EdwardJM: How about testing this classic sub: HSU TN1220 with dedicated 500 watt amp (2 Viewers)

[Arthur S]

Edward

The HSU TN 1220 is perhaps THE classic cylinder sub. It has been around for about 7 years and blew away the competition back in 1997. It has not been tested against any of the new high performance SVS cylinder models which it spawned.

HSU now has it for $1000 delivered with the dedicated 500 watt amp (42 pounds). This would make an interesting comparison to the new $1,000 Rocket UFW-12. Just how good is a $1000 sub?

HSU makes good stuff and doesn't get much "air time". How about checking this one out. The test by Don Keele in the old Audio magazine whetted my appetite. He got 101 DB at 12.5 Hz using a Crown Macro Reference (5000 watts?) but his review is not comparable to your current reviews.

I hope I can wet your appetite. This thing deserves another look.

Artie

 

[Edward J M]

Ask Dr. Hsu and John Johnson at Secrets if they would like it reviewed. If they both consent, you've got a deal.

I'm sure the TN1220 is a good performer; Poh Ser Hsu is one of the pioneers in modern high performance subwoofer design.

 

[Rob Bird]

Would you consider doing a comparo between the PB12-Plus/2 and the PC-Ultra? I'd really like to see those head to head with all the lovely measurements.

 

[Edward J M]

Tom Vodhanel at SVS can provide you with the differences in clean output between these two models in the various states of tune. Suffice it to say, the PB2+ is certainly the stronger unit.

The Ultra has a unique sound quality and a lower native tune with all ports open; it would be my preference in any mid size room. In a large room for high playback levels, the PB2+ gets the nod.

 

[Jason Dalton]

Just an FYI, to drive that sub to 101dB @12.5Hz probably takes about 100W.

 

[GabeAJ]

SVS also says that a pair of PC-Ultras will outgun a PB12-Ultra/2 from 20hz and below.

 

[Edward J M]

If you read Keele's review carefully, he measured a peak output of 101 dB @ 12.5 Hz with a 150 watt input and without respect to distortion. He measured 104 dB @ 16 Hz @ 22% distortion.

What's not clearly stated in the review is the forumula Keele uses to convert from 2 meter ground plane to the room. IIRC, he adds 6 dB to get the equivalent 1 meter ground plane value, and then he adds even more dB on top of that for room gain. I don't have the chart in front of me, but I think its around 8 dB at 20 Hz and progressively less as the frequency rises.

As we have discussed here before, there is not a hard and fast rule of outdoor to indoor gains. Keele has his formula, and he applies it equally to all speakers, so in that respect it is consistent. But some rooms are more lossy than others, and the distance to the subwoofer will vary greatly.

Designers like Mark Seaton have seen clean output levels DROP from the 2 meters ground plane figures when moving indoors if the room is large enough and the distance from the subwoofer is long enough.

Conversely, you can see an increase in the GP numbers when going indoors if the room is smaller and well built (rigid), and the distance to the sub is fairly close.

Just remember to compare apples to apples when quoting output figures and be sure to also state the circumstances and conditions under which the numbers were generated.

If I test the TN1220 (which might never even occur), it will be the straight numbers 2M GP for FR, THD, dynamic output, and power compression. I don't apply any type of formula to convert to an equivalent indoor reading.

I prefer to provide (c-weighted fast) SPL peaks at the listening position on DVD movies as a more useful real world indicator of indoor output capability in a mid-size room with the sub about 12 feet away.



The PB12-Ultra/2 can hardly be considered weak at 20 Hz, but the dual Ultra's would probably outgun it by about 4 dB in clean output. More internal volume, way more port = no surprise. Dual co-located Ultra cylinders are the performance king of the SVS line-up way down deep.

The only thing that would make me give up my PB12-Ultra/2 is a pair of powered SS cylinders.

 

[Arthur S]

Edward, I am going to contact Po Ser Hsu and John Johnson and ask exactly what you stated: would they like the TN 1220 reviewed. I spoke to Dr. Hsu once and apparently he is not reluctant to speak on the phone. I have never spoken to John Johnson but I am more than willing to try to speak to him or write, if necessary. I own 2 SVS products but it would be a thrill for me to see the old war horse TN 1220 tested. Just reading about a $1,000 sub that could do 12.5 Hz, back in 1997, was a thrill.

Edward, you are probably going to kill me but I think you compared some apples to oranges in pulling some of your data from the Keele review. Keele did several different types of measurements. The 101 db @ 12.5 Hz was obtained in the maximum peak output (short term peak input) test. In this test he got 110 db at 16 Hz, not 104 db as stated in your last post. The only reason I know this is that I subscribed to Audio for many years and I have the August 1998 issue with the complete review. The condensed version available on the HSU web site does not include any of the graphs in the magazine. One particular graph includes peak output with room gain, peak output without room gain and peak input. The paragraph describing these findings reads:

With room gain, the maximum peak acoustic output starts with a very high 101db at 12.5 Hz, passes through 110db at 16 Hz, then rises to a local peak of 114db at 20Hz...dipping to 113db at 25 Hz...rising to 117.5db at 50Hz...

You are correct though about the peak input at 12.5 Hz. It was 150 watts, rising to 660 watts at 16 Hz and 1,350 watts at 20 Hz.

Edward, I hope you are not put off by this additional information. You have joined a small group of professionals who have the privilege of testing subs for those of us who love them but don't have the expertise, the equipment, and the muscle power (to get these monsters outside and back in again), to conduct such tests. I have some stuff for you to add to your collection. I will be in touch.

Thanks

Artie

 

[Edward J M]

Hi Arthur:

I'm not put off at all, don't worry about it.

My point was the 101 dB at 12.5 Hz (and all the rest of the maximum output figures) were conducted without respect to distortion. And (as far as I can tell) also included Keele's formula for room gain.

So simply stating (as you did in your first post) that a given sub pulled 101 dB @ 12.5 Hz without any other frame of reference or context can be misleading.

I included the 104 dB @ 16 Hz @ 22% distortion figure in comparison only, and I realize the two test parameters were completely different.

I see from PM you will be sending me a copy of the review (thanks). The best thing in the interim would be for you to post the straight 2 meter ground plane numbers for: 1) maximum peak output and 2) steady state output with distortion included. Make sure they are not the 1 meter equivalent numbers, which would have 6 dB added.

Good luck in your conversations with John Johnson and Poh Ser Hsu.

Regards,

Ed

 

[Peter Marcks]

Greetings Artie,

The TN1220HO (Tom Nousaine 12 inch diameter flat response to 20Hz High Output cylindrical sub) is a subwoofer that the people at Hsu Research are extremely proud of. Dr. Hsu created this subwoofer in direct response to a challenge posed by legendary reviewer Tom Nousaine. Mr. Nousaine challenged subwoofer manufacturers to give more bass in less space, and this is exactly what Dr. Hsu set out to do.

The TN1220HO subwoofer system with 500 watt amp is what we would consider to be the ultimate performance package from Hsu Research for a high resolution audiophile 2-channel and HT system. The 500 watt is our highest quality and most fully featured amp, with built in active low pass and high pass crossover, in addition to some other nice features. Perhaps one of the nicest things about this purpose-built amp is that it can drive up to two TN1220HO series subwoofers in parallel, sending 400x2 watts into two TN1220HO's.

It should also be noted that the TN1220HO is not tuned at 20Hz, it is tuned below 18Hz, and the actual model number is in reference to the flat (+/- 0db) frequency response down to 20Hz. Some competitive offerings will need at least one port plugged in order to approximate the tuning point and frequency response of the TN1220HO. Also, a single TN1220HO has a heavily flared port with 4 inch inner diameter and about 7 inch outer diameter. The port is also extremely long, in excess of 28 inches long end to end. We estimate that it would take about four 3" inner diameter ports to approximate the port flow capabilities of a dual TN1220HO setup, and this in combination with the downfiring long port and low tune means that port noise on this system is essentially inaudible at all bass levels above 16Hz.

The current asking price is very good. For $1500 shipped for a dual TN1220HO subwoofer system with the 500 watt amp, we do not know of any other commercial offering that offers this much performance and features for such little floorspace occupied.

The Don Keele review was very impressive, even by today's standards. Mr. Keele really was able to appreciate Dr. Hsu's abilities as a subwoofer designer after testing the unit, as engineering such a slim tubular subwoofer with such good low frequency performance is extremely difficult to do.

That said, it should be known that Keele tested one of the original TN1220HO models many years ago. The TN1220HO has since received several very substancial driver and amplifier updates which ultimately result in our opinion in cleaner, more powerful, and more defined bass.

A test would ultimately be up to Dr. Hsu, but naturally we feel confident that the TN1220 will provide the most bass for given floor space, as it was designed to do.

 

[paul clipsel]

Artie can you post the graphs for all of us to see?
Those performance numbers are very good for a single 12".

PC

 

[Edward J M]

Peter, let me be the first to welcome you to both HTF and AVS. With the good doctor working on new designs, and Sasha manning Hsu's own forum, official Hsu Research support at the various other forums has not been strong. Your presence corrects that, and I'm sure will be welcomed and appreciated by everyone.



Again, the straight 2 meter ground plane numbers are the ones that will be the most useful and comparable to other data sets.

IF someone wants the 1 meter ground plane equivalent, they can simply add 6 dB.

And (as discussed above) the indoor numbers won't neccessarily be valid in every room. Indoor numbers can actually be lower than the ground plane numbers under certain (and not really unusual) conditions.

Regards,

Ed

 

[paul clipsel]

Ed comparing outright in room numbers was never an issue for my suggestion of posting the graphs from the Keele review, just as Nousaines figures are only good for Nousaine comparison's. I think we all know the pitfalls of comparing measurements from different reviewers, room, equipment, methods etc. I am just as interested in comparing the TN data to other reviews that the excellent Mr Keele has done. Its obvious he really knows audio, although unfortunately he is retired from reviewing now days.
Since Peter Marcks is from Hsu Research I wonder if he can confirm the Hsu forum rumor that Ultimate A/V is reviewing the VTF-3 in an upcoming issue? I really look forward to that review if that is the case, after all it was several years ago since they reviewed the older model VTF-3.

PC

 

[Peter Marcks]

Thank you for the warm greeting Edward! We feel very honored to be a part of this great online community.

Paul, to my knowledge, there will be no review in Ultimate A/V. Perhaps in the future we can set something up.

 

[paul clipsel]

Peter that is unfortunate if true. With the new models having been out a while and I bet they would review very well in comparison to other subs of similar value. My VTF-3 Mk2 has added another dimension to my music mainly because it blends in so well with the mains unlike many other subs that tend to draw attention to themselves. My system is mostly used for music not HT, so I think it is a shame that there seems to be a heavy concentration of interest in spl rather than just how good a sub melts into your system.

PC

 

[Edward J M]

While I can only speak for myself, I spend a LOT of time integrating the sub with the mains for the proper blend on music. I think music performance is vitally important to the overall rating.

Of course the better a sub measures objectively, the better it tends to sound on both music and HT. With that said, even the best sub can sound horrible with a bad set-up or poor room acoustics.

Just running sweeps and experimenting with placement, phase, the low pass filter, the on-board PEQ (if so equipped), and the overall sub level (usually 2-3 dB lower for music vice HT) can be very effective. Just look at the before/after in-room FR screen shots in my PB12-Ultra/2 review to see what can be accomplished at the critical mains/sub transition bandwidth with a little time and effort.

 

[Peter Marcks]

Hello Paul,

All of us at Hsu Research symphathize with you. There is no doubt that we could cook up a model that is a lot larger and a lot more powerful than the current VTF-3, but we find it more challenging to maximize sound quality and bass output for a given box or cylinder size. Pound for pound, inch for inch, it is really miraculous what Dr. Hsu can do with a subwoofer.

 

[paul clipsel]

Peter having changed from Velodyne to now owning two of your subs the VTF-3 Mk2 (STF-2 with Ascends) I am left in no doubt as to how good his design skill is.

My previous CHT Velodyne subwoofer would always get switched off anytime I wanted to listen to my music. With the Hsu in place switching to a CD on the AVM input is no longer a non event. The revelation for me was the Hsu's ability to add weight and depth to my music without overpowering the mids and treble. That seamless blend was easy to achieve with the Hsu, yet it was impossible with the Velodyne, which is why it was only ever switched on if we played a very rare movie. (85-90% listening for me is cd music)



PC

 

[Drew Bethel]

Quick question that has been on my mind for a while: Did Dr Hsu invent the cylindrical sub?

 

[CurtisSC]

No...Dr. Hsu did not invent the cylindrical sub, but he was one of the first to provide high output, ported, cylindrical designs to the masses. He has also helped many people work on their own DIY designs. Some of Dr. Hsu's designs have been the basis for other designs as well.

Remember those old "bazooka" car subs? I've heard they, at one time, tried to sue based on "trade dress".