[stvnharr]

Salva,
I just happened upon these latest posts about port length.
I went thru this same exercise a couple years ago.
NO port, just a hole, gave a very noticeable boominess to the bass.  If you like this now, I think you will soon grow tired of it.
I then tried a 2" port, got more bass and no boom.
I settled on a 3" port.  It sounded same as the 2" version, but was easily made by cutting the original 6" port tube in half.
I believe with the shorter port tube the rolloff characteristics get ruined, but since it's a 24db. rolloff, it's not really noticeable, certainly not to me.

Dave's 1/2" shortening method is really the proper way to do it, but I doubt you'll hear much difference with each 1/2" increment.  The difference is likely measurable however, if you have a way of measuring it.  And you'll likely get very tired of taking the woofer in and out in order to replace the port tube.

[salva]

Hi there, I'm finishing my second 1801F. I have posted some photos of it on a spanish DIY forum. I guess that they will help other people doing them. Mainly with the veneering thing.

http://www.matrixhifi.com/foro/viewtopic.php?t=713

Salva

[salva]

Hi there, I'm finishing my second 1801F. I have posted some photos of it on a spanish DIY forum. I guess that they will help other people doing them. Mainly with the veneering thing.

http://www.matrixhifi.com/foro/viewtopic.php?t=713

Salva

[David Ellis]

Thanks Salva, very good pictures!  I really like the lab coat too.  It's pretty professional looking!

Dave's 1/2" shortening method is really the proper way to do it, but I doubt you'll hear much difference with each 1/2"

There really isn't much difference with 1/2" increments.  This is the minimum amount that I hear audible impact.

And you'll likely get very tired of taking the woofer in and out in order to replace the port tube.

About 6 months after your 1801 kit order I purchased externally mounted port tubes.  These are now shipped with all 1801 kits.  The port process is MUCH easier and much quicker.  It simply slides a 2 1/8" hole from the outside of the cabinet and fits with friction.  The seal is actually very tight, but some folks may want a 100% air tight seal via a gasket.  Forming a gasket can be done with poster putty (temporary) or silicone (permanent).

Thanks a bunch for your continued contributions here gents

[MemphisJim]

I was telling Dave what I would do differently if I were to make another pair and my thoughts seem to fit in this thread, so here goes...

I would like to make a floorstanding speaker that was chambered just like the normal 1801. This would allow me to do several things such as put the xover in the bottom chamber portion of the cabinet, NOT build stands, put shot/ sand in the bottom cabinet, bi-wire in whatever fashion I wanted (side by side or over and under) and not have to worry about hookup because I would have a false bottom (or not bottom in the post area at all) allowing me to get in to the posts I'm just not sure about the baffle issues and the crossover though...

Thoughts?
Thanks,
Jim

[David Ellis]

I'm just not sure about the baffle issues and the crossover though...

Based on my experiments, I believe anything between a baffle width of 7 1/2" and 9" will be fine.  No crossover changes will be necessary.

[salva]

Hi, Just finished my second pair of 1801F's ..  (Hei, I just build three 1801's!!) Now, this time I have taken the oportunity to put a great deal of stuffing and to shorten the lengh of the standard port by an inch.

I can say that I like the bass of the 1801b more. I have constructed a adjustable BR port with a couple of PVC pipes and I am going to make a AB coparation in my home 1801b vs 1801F. Trying to match the bass caracter of the 1801b with the adjustable ports.

I'm thinking that perhaps having such a large side pannel can have a effect on rigitity hence the bass suffers. On the 1801b the area with no brace is smaller with will banefit the bass.

mids and higs are the same to my ears.

I'll post my AB results on monday and a photo tonigth.

By the way, I have discovered a coupe of tips for veneering and finishing:

Vennereing: White carpenters glue, dryed with a hot iron with a sheet of paper in the middle leaves a smooth no bubbles venner in no time at all.

Finishing: Use hand rubbing stuff, that gives excelent results with almost no effort. Using a brush and trying to get a smooth finishing surface or uniform tint is almost impossible.

Salva

[salva]

Salva[/url]

[Ron Stewart]

I finished building my 1801F's (except for the grilles) about a week ago.  If anyone is interested, I am also constructing a web site about the project. It's not complete, but it's getting there.

http://home.hiwaay.net/~rgs/ellis1801f/default.html

I just read Salva's post about his latest set of 1801F's. I also used the dry-bond, iron-on veneer method. I can't compare it to using contact cement, but I'm happy with the results I got (at least so far). I also used wipe-on stain and poly.

Salva, when you say you prefer the bass of the stand-mounted 1801, which type of bass are you referring to--upper bass, mid-bass, low-bass? Or is there some particular aspect of bass performance (slam, etc.) that you've noticed?

I will say that it was a blast building these speakers and firing them up for the first time. I'd definitely encourage any prospective kit builders to go ahead and take the plunge.

Ron

[salva]

Salva,
I just happened upon these latest posts about port length.
I went thru this same exercise a couple years ago.
NO port, just a hole, gave a very noticeable boominess to the bass.  If you like this now, I think you will soon grow tired of it.
I then tried a 2" port, got more bass and no boom.
I settled on a 3" port.  It sounded same as the 2" version

Yes, I started with 3", that was was not enough then I tried 2" that seems OK, sometimes seems to much (boomy) but at mediums and low volumes the soud has a lot of "body".
 
I guess that a little more than 2" will be the correct size. That is the case in my room. Beware room dinamics change how the speaker behaves bass wise.

A question to dave, Do you think that 2" can have other effects than increasin the frecuency tuning of the BR ?

Salva

PD. By the way, the 1801 still put a smile in my face each time I hear a good recording in them.

[David Ellis]

A question to dave, Do you think that 2" can have other effects than increasin the frecuency tuning of the BR ?

I am not sure what "BR" is, but this probably isn't critical.  

Making the port shorter will raise the tuning frequency where the bass from the port will reinforce the bass from the front side of the cone.  There really aren't any dangers.

I have thought about this phenomena of port energy change, and think that I hear something in this regard.  The bass seems to be more prominent at higher spl.  I think (??) this may be due to the lack of port flare.  This lack of port flare creates an inconsistent airflow through the port that is dependent upon port velocity.  As airflow volume through the port increases, the turbulence should also increase.  This would raise the tuning frequency.  I am not certain this is true, but it seems fairly reasonable.  

I really wish that I could a/b test this phenomena, but I can't.  I don't have any more of the straight sided ports.  The new port for the 1801 is an internally and externally flared unit.  It sure looks nice, and it might actually improve performance.

[salva]

I am not sure what "BR" is, but this probably isn't critical.  

Ah! sorry, I meant Bass Reflex.  OK, the only thing was that on my room/speaker positioning 6 cm seems to be the best bass compromise. My worry was if by cutting the port on more than half can have any other effect on the speaker than raising the tuning frecuency of the Basss Reflex.

One thing that I have tougth is the claim of B+W that the usage of "portflow" tecnology (that is, making small holes like in a golf ball) and having a flared port wil have any effects on bass.



Rigth, any way. I am more than happy with the bass of my 1801F. No sub needed for music.

Salva

Flowport link
http://www.bwspeakers.com/index.cfm/fuseaction/products.techfeatures/ObjectID/3A7554F4%2D4779%2D11D4%2DA67F00D0B7473B37

[David Ellis]

One thing that I have tougth is the claim of B+W that the usage of "portflow" tecnology (that is, making small holes like in a golf ball) and having a flared port wil have any effects on bass.

Well, if the port encountered omnidirectional air flow like a golf ball, the dimples make extremely good sense.  A very good M.E. (Mechanical Engineer) explained to me that a dimpled golf ball will fly about 30% further than a smooth golf ball from the tee-box.  The M.E. explained that the dimples in the golf ball essentially grab the air flowing around the golf ball and hold it securely.  The result is the turbulent trail behind the dimpled golf ball is much smaller than the turbulent trail behind a smooth golf ball.  The dimples really improve the drag/turbulence of the golf ball.  However, the reason dimples are used is because the direction of airflow over the golf ball is uncertain.  If the direction of airflow is known, ridges or fins will perform much better than dimples.

There is some dicsussion on this matter here:  

http://www.eng-tips.com/viewthread.cfm?qid=107764&page=1

However, this discussion appears incomplete.  These gents discuss airplanes, but not cars.  The example the M.E. used to describe the ideal trubulent reduction applied the model of the Mustang SVO.  The double fins on the back were postioned to accomodate airflow at a specific velocity.  


As the airflow over the SVO would become turbulent at the back end, the first fin would catch the air, and maintain the non turbulent flow.  Yes, the fin actually reduces turbulence.  This seemed strange, but the M.E. explained the dynamics and it made very good sense.  Then, as the airflow was again about to become turbulent, the second fin would catch the air and reduce turbulence.  These fins on the back of the SVO were engineered for a specific velocity in a linear direction through the air.  There are similar fins on the back of many race cars, but they perform other duties (i.e. downforce), and I cannot address this.  

Nonetheless, my point is;  When the direction of airflow is known, ridges/fins will outperform dimples.  The design/spacing of these ridges will be most effective when applied to the velocity and direction of airflow.  The velocity will obviously change, but the direction (fore and aft) will remain the same.  If a guy wanted to engineer an ideal flare for a port tube, ridges/fins should be used.  IMO, the only reason to use dimples is marketing.  Aparantly the B&W marketing department believes their customers are more familiar with Golf than NASCAR.  I think they are right.

Please understand that I am not an M.E. or Aero Engineer.  However, there are several of these guys in my office that golf.  There is another who is a NASCAR fan.  The subject of dimples versus fins is quite simple for these guys.

[Ron Stewart]

Yesterday was a good day for me and my 1801Fs.

First of all, I officially finished my speakers by finishing the grilles.
(http://home.hiwaay.net/~rgs/ellis1801f/grilles.html) The speakers are more domestically friendly now.

Better yet, I started getting much better sound from my 1801F's. Anyone who has read some of my recent posts knows that I've been bothered by my 1801F's sounding a bit forward. I had mistakenly attributed that sound to a tweeter level that was too high.

That wasn't the problem. The problem was the converse. The low frequencies were a little too low (in level). As a quick test, I just removed the ports altogether. I should have done that before, but the ports fit so tightly getting them out was a real bear. On one speaker, I had to remove my access panel, reach inside, and twist the port out. If I hadn't built those access panels, I'd still be wrestling with, and cursing at, one of the ports.

Now the speaker sounds much more balanced. Male singers now have chests. There's a better foundation for the music in general, and I'm starting to better understand what all the fuss about the 1801's is about. Before, most of my CDs sounded a bit "whitish" or "bleached." That's no longer the case.

I think I'm following Salva's footsteps. I know he started out with lean sound, then removed his ports (resulting in too much boom), then found an optimal port length. I still need to do that last step. But playing with the port lengths is going to be much easier than mucking around with resistors, which was the path I was about to take.

Anyway, I think I'm now well along the road of being another satisfied 1801 owner.

Ron

[smithsonga]

Ron-

Very nice grilles...I have been trying to decide the best way to add grilles.  I like your approach the best with magnets.

I have a few questions if you dont mind:

The grille frame, is it plywood or mdf?  and how did u get the large angle on the inside?  (e.g. profile...router?)...looks like a very large profile bit if it was a router.

Where did u find the best magnets?  I havent really looked but thought I would ask to reduce my search.

Again, very nice looking speakers!

Thanks-
Jim

[Ron Stewart]

Hi Jim,

Thanks for the kind words.

The grille frame, is it plywood or mdf? and how did u get the large angle on the inside? (e.g. profile...router?)...looks like a very large profile bit if it was a router.

The frame is 1/2" MDF. I used a 1/2" chamfer bit on the inside edge, and a 3/8" roundover bit on the outside.

Where did u find the best magnets? I havent really looked but thought I would ask to reduce my search.

I bought mine from Parts Express. I'm pretty sure this link will take you to the magnets I bought.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=329-042

I didn't shop around much for mine, because I was also placing an order for the spikes and grille fabric at the same time. My Rockler catalog includes magnets that look similar.

These magnets are really strong. Before I bought them, I worried if those small magnets would be strong enough to hold the grilles. After I got them, I worried if they were too strong. Both worries were unfounded.

At some point, I'll add a grille drawing to my web site.

Ron

[Al Garay]

Very nice work Ron, especially for documenting your experience in your website.

Did you use anything to have a tight-seal for the access panel?

[Ron Stewart]

Very nice work Ron, especially for documenting your experience in your website.

Did you use anything to have a tight-seal for the access panel?

Thanks, Al. I hope to finish my web site in a few weeks (but I've been hoping that for many weeks.)

I didn't seal the access panels. They fit very tightly, and I don't think they are leaking air. I did start to use weather stripping to seal them, but that made the panels stick out, so I removed it. (By that time, I was anxious to be done, and to start listening.) If I ever really start to wonder, I can run a rabbetting bit around the perimiter of the panels, then use the seal.

I tell you, I cursed those panels when I was building the cabinets. It took me two tries to make panels that fit properly. But I was glad I did it when I mounted the crossovers (and when I was fighting with that sticky port.)

Ron

[Al Garay]

I can understand the frustration. It's very tempting to make an external crossover.

Al

[pem]

Dear Dave,

for my curiosity, why did you choose to design a B-version? Do you
think that bookshelfs are as good/better than column versions (with same drivers and equivalent volume)?
 
  kind regards,
  Pierre-Etienne