP crossover. The performance gains are off the charts. I would never consider going back to a passive crossover at this point.
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I have to say, after spending a great deal of time listening over the weekend, I think I may have under-estimated the difference these have made to my listening room. I heard some really nice detail and spaciousness to the sound. This may be more of an improvement than I initially realized. Good stuff!
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15 minutes ago, Tarheel said:
Looks great. Would like to hear your system!
Send me a message any time you are in Winston-Salem!
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8 minutes ago, babadono said:
Nice work. I like. So 2 x2 staggered lengths? Only glue to fasten blocks to backing? Only 60 hours? That'd take me a couple hundred.
Actually the blocks were more like 1 3/8" square. They are pine staves from Home Despot. Like what you would use between your deck and the railing. Glued to 1/2" plywood that I had laying around. With the glue and 12 cans of spray paint, I probably have a little over $100 in them. By far the worst part was sanding the ~1000 wood blocks. Took sooooo long.
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There was definitely an improvement in the sound. It is a touch less harsh and a little more detail is audible. Not too dramatic. I would imagine this effect would be more pronounced in a room that was not already extensively treated with absorption, as mine is. The biggest difference by far is the improvement in imaging and soundstage. Before, it often sounded more like the music was coming from the speakers themselves, not the space in between. Now there is a more continuous sound field all the way across the front wall. I would say there is more depth to that sound field as well. Overall, I would say the absorption panels made a more dramatic effect than the diffusers, but both made an improvement.
As to whether it was worth the time or not is a question I guess you'd have to answer for yourself. I look at hi-fi as a hobby to spend time on, not just a way to spend money. I bought my LaScala Industrials in a very sad state. The cabinets smelled like beer and cigarettes and the tweeters were missing. I spent many hours refurbishing them and was very happy with the end result (though I only use the bass bins now). Likewise, I built a Bob Latino ST-70 a couple years ago from a kit, when I could have bought an already assembled amplifier. To me, the time spent and the satisfaction of building something for yourself brings as much joy as listening to the result. The fact that these are nice to look at just adds to the enjoyment.
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Receiver Headpone Jack (ouput) to Power Amplifier
in 2-Channel Home Audio
Posted
I have done this in the past. As others have stated, it is not ideal with regards to output impedance etc., but it will work. I ran a tube amp off the headphone jack of a cheap Sony Receiver for a few years until I could afford a proper preamp. Sounded pretty good to me at the time!