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

Brand:| Model: 8FR-8
Overview
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.
Highlights
  • Replacement for Pioneer B20FU20-51FW
  • GRS quality construction
  • 3 year warranty
  • Superb multipurpose speaker for DIY projects
Part # 
292-430
Weight: 4.15 lbs.  
IN STOCK
List Price$22.99
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Your Price
$14.33
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Part # 292-430
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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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Reviews

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 This was a great deal.These speakers sound great. It sounds like there are 2 separate speakers.
Date published: 2013-09-23
Rated 5 out of 5 by from Great bang for the buckI needed two replacement full range speakers to go in some small floor monitor cabinets, and since these were on sale and could handle the power, I thought I would try them out. The test I made after installation revealed nice, clean sound with enough definition in the highs and lows to suit my needs just fine. I could not have done better for less than $10 per cone!Thanks again Parts Express,Paul S.
Date published: 2013-09-20
Rated 5 out of 5 by from I am amazed!!I have just completed my latest project. After hearing a pair of these used as true full range, I decided to build a pair of towers for my 25 watt per channel tube amp. I used these with a pair of Goldwood GT-510 soft dome tweeters. I designed my own 2 way, 3rd order Butterworth crossed at 6KHz. Yes, 6KHz. The towers are 2.08 cubic feet each and ported, reaching 63Hz low end. After about 200 hours of break-in, I was absolutely amazed listening to live Miles Davis and John Coltrane on my reel to reel. I gave away the pair of Advent's I used specifically for this analog set-up. These GRS full range drivers are a steal at this price. Now realize that these are not Lowther, but for cost to performance ratio, I promise that you will not find a better driver. For under $150.00 I designed and built a pair of towers that will rival others costing 10 times as much. I will submit these to the speaker building forum, along with all specs, graphs and crossover design. Truely amazing.
Date published: 2013-08-30
Rated 5 out of 5 by from Impressive drivers, I am very happy listening themI purchased a pair of these drivers for using as mediums in a 3 way arrangement. I have taken the dustcap off and put a phase plug made by myself. I added a thik felt coating behind the basket, this gives them a superb and amazing clearness.I am using the drivers with a Zobel net: Condensers 12+1.5 = 13.5 uF and 9.2 ohm resistor. No matter if the frecuency range is not as high as others, because I have tweeters. They are perfect as mediums for a multi-way sistem.
Date published: 2013-04-24
Rated 5 out of 5 by from Easy Speaker purchaseVery helpful on finding what I needed and quick shipping. Will buy from them again.
Date published: 2013-04-08
Rated 4 out of 5 by from Nice for the moneyI have a pair of old, small bookshelf speakers with nice real oak cabinets I bought at the Good Will for $6 dollars that only had one speaker each rated at 15 watts. I bought a pair of these to replace them, giving them more range and power handling. While they don't have a booming bass, they are far better than the original 40 year old speakers for sure! It is hard finding ANY full-range speakers.
Date published: 2013-01-28
Rated 5 out of 5 by from Single Full Range Driver TestI purchased four of these specifically for testing an old but successful single full range driver design, the Karlson (/Weiss) "Klam" sound projector. This cabinet design incorporates a quarternary waveguide that acts as a frequecy dependent acoustic lens with a concominant spatial separation across the range of the effect. Although this BOFU clone may not have the spectral characteristics of its predecessor, it did seem to have good, clean output which is more important for this test sequence. In testing against a similar cabinet with no such curved vent, but with the same area of the "wedge" covered up, the Klam was definitely superior in output levels. In comparison with a box with no constriction, vocal components were understandable at 50% greater distance. While tHere are certainly better drivers available for single full range driver use, this one performs admirably in a role where this is a requirement. Testing completed, two of these will remain as is as directional horn components for a PA system.
Date published: 2012-09-19
Rated 3 out of 5 by from GRS 8"Background; I am a system's engineer for a well established A/V firm.These speakers were purchased for a customer who wanted to replace the 'rotten' drivers in two small cabinets. Being these cabinets were to be donated to a local organization, cost was a concern. I found, and selected these models for two key reason: 1) Specs matched the existing drivers very well 2) One pair of these GRSs cost less than a single 'professional' replacement driver.(Being as these were Realistic brand speakers, they never had 'professional' components in the first place)Overall, the customer is pleased. The only complaint has been how the slip on terminals are the same size, as opposed to two different sizes; ensuring polarity is correct through force. I corrected the existing cabling for free to make the customer even happier, job done. :)
Date published: 2012-09-12
Rated 5 out of 5 by from Very good for the priceThese are a bargain. Don't set your expectations too high, and you will be happy. Really needs a dedicated tweeter to fill in the high end. And these are not going to shake your house playing rap music, so if that's what you need, you'll want a sub or a larger woofer to accompany.
Date published: 2012-08-10
Rated 2 out of 5 by from Well!I bought a pair of these due to the great marketing at PE. I love PE, but the pioneer 8" and grs 8" I never had any good luck with getting them to sound well. I have to say after being in this hobby and audioholic addiction to looking at speaker specs. No speaker is the same as what its created too. That being said the guy that stated the new specs with the wt3 is a very helpful guy.The only thing Ive noticed is higher qts speakers have a lower bl. Which lack bass and sound very sloppy. Being in a sealed enclosure would be the best fit for this fr. But in a sealed enclosure this fr lacks bass. When playing at a half way volume Ive noticed the grs tends to break up the amp. Which Did I mention sounds terrible. I've never noticed that a speaker could make the amp darn near go into protection. Maybe its just a bad speaker or just a bad design. These well be outside speaker for the camping trip for sure.If I were looking for a pair of 8" Full range I would look at a pair of Tang Band's or Sea's!! That being said. Hope this is helpful.
Date published: 2012-03-14
Rated 5 out of 5 by from 100% MONEY TO SOUND RATIOAm building some 6 feet tall cabinets with the HiVi mag cone drivers. Each side will have 2 transmission lines for the 8 inch woofers. In the process of testing the first cabinet, I decided to install this full range driver in the hole and try it. (to utilize the 66 inch tapered pipe). Bass is phenominal, Higher freq's are acceptable. With some EQ these are wonderful drivers. Shocked am I at the sound they put out. Especially after building so many "high end" cabinets.....
Date published: 2012-03-09
Rated 5 out of 5 by from Simply amazing for the moneyI recommend building a big sealed floor standing enclosure that is very well damped for this driver. For the money you may notice that the high frequency response doesn't compare to more expensive full range drivers but the balance between the highs and lows (nice bass btw) is very well controlled. I recommend a 15w tube amp to drive these as well preferably push-pull. i tried my home built single ended direct coupled el84 amp with a mullard 12au7 as the driver and JJ Tesla power tubes but i found that these speakers sounded too "tuby with the se". Overall a great speaker (one of my favorites). Music like Michael Jackson and jazz sound unbelievable with my setup. BUY THIS DRIVER!!!!! ITS SO HARD TO BELIEVE THAT THEY ARE THIS CHEAP!!!!!!!!
Date published: 2012-02-20
Rated 3 out of 5 by from Ok speakerLike other reviewers have said these have not much under 70hz. They can get loud, just don't push it too much in the low end. Need EQ to smooth them out and distortion gets in the way past 6khz. so they need a tweeter.I think they are good value, just not Hi-Fi.
Date published: 2012-01-18
Rated 5 out of 5 by from Excellent guitar amp speakerI put this in my DIY build guitar amp. Its power is somewhat low (~ 4W) but the speaker has plenty of volume for such a small amp. It plays well with no mechanical vibrations or rattling and is a bit much for the amp. Nonetheless, good speaker. Much better than paying $350 for the speakers that Eddie Van Halen or Stevie Ray Vaughan used.OTOH, I paid as much for shipping as I did for the speaker. Whenever I buy speakers from PE again, I'm saving up for enough to get free shipping.
Date published: 2011-09-26
Rated 5 out of 5 by from Awesome Speaker.I ordered one of these puppies to play around with, and the sound quality was better that expected, the whizzer cone or, "dual cone" was a little wrinkled, but didn't affect sound quality, this speaker would be great with a seperate tweeter, for fullrange use, not so much for a woofer. I am pleased with the speaker, and will be ordering more, the shipping was quick as well!!
Date published: 2011-07-26
Rated 4 out of 5 by from just reading about itaccording to "bamaboy's" specs a 1 1/2 cubic foot ported cab. dimensions 13.7x22.14x8.5 w/ 4.85 sq in port, 0.8 l in long would giveFd 58 F-3 55.36. Not bad overall.
Date published: 2011-07-25
Rated 3 out of 5 by from Its not your daddy's Pioneer BOFOI ordered four of these for future projects and when they arrived I quickly put them through the WT3 tests. They are far from the advertised specs. Examples are: FS is 58Hz not 39Hz, Vas 0.815, Not 2.26 and Qts is .936 not .40. All four were within 5% of the above measurements. I placed one of them in a 1.0 cu Ft test box and found the bass adequate but the treble was lacking even with the wizzer cone. Serious music listening with these speakers will require a tweeter. Workmanship was poor as some of the whizzer cones were out of round and had creases in them.They can handle a lot of power and the overall sound wasfine for background listening. I am going to cut the wizzers off and use them as woofers.Overall not a bad speaker for the price buit PE needs to tighten up on the published specs and re-measure what they have in stock.
Date published: 2011-06-30
Rated 5 out of 5 by from Was not expecting them to sound this good.This was my first DIY speaker project. After getting my crude cabinets properly sealed I'm genuinely surprised at how good these drivers actually sound. Very smooth and linear. Jazz is where they shine the most however I've put a ton of different stuff through them and they haven't done half bad. A couple downsides. You have to EQ the heck out of them if you want a nice balance between the highs and lows. The baskets are plastic. They're very source dependent. Sound fine with my cdp and turntable but sound terrible with iPods/MP3's. I built these as large bookshelf speakers but I'd consider buying another pair and building larger floor standing speakers with this driver. I don't think this would impress more experienced builders/audiophiles but for a first build I am loving it.
Date published: 2011-05-23
Rated 4 out of 5 by from Decent Low Cost "BOFU" ReplacementThis is a pretty good replacement for the famous Pioneer "BOFU" speaker, although the specs are waaaay off from reality. Below are my measurements from WT3:* This data was exported from the Dayton Audio WT3 Woofer Tester** Manufacturer: GRS* Model: 8FR-8* Piston Diameter = 165.1 mm* f(s)= 63.25 Hz* R(e)= 7.43 Ohms* Z(max)= 49.80 Ohms* Q(ms)= 5.702* Q(es)= 1.000* Q(ts)= 0.851* V(as)= 32.170 liters (1.136 cubic feet)* L(e)= 1.14 mH* n(0)= 0.78 %* SPL= 91.00 1W/1m* M(ms)= 12.67 grams* C(ms)= 0.50 mm/N* BL= 6.12
Date published: 2011-04-23
Rated 5 out of 5 by from Full range built toughI built a full range set of speakers using this GRS speaker from plans found on diyaudio.com. This speaker performed perfectly and the quality is amazing for the price. Originally the plans called for the pioneer 8" but the GRS was a great replacement. I'll be buying again.
Date published: 2011-01-29
Rated 3 out of 5 by from Not the same parameters as Pioneer B20FU20-51FWA word of caution. The parameters for this speaker are not the same as the Pioneer B20FU20-51FW it says it is a "direct replacement" for. It is much less expensive so could be a good deal for the price.
Date published: 2010-12-19

Product Q&A

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

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

i have these mounted in 5 gallon buckets with approximently .67 cubic feet per bucket. should i port the buckets? If so, what diameter and length tube

Asked by: kodo
That volume is basically ideal as a sealed design, I would not recommend porting these if you want smooth bass response. You can expect in room response into the mid to lower 40's.
Answered by: MattP
Date published: 2014-04-26

What is the Sd of this driver? I'm trying to do some box modelling and this is required.

Asked by: Rookie
The manufacturer does not offer this specification, but I calculate 41.28 square inches for this one.
Answered by: Chrisf
Date published: 2013-06-26

What is the recommended size box for two of these both with port and sealed?

Asked by: djjim
Sealed: 1.43 cubic feet for both, F3 of 78 Hz.Vented: 3.6 cubic feet for both, 3" ID vent that is 1" long provides a tuning frequency of 37 Hz and F3 of 43 Hz.
Answered by: MattP
Date published: 2014-04-26

What size port for a 40" high cylinder with an 8 inch internal diameter?

According to BamaBoy's measurements, an 8" concrete forming tube about 40" high would approximate the Vas. I'm thinking of making el-cheapo omni-directional full-ranges out of these, and the 40" height should work well with an omni-cone above an up-facing driver... but it has been years since I tinkered and I don't have any software anymore.
Asked by: atropos
The port size for this driver in that enclosure would be 2" in diameter and 4" long. This will provide a tuning frequency of 36 Hz.
Answered by: MattP
Date published: 2013-06-29

Are the recommended enclosures dimensions the Outer Dimension?

To choose one - You list: 1) Ported bookshelf: 17-3/4" H x 11" W x 9" D. Use a 2-1/2" diameter port that is 8-1/2" long. That will tune the box to 45 Hz and give you an F3 of 64 Hz.Is the 17-3/4 ; 11 ; and 9 inch dimensions the OD assuming 3/4 inch MDF or Plywood? If so that gives about 17 Litres.
Asked by: agcuxtal guy
Yes those are external dimensions assuming 3/4" material.
Answered by: MattP
Date published: 2014-04-26

What is the exact OD and flange thickness for flush mounting?

Asked by: agcuxtal guy
Frame diameter is 7-31/32", I would recommend cutting it to 8" for clearance. The frame/gasket thickness is 11/32".
Answered by: MattP
Date published: 2012-11-12

Where's the frequency response graph for this driver?

Asked by: neobop
When we have graphs, charts, and additional specifications for a driver, we'll post them on the product page under the "Manuals/Resources" heading. Unfortunately, we do not have any such documentation on this particular driver.
Answered by: RussR
Date published: 2011-04-02

am i correct to assume that full range speakers dont require crossovers?

Asked by: fatuncle
Yes and no.It will work without a crossover. You may find you need a baffle correction filter or perhaps some other filters to compensate for resonance in the frequency response graph. The cost of this filter could easily talk you into a different driver but I think it might be neat to apply a little thought to a cabinet and try it out on the cheap. You may be satisfied.
Answered by: soxplayer
Date published: 2011-03-28

what tpy of box should l build for this 8" speaker.

GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW
Asked by: mbute
I've come up with three designs.1) Ported bookshelf: 17-3/4" H x 11" W x 9" D. Use a 2-1/2" diameter port that is 8-1/2" long. That will tune the box to 45 Hz and give you an F3 of 64 Hz.2) Ported tower: 36" H x 10" W x 10" D. Use a 3-3/4" diameter port that is 7-5/8" long. That will tune the box to 44 Hz and give you an F3 of 46 Hz.3) Sealed bookshelf: 17-3/4" H x 11" W x 9" D. The F3 would be 78 Hz and the Qtc would be 0.737.
Answered by: mikevv
Date published: 2014-06-23

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