STF-3 or PB12-ISD?

[craigsub]

good enough...sufficeth to say, both are excellent speakers!


but hey, if you are putting a gun to my head, then I would go with the ISD

As a card carrying member of the NRA, I can say with certainty, if I have a gun pointed toward your head, you are going no where ..

 

[Tomorrow]

As a card carrying member of the NRA, I can say with certainty, if I have a gun pointed toward your head, you are going no where ..

LOL!!

 

[Mark512]

So if no modifications are made, the stock pb12 gives greater performance?

 

[craigsub]

So if no modifications are made, the stock pb12 gives greater performance?

You can have Hsu send you the subwoofer with the one port, max extension setting as described earlier at no additional charge, all you need to do is ask.

In fact, the STF-3 was originally introduced in that configuration.

The answer to your question is "yes", but, using a car analogy, If Car "A" offers only an automatic transmission while car "B" offers a manual transmission or automatic, and you must specify which you want, and both are the same price, is it a "modification" or a "choice"?

Your choices are:

1. PB12-ISD $599
2. STF-3 two port $599 (giving the "weaker" SPL numbers Shervin listed earlier)
3. STF-3 one port $599 (giving the "stronger" SPL numbers as I listed earlier). This will have a removeable port blocker should you decide to get the turbo upgrade.

All three are excellent performers.

"3", as listed above, gives the most options, because it is upgradeable later.

Those are the options in the $599 price range for both companies (well, there is the SVS cylinder, but in essence, it matches the box sub for performance and price) ...

 

[ssabripo]

You can have Hsu send you the subwoofer with the one port, max extension setting as described earlier at no additional charge, all you need to do is ask.

In fact, the STF-3 was originally introduced in that configuration.

The answer to your question is "yes", but, using a car analogy, If Car "A" offers only an automatic transmission while car "B" offers a manual transmission or automatic, and you must specify which you want, and both are the same price, is it a "modification" or a "choice"?

Your choices are:

1. PB12-ISD $599
2. STF-3 two port $599 (giving the "weaker" SPL numbers Shervin listed earlier)
3. STF-3 one port $599 (giving the "stronger" SPL numbers as I listed earlier). This will have a removeable port blocker should you decide to get the turbo upgrade.

Let me just add my 0.02, just for clarification purposes, and I will leave this be (see final comment at the very end of reply ):

The STF-3 stands for SINGLE TUNING FREQUENCY. It was never designed to be a variable tune subwoofer. That is why Ed compared it to the PB12-ISD - also a single tune subwoofer.

Hsu reacted to the advantage in distortion limited output posted by the PB12-ISD below about 25 Hz by plugging a port on the STF-3 to bolster its low end THD numbers.

Here's the rub: There is no tune switch on the STF-3 that allows a custom EQ curve and lowered high pass filter setting to take full advantage of plugging a port (which results in an Fb of about 20 Hz). That is why the VTF-3 exists.

The STF-3 with a plugged port will retain the EQ curve an the high pass filter setting which was optimized for the 25 Hz Fb native tune setting. This would be akin to you plugging a port on a PB12-Ultra and leaving the tune switch set to 20 Hz.

Yes, the STF-3 gains quite of bit of clean output down deep by plugging a port. It also loses about 4 dB in the 25 Hz region, but no one mentions that. This is just basic sub physics. The fact remains the STF-3 is not advertised or sold as a variable tune subwoofer, there is no mention of it in the manual, and there is no port plug included in the box. In short, plugging a port is a misapplication of the intended use of this product.

And Craig, I just checked with various resources, and No, the STF-3 was not originally sold this way. There was a run of amps built with the INCORRECT EQ curve and high pass filter setting. Again using the Ultra analogy, this would be akin to setting your tune switch to 16 Hz and leaving all three ports open.

Since running both ports open with this amp setting could bottom the woofer, Hsu had no choice (other than to junk the amps) but to sell that particular run of STF-3's with a port plug and advertise them as a "limited edition" run of "maximum extension" STF-3's. They were basically like a VTF-3 stuck in the max extension mode.

The fact remains the STF-3 is a single tune subwoofer with an Fb of 25 Hz and is advertised and sold that way(thus,tested that way). If someone wants to plug a port - great - do it. But it's not an optimized configuration. If you want something like that, buy the VTF-3 instead. Furthermore, it is underported with a single 3" port and prone to chuffing, and that's the whole reason Hsu developed the turbo.

The turbo can ONLY be used on an STF-3 IF the customer yanks the amp and sends it back to Hsu to change the EQ curve and HPF setting (or DIY, but will void the warranty). And then there's no going back - you're stuck with that setting. The VTF-3 is a much better candidate for the turbo because it has an external tune switch setting on the amp, unlike the STF-3.

So there was nothing "incorrect" about the data in Ed's test, AFAIK. He simply tested the subwoofer in the configuration intended by the manufacturer. At the time of the test, there was no mention - anywhere - that Hsu officially or unofficially condoned running the STF-3 with a port plug. This suggestion only came out after his review, as the HTF thread clearly proves. The name of the subwoofer says it all - STF -

All three are excellent performers.

YES, amen! you won't go wrong either way

 

[Peter Marcks]

Dear ssabripo,

The STF-3 stands for SINGLE TUNING FREQUENCY. It was never designed to be a variable tune subwoofer.

All that is meant by single tuning frequency is that tuning frequency is fixed, as opposed to variable. This is quite different than saying that a fixed tune STF-3 with both ports open will always be preferrable to a fixed tune STF-3 with one port plugged. In fact, according to our consumer feedback on the VTF-3, 20Hz mode with one port plug actually seems to be the preferred tuning mode!

Hsu reacted to the advantage in distortion limited output posted by the PB12-ISD below about 25 Hz by plugging a port on the STF-3 to bolster its low end THD numbers.

Since the STF-3 is based on trickle-down technology from the VTF-3, it is also able to reap some of the benefits of the VTF-3. One of these benefits would be the ability to plug a port to effectively lower the port tuning.

Dr. Hsu's formal response was here:

http://www.hometheaterforum.com/htforum/showthread.php?postid=2224173#post2224173

Here's the rub: There is no tune switch on the STF-3 that allows a custom EQ curve and lowered high pass filter setting to take full advantage of plugging a port (which results in an Fb of about 20 Hz). That is why the VTF-3 exists.

Based on customer feedback and reviews such as that in reference above, we have reconsidered out stance on what tune to offer with the STF-3. If a consumer wishes to have an STF-3 in maximum extension mode, all they need to do is inform us, and we will set the amplifier for 20Hz mode in addition to supplying a port plug. This is a no-cost option. In fact, this offer is extended to those who currently own an STF-3 in 25Hz mode. For a small fee (no more than $50), we will modify their amplifier for 20Hz mode, and supply a port plug.

The STF-3 with a plugged port will retain the EQ curve an the high pass filter setting which was optimized for the 25 Hz Fb native tune setting.

There is nothing wrong with plugging a port on the STF-3, even if the amplifier is not modified for the lower port tune. This will result in an overdamped response, which some people actually prefer and feel gives a tighter bass. Dr. Hsu talks about this in his response linked above.

Yes, the STF-3 gains quite of bit of clean output down deep by plugging a port. It also loses about 4 dB in the 25 Hz region, but no one mentions that

The reduction in distortion-limited output over the common bass range is not nearly as bad as you think. This is what Dr. Hsu said about it:

The loss in output with 10% harmonic distortion when switching to one port is not as bad as you think. Thanks to the soft power supply of the BASH amp, with one port open, the impedance at 25 Hz is much higher than when both ports are open. With both ports open, the impedance at 25 Hz is very low. The maximum voltage swing the amplifier can deliver is much lower than when one port is open, where the low impedance is shifted down to around 18 Hz. The result is no loss of output at 25 Hz for 10% harmonic distortion. The woofer has a much higher excursion at that SPL compared to the two port open case (roughly 10 times higher), but harmonic distortion is still below 10% up to the same SPL. The only 1/3 octave spaced frequency measured that showed significant reduction in output with the 10% harmonic distortion criteria is 31.5 Hz where we measured a 2 dB reduction.

No doubt, there are tradeoffs involved with lowering the tune. Efficiency and port flow area both decrease, which leads to a decrease in maximum output over the common bass ranges. However, low frequency extension becomes better, and output in the lowest bass becomes cleaner. Most of our customers actually seem to prefer the maximum extension mode on the VTF-3.

Since running both ports open with this amp setting could bottom the woofer, Hsu had no choice (other than to junk the amps) but to sell that particular run of STF-3's with a port plug and advertise them as a "limited edition" run of "maximum extension" STF-3's. They were basically like a VTF-3 stuck in the max extension mode.

On the limited run of maximum extension STF-3's, the amplifiers were accidently set in 20Hz mode. So the natural thing to do was to include a port plug and offer the limited run as maximum extension STF-3's. The only setting we would really discourage and not recommend is to run the subwoofer in 20Hz mode with both port open, as this can cause damage to the unit.

Furthermore, it is underported with a single 3" port and prone to chuffing, and that's the whole reason Hsu developed the turbo.

At higher output levels, it is true that with the single 3" port there can be some noticeable port turbulence-related noises. Turbocharger allows us to achieve the very low tuning without much port turbulence-related noise.

The turbo can ONLY be used on an STF-3 IF the customer yanks the amp and sends it back to Hsu to change the EQ curve and HPF setting (or DIY, but will void the warranty).

This is actually not quite correct, turbocharger will be beneficial on STF-3 even without having the amplifier modification. I will speak more about this in the next month or two. However, to take full benefit of the turbocharger, it is recommeded to have the amplifier modified. This is a relatively easy fix, only one resistor needs to changed.

And then there's no going back - you're stuck with that setting. The VTF-3 is a much better candidate for the turbo because it has an external tune switch setting on the amp, unlike the STF-3.

STF series is less cost for the consumer, VTF series is higher cost but more flexibility. Another tradeoff in a sense! Keep in mind that those who add a turbocharger to VTF-3 Mk2 will essentially be running the subwoofer in a fixed tune, meaning maximum extension mode. So if one is set on using a turbocharger at some time in the future, then the STF-3 in maximum extension fixed tune is actually the more cost effective way to do it.

So there was nothing "incorrect" about the data in Ed's test, AFAIK.

The important thing to remember is that the STF-3 is flexible enough to use in various porting and amplifier configurations. Some of these configurations will lead to MUCH improved low bass output and extension versus what was seen in the review. This is in large part due to the fact that STF-3 shares technology with the VTF-3 Mk2, in addition to being able to accept some of the new technology like turbocharger too.

Sincerely,

 

[craigsub]

Shervin ...

1. Hsu offered the STF-3 in max extension mode. That is a fact.

2. Hsu still offers the STF-3 in ME mode, WITH the necessary amp mod at no additional charge. For years, SVS has offered a 22-31 PCi. It is not on their web site, but it is available. Does this mean we don't talk about it ?

3. It was Ed's decision not to include the SPL numbers for the STF-3 in ME mode. I have no problem with Ed's decision.

However, I am also not going to watch while someone is given one set of numbers which was clearly intended to sway a buyer while ignoring the fact that one of the "players" was capable of higher performance. A potential purchaser should be informed of ALL the available performance options on a product he is thinking of purchasing. The purpose of these forums is to assist, not to sell our favorite brand.

4. I had a pair of VTF-3's here for months. In the single port mode, chuffing was never audible except with high level sine waves.

Happy Thanksgiving.

 

[brian32672]

Very well said Peter. Also thanks for the link........

 

[ssabripo]

Thanks for that clarification Peter....I appreciate the updates!

Craig...man, is there a subwoofer you DO NOT own?? Can I borrow any of the ones you are not using?

 

[Sheep]

Thanks for that clarification Peter....I appreciate the updates!

Craig...man, is there a subwoofer you DO NOT own?? Can I borrow any of the ones you are not using?

I second that

SheepStar

 

[craigsub]

Thanks for that clarification Peter....I appreciate the updates!

Craig...man, is there a subwoofer you DO NOT own?? Can I borrow any of the ones you are not using?

LOL ... Just keeping you on your toes, my friend.

 

[Peter Marcks]

My pleasure to assist, gentlemen! I feel quite proud and happy about the upgradeable bass characteristics.

Have a good night, all!

 

[Tomorrow]

My pleasure to assist, gentlemen! I feel quite proud and happy about the upgradeable bass characteristics.

Have a good night, all!

Thanks for the information, Peter. It's much appreciated.

I read most of the link you provided. It was quite informative. But reading some of the arrogant and insulting remarks over there within the thread, I am impressed by your and Dr. Hsu's restraint and dignity. The motto of AH is Pursuing the Truth in Audio and Video. It seems like quite a few on that forum are less interested in the truth of a matter, or open discourse, and more in their own biases and 'clever' smart-mouth comments. The Chinese call this inflexibility Wu Li...to hold one's own ideas tightly. That kind of behavior certainly gets in the way of learning and growing, and IMHO diminishes this hobby. As it also occurs here, but very little, I am reminded that it is but the nature of the internet and the anonymity it provides.

But most of us are trying to separate the chaff from the wheat here, and appreciate your input. A very happy Thanksgiving to you and yours.