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[Michael Young]

Hello everyone! I've been a frequent lurker...but finally decided to register. this is my first post..so be nice.

I did a comparison of three subs for everyone to read..I hope it will help to clarify what the Tuba 24 (Bill F's home build box) can and cannot do.  Once again..this is LONG!!!
Subjective Impressions from Subwoofer comparison.

First., let me give a little background information. I am a Mobile DJ, and do about 30 gigs a year. I’ve been DeeJaying for 15 years, and have worked in clubs, done raves & afterparties, and played for 12 year old birthday parties. Let’s just say I’ve had a lot of experience behind two turntables (or Cd players) and a microphone. Currently  about 70% of my events are for high school events or fraternity parties. So..I play a LOT of current rap, R& B, and deal with kids that always want it to be LOUDER. I am really picky about quality of sound as well as quantity, and I’ve heard enough sound systems in my 15 years of experience in the industry to know really good sound when I hear it. My ideal system would be the clarity of studio monitors with enough output to fill a ballroom that holds 500 people.

On to the comparison….

We listened to current songs on CDs. The system consists of a Denon double cd player, denon DJ mixer, a rane RPM 26z multiprocessor, and crown and QSC amplifiers. The High Mids were supplied by a pair of EAW LA212 speakers running off of a crown CE2000, and the crossover (24db per octave) was set at 100 hz. We had the three single subwoofers in the comparison set up side by side in between the left & right speakers, in the same plane. We were in a heated two car garage, and did tests with the garage door open and closed.

The first Subwoofer was the oldest, a Mackie SRS1500. It is the only box of the three that has its own amplification built in, and was supplied a balanced input from the back of the multiprocessor. I have to say, after listening to it all by itself, and in comparison to the other subs, I’m still impressed by how well it does at several things. It is able to reproduce all of the frequencies that are sent to it, even down to 35hz low tones in some current rap songs. If you put your hands in front of the ports, you’ll be surprised by the velocity of the air coming out of the box. With the garage door closed, it seemed to do the best job of giving the listener real low frequency in a small room. No subwoofer is perfect, and it’s got some weaknesses too. It has less  “punch” or “impact” than the other subs in this comparison with kick drums and other sharp transient sounds. It also seems to have a limited radius of effectiveness. By that I mean, when you open the garage door and get it out in the open, its sound does not carry well. If you walk twenty feet away from it, the subjective loudness has fallen way off in comparison to the loudness of the other subs at the same distance.

The next subwoofer in the comparison was a Yorkville LS608. It was fed by a QSC USA series amp (the USA 1310) which was mono bridged, supplying about 1300 watts to the cabinet at 8 ohms. First impression…WOW..talk about a Difference from the fist sub. This sub is ALL punch. Kick drums and transients practically knock you over with this one. It has great tone within its range, and provides a lot more raw volume than the Mackie SRS1500. I’d say at least 6db more. It’s very noticeable how much louder this one goes, and it doesn’t mind being thrown the full power of the amp. Given’s it’s quasi-horn loaded design, the efficiency is to being expected. It also throws the sound well, although it may be louder far away because it so much louder up close. It’s weakness is it’s frequency response. In some of the current rap songs, the 35 to 40 hz tones are important fundamentals for the beat, and this sub has NOTHING down there. Really, I mean nothing. If your bass is above 50 hz….you’ll get all you can handle from this sub, but it drops off very sharply below that frequency. I guess that goes to show that you can’t expect miracles from a single 18” driver in a relatively small box, even if it is quasi horn loaded.

Last was the Sub I was most interested in. I’ve owned the other two for 4 years and over a year respectively, so I know their strengths and weaknesses pretty well, and have been happy with both. This was a homebuilt sub, called the Tuba 24. It’s a horn box with a spiral horn and a 10” driver, specially designed for use in a horn. It’s 24” square, and only weighs about 65 pounds, which is about 30 pounds less than either of the other two subs. It was fed power by a USA900 amplifier, which was also run in bridged mono mode, supplying about 900 watts at 8 ohms to this cabinet. One note of caution…the driver is only rated for 300 watts, and we did not run the sub non stop to test its long term durability.
Ladies and Gentlemen:, hold on to your jaws..or they’ll drop to the floor. This little 24” cube with a ten inch driver generates VOLUME at REALLY low frequencies. I was floored by its extension. 35 hz? No problem..i’ll give it to you. It rattled anything that wasn’t tied down, and knocked off several items on the garage shelves with the vibrations it could produce. Switching back & forth between the Yorkville and the Tuba 24, I noticed that the tuba 24 produced almost the same volumes in the 30-60 hz range that the Yorkville does above 60 hz. When I walked outside with the garage door open, i was floored by the volume level at 20 feet away. In direct contrast to the Mackie, the low frequencies seemed to carry much further than I expected…hope the neighbors weren’t too pissed off. Its efficiency at these low frequencies really amazed me. I haven’t heard really low frequency that loud come out of anything but HUGE LF systems in nightclubs or at concerts. Ok, I know, that’s a totally different thing…but this little box does amazing stuff. It provided good even volume from 30 hz to 100 hz, with maybe a slight rise in volume near the 30hz low frequency cutoff. I wasn’t able to set up any kind of delay for the mains due to the short amount of time I had, but I’m sure it’s attack characteristics would be much better with a little delay added to the mains. It didn’t have bad attack transients, and they were better than the Mackie, but they were nothing like the Yorkville’s transient response.

So…here are my final impressions and conclusions…and remember, these are my opinions…so you may or may not agree with them.

Mackie SRS1500:
A great box for small gigs. If you have a 15” LF plus horn HF box that you can put on a pole above it, and you’re playing in rooms that only hold 100- 150 or for weddings..this thing is perfect. I’m sure I’ll keep mine for exactly this reason. I wish it weighed a little less though. The older I get, the tougher it is for me to carry a 100 Lb box around.

Yorkville LS608.
An efficiency monster. Indestructible 18” woofer. If you don’t mind having your frequency response stop at about 50 hz, this thing is your perfect box. It’s transient response and attack is something to behold. Two of them would easily fill a room that holds 500 people with 50 hz to 120 hz stuff that sounds GREAT.

Tuba 24
A Little LF generator extrordinaire. At about $300 of total materials cost, plus labor time to build it it’s a fantastic value. In a word, amazing. Bill F is a genius. I still can’t believe how much truly low sub frequency this lightweight (65lbs) box generates. And it did all of this amazing stuff with about half the amplifier power of the other subwoofers.

In summary..I think I’ll keep my two Mackie SRS1500s for small gigs, and use 2 LS608s and 2 Tuba 24s for the large gigs. I know I’ll probably make people shudder when I say I’m Mixing subs, but the combination of efficiency, punch, and LF extension that the combination of the LS608 and the Tuba 24 will produce is going to be something to behold. I’ll report back in late February after I’ve deejayed for two high school winter formals and at least 4 Fraternity/Sorority Parties. The High school Dances are in Gymnasiums, which are notoriously large spaces that are tough to generate bass in. The Fraternity formals will be in large (200 person approx) ballrooms in hotels, so they’ll give me a chance to see how well they’ll do in that environment.  

[[x]]

With the Tuba 24, it is important to specify which driver is being used. There is the Beta 10, which you're probably not using, since it runs into major power compression at lower frequencies, and then there is the HL-10, which is designed for higher output at those same low frequencies. The strange thing is that on the surface, it doesn't look like the HL-10 would model too well in that box, but many report really good results using the HL-10. I guess the proof is in the pudding, so to speak.

You should build four Tubas, for the big gigs, and sell the Yorkvilles for money to offset the cost of the two extra Tubas. Then you put the tubas side by side on the floor so the mouth areas combine, and you'll get flatter, better bass. Or, stack the four together in the middle, for some really good stuff. When I come out with my design for the HL-10 (I've been refining the horn folding and the front and rear chamber), you will be able to use them in a similar configuration. My horn will be simple to build. Think of a smaller Punisher, with single-dimension miters, but a different folding and smaller mouth. My horn takes advantage of a quarter wave resonance at the bottom of its range to extend its response to about 45 Hz when used in pairs.

[Michael Young]

Sorry- Forgot to specify. The driver in the Tuba 24 was the HL-10. So I'm sure that is why I got such good LF performance.

I'm glad someone chose to respond!

Would this post be more appropriate in the "lab lounge" area?

[[x]]

Actually, this is an ok place to post this. Ever since the HL-10 came out as a little brother to the Lab12 driver, people have been looking for a good design to use it in. People like the LAB12 for its sheer all-out performance, but they'd like a smaller option for  smaller gigs where LABs are overkill. They want something easier to transport. That's why I'm developing my "Crusher" horn, which is for the HL-10 specifically. I'm almost ready to unleash it. The design will probably be ready right after Christmas. As you probably have seen, there is a bit of controversy regarding the Tuba 24 and how well it works. Your review should help people understand that the claims are real, and what the performance compares to.

[Walt de Jong]

Punisher also has single-dimension miters. Could you give me the data I need to simulate your Crusher horn?

Best regards,

Walt

[[x]]

I'm getting close. The HL10 requires really crazy small front and rear chambers, and my last version of the folding didn't have that. It also needs an really small mouth. The new one is on paper a few feet away from me. Once I get the front and rear chambers optimized, I'll post up the data and a scan of the horn folding, and then I'll work up some cut sheets.

Here's the response graph of an earlier, failed try. The mouth, front, and rear chambers are all too big in this version, causing the dip at about 60 Hz. When the horn mouth is made tiny, then the dip is alleviated. Also, the smaller front chamber of my next version of my design will smooth response a great deal. I'm trying to make sure that when I relase my design, I'm not releasing a spud.

Addendum: I've just corrected "The Dip". Very soon I will have the final design, like in a week or so. Average sensitivity should be 105 dB. A single box does 102dB at 60 Hz, 1w/1m. You'll want to use at least a pair of them.

The response graph is for a single enclosure, in 2.0xPi space. But corner-loaded, one box gets really loud, like 108dB 1w/1m, and goes to 50 Hz. I'll simulate a multi-box stack for 2, 4, and 6-box stacks so you will be able to know that info as well.

[[x]]

One more update: With a final modification to the horn folding, you can use Crushers in pairs per side with flat output to 55 Hz (+/-3dB) and a usable lower limit of 50 Hz (-5dB). Then if you use four per side, you get flat output to 50 Hz (+/-2dB), and a usable lower limit at 42 Hz. With two boxes, average sensitivity is 105dB 1w/1m, and with four boxes, it jumps to 108dB 1w/1m, so you'll be able to get away without an insane amount of power. I'll go ahead and say that the program power ahndling of the final box should be 500w, with 300w RMS power handling per box. It looks like this horn is going to exceed expectations. However, I recommend that you don't try to use them as a single box per side, because more than one box is needed to prevent severe response anomalies.

Plans should be ready by next weekend, but probably this weekend.

[fernand]

Great post Michael,

Would it be possible to compare the Yorkville LS608 with the Tuba when all frequencies below 50 Hz are filtered out ?
The low bass extension tends to change the perception and/or behavior in the 50 to 100 Hz range.
Thank you.

[Michael Young]

I'll be doing some more testing in January & February of next year.
I''l be sure to test the above 50hz performance of the tuba vs the LS608, and post my impressions.
All the testing I did for the review above was with a signal crossover at 100 hz at the high end, and 30 hz at the low end.
so all the impressions were of the performance in that frequency range.

[fernand]

Great Michael.

Looking at the hijacking of your post, I suppose that someone will send you two stacks of 4 Punishers and Crushers so you can test it against your Mackie