JBL studio 230....SUPERB!

[lovinthehd]

...or the JBL may have had a defect like a bad solder joint. Being nicer to your ears might be a good thing to come out of it, tho. You still have the Polks for backup?

 

[jsf0656]

...or the JBL may have had a defect like a bad solder joint. Being nicer to your ears might be a good thing to come out of it, tho. You still have the Polks for backup?

yes, and maybe start trying to listen at a more moderate level!

 

[lovinthehd]

yes, and maybe start trying to listen at a more moderate level!

Still, would be interesting to have an actual spl level to go with the volume knob positions....

 

[zieglj01]

I still think you may have gotten 1 lemon -- the JBL are not Mickey Mouse speakers. However some caution needs to be taken. But the Polk are about 4 db more sensitive and are easier to drive. .... Also if you are going to do YPAQ, then reset it for the JBL, because the auto calibration can stress your speakers in certain areas .... When you get the new set and just for a test, turn YPAO off and just set the size and distance and level of your speakers and see how that sounds to you. If you decide to run YPAO again, then rerun it for the JBL. ... My set can get quite loud, but are better below 90 db spl for music.

 

[lovinthehd]

I still think you may have gotten 1 lemon -- the JBL are not Mickey Mouse speakers. However some caution needs to be taken. But the Polk are about 4 db more sensitive and are easier to drive. .... Also if you are going to do YPAQ, then reset it for the JBL, because the auto calibration can stress your speakers in certain areas .... When you get the new set and just for a test, turn YPAO off and just set the size and distance and level of your speakers and see how that sounds to you. If you decide to run YPAO again, then rerun it for the JBL. ... My set can get quite loud, but are better below 90 db spl for music.

What I could find on the Polk RTi6 was 89 dB sensitivity, 88 for the JBL....

 

[jsf0656]

yep that is correct. I always have thought that JBLs are some of the louder and robust speakers out there!
I was surprised that polks can take a lot of power. never heard that

 

[jsf0656]

yep that is correct. I always have thought that JBLs are some of the louder and robust speakers out there!
I was surprised that polks can take a lot of power. never heard that

I guess klipsch must be able to since they have really good sensitivity a lot higher than most!

 

[zieglj01]

The good bass response is not free -- they are 85.5 db in the sensitive area
https://www.soundandvision.com/content/jbl-studio-2-speaker-system-test-bench

 

[lovinthehd]

The good bass response is not free -- they are 85.5 db in the sensitive area
https://www.soundandvision.com/content/jbl-studio-2-speaker-system-test-bench

I wonder if the Polk spec would also drop with 3rd party measurements, tho....

 

[lovinthehd]

I guess klipsch must be able to since they have really good sensitivity a lot higher than most!

Higher sensitivity does not go hand in hand with higher power handling capabilities particularly....

 

[jsf0656]

Higher sensitivity does not go hand in hand with higher power handling capabilities particularly....

I have a lot to learn apparently!

 

[Irvrobinson]

You played them too loud. That is what happened. They have cheap Chinese drivers, and the power rating is only 45 watts continuous. With rock music which is generally highly compressed you would overpower these speakers easily. Peak power is 150 watts, bit no spec. as to duration. My guess is a msec or two.

There seem a lot of vendors selling these refurb, so I suspect customers are blowing these up with abandon.

When you get your replacements, then you need to play them at a much lower level.

It is difficult to follow your reasoning. While the drivers may have been made in China (I have no idea),and they are likely to be relatively inexpensive in this price range, they are custom for Harman or made in a Harman facility. You can tell because they have those silly legacy PolyPlas/CMMD technologies that are exclusive to JBL speakers. (I call them silly because I dislike legacy implementations for the sake of marketing.) While I've never had a driver failure myself, I know people who have, and for multi-driver speakers the product being totally dead wasn't a failure mode. It was always a tweeter in a two-way box, and the highs went away or the owner heard scraping sounds. Where I have seen total failure before on other people's speakers was a bad input terminal and a failed crossover board (and in that one case it turned out to be a bad solder joint on the positive wire connection from the terminal). I'm not much of a betting man, but I'd put my money on one of those causes or something similar.

 

[TLS Guy]

It is time for more education, despite having gone over this ground before.

First sensitivity is measured on axis at 1 meter with a 1 KHz tone. That is how it is usually done, but some with an averaged sweep tone which is better.

The problem with the usual sensitivity test in isolation is that it tells you very little. It is actually close to useless.

The reason is that it can not be considered in isolation from the impedance curve. Also the speakers dispersion characteristics have a strong bearing on its significance.

Sensitivity tells you nothing about efficiency and surprisingly little about how much power will be required to drive a speaker to a given spl. in a room. Now that surprised you didn't it!

Nowow a bit of history. Tubes once ruled. They are not constant voltage devices driving a variable impedance load. That is why you need a speaker that does not have a speaker with a mountainous impedance curve if you own a tube amp. It will deliver an FR that wants to follow the impedance curve.

Solid state amps however are constant voltage devices, so that is why sensitivity came to be specified as 2.83 volts at 1 meter. That is 1 watt into 8 ohms which was prevalent in tube amp days. So in essence a solid state amp within limits of the current output of the output stage will maintain voltage with frequency into a load that has varying impedance with frequency.

So here is why a sensitivity spec. is pretty much useless without knowing the impedance curve of the speaker as well.

Lets just take a pretty typical speaker impedance curve I picked at random.

So a solid state amp will deliver I watt to that speaker at 21 Hz, 40 Hz, 60 Hz, 500 Hz and 15 KHz only. Now we do the sensitivity test at i KHz where the impedance is 12 ohms. So it will deliver 0.667 watts at I KHz. Now lets take a look at 180 Hz where the impedance is 5 ohms the amp delivers 1.6 watts. So the speaker is receiving 2.4 times the power at 180 Hz than at 1 KHz.

Now I have to make an educated guess, as I don't know the DC resistance of the drivers involved. However if I estimate it a 6 ohms I will be very close.

Now the heating effect of the power driven to the speaker is the square of the current times the DC resistance. The current delivered at 1 KHz is 0.057 amps, and at 180 Hz 0.32 amps. When you do the calculation the heating in the VC is 0.02 watts at 1 KHz and 0.61 watts at 180 Hz, which is 30 times greater!

So now it is easy to see that a speaker showing high sensitivity measured at 1 KHz may well draw massive power and incur dangerous VC heating if the impedance is much lower from 80 to 400 Hz say. That would not be at all unusual. So the sensitivity measurement of the speakers tells you next to nothing about the power requirements as an isolated specification.

So it gets even more nebulous when you add in dispersion. If speaker A has a narrow dispersion window and the same sensitivity as speaker B that has wide dispersion, then speaker B will in fact take less power to give room filling sound. In general horns have a narrower dispersion pattern and therefore show up as more sensitive, but actually are likely not as efficient as sensitivity alone would suggest.

So the bottom line is that a sensitivity spec in isolation tells you next to nothing about the power required to drive the speaker. You need much more data.

Lets try and remember this as we have been over it before and people seem to have a short memory for it. It is not helped by the fact there is no impedance curve for the vast majority of speakers unless you measure it yourself. Really everyone here should be able to measure the impedance curve and phase angles of their speakers and invest in the equipment to do so.

Lastly people need to use common sense. As stated before high powered drivers are expensive propositions, with specially shaped wire, edge sound and complex VC gap designs. These drivers will not be in speakers in the $200.00 per pair range and a long way above that. So watch your volume settings, especially with lower priced speakers. And please remember that the heating effect in the VC, which is what causes failure is the current delivered squared time the DC resistance of the voice coil.

 

[Irvrobinson]

Really everyone here should be able to measure the impedance curve and phase angles of their speakers and invest in the equipment to do so.

That was a pretty good post, Mark (though I haven't checked your math on the current calculations), but you can't be serious that "everyone here" should invest in test equipment like that from Audio Precision. Or are you serious?

 

[TLS Guy]

That was a pretty good post, Mark (though I haven't checked your math on the current calculations), but you can't be serious that "everyone here" should invest in test equipment like that from Audio Precision. Or are you serious?

Well Irv, Do you want the 10 minute argument or the full half hour?

I'm serious that members audio equipment to test gear ratio is sub optimal.

This Dayton woofer tester for $100.00 is a case in point. It will give you a lot of information. It is very easy to use. In addition to getting the impedance curve and phase angles, it gives you other information. For instance it is highly accurate in detecting even small amounts of gap rub. It also is good for crossover trouble shooting and will measure capacitance. How often do we get posts "Should I recap my speakers." Our response ought to be measure them and find out. Now I think about it, I think I will respond to buy that device and find out in future.

I note a lot of members are investing in speaker measuring equipment which is good. I also think that investing in an amplified meter rather than a cheap basic multi meter is to be encouraged.

There is almost always a lot of high value older test gear to be had on eBay. If you are patient you can pick up a good signal generator and dual channel O-Scope for little money. Good older HP distortion analyzers often come up as well. Variable voltage auto transformer Variacs also come up a lot, but seem to hold their value well.

I do actually believe we have quite a few members here that could solve quite a few problems themselves with faults in equipment that do not merit professional service. I have a feeling quite a few members would actually be able to successfully postpone trips to the recycling center. The biggest impediment is the disgraceful lack of circuits and service manuals.

I'm serious in that I believe a sensible investment in service equipment is part and parcel of this hobby.

 

[Irvrobinson]

Well Irv, Do you want the 10 minute argument or the full half hour?

I'm serious that members audio equipment to test gear ratio is sub optimal.

This Dayton woofer tester for $100.00 is a case in point. It will give you a lot of information. It is very easy to use. In addition to getting the impedance curve and phase angles, it gives you other information. For instance it is highly accurate in detecting even small amounts of gap rub. It also is good for crossover trouble shooting and will measure capacitance. How often do we get posts "Should I recap my speakers." Our response ought to be measure them and find out. Now I think about it, I think I will respond to buy that device and find out in future.

I note a lot of members are investing in speaker measuring equipment which is good. I also think that investing in an amplified meter rather than a cheap basic multi meter is to be encouraged.

There is almost always a lot of high value older test gear to be had on eBay. If you are patient you can pick up a good signal generator and dual channel O-Scope for little money. Good older HP distortion analyzers often come up as well. Variable voltage auto transformer Variacs also come up a lot, but seem to hold their value well.

I do actually believe we have quite a few members here that could solve quite a few problems themselves with faults in equipment that do not merit professional service. I have a feeling quite a few members would actually be able to successfully postpone trips to the recycling center. The biggest impediment is the disgraceful lack of circuits and service manuals.

I'm serious in that I believe a sensible investment in service equipment is part and parcel of this hobby.

That woofer tester is cool. If I were a speaker builder I'd order one. But I'm not. I do have an OmniMic, as you know, and I've spent countless hours with it, however the OmniMic is physically just a mic. What you're talking about, especially to measure phase angle, is going to be more serious in cost and space requirements, and measuring equipment like that takes a fair amount of technical knowledge to use *properly* and to interpret the results. How many reading this can define phase angle of an electrical load without resorting to a search engine? I suspect not many.

I do have a Fluke 87-V multimeter siting in a drawer in my tool cabinet, but I admit I haven't used it in a while. I just haven't had the need. Though I can probably afford the test equipment you're discussing, I also have to admit that since my speaker and amplifier replacement cycle is about 10 years, that equipment would probably sit around doing nothing most of the time. Not a good case for investment.

I have hundreds and hundreds of hand tools and pneumatic tools (and lifting equipment) for working on cars, I work on cars regularly (we have multiple cars, and IC-engined cars need a lot of maintenance, as you know), so the investment and the space they take seem worth it. And when you're working on a car, not having the right tool to finish a project when you''re 40-60% through it is one of life's greatest PITA. But having dedicated audio test equipment sitting around for years waiting for just the right opportunity seems like a bit much. And good test equipment gets obsolete too. In *your* case you're so active in the field, and you use a variety of vintage equipment that is probably difficult to get service for, so I can totally understand why you have such electronics test equipment around. I also hear you've designed and built speakers now and then, so that's another factor, and you have space for a sophisticated test bench (many don't). I never use vintage equipment, and I'm not fascinated by building my own speakers (another thing most people here don't do). So I think you're expecting too much from the rest of us.

BTW, people don't talk about re-capping speakers, it's about re-capping amplifiers. Perhaps just a typo on your part. (An 87-V works for testing most amplifier caps too.)

 

[TLS Guy]

That woofer tester is cool. If I were a speaker builder I'd order one. But I'm not. I do have an OmniMic, as you know, and I've spent countless hours with it, however the OmniMic is physically just a mic. What you're talking about, especially to measure phase angle, is going to be more serious in cost and space requirements, and measuring equipment like that takes a fair amount of technical knowledge to use *properly* and to interpret the results. How many reading this can define phase angle of an electrical load without resorting to a search engine? I suspect not many.

I do have a Fluke 87-V multimeter siting in a drawer in my tool cabinet, but I admit I haven't used it in a while. I just haven't had the need. Though I can probably afford the test equipment you're discussing, I also have to admit that since my speaker and amplifier replacement cycle is about 10 years, that equipment would probably sit around doing nothing most of the time. Not a good case for investment.

I have hundreds and hundreds of hand tools and pneumatic tools (and lifting equipment) for working on cars, I work on cars regularly (we have multiple cars, and IC-engined cars need a lot of maintenance, as you know), so the investment and the space they take seem worth it. And when you're working on a car, not having the right tool to finish a project when you''re 40-60% through it is one of life's greatest PITA. But having dedicated audio test equipment sitting around for years waiting for just the right opportunity seems like a bit much. And good test equipment gets obsolete too. In *your* case you're so active in the field, and you use a variety of vintage equipment that is probably difficult to get service for, so I can totally understand why you have such electronics test equipment around. I also hear you've designed and built speakers now and then, so that's another factor, and you have space for a sophisticated test bench (many don't). I never use vintage equipment, and I'm not fascinated by building my own speakers (another thing most people here don't do). So I think you're expecting too much from the rest of us.

BTW, people don't talk about re-capping speakers, it's about re-capping amplifiers. Perhaps just a typo on your part. (An 87-V works for testing most amplifier caps too.)

Well last point first. We have had numerous posts about asking whether speakers should be recapped.

I also have probably fielded at lot more posts about failed equipment including PMs than you have over the years. It would be really helpful if people did invest in test equipment. Everyone has trouble over time. When I do get an OP asking for help that has test equipment or access to it, they is often happy outcome, without it seldom.

Lastly measuring phase angles is easy. The woofer tester does it with every impedance curve.

If you click on this link you can see the impedance and phase angles of many of my speakers.

You will note that I try to avoid crazy impedance curves and phase angles. That is a combination of coming out of the tube era, as tube amps FRs tend to follow the impedance curve as they are not constant voltage devices.

Part of it my mentors. Raymond Cooke in particular felt strongly that these all too common swings of impedance and severe phase angles were a very bad thing and mitigated against good sound.

Peter Walker was of the same persuasion and of the view that testing amps under resistive load conditions was of limited value. He was at pains to make the performance of his amps as independent of load conditions as possible. I'm certain that is why speakers can sound different with different amps.

I really think phase plots and impedance plots that look like the rocky mountains is not the best approach. I will say categorically that any speakers whose impedance dips below the DC resistance of the drivers, is not fit for purpose. They are around and clustered actually at the top end of the market.

 

[Irvrobinson]

Well last point first. We have had numerous posts about asking whether speakers should be recapped.

I'll take your word for it.

I also have probably fielded at lot more posts about failed equipment including PMs than you have over the years.

That is absolutely correct.

Lastly, measuring phase angles is easy. The woofer tester does it with every impedance curve.

Okay, I was in a rush and you calling it a "woofer tester" distracted me; I didn't read the entire web page. It is a lot more than a woofer tester, so I'm ordering one.

I really think phase plots and impedance plots that look like the rocky mountains is not the best approach. I will say categorically that any speakers whose impedance dips below the DC resistance of the drivers, is not fit for purpose. They are around and clustered actually at the top end of the market.

That would be pretty much all commercial loudspeakers with multiple woofers, not just the top end of the market. Given the capabilities of modern solid state amplifiers to drive low impedance loads with challenging phase angles, why are you so adamant? There are some speakers with impedance that falls below 2 ohms, which are arguably ridiculous loads (I used to own a pair), but even those can be driven by very capable amplifiers.

 

[shadyJ]

Manufacturers should be posting impedance graphs. Reviewers should be confirming their data. It's worthwhile for heavy-duty audio enthusiasts to have the means to test the electrical load of their speakers, but most people in the audio hobby are more casual about it, and its probably not worth it for them to get into it that deeply. You may not think so, but most loudspeakers are competently designed enough that running them on a typical AVR isn't likely to damage them, even at high levels relative to the AVR's amp. My guess is that the problem with the broken speaker in question was a manufacturing defect, not a design defect.

I think a better use of audio enthusiasts energy is, instead of everyone buying DATS systems, boycott speaker brands that do not provide the adequate data for consumers to make an informed choice, such as posting an impedance graph.

 

[TLS Guy]

I'll take your word for it.



That is absolutely correct.



Okay, I was in a rush and you calling it a "woofer tester" distracted me; I didn't read the entire web page. It is a lot more than a woofer tester, so I'm ordering one.



That would be pretty much all commercial loudspeakers with multiple woofers, not just the top end of the market. Given the capabilities of modern solid state amplifiers to drive low impedance loads with challenging phase angles, why are you so adamant? There are some speakers with impedance that falls below 2 ohms, which are arguably ridiculous loads (I used to own a pair), but even those can be driven by very capable amplifiers.

I can tell why I'm adamant. If the impedance drops at any point below the DC resistance of the connected drivers, then the crossover components and the drivers are in resonance and that speaker is a dud design. That condition is absolute evidence of a resonant circuit and is one of the most incompetent issues a designer can create.