HoldOuts: An All RS TMM 2.5-way

[jclin4]

Based on the shielded RS150's, I used to call these the Legacies, as in the last of their kind. But since the new RS150's are a drop in replacement, keeping the design alive, I'm calling them the holdouts.





The crossover is a symmetrical, acoustic Butterworth 3rd order, crossed with the RS28F's at 1.4kHz.






The cabinet is 3/4 MDF all around at 40 liters internally. I used the iron-on method with Better Bonds heatlock glue raw walnut veneer. The RS150's modeled the best in Unibox of all the reasonably priced 8-ohm 5 1/4 midwoofers I could find. With a port is 6" x 3", I'm able to get an F3 of about 30Hz.




How do they sound? Well I voiced them actively over 3 months of Winter, logging many hours of listening and tweaking. I used a wide variety of material and musical genres, standard and hi-res digital formats, as well as vinyl and even cassette tape sources. Throughout the process, a new source or material would reveal problem or issue, that I would address in subsequent tweaking. Previously, I've also received feedback that my voicing tend toward "polite" or "laid-back", so I made a conscious attempt at a more balanced sound.

I'm extremely pleased with the results. I'm already a fan of the RS28A and Usher 9950-20 tweeters, so I new I would like the fabric dome. I didn't know how much! I would say its sound is somewhere between the clean and lean sound of the RS28A and the super warm and smooth sound of the 9950, with the best characteristics of each.

The RS150 is one hell of a 5 1/4" midwoofer, very clean without any fatigue-producing harshness or false detail. I'm getting great bass performance paired up in this tower configuration. A full symphony, with even a large chorus or organ thrown in, is reproduced with authority.

UPDATE:

An alternative XO for a flatter response can be seen here:

http://techtalk.parts-express.com/sh...26#post1886326

[arlis_1957@yahoo.com]

very nice.

[johnnyrichards]

I'm sorry those cabinets are terrible, you should probably just send them to me for disposal.

Nice work, sir. Very nice. I wish I had the fortitude to attempt a veneered finish.

[Leroy R]

Nice cabinets. They look bigger in the photos than they actually are. The veneer has a lot of character. I'm in the process of building some large cabinets that will have a beveled baffle like yours. Did you veneer the bevel first or the adjacent faces?

[Paul Carmody]

Great job! Well-executed build all-around.

[Randall Kepley]

J, very nice build indeed. Veneer looks great, nice clean lines and Im realey digging the feet on those bad boys. Please explain a little more of your "Tweeking" process if you dont mind. Thanks, R.K.

[Brewski]

They look very nice congrats on the build.

Take it easy
Jay

[3cyltrbo]

Beautiful work and super informative thread

Cheers

Will

[jclin4]

Thanks guys for the compliments!

Nice cabinets. They look bigger in the photos than they actually are. The veneer has a lot of character. I'm in the process of building some large cabinets that will have a beveled baffle like yours. Did you veneer the bevel first or the adjacent faces?

The bevels were the biggest challenge in the veneer trimming stage. For 90° angles I used the router with flush trim and flush trim-small pilot bits. For the bevels and adjacent surfaces I had to use a veneer saw.

It was really difficult to cut the veneer at the 22.5° angle (67.5° -no problem), especially along the grain: the cut wanted to follow the grain and not a straight line. There was some tearing and chipping of the veneer which I had to cover by using walnut wood filler (Elmers) for the small gaps. And for the larger gaps, I placed a sheet of paper over them and traced outline by rubbing a dull pencil.I then cut a replacement patch using that outline. Looks pretty good after finishing. In hindsight, I would just trim the shallow angles with a hobby knife and a metal straigt edge.

Here's the order of veneering: back, sides, top, bevels and finally baffle.

[jclin4]

Oh, and I can't resist...some more pics

[joeybutts]

Those look fantastic! I'm really coming around to the small towers (not for me but for other people).

if I can swing it I think I may save up to build these for my grandmother for Christmas.

[Mark65]

Those are very nice indeed. Well done, sir!


Mark

[jclin4]

J, very nice build indeed. Veneer looks great, nice clean lines and Im realey digging the feet on those bad boys. Please explain a little more of your "Tweeking" process if you dont mind. Thanks, R.K.

Thanks!

Here is a bit more info on the outrigger feet:

http://techtalk.parts-express.com/sh...52&postcount=4

Regarding tweaking or voicing, at a high level...basically it is just brute force trial and error.

But practically speaking, for me it is fine tuning the high-pass portion of the crossover. The low-pass is harder to "tweak", unless you have a deep inventory of inductors on hand. I do not...due to cost constraints. For the high-pass, switching out capacitors and resistors is easier and requires less investment.

In this project, I initially had just a [paralleled small value inductor and resistor] in series with the tweeter for padding. No matter what values I substituted for the resistor, I would hear blare from forte brass musical passages. It wasn't until I put in an L-pad (still with a paralleled small coil on the series resistor) that everything fell into place....then it was just a matter of trying out different values and combos for the series and parallel resistors until it sound right.

[johnnyrichards]

Thanks!

Here is a bit more info on the outrigger feet:

http://techtalk.parts-express.com/sh...52&postcount=4

Regarding tweaking or voicing, at a high level...basically it is just brute force trial and error.

But practically speaking, for me it is fine tuning the high-pass portion of the crossover. The low-pass is harder to "tweak", unless you have a deep inventory of inductors on hand. I do not...due to cost constraints. For the high-pass, switching out capacitors and resistors is easier and requires less investment.

One thing I have found is it behooves a designer to pay close attention to buyout crossovers. I have stocked a wide variety of coils through buying various cheap speakers and buyout crossovers.

Ken McCullough is selling a lot of coils at a great price in the classified right now.

Seriously, your cabinets need to be disposed of - send them to me

[6thplanet]

Beautiful build j !! But I have a question...

In this project, I initially had just a [paralleled small value inductor and resistor] in series with the tweeter for padding. No matter what values I substituted for the resistor, I would hear blare from forte brass musical passages. It wasn't until I put in an L-pad (still with a paralleled small coil on the series resistor) that everything fell into place....then it was just a matter of trying out different values and combos for the series and parallel resistors until it sound right.

You bypassed/paralleled the series 2.7 ohm resistor with the .05mH coil? Wouldn't the fact that the DCR of the coil being like basically a dead short negate the resistor being there in the first place? Then when you placed the parallel resistor across the tweet that became the actual padding component.

[gabel87]

Wow, those are gorgeous! I'm doing similar outrigger feet on the tmm's I'm working on, it's a good look. Awesome job on those cabinets all around!!

What was your technique for keeping those large peices of veneer from rolling up while the glue dried? I find that to be one of the hardest things to deal with when using heatlock.

[cantgetitright]

They look fantastic. Was that your first experience with veneering? Anyways killer job J!! Keep up the good work!

[jclin4]

One thing I have found is it behooves a designer to pay close attention to buyout crossovers. I have stocked a wide variety of coils through buying various cheap speakers and buyout crossovers.

Ken McCullough is selling a lot of coils at a great price in the classified right now.

Seriously, your cabinets need to be disposed of - send them to me

I knew I could get a useful money-saving tip from you

About disposing of the cabs, let me think about it...I'll get back to you later

[jclin4]

Beautiful build j !! But I have a question...



You bypassed/paralleled the series 2.7 ohm resistor with the .05mH coil? Wouldn't the fact that the DCR of the coil being like basically a dead short negate the resistor being there in the first place? Then when you placed the parallel resistor across the tweet that became the actual padding component.

You might be right there. But I used the resistor paralleled with the small coil to flatten the slight rising response of the tweeter as well as pad it. I imagine the DCR of the coil to be very small, so I never included it in any simulations I did in PCD. Before swapping out different values for this resistor, a sim in PCD would give me an indication of the level of padding. Still, I started out with 1.2 ohms IIRC and went all the way to 6 ohms, and it never seemed to do the trick until I added a parallel resistor.

Not sure why this would be the case, but I suspect that a proper L-pad provides an added benefit of flattening impedance and this must have been what was missing, especially for loud and complex passages in the music.

Anyway, it could be the case that the small coil could be taken out and might provide more "air". But I didn't think to try this out as I was quite happy with the sound in the end.

[6thplanet]

Dig, I think we're both right, the coil would roll off the top end like a 6dB x-over (basically attenuating the top end) and the parallel resistor bringing the whole level of the tweeter down. Sounds right? Either way, congrats on an awsome set o' towers !!