JBL 2279H data

[lbstyling]

Hello,

I cannot find much data on this driver

does anyone have any measurements?

Its very cheap here:
JBL 5048239X 2279H Low Frequency Driver for SRX828S - Speaker Exchange

I can get the distortion data at 115db/1m for the 2268 driver (possibly similar?)
https://jblpro.com/en-US/site_elements/tech-note-jbl-s-differential-drive-transducers

Which gives a peak of about -38db for the 2nd harmonic, but its at 115db/1m, so I cannot compare it easily to my data of the AE TD12m at 100db at -55db for 3rd harmonic

AE Speakers TD12M - drivervault

Any suggestions on comparable distortion?

Use case is:
Cabinet volume unlimited.
max SPL about 110db ish?


td10/td12m would be used between 200hz and 620hz, with a 2242 (or the 2279) below that,

or

run a 2242 or 2279 from 25hz-620.

Alternatively, another driver entirely of your suggestion, but it must be good value, so either available second hand or just well priced.

Thanks.

 

[lbstyling]

Looking here:
Lambda Acoustics TD15X-Apollo | HiFiCompass

Generalising....

Under 'HD frequency response', selecting between 2v and 11v, I get about 12db increase in distortion.

Looking at other drivers, I get similar increases by changing the level between 2v and 11v.

Question 1: What is the Wattage for 2V and 11V?

Question 2: Given most large drivers on the site increase distortion between 2V and 11v by about 12db, is it a reasonable projection (guestimate) to suggest the JBL 2242 measured in the last post at 80w/1m and -48 db distortion would be around -60db or lower at 1w (99db/1w driver)

Thanks!

 

[weltersys]

1) "Wattage" for 2V and 11V for a nominal 4 ohm driver is 1 and 30.25, for a nominal 8 ohm driver is .5 and 15.1.
2) A drop from 30 watts to 1 watt is around -15dB, from 80 to 1 around -19dB, so may result in a slightly greater reduction.

 

[lbstyling]

Thanks Weltersys, prob a stupid question, but does that mean I'm it's reasonably likely that the JBL 2242 produces distortion at approximately -62db relative to the signal at 99db then?

 

[weltersys]

It's possible that the JBL 2242 distortion levels might be approximately -62db relative to the signal at 99dB.
Human breathing is around 35-40dB SPL at 10cm, so the <.1% distortion would be masked unless you hold your breath ;^)

This site has tests available to determine what level of distortion you can detect:

Listening Test

Using Sony 7506 headphones I was surprised to find today that my distortion detection level was a lot lower than it was last year (-51dB compared to -33dB), though my hearing is slightly worse (less sensitive) now.

That said, using music as a source, I find it much harder to detect distortion than with the mixed pure tones.

Art

 

[lbstyling]

It's as I was hoping.

I appreciate that it should be inaudible at reasonable listing levels, and this is what I was hoping for.

My thinking is that the worst case torture test for the speaker would be large scale orchestra, where the peak SPL would reach maybe 120db SPL momentarily, so I would want to get as close to inpercevable under this senario, and also as good or better at lower SPLs.


Were good at 100db, and by the trend, it's probably even better at lower SPLs. -48db distortion would probably be inpercevable at 115db SPL, but the question is 'how close to percievable is it?'



For your headphone test, surely you would need to know the headphone and amp does not generate its own distortion anywhere near the level you are testing to though?

I think that might be the headphone ASR forums tested last week

Sony MDR-7506 Review (Headphone) | Audio Science Review (ASR) Forum

Distortion was notably high in that headphone by today's standard (by amir's test anyway).

I use the 1more triple driver in ear, with memory foam inserts added. They are dirt cheap on eBay at the moment, so I bought 5 pairs for work.
1More Triple Driver Review - RTINGS.com
Great without, but With EQ, added the distortion figures are very hard to beat.

One way I can think of stating an absolutely inaudible THD figure would be max SPL - lowest perceivable SPL sound, so that's 120db- 35db, hence -85db should do it.

Obviously, in the real world, you don't need that much, as you definitely cannot hear a pin drop at a concert. 😀 but -60db THD would probably do it as 120db spl.

 

[weltersys]

1)Were good at 100db, and by the trend, it's probably even better at lower SPLs. -48db distortion would probably be inpercevable at 115db SPL, but the question is 'how close to percievable is it?'
2)For your headphone test, surely you would need to know the headphone and amp does not generate its own distortion anywhere near the level you are testing to though?

I use the 1more triple driver in ear, with memory foam inserts added. They are dirt cheap on eBay at the moment, so I bought 5 pairs for work.

I know from experience that my hearing generates distortion components at high SPL that are an independent issue from that of the source-at 115dBA it won't matter if source is clean, it will sound distorted.

In-ear headphones have an inverse distance advantage over an over the ear phone as can be seen in the low frequency distortion comparison between the 1More vs the 7506, though above 1kHz, that disadvantage pretty much is gone, and I certainly could not detect the differences of under .1% distortion anyway.

1)I can't answer that question for you, but for most, -48 dB speaker THD would not be remotely noticed. Think of the vast array of harmonics present in orchestral instruments. In many cases the second harmonic may be equal or exceed the fundamental, and third and fourth may be only -10dB or -20dB. If you can detect an additional contribution -60dB as separate from the originals, good for you!
2) I'd agree that harmonic distortion in a loudspeaker can mask that from the source.
That said, yesterday, the test using the Sony MDR-7506 was at probably no more than 75dB SPL, which would put THD well under .1% THD (-60dB), since they don't exceed .1% even at 100dB SPL.

I still could not perceive under -51 dB with the two-tone test, and from experience know that my threshold moves up considerably when listening to music, rather than pure tones. Pure tones are virtually non-existent in acoustic music, and seldom used in synthesized music.

Anyway, you have low distortion phones, give the Klipple tests a go, learn what you can and cannot detect.

Cheers,
Art

 

[lbstyling]

-48db for me.

I went past this, but I was guessing tbh.😀

 

[weltersys]

I have been listening to sine wave tones to detect speaker problems since around 1977, so have a lot of experience, but was surprised to get down to -51dB yesterday.

That said, after reaching -30dB (around 3% HD) , it started to take me more than one A/B to tell the difference, and was definitely fatigued by the end of the test.