Greets!
Ideally need to draw a dimensioned plan view to find optimal polar response to find what basic speaker design is ideally required with baffle width and/or driver size often setting horizontal dispersion and vice-versa, so as previously noted, drivers vertical for a wide polar response, which in turn sets the vertical polar response and can be simmed with any box design program that includes flat baffles such as Hornresp.
Ideally need to draw a dimensioned plan view to find optimal polar response to find what basic speaker design is ideally required with baffle width and/or driver size often setting horizontal dispersion and vice-versa, so as previously noted, drivers vertical for a wide polar response, which in turn sets the vertical polar response and can be simmed with any box design program that includes flat baffles such as Hornresp.
I'm going to attempt something like this using the drivers I have: two 8 inch 4ohm woofers wired in series, two 5 inch 4 ohm mids wired in series, and one 6ohm tweeter
The other option is to place the mids below the tweeter, but I can find the example that I saw.
The other option is to place the mids below the tweeter, but I can find the example that I saw.
Last edited:
Best to use MTM if within ~1/4 WL of the XO point which puts its response overlapping on axis whereas the TMM requires some extra XO design effort to counteract its axis off center 'beam steering' unless using DSP.
When I built my main speakers, I had an AVR and a projector, and building a center speaker was always pending. Thinking about building it in such a way as to make a good match, I went to the builder's page and according to him, the addition of a small (4") dedicated media speaker is necessary. All the models he built have it.
Finally something exploded in the projector - it wasn't the lamp - and I abandoned the HT. But maybe it would help the OP to read something from this link.
He says :
" This center speaker has been on the to-do list for a long time and started as a "classic" horizontal d'Appolito set-up. However, unless we cross over at a very low frequency between midbass drivers and tweeter, we may experience crossover lobing, that is uneven frequency response as we move from seat to seat in our home cinema. Usually we have an even horizontal dispersion from vertical aligned drivers if the chosen points of crossover have been done with respect to the diameters of the drivers and slopes of crossover. When wavelength hits a value equal to the diameter of the driver, we start having beaming (wellknown from fullrange drivers) and if the point of crossover is above this frequency we may have irregularities off-axis.
Most good center speakers are - at least - 3-way. Some manufacturers go even further and use a whole range of tweeters to overcome the problem - like McIntosh."
http://www.troelsgravesen.dk/8008CENTER.htm
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm#CENTER__SPEAKERS_FOR_SURROUND_SOUND
Finally something exploded in the projector - it wasn't the lamp - and I abandoned the HT. But maybe it would help the OP to read something from this link.
He says :
" This center speaker has been on the to-do list for a long time and started as a "classic" horizontal d'Appolito set-up. However, unless we cross over at a very low frequency between midbass drivers and tweeter, we may experience crossover lobing, that is uneven frequency response as we move from seat to seat in our home cinema. Usually we have an even horizontal dispersion from vertical aligned drivers if the chosen points of crossover have been done with respect to the diameters of the drivers and slopes of crossover. When wavelength hits a value equal to the diameter of the driver, we start having beaming (wellknown from fullrange drivers) and if the point of crossover is above this frequency we may have irregularities off-axis.
Most good center speakers are - at least - 3-way. Some manufacturers go even further and use a whole range of tweeters to overcome the problem - like McIntosh."
http://www.troelsgravesen.dk/8008CENTER.htm
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm#CENTER__SPEAKERS_FOR_SURROUND_SOUND
Attachments
Thanks for the links academia50. I will be using a 3 way design.
Report from the battlefield today: My main router broke during my last build, so I tried attaching my trimmer to the table and that broke too
. I ended up using a sawzall to cut the holes, they work, but they aren't pretty. The hard part is out of the way, Any thoughts on whether I should port this or leave enclose it ? Current dimensions are 36 wide x 12 high x 12
Report from the battlefield today: My main router broke during my last build, so I tried attaching my trimmer to the table and that broke too
. I ended up using a sawzall to cut the holes, they work, but they aren't pretty. The hard part is out of the way, Any thoughts on whether I should port this or leave enclose it ? Current dimensions are 36 wide x 12 high x 12
Portado is difficult to calculate the correct dimensions of the port, so you must use some software for this, I used Win Isd with good results, although here they prefer Horn Resp, but it is much less intuitive.
The sealed cabinet has less performance in bass and midrange, and you need more power from the amplifier to match the ported one. But it has the advantage that it is easy to build, you throw the polyfill inside, seal the box well and it will be ready.
Although I don't remember seeing many sealed center speakers, except for the Klipsch RC-3, it seems to me.....
The sealed cabinet has less performance in bass and midrange, and you need more power from the amplifier to match the ported one. But it has the advantage that it is easy to build, you throw the polyfill inside, seal the box well and it will be ready.
Although I don't remember seeing many sealed center speakers, except for the Klipsch RC-3, it seems to me.....
Last edited:
It's probably not necessary, it's just the theory that says that to upload 3Db you need to double the power......I don't know how much power you have available for your center channel........there are many people too enthusiastic about looking for constant and obsessively technical articles that do not adapt to reality......good luck with the project !
I completed the first version yesterday. This was also the first time I worked with MDF (I scored some discount MDF at a local hardware store), its much easier to sand than plywood, easier to drill holes, and very very dusty.
The imaging is much better than the Polk and voices are easier to hear. Surprisingly, it doesn't require that much more volume to reach listening levels. I thought that my amp wouldn't be able to handle it. The bass is okay, so porting it is still a possibility. Someday I will buy the right equipment to measure it, I have a microphone, but it's not designed for speaker measurement.
Overall this center adds a lot more to the listening experience and I'm pleasantly surprised how good it sounds. Thank to all those that helped.
The imaging is much better than the Polk and voices are easier to hear. Surprisingly, it doesn't require that much more volume to reach listening levels. I thought that my amp wouldn't be able to handle it. The bass is okay, so porting it is still a possibility. Someday I will buy the right equipment to measure it, I have a microphone, but it's not designed for speaker measurement.
Overall this center adds a lot more to the listening experience and I'm pleasantly surprised how good it sounds. Thank to all those that helped.
http://yamaha-pt.com/productos-yamaha/audio_visual/receptores-av/rx-v477/index.html
What turned out to be the total impedance? I assume you have a multimeter. That way you could easily calculate the power you have available in the AVR for the center channel AND configure it correctly, according to that impedance, and if you consider that it should be configured as "small" or "large", etc.. You can also configure - as you already know - the time delays between "front" and "rear", I don't remember you mentioning the rear speakers you have in use.
What turned out to be the total impedance? I assume you have a multimeter. That way you could easily calculate the power you have available in the AVR for the center channel AND configure it correctly, according to that impedance, and if you consider that it should be configured as "small" or "large", etc.. You can also configure - as you already know - the time delays between "front" and "rear", I don't remember you mentioning the rear speakers you have in use.
If the AVR has 4 and 8 Ohm options, always set it below the speaker impedance value, which is actually the resistance of the coil to DC, but....that's how it is considered "correct".
Put the new 6.7 Ohm center at 4 Ohms, NOT at 8. This way the circuit will work without the risk of activating the protection.
Put the new 6.7 Ohm center at 4 Ohms, NOT at 8. This way the circuit will work without the risk of activating the protection.
My AVR has 6ohm or 8 ohm options and cannot individually assign ohms to speakers. As of right now, the ohm rating on the speakers are: 8ohm L/R, 6.7ohm center, and 5ohm's in the back. Does it still make sense to set the AVR to 6ohms? Also, If I were to make some new rear speakers what ohms should I shoot for?
My Yamaha RX520 AVR had 4 and 8 Ohm options, if yours has 6 and 8 but does not allow separate impedance adjustment for the different channels, in this particular case, I would select everything at 6. Higher impedance in the speakers is not a risk, is a benefit. Transistor circuits deliver more power when the load impedance is lower, but the drawback is, 1) greater distortion (something very debatable if we only use the AVR to watch movies, that extra distortion is not audible to ordinary mortals ) and 2) that the protection acts when the impedance drops to less than 3 Ohmn, which occurs when reproducing low frequencies at high volumes. So I would aim for all speakers with as high an impedance as possible. But it's not a topic to worry too much about, at least I always considered it that way. Suppose you have 4 Ohm speakers and they trip the protection, what do you do? Do you change the speaker? There is a very simple solution, you add a series resistor of around 4 Ohms and corresponding wattage to raise the impedance and the problem is solved. Audio purists (and I am one) will say that this is heresy, that it introduces distortion, etc., etc. and that you have to put the correct speaker. But we are talking about watching movies, that is, listening to dialogue cleanly and enjoying the sound effects or background music, not about perfectly emulating the sound of an instrument in a musical work. You have a lot of information on the web . I hope that helps.
Good luck !
https://www.audiosciencereview.com/...-questions-about-avr-speaker-impedence.28610/
Good luck !
https://www.audiosciencereview.com/...-questions-about-avr-speaker-impedence.28610/
Last edited by a moderator:
No way, I'm glad to be useful, I found this that will surely help you. Greetings !
https://soundcertified.com/how-to-add-resistor-to-speaker-to-change-match-impedance/
PS: Keep in mind that a resistor in series with the (+) or (-) terminal of the speaker - it is indistinct, as a rule I do it in the (+) - it will raise the impedance that the amplifier sees, and on the contrary, the other way around. , in parallel, will lower it. You have some very nice graphics here.
https://soundcertified.com/how-to-add-resistor-to-speaker-to-change-match-impedance/
PS: Keep in mind that a resistor in series with the (+) or (-) terminal of the speaker - it is indistinct, as a rule I do it in the (+) - it will raise the impedance that the amplifier sees, and on the contrary, the other way around. , in parallel, will lower it. You have some very nice graphics here.
Here's a graph from REW. ** Important Note** This is from an uncalibrated soundcard and mic. The mic is a standard usb mic. So I'm not really sure you can make any conclusions with it. Eventually I will get the right equipment. Also I had know idea what volume to set the amp and computer output at when conducting the measurement. I think the AVR was around -14db.
