Here is the basic idea for visualizing when the sub and the mid-bass driver would get into the compression zones, and how often. Red is the compression zone.
3 different signals:
You'll see how much the sub would be into compression, when the mid-bass driver is just touching that zone. This is based in the graphs published for John's system.
3 different signals:
- 1812 overture finale
- Pink Floyd - Wish You Were Here
- pink noise
You'll see how much the sub would be into compression, when the mid-bass driver is just touching that zone. This is based in the graphs published for John's system.
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I think most people that are into realism in their playback knows this and probably uses enough drivers that will move the air in the bass and deep bass with little to no compression (enough power too!.) IOW single 8, 12, 15, 18" drivers are not enough for facsimile of the real thing unless all you listen to is a flute. There are other people (a lot in this thread) that don't care about realistic playback - they use tiny little 10-30 watt amps praying to the invisible audio god it will be enough.
I suppose I'm into realistic playback when i want realistic playback. To achieve this there are many variables. 10-30 it really ain't going to happen with direct radiators
Depends on the direct radiator system. Dome tweeters are a key limiting factor, ribbons can be pretty efficient for the top octave or two. If one uses an MTM with something like the PR17OMO (which I know you're familiar with) and several bass drivers, a pretty high efficiency/output system can be assembled using direct radiators that can reach reference levels.
The bass is actually the easiest part. A pair of JBL 4638 per side in series will get you 100dB and 6 ohms, and they come pretty cheap on the used market with the very nice 2035h driver. The 2035h is cool because it is a less expensive 2226 with a 3" coil and a copper sleeve for very low inductance, basically, the choices made for budget reduction align perfectly to using in a home rather than pro setting (smoother top end, less inductance, lower Mms)
Of course at the scale of a pair of dual 15"s per side vented, you could just as soon do a horn, with the upsides and downsides associated.
The bass is actually the easiest part. A pair of JBL 4638 per side in series will get you 100dB and 6 ohms, and they come pretty cheap on the used market with the very nice 2035h driver. The 2035h is cool because it is a less expensive 2226 with a 3" coil and a copper sleeve for very low inductance, basically, the choices made for budget reduction align perfectly to using in a home rather than pro setting (smoother top end, less inductance, lower Mms)
Of course at the scale of a pair of dual 15"s per side vented, you could just as soon do a horn, with the upsides and downsides associated.
Interesting post.
Is there a reason (coupling?) that the field coil is a DC simulation of a permanent magnet? I'd have though the obvious method of a magnet free speaker driver would be to suspend the voice coil into another - slightly bigger voice coil and wire them in anti-phase.
You might have to horn load (or Infinite Baffle) the result to prevent it flapping in and out too much (and hence keep the coils axially close to each other) but it would be an interesting 'air cored' experiment in driver sound.
What's the catch?
While this is pretty much factual, I knew it would stir up troubles in micro-watt land. I have many friends that use 4watt, or even less, amplifiers. I can hear them being run into clipping all the time. Doesn't seem to bother them in the least. There's even a few to the east of me that bow down to the 3/4 watt God. I am on the brink of giving up having an opinion. I just wanted to let Mr. Pooh know, there's at least one other person who shares his sentiment.
Sure, but there are rational limits to consider. No one wants to use more drivers and amp power (think $$$) than is really necessary. I use lots of LF drivers so compression is not an issue with me, but I tend to do that not for compression issues, but for directivity and modal smoothing. Lack of compression is just a side benefit.
My system is flat (slight LF rise) to 20 Hz with direct radiators, so I don't accept your last statement.
Yes, of course. When I ran Altec A5 speakers in a modest room, 2W on the horns allowed 112dB peaks, no clipping. On the woofers I needed about 18 volts, or 40 watts.
With in inefficient open baffles in a medium sized lava cave, my hulking Crest 650 WPC amp was just enough. Still couldn't get the levels I wanted, but I did burn out a few tweeters.
What I was trying to say is 10-30 watts driving direct radiators in the low bass at realistic (live) levels without clipping -- tough road. Surely that doesn't mean people can't enjoy low powered amps with direct radiator bass. So my conclusion is compression (what i was commenting on) doesn't really mean much to people that would build this direct radiator BTA speaker optimized for a single 15 watt amplifier.
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Yes, of course. When I ran Altec A5 speakers in a modest room, 2W on the horns allowed 112dB peaks, no clipping. On the woofers I needed about 18 volts, or 40 watts.
With in inefficient open baffles in a medium sized lava cave, my hulking Crest 650 WPC amp was just enough. Still couldn't get the levels I wanted, but I did burn out a few tweeters.
Of course, this all makes perfect sense. Open Baffle bass is the most inefficient method of all. And there are some producers of open baffle that claim 3.5 watt s.e. tube amps are perfectly compatible. That's just one example of what I was saying earlier.
Hello Bernd
Perhaps it was lost in translation or brevity that I meant the term 'original' in a complimentary way. The visual design is stunning, and the overall speaker appears to be daring and non-conformist. Add field coil drivers and you have all my attention. Cool
. Any commentary on how they sound would be welcome.Also, thank you for posting your graphs on baffle step compensation. They are very informative. It appears your BSC is comparable in shape and magnitude to what I chose, except yours is lower in frequency, which is to be expected owing to the wider baffle.
Oh, and you have a private message.
Regards - Pierre
This is why we should error on being too precise in posts. I thought you meant Hz not watts.
Sure is.
I've heard a few of those open baffle speakers that claim to work with SET amps - and you know what? They do. Sort of. The reason is no bass. These speakers start with high efficiency drivers, then make little or no provision for OB bass loss. They retain the high efficiency, but at the cost of bass response. If you want proper tonal balance you often have to give up 8-10dB of efficiency on the woofer. That's the devil's trade-off.
Hello!
I am wondering a little bit about the dogmatic discussion with respect to high or low efficiency or open baffle vs closed box.
Btw, Lynn mentioned open baffle already in his first post of this thread... Let us - or who is willing to believe - in open baffle or high efficiency and we will let you believe in closed box and low efficiency with high power amplifiers.
At the end of the day everything is a compromise and has it's advantages and disadvantages...
So far as I understood one of the end pathes of the discussions here in this thread ended at a Radian compression driver with an round horn. A really high efficient combination. Why feeding this combination with an 100 Watt amplier?
Concerning an open baffle you need to take care not to acoustically short the driver. A front loaded design like this is the right way in my opinion and at the same time looks good:
https://www.youtube.com/watch?v=Az-xXR1-CKI
I am wondering a little bit about the dogmatic discussion with respect to high or low efficiency or open baffle vs closed box.
Btw, Lynn mentioned open baffle already in his first post of this thread... Let us - or who is willing to believe - in open baffle or high efficiency and we will let you believe in closed box and low efficiency with high power amplifiers.
At the end of the day everything is a compromise and has it's advantages and disadvantages...
So far as I understood one of the end pathes of the discussions here in this thread ended at a Radian compression driver with an round horn. A really high efficient combination. Why feeding this combination with an 100 Watt amplier?
Concerning an open baffle you need to take care not to acoustically short the driver. A front loaded design like this is the right way in my opinion and at the same time looks good
:https://www.youtube.com/watch?v=Az-xXR1-CKI
This claim is used all the time and its true to an extent. But lets not kind ourselves that all compromises are equally audible. That is simply not the case. There are "optimum" designs where the audible compromises are minimized.
To the OB discussion. I recently measured an OB system that claimed high efficiency and yes, there was very little bass. I'll post this at some point.
I've built OB systems that are more sensitive 80 hz up (six 16 ohm tens per channel - still have them lol) than a pair of Altec 416's. It is doable and I prefer it over a pair of 15's. Better yet (in my room) use a good front horn with an 8".
I agree though most open baffle systems are weak in bass efficiency
I agree though most open baffle systems are weak in bass efficiency