1850 horn measured plots
Printed From: Speakerplans.com
Category: Plans
Forum Name: 1850 and 186 horns
Forum Description: Discussion / Questions about the 1850 and 186 horns
URL: https://forum.speakerplans.com/forum_posts.asp?TID=26669
Printed Date: 26 March 2026 at 11:31pm
Software Version: Web Wiz Forums 12.08 - https://www.webwizforums.com
Topic: 1850 horn measured plots
Posted By: pfly
Subject: 1850 horn measured plots
Date Posted: 10 May 2009 at 7:03pm
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I spent this afternoon with my friend and sound system co-owner measuring and tuning our sound. We took frequency response plots from different stacks of 1850 horns. Horns have V18-1000s in them. They don't have mouth braces (lazy us!) and there is surprising amount of build tolerances between the cabs (one of them is approx 1cm shorter than the rest!) Measurement was done in proximity of a wall, about 4-5 meters away from it. Mic placement wasn't measured, you can see it from the pictures. Equipment used was Klark-Teknik 6051 -measurement microphone, Edirol UA-25 Interface and Easera Systune. Horns were driven by single QSC RMX 2450 in bridge mode, so we drove it ultimately into 1 ohm nominal load, but we didn't drive it too hard. Levels were kept the same so everytime we plugged another cab in, volume was increased due to lower impedance and mutual coupling. Edirol was plugged straight into the amp and all amp's limiters, filters and such were cut off. Mic was uncalibrated so no actual SPL figures. We started with single 1850 horn standing upright  We continued with the same cab on its side   Then we added another one   Then we stacked them   Then we put them upright next to each other  Third one   Stacked   And finally fourth bin was added, first all standing in the same line   And stacked in the most optimum way   I'll put the second measurement (single cab on its side) again so it can be easily compared to the stack of four So by adding cabs this way we got 12db more sound around 50hz, flatter frequency response and nice bonus extension. Now if that stack would only go to 40hz flat, it would be real winner. I think getting from 50hz to 40hz is way more important than getting from 40 to 30hz, there is so much more relevant musical information in 40-50hz area. |
Replies:
Posted By: Sinfinity
Date Posted: 10 May 2009 at 8:23pm
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Thanks for the effort Any chance of stacking another two on top please  ------------- Matt at ukamp dot co dot uk |
Posted By: pfly
Date Posted: 10 May 2009 at 8:25pm
| So all four on top of each other? We couldn't lift them like that... |
Posted By: Sinfinity
Date Posted: 10 May 2009 at 8:27pm
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No sorry, a stack of six 1850's please 2 wide 3 high ------------- Matt at ukamp dot co dot uk |
Posted By: Sinfinity
Date Posted: 10 May 2009 at 8:29pm
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I understand you have probably allready upset your neighbours, and therefore apologise in advance. ------------- Matt at ukamp dot co dot uk |
Posted By: pfly
Date Posted: 10 May 2009 at 8:32pm
We don't have six  and these four are the only four in Finland as far as I know.We are going to upgrade to Looneys if all goes well so no more 1850 building... The price of Looney is so cheap that I don't feel like building 1850s myself, even with shipping costs. |
Posted By: Sinfinity
Date Posted: 10 May 2009 at 8:34pm
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I wish you luck on you Looney acquisition
------------- Matt at ukamp dot co dot uk |
Posted By: LjudLahger
Date Posted: 10 May 2009 at 11:03pm
 
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Posted By: Rog
Date Posted: 11 May 2009 at 2:21am
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Sorry to say this but those measurements are compleatly irrelevant.
You never take readings with a measurement mic at x distance from the ground. The mic to floor distance doubled with exhibit gain as you have half space condidtions. Above this you are working in free space. So you are in effect working in two different loading condidtions with the frequency set by the mic to the floor distance.
Please try to learn something about proper groundplane measuremnts before you undertake any measurments. You had a great opportunity and some good measurement kit at your disposal, and if you had taken the measurements correctly some very valid plots to share.
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Posted By: jethrocker
Date Posted: 11 May 2009 at 4:09am
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So would you say that for measuring groundplane response of bassbins mic should be close to the floor so any halfwave gain would be well out of band? Though the plots may not be accurate in terms of overall response, i think they're useful to demonstrate the changes in response from different stacking configs...something that comes up here again and again. The results seem to follow theory at least in that respect, you can see the slight extension gained by coupling and the general response slope lifting at bottom end. |
Posted By: Rog
Date Posted: 11 May 2009 at 4:44am
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Yes for comparsion the plots are very usefull.
For groundplane measurements the mic should not be close to the ground, it should be on the ground. Halfspace loading will give 6dB of gain, so if you postion the mic 2 meters away, which will lose you 6dB, you will end up with a 1 meter reading.
2.83 volts in for 8ohms or 2.00 volts on for 4 ohms. I don't understand why they needed to bridge an amp into 1 ohm. Most measurements are taken with between 1 watt and 100 watts. Unless you are measuring power compression, there is no need for mega power amps when doing freuqency responses.
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Posted By: jethrocker
Date Posted: 11 May 2009 at 4:56am
So if you wanted to measure the actual halfspace response you would keep the mic at 1 metre, or do you mean that the extra 6dB results from the halfspace loading on the mic itself. I see now that mic on the ground makes sense to maintain the same loading conditions at all frequencies, though I'd still assume that the mic being a very short distance of the floor would make very little difference at low frequencies? |
Rog Mogale wrote:Posted By: Rog
Date Posted: 11 May 2009 at 5:23am
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You place the speaker on the ground and then place the mic 2 meters away from the front of the speaker pointing at it. The mic must be on the ground with the capsule touching the ground. If you then feed the speaker 2.83 volts (presuming its an 8 ohm load) you will get a 1w/1m reading.
The mic must be at 2 meters as you gain 6dB from halfspace loading, but lose this 6dB by the mic being double the distance away from the speaker.
It dosen't take much of a distance to effect the reading if the mic is rasied of the floor, even at LF. The mic in some the the pics from the 1850 horn measurements looks like its about 1 meter from the floor, which would still effect the reading.
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Posted By: pfly
Date Posted: 11 May 2009 at 7:06am
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The point wasn't being really scientific, but to test out the equipment (1850s and the measuring software) I wanted to see how different ways of stacking affects the response. As I said we didn't drive them hard. Amp was bridged because it was wired that way already. Thanks for the info though, we'll try to be more accurate next time  |
Posted By: pfly
Date Posted: 11 May 2009 at 7:26am
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Rog Would that 60-70hz dip be there because of some cancellation stuff going on between the ground and the mike? |
Posted By: Jake_Fielder
Date Posted: 13 May 2009 at 12:17am
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If the height of the mic makes so much difference, wouldnt it be more usefull to have it the same height off the ground as an average persons height?? |
Posted By: jethrocker
Date Posted: 13 May 2009 at 5:37am
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Read back Jake.. the mic is on the ground so that its loading conditions are the same throughout the frequency spectrum. If were at a given height, it would couple with the floor up to a given frequency, but not above that frequency. The idea is to take a groundplane (halfspace) reading. That's the way I got it anyway. |
Posted By: schiller
Date Posted: 19 September 2009 at 7:31pm
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I just saw your plots , thanks a lot for sharing your efforts with us. Really a pity you didn't put that mic on the ground, but i believe the difference under 100 Hz wouldn't be much-if any. This is the only 1850 measurement available in the universe :-) What i see from the plot, is that in case of a single horn per side and in a room (yes there are people using this designs for hi-fi) bass from 50 Hz will be awesome. Maybe the 186 can better this, because of higher Qes driver, which loads better down low. Does the peak at cutoff indicate a smaller than needed back chamber, a larger throat or both?? Thanks again, greetings from Athens (Greece) Konstantinos |
Posted By: Vaso_Bobinata
Date Posted: 13 October 2018 at 11:59pm
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Only ifi could see that graph the links are broken. Thanks
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