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Chorus 1 Questions


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Been reading/learning alot, now my 1st post is a speaker mod question¬†ūüėÉ

 

I have a pair of mint Oak Chorus 1's with Crites crossovers & titanium diaphragms. Chorus 1's have 2 front ports & no rear passive. I've seen an older thread online where someone put in 7" long tubes where the two factory "ports" (really just 2 holes thru the mdf) are to increase/lower the bass freq response.

 

Anyone here ever done that? If so, what fit? I ordered a 4" port from speaker express, but the 4" is the tube Internal diameter, not outer, so it didn't fit...Also went by my local carpet dealer, same problem, outer diameter is too big. & btw I don't want to enlarge/recut the factory holes. Ideas?

 

 

 

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@Matthews was the member that added the ports to the Chorus I rebuild. I made the cabinet for him and the motorboard  was cut exactly as the original. He was pleased with the results of the ports. Now @Shaun K has them. He recently posted that he thought they were a little bass shy. I had only heard them briefly once assembled and did not have that impression. Matthews is now working on hotrods instead of speakers and isn't here much, if at all. He could shed the most light. Shaun may be able to answer questions as well.

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Yes the diameter of the ports are pretty much spot on from my past measurements. There are some ports I was considering like the T-3000 dual front ported speaker by Klipsch (Tangent) that looked like 4 inches but never measured them. Finding a solution like that may be frustrating as well as time consuming.

Using a material with an outside  diameter(OD) may be easier somewhere.

The idea above using cardboard roll or rolled up and taped(heavy paperboard to fit I would try, just to get an impression. Would start at nine inches + inside and whittle it down to 4 in 1 inch increments to let you know what your ears tell you. Then, final product more permanent would do similar, starting long until by chopping you get  a decent to your ears, once again, result. Going out on a limb here to you by saying with tuning of port that, your bass response should be lower of course. By how much, I will hazard a guess of maybe as much as 5 hz. or more given typical bass response with a +3db/-db at threshold.

In any case, was going to do it but, did not. Still consider it a worthy endeavor and if you do, let us know the exact length you come up with.

Meanwhile, enjoy your Chorus as I did...thanks!

 

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@4JaxJags   I bet those ports work like they did on my CF-3's when I extended them.  Doesn't the Chorus have some sort of plastic flared edge port that goes into the cabinet a little ways?  On the CF-3's, I added port length to the back side of the existing port because all I had to do was take a 4" i.d. tube (carpet roll tube was perfect) cut to the length I needed, then took the bottom woofer out and fitted the extension onto the existing port which fit snug and worked like a champ.  

 

How far into the cabinet does the stock port go?  I would almost guarantee that you could just connect it on to the existing plastic port and call it good.  Easy peasy...hopefully.

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  1. 1 hour ago, avguytx said:

@4JaxJags   I bet those ports work like they did on my CF-3's when I extended them.  Doesn't the Chorus have some sort of plastic flared edge port that goes into the cabinet a little ways?  On the CF-3's, I added port length to the back side of the existing port because all I had to do was take a 4" i.d. tube (carpet roll tube was perfect) cut to the length I needed, then took the bottom woofer out and fitted the extension onto the existing port which fit snug and worked like a champ.  

 

How far into the cabinet does the stock port go?  I would almost guarantee that you could just connect it on to the existing plastic port and call it good.  Easy peasy...hopefully.

They do not come with the flared round edge port but, was going to suggest some to doll it up when finishing project. Thanks for the description and reminder. A flare that was attached to whatever material would be cool looking in black and maybe more solid to finally seal holes at port holes. Of course, grilles may be used.

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13 hours ago, moray james said:

why don't you try some poster board (heavy craft paper) and see what you think of the mod before you go crazy searching for parts that fit?

 

Good advice, (slow down) The crossovers & diaphragms were done when I got em, so I was wanting to finish off the job :-)

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3 hours ago, billybob said:

They do not come with the flared round edge port but, was going to suggest some to doll it up when finishing project. Thanks for the description and reminder. A flare that was attached to whatever material would be cool looking in black and maybe more solid to finally seal holes at port holes. Of course, grilles may be used.

 

Below is a pic of a Scotch mailing tube, which is the closest thing I've found that seems like it has "possibilities". I will probably try Moray's rolled paper idea 1st, then try to find this Scotch tube as a single at a reasonable price, which is easier said than done, most places want you to buy a case!  (a mailing tube would hopefully be sturdy enough to hold up long term)

 

And, I didn't buy the whole 4" tube from parts express, only the flared end. (it was CLOSE, but slightly too big)  I may try to put the flare on the inside end to cut down on turbulence, especially if it fits snug on whatever tube I end up using.

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Whatever works and sounds like a decent plan. Nothing like some Jaguar ingenuity and, if not said by me, welcome to the forum.

BTW, Watch out for the tube length as it may want to come closeby to the crossover at the rear... will follow  for your results...like the avatar...:)

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11 hours ago, MookieStl said:

Should be below the crossover but not by a lot. Key is to keep from getting too close to the back of the speaker. That would restrict air flow. Rule of thumb is to keep the distance greater than the diameter of the port.

 

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Just so you know (not picking on you most folks just don't know this) the air in a reflex vent will move 1.5 time the total vent length in and out of the vent so looking at your posted photo your vents are already too close to the rear wall of the cabinet for ideal non constricted air flow. Most vents are do don't have a heart attack but just know they are not working as well as they could.

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I'd always heard from manufacturers and builders in my early audio years, late 70s to early 80s, that the "rule" for ports was twice the distance of the diameter away from a solid object. I would believe that as there is restriction for air trying to "escape". I've done ported enclosures with 90 degree ports using PVC cut at a 90 and glued together to make sure I stayed in that rule. 

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3 hours ago, moray james said:

Just so you know (not picking on you most folks just don't know this) the air in a reflex vent will move 1.5 time the total vent length in and out of the vent so looking at your posted photo your vents are already too close to the rear wall of the cabinet for ideal non constricted air flow. Most vents are do don't have a heart attack but just know they are not working as well as they could.

Don't have a heart attack, but you missed the point. These aren't my speakers, I only built the cabinet. I posted the photo from Matthews thread to illustrate the relationship of the ports to crossover as had been mentioned by Billybob. I too thought they looked a little long (or close to the back wall) so I mentioned that keeping it short by at least the diameter of the port (a tip in the instructions from an adjustable port I bought from PE many years ago). Matt tried many lengths and was going solely by ear. I am not sure what length he ended up with but this was the only photo in his thread.

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8 hours ago, moray james said:

Just so you know (not picking on you most folks just don't know this) the air in a reflex vent will move 1.5 time the total vent length in and out of the vent so looking at your posted photo your vents are already too close to the rear wall of the cabinet for ideal non constricted air flow. Most vents are do don't have a heart attack but just know they are not working as well as they could.

 

So If I end up using a 7" total length tube/vent, would 4" away from the back wall be enough? 

(Someone who was an experienced speakerbuilder did some calcs & said a 7" vent would be ideal in a Chorus 1)

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at the end of the day if things are sounding ok then there is not a lot to worry about. From my experience by the time a guy is installing vents he is not into experimenting much any more he just wants to get done. I wanted to plant the seed about the amount of air space vents actually need to perform at their best and it also helps folks to understand one of the distinct advantages to a passive radiator. As to vents the top of the cabinet is generally a much better place to install one so long as you don't have kids or a wife who like to put stuff on top of your speakers.

   The double the vent dia. foe spacing a vent off of a reflective surface is simply a decent compromise. From a designers point of view vents are a real P.I.T.A. and top mounting is generally not a go same for bottom venting for more good reasons and putting bends in ducts is also something that vents don't seem to like either. There is no easy solution.

   My heart is ok today. I wish I had a buddy like you to build up my cabinet ideas for me as that is always a lot of effort for me. I have built my fair share but they are always a little more work for me than I would like them to be.

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