Question on some older Vifa drivers in Definitive Tech

[Ernie Schmuntz]

I’m having an issue with a speaker that’s famed for its low end. I’m using very high quality amplification. When I use test tracks, I’m not getting anything usable below 50hz. When checking the eight 6.5” Vifa drivers, there is no damage, Cones all move clean. When I hit them with a 20 Hz tone, they sort of splatter in the frames with very non-musical noises. This is done with moderate volume.

I have checked all the Vifa 6.5” P17WJ (8) woofers. The suspensions are solid, clean. They all look mint. I did order a new driver just to have an A/b, but the new driver moves just as easily in the frame. it’s a really loose suspension. Other than the color on the new one, I could not tell them apart. Also, each driver is $90 bucks x eight. Ooof

Im a network engineer by profession. I feel like I’m pissing in the wind. The BP10b is famous for the low end with four 6.5. This is the big brother that can hit 16 Hz using 8. Hell, my Bp6 pair had better bass. I need some ideas from someone that has a better methodology for this. I would love a mic and software, but I only have a sound meter.

 

[Ernie Schmuntz]

I’m having an issue with a speaker that’s famed for its low end. I’m using very high quality amplification. When I use test tracks, I’m not getting anything usable below 50hz. When checking the eight 6.5” Vifa drivers, there is no damage, Cones all move clean. When I hit them with a 20 Hz tone, they sort of splatter in the frames with very non-musical noises. This is done with moderate volume.

I have checked all the Vifa 6.5” P17WJ (8) woofers. The suspensions are solid, clean. They all look mint. I did order a new driver just to have an A/b, but the new driver moves just as easily in the frame. it’s a really loose suspension. Other than the color on the new one, I could not tell them apart. Also, each driver is $90 bucks x eight. Ooof

Im a network engineer by profession. I feel like I’m pissing in the wind. The BP10b is famous for the low end with four 6.5. This is the big brother that can hit 16 Hz using 8. Hell, my Bp6 pair had better bass. I need some ideas from someone that has a better methodology for this. I would love a mic and software, but I only have a sound meter.

I stripped one of the cabinets, and discovered that all the screws holding the base on have rust, and they aren’t holding. These may be flood damaged. I don’t know if a crossover will get horked in water. It looks ok visually

 

[Pogre]

Looks like you just discovered why everyone gets prickly when talking about DefTech. One of their biggest claims to fame is being known for fudging their published specs...

 

[Verdinut]

Im a network engineer by profession. I feel like I’m pissing in the wind. The BP10b is famous for the low end with four 6.5. This is the big brother that can hit 16 Hz using 8. Hell, my Bp6 pair had better bass. I need some ideas from someone that has a better methodology for this. I would love a mic and software, but I only have a sound meter.

You would need the following acoustical testing equipment:

https://www.parts-express.com/dayton-audio-omnimic-v2-acoustic-measurement-system--390-792

 

[TLS Guy]

I’m having an issue with a speaker that’s famed for its low end. I’m using very high quality amplification. When I use test tracks, I’m not getting anything usable below 50hz. When checking the eight 6.5” Vifa drivers, there is no damage, Cones all move clean. When I hit them with a 20 Hz tone, they sort of splatter in the frames with very non-musical noises. This is done with moderate volume.

I have checked all the Vifa 6.5” P17WJ (8) woofers. The suspensions are solid, clean. They all look mint. I did order a new driver just to have an A/b, but the new driver moves just as easily in the frame. it’s a really loose suspension. Other than the color on the new one, I could not tell them apart. Also, each driver is $90 bucks x eight. Ooof

Im a network engineer by profession. I feel like I’m pissing in the wind. The BP10b is famous for the low end with four 6.5. This is the big brother that can hit 16 Hz using 8. Hell, my Bp6 pair had better bass. I need some ideas from someone that has a better methodology for this. I would love a mic and software, but I only have a sound meter.

You are under a severe misapprehension. A 6.5 " driver will not as a rule perform below 50 Hz. The low frequency cut off is determined by the Thiel/Small parameters, especially the free air resonance. For your drivers this number Fs is 37 Hz. Usually frequency output falls off somewhat above Fs. This is the case with your drivers. This is the frequency plot published by Vifa.

Note that output is falling off rapidly below 60 Hz.

Your next mistake is to assume adding drivers will extend the lower frequency limit. It will not. You could have a thousand drivers and the output would not extend lower. It would still fade starting at 60 Hz. What adding drivers would do is increase sensitivity and sound output, but NOT bass extension.

There is nothing wrong with those speakers. They are working as designed. If you persist in driving them with frequencies they can not reproduce, you will just incite useless cone motion and damage the drivers.

 

[slipperybidness]

I’m having an issue with a speaker that’s famed for its low end. I’m using very high quality amplification. When I use test tracks, I’m not getting anything usable below 50hz. When checking the eight 6.5” Vifa drivers, there is no damage, Cones all move clean. When I hit them with a 20 Hz tone, they sort of splatter in the frames with very non-musical noises. This is done with moderate volume.

I have checked all the Vifa 6.5” P17WJ (8) woofers. The suspensions are solid, clean. They all look mint. I did order a new driver just to have an A/b, but the new driver moves just as easily in the frame. it’s a really loose suspension. Other than the color on the new one, I could not tell them apart. Also, each driver is $90 bucks x eight. Ooof

Im a network engineer by profession. I feel like I’m pissing in the wind. The BP10b is famous for the low end with four 6.5. This is the big brother that can hit 16 Hz using 8. Hell, my Bp6 pair had better bass. I need some ideas from someone that has a better methodology for this. I would love a mic and software, but I only have a sound meter.

Were the Vifa woofers the OEM drivers in those DTs?

Or, did you swap out the original DT drivers for Vifas?

You are not very clear on that item, and I don't know enough about the stock DT.

 

[Ernie Schmuntz]

You are under a severe misapprehension. A 6.5 " driver will not as a rule perform below 50 Hz. The low frequency cut off is determined by the Thiel/Small parameters, especially the free air resonance. For your drivers this number Fs is 37 Hz. Usually frequency output falls off somewhat above Fs. This is the case with your drivers. This is the frequency plot published by Vifa.

Note that output is falling off rapidly below 60 Hz.

Your next mistake is to assume adding drivers will extend the lower frequency limit. It will not. You could have a thousand drivers and the output would not extend lower. It would still fade starting at 60 Hz. What adding drivers would do is increase sensitivity and sound output, but NOT bass extension.

There is nothing wrong with those speakers. They are working as designed. If you persist in driving them with frequencies they can not reproduce, you will just incite useless cone motion and damage the drivers.

I understand all of these points clearly. I was curious about driver longevity in general. Thanks for your time. Love to learn. It’s interesting that they publish such wild numbers for the low end.

cheers guys

 

[Ernie Schmuntz]

Looks like you just discovered why everyone gets prickly when talking about DefTech. One of their biggest claims to fame is being known for fudging their published specs...

Bastards

 

[Verdinut]

And unfortunately, they're not the only bastards in the audiophile industry!

 

[Pogre]

And unfortunately, they're not the only bastards in the audiophile industry!

Truth. They are not. A lot of companies do fudge, especially low end extension. DefTech is known for pushing the envelope a little more than most tho.

On the upside, I've heard their speakers and they're not bad sounding speakers, if slightly dishonest.

 

[Ernie Schmuntz]

And unfortunately, they're not the only bastards in the audiophile industry!

Ain’t that just the truth? I’ve got most of my old US built JBL. I’ve stuck with RBH be

Were the Vifa woofers the OEM drivers in those DTs?

Or, did you swap out the original DT drivers for Vifas?

You are not very clear on that item, and I don't know enough about the stock DT.

This model was made in the early days. It used off the shelf drivers from Vifa. I have a few woofers from a newer BP10b. They are identical other than inverted surrounds and their company logo on the frame.

 

[Ernie Schmuntz]

Truth. They are not. A lot of companies do fudge, especially low end extension. DefTech is known for pushing the envelope a little more than most tho.

On the upside, I've heard their speakers and they're not bad sounding speakers, if slightly dishonest.

Which is why I am an RBH customer. They are located 5 miles from my home. 10 or maybe 11 pair thus far, and not one stinker.

 

[Pogre]

Which is why I am an RBH customer. They are located 5 miles from my home. 10 or maybe 11 pair thus far, and not one stinker.

If I were looking for new speakers RBH would definitely be on my short list.