# AudioFrog GB40 4" Midrange (Objective Review)



## ErinH (Feb 14, 2007)

Review can be found here:
http://medleysmusings.com/audiofrog-gb40-4-midrange/













PS: If you would like to help me keep up funds for testing, there’s a little ‘contribute’ button that goes through Paypal all the way at the bottom of every page. Any little bit helps.


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## Huckleberry Sound (Jan 17, 2009)

More reading.


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## Elgrosso (Jun 15, 2013)

And gb40!
Very cool Thx
Really perfect for 30 degree.
I'm even more interested in seeing the gb25 now.
to check THD around 200Hz (I cross it here at 24db).


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## 14642 (May 19, 2008)

Thanks Erin!

A few notes about these drivers and also about crossover recommendations:

1. All of these things have been designed to work together in systems. The sensitivity of the drivers has been scaled using all sorts of tools so that when they are used with the same amp and a passive network, they all play at about the same level. The tweeter is design with HIGHER SENSITIVITY to provide a wide range of adjustment. The PRIMARY use of the 4" is in a 3-way system with the 6" and either of the tweeters.

2. The secondary use of the 4" is in the doors of a BMW. The depth has been designed to fit that space. 

3. These are NOT "widebanders". Rather than compromising sensitivity and power handling to extend the bass and the high frequencies in the on axis response, we have opted for higher power handling and higher efficiency that you'll find with "widebanders". These are midrange drivers. The design goal was fllat response and low distortion in the passband. Reducing the resonance requires a looser suspension or a heavier moving mass. That reduces sensitivity. I do recommend crossing above resonance, but remember the crossover frequency is the -3dB point or the -6dB point. -3dB is half power and -6dB is 1/4 power. Run the distortion test signal through a 110Hz 4th order filter and check out the distortion again. I think you'll find that under those circumstances, that crossover is still OK. In a 3-way, there's no reason to cross that low.

4. All of these drivers include a cooper cap on the polepiece to reduce inductance and the distortion that's caused by changing inductance as the coil moves in and out over the polepiece. The GB60 includes an additional shorting ring because that speaker will always be used close to it's resonance and will often be using much of it's excursion potential.

5. The GB40 and the GB25 also include a bucking magnet on top of the copper ring. That bucking magnet focuses the energy in the gap and provides higher sensitivity. 

6. The GB 40 is designed for use in a door or dash (IB). For A-pillars, we have the GB25. It's designed so that it can be used in a box as small as 2" x 2" x 2" and still play pretty flat to about 200Hz. There are no other midrange drivers that I know of designed specifically for this application. Most of the mids I see people putting in A-Pillars are designed for IB and often produce a high-Q response in the A-Pillar application.


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## 14642 (May 19, 2008)

Oh, one more thing--the power handling numbers are absolutely real. 100 Watts RMS and 300 Peak. The designs are tested using a shaped noise signal that has an average output of 100 Watts and peaks of 300. We hang the speakers from a chain and drive them with this signal for 100 hours. 

They're also tested to withstand heat, humidity, thermal shock, exposure to ultraviolet light and vibration in a routine designed to simulate 50,000 miles of operation in a moving vehicle. That's VERY different than the kind of reliability testing required to make a driver that will withstand the rigors of your living room.


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## nstaln (Feb 11, 2009)

-Andy-

I recently purchased a set of GB10's, GB25's and GB2510c's...My plans for the GB25's are dash mounted (facing the cabin not the windshield) IB....what crossover point would you recommend for the high-pass. Power will be 100rms.

I could create a cup or enclosure if needed.


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## 14642 (May 19, 2008)

You don't need an enclosure...the high pass filter will accomplish nearly the same thing. Choose that crossover based on a measured response of that speaker and whatever you'll use for a midbass. Anywhere between 200Hz and 1kHz is fine.


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## kaigoss69 (Apr 2, 2008)

Andy, thanks for clarifying. When using in a 3-way where you get tremendous benefit from the door mid being able to play 110Hz (as in the BMW), are you saying the recommended crossover slope is 4th order, and not 2nd order as it says on your website?


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## ErinH (Feb 14, 2007)

Andy Wehmeyer said:


> Run the distortion test signal through a 110Hz 4th order filter and check out the distortion again.


This is a good point. While the suggestions I make and often glean from others' testing is based on the THD of a driver tested 'wide open', it's worth noting a high-pass filter alters the distortion results. I've actually done testing on this ... and for the life of me I can't find where I posted it. Not knowing how people will use a drive unit, I tend to err on the side of caution so my suggestions may seem a bit high to some but in general I think they are pretty reasonable.


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## rton20s (Feb 14, 2011)

Thanks for this one was well Erin. I'm hoping to get to hear some of the AF stuff for myself soon.


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## 14642 (May 19, 2008)

kaigoss69 said:


> Andy, thanks for clarifying. When using in a 3-way where you get tremendous benefit from the door mid being able to play 110Hz (as in the BMW), are you saying the recommended crossover slope is 4th order, and not 2nd order as it says on your website?


I always recommend 4th order crossovers. The recommendation in the manual and on the box is "greater than or equal to 12dB" so second is a minimum.


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## quietfly (Mar 23, 2011)

these also make me drool....


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## JerryK73 (Mar 20, 2011)

What is the mounting depth of the 4"? I know you stated that it was designed to be installed in the doors of a BMW but there are certain model BMW's that require a very shallow mounting depth (such as the E92 or the F25's).


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## 14642 (May 19, 2008)

41mm


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## thehatedguy (May 4, 2007)

I like the fact you took efficiency over low end extension.


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## cajunner (Apr 13, 2007)

thehatedguy said:


> I like the fact you took efficiency over low end extension.


agreed.

I'd like to know more about a secondary (bucking) magnet increasing efficiency, as in how and where it is placed, and whether or not it is proprietary technology or licensed from somewhere.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> agreed.
> 
> I'd like to know more about a secondary (bucking) magnet increasing efficiency, as in how and where it is placed, and whether or not it is proprietary technology or licensed from somewhere.


A little info.

Scan-Speak


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## 14642 (May 19, 2008)

Here's a better explanation of how they work...so I don't have to type. LOL

Request Rejected


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## Picaro (Feb 18, 2015)

Great job of the data compilation. Really love the build quality of this speaker, especially the speaker connectors and also shallow depth design. Gives me some hope again of possibly using a 4" mid that I can cross over low enough for my possible application, and not have depth mounting issues, though I would probably have to trim the overall diameter a bit, ouch, since I have an oval opening for one, not round. I'll definitely be researching these more when the time comes. Looks like a very promising company, who I had not been aware of previously.


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## tjswarbrick (Nov 27, 2013)

Looks good.
Thanks for doing that, Erin.

Any experience with Morel's Hybrid MW4 to see how that competes in this space?


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## lv_v (Aug 24, 2005)

Are there any real-world reviews on these? How do they stack up against other offerings? These or the GB25's look interesting for my a-pillar install as part of a 3-way with an 8" on bottom.


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## Fyalinks (Mar 6, 2016)

Andy Wehmeyer said:


> Thanks Erin!
> 
> A few notes about these drivers and also about crossover recommendations:
> 
> 2. The secondary use of the 4" is in the doors of a BMW. The depth has been designed to fit that space.


Andy, since you have created drivers for specific applications like mentioned above about your 4" drivers for BMWs, do you have any plans on creating an 8" woofer for the growing number of manufacturers who have that size driver as factory equipment, such as BMW, Infinity, Chevy, Porsche, and maybe other?

I know the 8" driver market is a small one but its growing, and I would rather having a matching driver that blends with the rest of the system rather than be relegated to relatively expensive Morel and Dynaudo 8" drivers, or pro audio drivers that aren't designed to thrive well (untreated paper cones) in a car environment.

My cayenne comes with 6.5" or 8" drivers in a 3 way system and I've heard both, the eights sound a lot fuller and more effortless in the mid-bass region is such a big vehicle. I know your speakers may be way better that the stock Porsche 6.5" and even the factory upgrade Bose but something just doesn't feel right about downgrading the size in my system. I love the effortless sound created by bigger woofers, especially when there is already a 4" to handle all that midrange goodness. 

Well enough rambling, I just tired of seeing so many new speakers coming out and the 8" market being neglected. Yes, its a small market, but it is growing, and deserves more attention. Besides, a lot of folks are alway either doubling up on 6.5" drivers or upgrading to 8s or 10s to get the desired impact from their front stage.

Thats it, I'm done, just some food for thought, this probably shouldn't even be in this thread lol.


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## alachua (Jun 30, 2008)

Fyalinks said:


> Andy, since you have created drivers for specific applications like mentioned above about your 4" drivers for BMWs, do you have any plans on creating an 8" woofer for the growing number of manufacturers who have that size driver as factory equipment, such as BMW, Infinity, Chevy, Porsche, and maybe other?
> 
> I know the 8" driver market is a small one but its growing, and I would rather having a matching driver that blends with the rest of the system rather than be relegated to relatively expensive Morel and Dynaudo 8" drivers, or pro audio drivers that aren't designed to thrive well (untreated paper cones) in a car environment.
> 
> ...


Andy weighed in on the need for an 8" GB series driver in another thread here.



Andy Wehmeyer said:


> Sorry guys. Traveling in China and this website isn't easily available here because it uses some Google sign in thing. No Google in China.
> 
> The GS and GB are completely different drivers but they both sound great. GB has a copper cap on top of the pole piece to dramatically reduce distortion, a really stiff paper cone and milled flat single layer coils and neodymium magnets. *The GB60 is a much better midbass driver than most 8". It had a 2" coil and 9mm of linear one way excursion. No need for an 8".*


I added the emphasis. It seems that people on the site lust for a shallow 8" driver, begging any manufacturer who stops by to produce one. The fact that nobody has leads me to believe that either it is technically difficult to do so at a price point people will pay for (see: Stereo Integrity 'I can sell as many speakers as I can build as long as I make no money on them'), the market is small enough that the first mover (Illusion Audio) has captured enough of the potential buyers that it makes no sense to enter, or while everyone on the site says they want one, nobody will actually buy them when they are available (see: Soundstream Human Reins amps 'we build what people begged us for and were left with a warehouse of unmovable stock')


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## Shapin (Jun 23, 2015)

@eddieg You really need to convince someone to import this products, i have to hear it.


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## Fyalinks (Mar 6, 2016)

@ alachua - Thanks for the link to the 8" inquiry. No further comment.


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## alachua (Jun 30, 2008)

Fyalinks said:


> @ alachua - Thanks for the link to the 8" inquiry. No further comment.


If you know of a few people who really want a shallow 8, you may want to point them towards 

Product Polling - Kravchenko-Audio

He designed a really well received XBL tweeter, though there were some teething issues along the way. He is the most likely candidate to put together a small run, high quality, driver backed by a high level of customer service.


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## Fyalinks (Mar 6, 2016)

alachua said:


> If you know of a few people who really want a shallow 8, you may want to point them towards
> 
> Product Polling - Kravchenko-Audio
> 
> He designed a really well received XBL tweeter, though there were some teething issues along the way. He is the most likely candidate to put together a small run, high quality, driver backed by a high level of customer service.


I checked the site and it looks great, the guys apparently does "made to order" parts?

I was also browsing JL Audios website and came across the ZR800-CW. I don't know how good those are for SQ though. I will have to do some digging.


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## thehatedguy (May 4, 2007)

The ZR800 is an outstanding midbass.


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## Fyalinks (Mar 6, 2016)

thehatedguy said:


> The ZR800 is an outstanding midbass.


Oh yeah!?

Well I'm currently debating weather to use the ZR800 or the Audiofrog GB60 as a dedicated midbass in a 3way setup, both manufacturers are claiming 9mm of 1 way xmax (no idea how much of that is linear). The ZR800 has more cone area though...decisions...decisions...


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## ndm (Jul 5, 2007)

Fyalinks said:


> Oh yeah!?
> 
> Well I'm currently debating weather to use the ZR800 or the Audiofrog GB60 as a dedicated midbass in a 3way setup, both manufacturers are claiming 9mm of 1 way xmax (no idea how much of that is linear). The ZR800 has more cone area though...decisions...decisions...


If yo can fit the ZR800......hands down....it is the right choice. I made the switch from the TM65 (which holds its own for sure) and It is no contest. The ZR800 is sick. 

Only point that I would have to give to the GB60 is that it can play higher.


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## tonynca (Dec 4, 2009)

Love your reviews. Going to try to start understanding some of those terms you used. Still new to all this.

I really hate that those speakers are $$$ but they're Made in China... =/ But wow at the build quality and flat response curve.


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## Fyalinks (Mar 6, 2016)

Well enough about the 8" drivers. I'm going to use the GB60. Well time to get this thread slightly back on track lol

@ErinH nice review, when are you going to test the GB60?


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## mitchyz250f (May 14, 2005)

Andy Wehmeyer said:


> Oh, one more thing--the power handling numbers are absolutely real. 100 Watts RMS and 300 Peak. The designs are tested using a shaped noise signal that has an average output of 100 Watts and peaks of 300. We hang the speakers from a chain and drive them with this signal for 100 hours.


Andy is max power increased with a higher crossover like [email protected]?


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