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 Save38%
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
    (33 Reviews)
  • Weight4.15 lbs.
  • California Prop 65

    Warning: California residents only. Please note per Proposition 65 that this product may contain 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 4.4242 out of 5 by 33.
Rated 5 out of 5 by from Work Great !I have a pair of 30+ year old Advent speakers. The 8" speakers inside the cabinet had all the foam rubber disintigrate causing the speakers to sound awful. I just installed these two replacement speakers and the old Advent speakers sound great again !
Date published: 2014-12-03
Rated 5 out of 5 by from Great guitar speaker.I built a custom retro half stack with 4 of these speakers and it produces a wonderful wall of sound. Lots of depth, with all the notes singing. I spent 70 bucks on a 10" Rajun Cajun years ago and it still sounds awesome but it can't beat four 8's. I wish a 10" or 12" full range was available because I'd get a bunch of them as well,
Date published: 2014-10-31
Rated 5 out of 5 by from Great Drop In ReplacementI bought these speakers to replace two overhead ceiling speakers. The old speakers had simply died of old age. (20 Years old) These drivers installed on the old mounting plates precisely with no modifications required. They are now performing better than the old ones.
Date published: 2014-09-29
Rated 5 out of 5 by from Nice for acoustic PA systemI bought 10 of these nearly a year ago and finally got around to designing the cabinet for them. The concept was to build a vertical array (4 to a cabinet) that could be stacked either with the other 4 x 8" driver cabinet or some older 4 x 5.25" coaxial driver cabinets I previously built. Honestly, I did not expect much with drivers that are so inexpensive, but I was very pleasantly surprised. By itself, the cabinet has a very nice sound. The bass is full and punchy, the mids are forward and clear and the trebles are smooth. They would work as a respectable PA FOH speaker in small to medium large venues (coffeehouses to church size). When matched up with one of the smaller cabinets stacked on top, these sound nothing short of amazing! The addition of the smaller cabinet brought the sound more forward and more lively. With these two 4 x 8" cabinets and the two 4 x 5.25" cabinets, I could see this working nicely for an audience up to 1000+. They act like a line array in that they throw a great distance without needing to be overly loud up close.
Date published: 2014-08-27
Rated 5 out of 5 by from Exactly what I needed.These were just what I needed. Just as advertised. Easy to install and sound great. Made the old tired cabinets sound new again.
Date published: 2014-08-19
Rated 3 out of 5 by from Beware. You get what you pay for.I am a passionate speaker lover and my Emotions revolves around sound and music. I wanted to see if I could take relatively cheap speaker as far as price with decent promoters and make amazing box to enhance there sound qualities. I was impressed by the sensitivity of the speaker in the reviews but this speaker really lacks audio quality.also it's classified as a full range but really suffers above 6000 Hertz.the actual construction of my box took me about 90 hours which now I feel that was a huge waste of time and quadruples the price of the speakers.all in all if you're going to use this speaker be sure to use it in a two-way system at least with a nice quality Twitter.
Date published: 2014-08-08
  • 2015-04-26T06:59CST
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Product Q&A

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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

At what approximate frequency does the breakup mode start on this driver?

Asked by: PeteL

I also have the original B20 speakers I ordered few years back from PE. for vented 1.  can I use the original B20, parameters similar? 2.  my calculation inside volume , is this correct (10"-W, 12-L, 15-H) 3. diameter, length of vent?

Asked by: gychang
This requires a bit more information in order to proceed. Please contact our tech support for more help with this question, tech@parts-express.com or 800-338-0531
Answered by: MattW
Date published: 2015-04-01

Some response and impedance graphs would be invaluable for this driver. Could somebody please supply some?

Asked by: PeteL

Hi, I'm planning to make a large sealed cab with these, using your Goldwood GT-25 4" cone tweeters to cover up the top. Do you have any suggestion or recommendation on what frequency I should cross them over?

Asked by: PeteL
You could cross the tweeter over just about anywhere between 2kHz and 16kHz. If you want to use it as a super tweeter I would cross it somewhere around 10k.
Answered by: MattP
Date published: 2015-03-19

I'm trying to make a portable speaker with 2 of these drivers. I'm would like relatively good bass responce so what is the smallest ported box size I could use and how big should the port be? 

Asked by: mosbro18
The smallest volume I would recommend is 1.6 cubic feet, with two ports that are 2-1/2" in diameter and 1-1/4" long for a tuning frequency of 65 Hz.
Answered by: MattP
Date published: 2014-11-24

So im planning on using this in two cabinet, each with two 15 inch subs totalling 1000w RMS, at 98.5db sensitivity. How many of this speakers will I likely need per cabinet to keep up with the subs?

Asked by: JoSmy
1000w RMS per cabinet*
Answered by: JoSmy
Date published: 2014-10-15
  • 2015-04-26T09:11CST
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