Mini curved Statements II

[Jim Holtz]

Hi Andy,

I "think" the port will be OK since the flare is at a 90 degree angle from the backwave of the driver. The only other option you have at this point is an elbow to angle the port away from the driver. That would require the tube to be shortened to compensate for the distance added by the elbow. I have no idea what the dimensions would need to be to maintain the same box tuning. I think you'll be fine but an email to Curt at his website might give you a better answer than I can.

Jim

[Andy_F]

Hi Andy,

I "think" the port will be OK since the flare is at a 90 degree angle from the backwave of the driver. The only other option you have at this point is an elbow to angle the port away from the driver. That would require the tube to be shortened to compensate for the distance added by the elbow. I have no idea what the dimensions would need to be to maintain the same box tuning. I think you'll be fine but an email to Curt at his website might give you a better answer than I can.

Jim

Thanks Jim, I've just dropped Curt an email.

Best wishes,

Andy

[Andy_F]

Second ply layer applied:






So I've giving a lot more thought to the port length, my biggest concern with the port placement was the "blowing on a milk bottle effect" of the rearward movement of the driver blowing directly over the port flare.




I've been doing a lot of reading on port design and putting elbows (whether 45 degree or 90 degree) apparently is a big "no-no".

So I loosely refitted the bottom 8" to check the alignment with the port flare:



When aligned, the magnet should block any direct "blowing" across the port flare. Is my thinking correct on this?

If so, it will permit me to use the correctly calculated port length as designed by Jim / Curt.

Alternatively I could add some additional foam to the port flare which is closest to the driver to act as a bit of a screen?


Any thoughts / ideas greatly appreciated. :T

Thanks,

Andy

[Andy_F]

Well Curt has been in touch and suggested to put a 45 degree bend into the port - confirming what you suggested Jim and the information I read on another DIY speaker forum about keeping ports straight is complete nonsense.

So tomorrow I'll be out sourcing 2x elbow joints and hopefully can get the second side closed up.

[Andy_F]

Update:

So I started by using hot glue to secure the hook-up wire to the internals to prevent any loose wires vibrating:






Fitment of foam to all surfaces that could reflect back to the 8" drivers:










I could only source a 90 degree bend with the perfect diameter but by cutting in half allows for the 2x 45 degrees I need. (Over here in the UK it is nigh on impossible to get hold of 3" pipe, standard sizes are 2.5" and then 4") :roll:





I need to point out that the external diameter of the 90 degree bend was larger than the port supplied in the kit but the internal measurement was 75.9mm (which is exactly the same). Loose mock-up:




Loose fitment in the bottom of the cabinet to check the alignment:




I then needed to figure our the exact volume the curve added to the port tube so that I could shorten the straight section the correct amount to remain with the exact same port length. I taped both the spare straight section and the one with the elbow, filled the straight piece with water and then poured into the bent piece; the level in which the water sat shows the equal volume and where I needed to cut the length to. :T








Once cut to size the port was then secured in place using hot glue:




I had some spare foam remaining so I cut thin strips and added them onto the smaller reflective surfaces (probably over-kill but hey-ho).








Final check of everything before closing up:








Fitment of first layer of plywood to form second curved side:






Now to leave it to dry for 24 hours. :B

[Curt C]

Nice job on the 45 degree angles on the port! MacGyver would be proud of you! The rest of your work appears top notch as well. I certainly envy your talents and execution of the cabinet construction...

C

[Andy_F]

Nice job on the 45 degree angles on the port! MacGyver would be proud of you! The rest of your work appears top notch as well. I certainly envy your talents and execution of the cabinet construction...

C

Cheers Curt

[Andy_F]

So another update:

Once the second sheet of plywood (on the second side) was on, I then fit the pyramid foam to the bare side to hide any reflective hard surfaces:






Whilst the glue was setting, I set to work on the transmission tunnels of the second cabinet:






The rear baffle marked, cut and T-tunnels glued and clamped:












The excess plywood edges on the first cabinet were smoothed flat:









To provide extra reinforcement and to strengthen the entire cabinet I am going to cut a top "cap" piece (using the original brace as a template). The cap will also hide the plywood edges (so that only an oak veneer can be seen from the side profile).






Any small gaps were filled with wood filler to ensure an airtight seal when the drivers are mounted:








T-tunnel reinforcing spacers glued and clamped:




I started to cut the second front baffle, when my Dremel died on me... (I'm not having much luck in terms of power tools on this build!)




So now the end of the construction part is on the horizon, I have been giving more thought to the finish. I've decided to keep it simple with a black satin for the base, front, top and rear. Then an oak veneer; stained dark(ish) or maybe even a Rosewood tint to finish the sides. This is when I've got to be super careful, if I don't have a perfectly smooth base layer (either for the veneer or the paint) then it will show through. So I'm gonna need a lot of patience, elbow grease and extremely fine grit sandpapers!

Oh and I've got to make some grills for both towers too!


Andy

[Andy_F]

So it's been a while since my last update due to a new addition to the family! :B

Building has slowed somewhat due to Daddy duties as there are now higher priorities than a pair of speakers! :lol:

Anyhow, here's the progress made since the last update:


Feet and port mounted onto second base:




Second front baffle cut and T-nuts secured into place:




Final plywood layer applied to both sides of speaker number 1:






Top "cap plates" (which sit on top of each cabinet) marked and cut:






Dry fitment of second cabinet as a test run, then re-assembled with lots of glue!:




After 24 hours of drying time I could then apply the first plywood layer of the second cabinet:




Now I'm starting the prep work for the finishing of the first cabinet! Woohoo! :B

I marked the front baffle to continue the sweeping curve of the sides:




Then continued the line vertically down the front so that I have a guide as to where I need to sand too:






The baffle shoulders were then sanded flush:










Now it's time to drop down to a finer grit paper and make the entire cabinet fairly smooth. I won't go higher than 240 grit however, as I still need a slightly rough surface for the primer to bond too.

[TEK]

Wooha!

First, congrats on your new addition to the family.
:dothewave:

arty:

Second - lovely pictures, great workmanship and a great work done so far!

[Andy_F]

Wooha!

First, congrats on your new addition to the family.
:dothewave:

arty:

Second - lovely pictures, great workmanship and a great work done so far!

Thanks Tek

[wkhanna]

your killing it, Andy!!!

[Andy_F]

So I've finally started to dress the first speaker cabinet!

Oak veneer was liberally covered in glue, held in place with masking tape:






And then sandwiched tight using off-cuts of plywood to form a curved press:




This was left for 24 hours to fully cure, so I then continued with the second cabinet.

Binding posts cut and fitted:




Crossovers soldered and mounted using Velcro tape, again using spare foam to form cushions underneath the XO boards:




Second plywood layer set:




24 hours later - perfectly curved and flush veneer ready for trimming:




Testing of second cabinet XOs with drivers (photo taken mid-way of screwing bolts):




The next day the veneer was trimmed flush (there is still some sanding to complete on the front baffle but I purposely kept a "lip" to have a straight edge to push the veneer up to).






Third layer of ply on the second cabinet:




Second port put together, this time I took a photo of the internal too - so although it looks like a Frankenstein project from the outside; the internal is wonderfully smooth! :B






Foam fitted, internal wires hot glued and port set into place:






Veneer lightly sanded and then stained - upon application I could see the oil soaking straight in to certain areas and will need at least another coat (or three). :lol:








Top cap coated in glue and then clamped, any small gaps filled with filler ready for sanding:




Next on the list is the cutting of the speaker grill which when wrapped in acoustic cloth should help protect the drivers against little fingers and thrown toys! :T






Top cap now set ready for sanding (and obvious patches in the stain - which has annoyed me more than it should have!) :roll:




Anyway, hopefully I make some more progress over the next few days as I slowly creep towards the finishing of the second cabinet too. :B

[Andy_F]

So I continued with the speaker grill build as once the drivers are fitted I want to make sure they are adequately protected!

The board was marked up with cross braces that added strength but didn't impede on the drivers:






The board was cut and offered up to the cabinet to check alignment:




All was good. So I used it as the template for the second speaker grill. :T




I decided I wanted a more distinctive look and cut some "hockey sticks" in 3mm HDF and glued it to the sides:

BEFORE


AFTER



I think it'll create a better "flow" of black colour from the front baffle to the rear but appreciate it's not to everyone's taste.


The speaker grill was re-positioned and securely clamped. NO GLUE THOUGH!!!




This allowed me to drill a small pilot hole through the grill and into the front baffle so that I could accurately fix the male/female grill attachment into place.



(I forgot to take mid-drilling photos) :roll:

But to explain what I did...

Using the small 2mm pilot hole, I used a 19mm hole saw to cut the diameter for the outer female part, and then using a 14mm hole saw I then cut the space for the female cup INSIDE the 19mm hole.






The male section was then measured and then on the rear of the grill a 10mm hole was cut to accommodate the male plug:




The male plugs were gently hammered into place and voila! One snugly fitting speaker grill. :B









The next stage was to sand the square edge of the grill so that it was inline with the front baffle.




So the front was marked and the sanding began:










I then routered the internal edges so that there were no sharp edges for the sound waves to hit (I'm probably being hyper-critical here). :lol:




And to further "child-proof" the fronts, I added additional bracing which provides a rigid deflection board (against toys) and moves the acoustic fabric further away from the drivers in case of inquisitive fingers! :lol:




Now I appreciate the grill will now probably hamper the sonic sound stage, but for my serious listening binges then the grills will be removed and kept firmly in place for casual listening when the kids are around!


So last night I applied the first veneer sheet to the second cabinet and removed the clamped plywood today:






So I have begun the final sanding process of the first cabinet ready for the primer. Hopefully by the weekend the second cabinet will be fully prepped and I'll start the painting process on the first cabinet. :B

[ratchetfps]

This worklog is phenomenal! Thanks for the detailed write-up, this appears to be quite the task with no shortage of interesting challenges, and I'm loving the creativity and dedication!

I am truly fascinated by this project given that it's a new version of the mini statements (which I've built), features a speaker grill (which I contemplated for longer than I care to admit during the tail end of my project), and, best of all, it's curved which is something I admire greatly and hope to tackle some day!!

Can't wait to see them finished!!

[Andy_F]

Alignment of front grill now that it's all cut and sanded - the twin bars shouldn't interfere with the sound too much *fingers crossed* but should provide additional protection to the drivers.




Second cabinet veneered and then left for 24 hours.






It was then time to start tidying the rear ports:




The most external edge was stapled down - making a nice gentle curve towards the exit.






I then cut small strips of plywood to form small angle "trim" pieces to cover the rough ends of the foam and to hide the staples. They were secured into place and then covered liberally in filler - later to be smoothed with fine grit paper.






Whilst the filler set, the first cabinet was covered in masking tape ready for primer.










I used this Zinsser as the base coat. It is solvent based (less chance of the MDF warping) and is also a stain cover which will help achieve a uniform finish (as there are different grades / colours of wood).




The grill and cabinet were then evenly coated.










These were left for 24 hours and then sanded using 240 grit paper to achieve a good "flat" base layer. The minor scratches (some of which I didn't even know existed!) were evenly filled and the final layer was lovely and smooth. :B














Edge of speaker grill before and after sanding. (Rough and then smooth)






The grill was then painted black (getting there!) 8)






On inspection of the cabinet tonight, there were imperfections and even two large gashes in the woodwork which I hadn't seen prior to primer 8O so these there sanded, filled and then another layer of primer applied.






Which now I must leave until tomorrow and hopefully will be able to complete a final sand, vacuum and wipe down (using lint free tack cloth). Then I should be ready for my first top coat of black :B

[Andy_F]

The next stage was to sand the primer nice and smooth all around the cabinet and then vacuumed and wiped with a tack cloth.








The satin black application! I'm so chuffed that I got the prep work right as the finish is mirror perfect! :B










The following day the cabinet was closely inspected and some slight over-spray had pooled slightly, so this was rubbed back using fine grit papers (400, then 600 then 1000) and re-coated.
















Next up was sealing the base of the cabinet.






Primer, sand, black:











The reveal!











Some parts of the sides needed tidying up as the stain didn't adhere evenly. :roll:

The patches were sanded down and then re-coated. I then applied another two coats as I wanted darker sides.








There is some very slight discolouration at the very edge (approximately 1mm to 2mm wide) so I've ordered a mahogany touch-up pen to keep it nice and neat. :T

So other than the minor colour correction I'm well chuffed with how it looks. :B

Once the edges have been corrected, I'll spray the entire cabinet in a matt finish polyurethane clear top coat to make the finish very hard wearing; which should help protect against knocks and scratches. 8)






My attention has now shifted back to cabinet two and I'm sanding the front edge to follow the curve of the sides.








Christmas is looming, so hopefully I'll progress quickly over the holiday break and should have both of them set up in the New Year!

[Steve Manning]

I like the color combination.

[BrechtVD]

They look really fantastic.
Thanks for posting so much pics so we can follow the build nicly.

[TEK]

Really nice job. Love it!

[Andy_F]

My paint correction pens arrived, I touched up the edges and sprayed the entire cabinet in a clear protective coat. :B






Detailing shot of the binding posts (without the copper bridge pieces).




Fitment of the drivers:




And placement in the room:






This has now forced me to re-arrange all the furniture in the living room (aka listening room! :lol: ) as I don't want the speakers to be boxed-in and cause a 'boomy' sound stage.

On initial listening though (taking into account the fairly cramped space until everything is moved), the sound is absolutely amazing. So much so I went through a number of my favourite tracks and the clarity coupled with the thumping bottom end gave me goosebumps, it really was that good. :B (My opening track was "Money for Nothing" by Dire Straights and the slow build-up just got better and better before the thumping guitar / bass / drum rift came in).

I don't want to use it too much now as I appreciate the drivers will require a bedding-in period and I want the drivers in each cabinet to be at the same level (if that makes sense?), so it's spurred me on to get cabinet two finished and then I think I'll be like a pig in the proverbial! :lol:


I'm so so happy, and glad I took the punt on building some speakers I had never heard in person. Obviously a massive thanks goes out to Jim and Curt for their help, support and guidance. :T ;x(

I'll update once the second one is finished and I've created plenty of space around them both.

[BrechtVD]

Andy,

One question, did your wife/ girlfriend already forgive you?
Because you didn't told how big they would be (first post)

With such beautiful speakers she has to =D

[wkhanna]

great to see a completed project that comes our looking & sounding so nice!!!!!!

[Andy_F]

Andy,

One question, did your wife/ girlfriend already forgive you?
Because you didn't told how big they would be (first post)

With such beautiful speakers she has to =D

My wife loves the design / finish but still thinks they're too big!

Sent from my SM-N950F using Tapatalk

[Andy_F]

The second cabinet is beginning to take shape but I hit a few delays so it still isn't finished! :lol:

Anyhow I thought I'd put some additional content on - which shows in more detail how I put the speaker grill together (using photos from the second grill build) and the fitment to the cabinet.

The skeleton clamped against the cabinet and a 2mm pilot hole drilled through:




The pilot hole in the front baffle:




This was then opened up using a 19mm hole cutter to accommodate the larger diameter of the female cup:






The center was then bored out using a 13mm hole cutter (but wiggled around slightly as I needed a 14mm hole! :lol: ):




The cup was then gently tapped into place using a hammer until flush. This was then repeated another 5 times.






The skeleton was laid flat and on the reverse side the male components were drilled and again gently hammered into place:




The skeleton was flipped and at the top and bottom I glued sloped edges on and the twin reinforcing braces down the center:










After the glue was left for 24 hours (firmly clamped too I should add). I stretched acoustic cloth around the frame and stapled on the inner side so that the staples aren't visible and more importantly wouldn't rub against the front of the cabinet)!

**I didn't take photos of this bit as I was properly fighting to keep the cloth nice and tight and did quite a bit of swearing too** :M

However I am rather pleased with the finished look, I think it finishes the front off quite nicely and haven't noticed a difference in sound to be honest. :T
















:B

[Jim Holtz]

They look super! :T

After all of your hard work, have you had a chance to listen to them yet? I'd suggest you not do any critical listening until they break in for about 20 hours.

Great job!

Jim

[Andy_F]

They look super! :T

After all of your hard work, have you had a chance to listen to them yet? I'd suggest you not do any critical listening until they break in for about 20 hours.

Great job!

Jim

Hi Jim,

I'm just finalising the second cabinet (the paint is drying as I type this!)

With regards to bi-amping, what load will be presented to the amp for the subs and what load would be presented for the MTM please?

Thanks,

Andy

Sent from my SM-N950F using Tapatalk

[Jim Holtz]

Hi Jim,

I'm just finalising the second cabinet (the paint is drying as I type this!)

With regards to bi-amping, what load will be presented to the amp for the subs and what load would be presented for the MTM please?

Thanks,

Andy

Sent from my SM-N950F using Tapatalk

Sorry, I don't have any idea. If you're referring to bass section as subs, they will require much more power than the mid/tweeter section. The bass drivers are the limiting factor in dynamics of a speaker. How much more power? That is a question from someone that has measured the differences. Also be aware that bi-amping requires amps with the same rate of gain to have any chance of integrating correctly.

Jim

[Andy_F]

Sorry, I don't have any idea. If you're referring to bass section as subs, they will require much more power than the mid/tweeter section. The bass drivers are the limiting factor in dynamics of a speaker. How much more power? That is a question from someone that has measured the differences. Also be aware that bi-amping requires amps with the same rate of gain to have any chance of integrating correctly.

Jim

Sorry I should have worded my question better.

Would the bass drivers present a 4ohm load and the MTM also be 4ohm or would they be 8ohm each.

The bi-amping will be done using a pre-out so when controlling the volume from one amp will directly increase the gain to the second amp so that the soundstage will be balanced.

Thanks for your help with this.

Andy

Sent from my SM-N950F using Tapatalk

[Jim Holtz]

Sorry I should have worded my question better.

Would the bass drivers present a 4ohm load and the MTM also be 4ohm or would they be 8ohm each.

The bi-amping will be done using a pre-out so when controlling the volume from one amp will directly increase the gain to the second amp so that the soundstage will be balanced.

Thanks for your help with this.

Andy

Sent from my SM-N950F using Tapatalk

Hi Andy,

The impedance will vary from 4-10 ohms throughout the frequency. If it was a commercial speaker, it would probably be rated as an 8 ohm speaker.

What I was talking about in rate of gain isn't the signal coming out of the preouts but rather the ability of each amp to amplify the signal at the same rate and the same maximum signal. If you look at amp specs they usually list a maximum gain.

I explored bi-amping 25-30 years ago and had one of the amps modified to mimic the same rate of gain as the other. That's what I'm talking about.

It's one of the reasons DSP units have become popular for DIY'ers that want to ply but not dive into passive crossovers so they can adjust the volume for each group of drivers.

HTH

Jim

[Andy_F]

Hi Andy,

The impedance will vary from 4-10 ohms throughout the frequency. If it was a commercial speaker, it would probably be rated as an 8 ohm speaker.

What I was talking about in rate of gain isn't the signal coming out of the preouts but rather the ability of each amp to amplify the signal at the same rate and the same maximum signal. If you look at amp specs they usually list a maximum gain.

I explored bi-amping 25-30 years ago and had one of the amps modified to mimic the same rate of gain as the other. That's what I'm talking about.

It's one of the reasons DSP units have become popular for DIY'ers that want to ply but not dive into passive crossovers so they can adjust the volume for each group of drivers.

HTH

Jim

Cheers Jim,

The only reason I wanted to clarify is because my valve amp has got 4ohm or 8ohm speaker connections and this is what I intend to power the MTM; with a seperate amp for the bass drivers because the valve amp isn't powerful enough to drive the entire cabinet sufficiently.

Thanks again,

Andy

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[Jim Holtz]

Cheers Jim,

The only reason I wanted to clarify is because my valve amp has got 4ohm or 8ohm speaker connections and this is what I intend to power the MTM; with a seperate amp for the bass drivers because the valve amp isn't powerful enough to drive the entire cabinet sufficiently.

Thanks again,

Andy

Sent from my SM-N950F using Tapatalk

LOL! Let's try that again. Here's an impedance graph Curt did that will give you an idea of what your amps will see.



If it was my amp, I'd set it on 4 ohms and run with it.

Jim

[Supernova]

Congratulations on the newborn!

Great work on the speaker.

There are so many pictures I think I'm going to need a new mouse wheel and a splint for my finger.