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In the Forum: Horn-Loaded Speakers
In the Thread: A Frankenstein Macondo - Injection channel - trying it as open baffle.
Post Subject: I think you misuse my terminologyPosted by Romy the Cat on: 7/2/2013
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 Rewind wrote:
Hi, I am slowly building my own Macondo. I understand why the injection channel is there. It brings some kind of softness that the compression drivers lack.

OK, but it is not how I feel about the service of injection channel. I do not know what compression drivers you use but if they are good compression drivers then they shall not lack any softness. I might only presume that in case of your playback you use ether inferior compression drivers or amplification with too much higher harmonics if you have a feeling that your compression drivers are too hard. If you wish then let me know the content of your Macondo and I might pitch you some tests to confirm it.
 Rewind wrote:
I am using a 12" JBL midbass driver (~100dB sensitivity) in a 50L single driver Marshall cabinet, that I have turned into a U-form open baffle (with a roof). The difference between sealed and U-form open baffle above 150Hz was huge! Everything becomes more open and relaxed, no more muffled bass distortion, as can be heard from many cheap vented or sealed home theater subwoofers. I do have to use a lot of EQ to get bass, which I am not sure I can live with. It is probably better to get a dedicated subwoofer. The tricky part will be to fit a sealed sub to an open baffle midbass injection channel. The dispersion is very different, and a lot other things that I don't grasp yet are probably also different.

Well, we need to agree that there are no rules how acoustic injection might be used and I can judge only from what I tried. It sound to me that you do not use injection per se but rather a correction. You shall not be able to hear (in my mind) openness and relaxed feeling of open baffle and if you do then your injection is set to run way too high. In this case it acts more like dipole bass corrector. Dipoles by nature act as neutralizer for lower octave; it has to do with the way how dipole bass loads rooms. Anyhow, sine I do not know what you use for upper and midbass it is hard to say anything further.

 Rewind wrote:
I did however confirm my worries that the 2" Radian driver I am using would be much faster. Overlapping both drivers sound wrong. I will try my best to time align them. We might be using them differently. I can still hear my injection channel a little at 2500-4000Hz.
I am bit at lost in here. You say that you use 12" JBL midbass driver for injection and you feel that 2" Radian driver will be “faster”. They are so much not the same drivers and so much used for different peruses. I truly do not feel that they might be contestants for any type of analogues injection. Ether you or I are confused.
 Rewind wrote:
Onto another open baffle dipole experiment in my Frankenstein Macondo:I have also tried to exchange the 1" Beyma compression driver in a small AG Trio horn, for a Beyma TPL-150, with mixed results. The TPL-150 sounds very pleasant to the ears in chaotic music, but I prefer to use the 1" CD and just stop listening to music not scored for horns. It is a more rewarding experience. It should not be my job to fix badly recorded material with forgiving speakers like the AMT.  Switching between 1" CD and TPL-150 is like listening to live music, versus dead music. The TPL-150 is very analytical, and accurate, but I am not as involved in the music. The Beyma TPL-150 is also in a smaller U-form open baffle dipole, because it sounded best like this. More open and relaxed. A little less sensitivity and probably less midrange, but I am okay with that. Taking off the back chamber did not change my bored impression of it. I wish I could be this black and white always, but sometimes I do listen to popular music. Therefore I will try my best to build a bass AMT to better fit with the TPL-150, than the 2" horn. These horn speakers are more like instruments. You don't try to play angry electronica with a bass tuba. I guess I just need a second pair of speakers for those days when angry electronica is high on the playlist.
I have seen somewhere a lot of noise crated around TPL-150 by a fool from Brazil who goes under name Angeloitacare. I never used TPL-150 and I do not know it and frankly the only fact that this idiot promotes this driver say a LOT to me about sonic character of this driver. This Brazilin guy is superbly predictable. He runs from site to site, copy verbiage from forum to forum, expressing absolute foolishness that he himself does not understand. Him is juts mouth attached to no brain, no soil, no ears; with own cognitive function of scared chayote. He started his world tour right here at this forum but it was too revolting to tolerate him around. When a few years back he “discovered” TPL-150 I did read his comments about the driver. Unfortunately the fool can’t escape himself. Reading between the lines of his comments, knowing what level of primitivism he is targeting and understanding that fool spirit I got 100% reference about the performance of TPL-150. I had no interest in this driver a few years back and I have no interest in it now. 
 Rewind wrote:
I am also building a GOTO horn for the 2" in wood. Because I can. I just have to hear the difference between Avantgarde Trio type midrange horns and the GOTO. Progress is slow, but one half is done. Will report back.
Good for you. GOTO are very different from Avantgarde midrange. Avantgarde is heavy cone ceramic, very low compression with no back chamber driver damped in ferrofluid. GOTOs are VERY different.
 Rewind wrote:
It is possible your Tannoy Red 10" won't cut it as an open baffle driver. It needs a lot of excursion and large area. My 12" JBLs are actually too small and have too low Xmax. Best drivers would be the 21" Beyma's. Some use them in dipole line array with high pass 200Hz.
Rewind, vintage Tannoys are very different drivers then 12" JBLs or 21" Beyma. I do feel that even though you use the same word “injection” but we are taking about very different duties. To me it is absolutely irrelevant if Tannoy would be open baffle or sealed. I can assure that that it would make no difference at all.

Rgs,
Romy the Cat

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