GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW

Brand:| Model: 8FR-8
The GRS 8FR-8 full-range 8" speaker is engineered to withstand rigorous commercial use, but will also deliver great results when used in point-source hi-fi applications.
  • Replacement for Pioneer B20FU20-51FW
  • GRS quality construction
  • 3 year warranty
  • Superb multipurpose speaker for DIY projects
Part # 
Weight: 4.15 lbs.  
List Price$22.99
You Save37%
Your Price
Buy 4-up$11.46
Part # 292-430
Qty:  EA
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Product Details

GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW

The GRS 8FR-8 full-range 8" speaker features a paper cone with poly foam surround. A whizzer cone extends high frequency response and dispersion. Engineered to withstand rigorous commercial use, this driver will also deliver great results when used in point-source hi-fi applications. Affordable pricing makes it perfect for DIY applications. Ideal replacement for the Pioneer B20FU20-51FW (also known in DIY communities as the BOFU)

Product Specifications
  • Nominal Diameter8"
  • Power Handling (RMS)60 Watts
  • Power Handling (max)85 Watts
  • Impedance8 ohms
  • Frequency Response39 to 16,000 Hz
  • Sensitivity91 dB 1W/1m
  • Voice Coil Diameter1.5"
Thiele-Small Parameters
  • Resonant Frequency (Fs)39 Hz
  • DC Resistance (Re)7.02 ohms
  • Voice Coil Inductance (Le)1.28 mH
  • Mechanical Q (Qms)2.94
  • Electromagnetic Q (Qes)0.46
  • Total Q (Qts)0.4
  • Compliance Equivalent Volume (Vas)2.26 ft.³
  • Maximum Linear Excursion (Xmax)3 mm
Materials of Construction
  • Cone MaterialPaper
  • Magnet MaterialFerrite
Mounting Information
  • Overall Outside Diameter8"
  • Baffle Cutout Diameter7.25"
  • Depth3.875"
  • # Mounting Holes4
Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)
  • Sealed Volume0.71 ft.³
  • Sealed F378 Hz
  • Vented Volume1.76 ft.³
  • Vented F343 Hz
GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW
  • BrandGRS
  • Model8FR-8
  • Part Number292-430
  • UPC844632089800
  • Product CategoryWoofers
  • Unit of MeasureEA
  • Product Rating
    (27 Reviews)
  • Weight4.15 lbs.
  • California Prop 65

    Warning: California residents only. Please note per Proposition 65 that this product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

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GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW
GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW is rated 4.3704 out of 5 by 27.
Rated 5 out of 5 by from Great speaker valueThese fit my old (1977) Marantz speaker enclosures perfectly,sound is great.I use this in my shop/garage.
Date published: 2014-06-10
Rated 4 out of 5 by from Impressive!I wasn't expecting much at this price point as I was making some speakers for my garage. I made a simple 1.5 cu ft. ported box and was blown away with the bass these produced! The kids and highs were harsh, but like any other speaker, these will smooth out over time. I added a tweeter to get a "crisper" top end. Overall, great sound for such a small speaker and you can't beat this price! They are also very flexible with box sizes, so will perform well in anything from a bookshelf to a tower.
Date published: 2014-05-01
Rated 5 out of 5 by from Great SpeakerI bought these speakers (pair) to put in my existing Tannoy speakers. They were easily installed and sound awesome. Very nice product and I recommend them to anyone. Great price for a really quality product.
Date published: 2014-03-15
Rated 4 out of 5 by from Great replacement speakerI had replaced the original name brand speaker not available from the factory for this one, the speaker sound like never had before, good bass, natural mid-range and the high frequency was provided by the original tweeter, our customer was very satisfied
Date published: 2014-02-03
Rated 5 out of 5 by from Good speaker at a resonable price.Bought these speakers to replace some blown speakers that been sitting around for years since the late 80s. Used to buy my speakers at Radio Shack and realized that theyre selection was quite limited from what I remember before so i decided to do some searching online and found this website and was surprised to find a huge selection and will be using your site in the future.Thanks
Date published: 2014-01-21
Rated 4 out of 5 by from bargin priceI purchased these as replacements for speakers that I have in my garage. They sound very good for the price. I would buy from parts express again
Date published: 2013-10-07

Product Q&A

Get your questions answered from other customers
who own this product or have experience with it.
If your question requires design or troubleshooting information,
please email tech@parts-expresss.com  for a prompt reply.
GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW

I'm looking to replace all the speakers in 2 'Kustom Kasino' PA towers from the 70s (4x8s).They are vented in the back.  Would 4 of these drivers wired series- parallel handle 200watts at 8 ohms. Would this be suitable for band vocals and DJ applications?

Asked by: skinnyPete
These will work as replacements and handle 200 watts if wired series/parallel. I would recommend a high pass filter around 50-60 Hz to get the most output from them however.
Answered by: MattP
Date published: 2014-05-29

I have a box of 3.84 cubic feet and would like to use these speakers as my mids. My woofer is 12". Should I use ported or sealed unit. Or these too bassy? Am I on the right track and would appreciate any suggestions.

Asked by: johncee
The type and size of enclosure depends entirely on how low you plan to cross this over. If it is any higher than about 250 Hz, the box size and type will make no difference.
Answered by: MattP
Date published: 2014-04-26

I'm sorry this is a trivial question, but how do you connect one of these speaker drivers to an amplifier? I'm a high school student looking to make a rubens tube and want to use this with a keyboard amplifier. Thanks!

Asked by: DanceGirl
This speaker will have two terminals on it, a positive and negative just like the amplifier. You can use standard 16-18 gauge two conductor speaker wire to connect the two together.
Answered by: MattP
Date published: 2014-02-21

Would this work well in an open baffle setup?

Asked by: boby
This would work well as long as you don't expect much below about 80-100 Hz from it. It would need to be paired with a woofer or subwoofer for best results.
Answered by: MattP
Date published: 2014-04-26

How would these work in a line array?

I would like to build a stackable, portable line array for use with an acoustic instrument group. I will have 2 drivers in each box and those boxes will stack 8 drivers (4 boxes) tall. I would like to keep the boxes as narrow as possible (9.25" wide) for the widest dispersion. If these boxes are sealed, and are 9.25" wide (8.25" interior) by 17.5" tall (16.5" interior), how deep would they need to be for the deepest bass response ?
Asked by: drguitar
0.71 cubic ft per speaker is what is required. Multiply 8.25 X 16.5 then by a variable depth to get the number of inches front to back [interior]. My only concern, is that you want a wide dispersion. The nature of a line array is to "throw" sound to the back of the room without causing as many reflections. That means narrow dispersion. The "critical distance" [that point in the room where direct & reflected sound is equal], becomes farther back from the speakers. I have two suggestions. Stack 2 X 2 speakers at around 15-25 degrees to get better side to side dispersion [you could consider a trapezoid box to maintain speaker coupling],AND include a tweeter in every other box to get that clarity needed for acoustic music. I have suggestions below. Nice project!!
Answered by: Joe from San Francisco
Date published: 2013-11-01

What is the Port/Vent Dimensions/Volume?

What is the volume/dimension for the port/vent in the vented volume listed in box size section? 1.76 cu. ft., 43hz
Asked by: alrightkid
The port dimensions for this volume and F3 would be 2" diameter and 1.6" long.
Answered by: MattP
Date published: 2014-04-26

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