Dayton Audio BR-1 Manual
Contents
1. As can been seen on the graph above the impedance is now very flat through the crossover region From 250 Hz to 10 KHz the impedance is 7 ohms 0 5 ohm Page 4 LRE Lgydspaaksr is asurement System U3 72 C 19 LinearX Systems Inc gstE spl Maq gt Sound Pressure Level and Impedance lt Mag DEL BE i HE Eerd EE EN EE ENE Ar IE AE Se IEEE ELLEN ee 1 1 8 Dome On Axis Frequency Response and Impedance Swee The Crossover Network and Description Here is the BR 1 crossover schematic C1 R2 6 2UF 4 0 Ohms 5W L2 1 5mH 18 gauge L1 j 40mH 20 gauge T 1 1 R1 2 2 8 0 Ohms 10W C2 3 0UF Dayton 6 5 Dayton Audio 1 1 8 dome C3 47 1uF Dayton Audio BR 1 Crossover The low pass filter is a four element filter L2 and C2 form an electrical 2nd order filter a filter using 2 components to yield an approximate 12dB per octave roll off and yields a 2nd order acoustic response The impedance compensation circuit consists of C3 and R1 which effectively flattens the woofer s inductive rise yielding a smooth impedance curve C3 is actually two capacitors one a 47uf non polarized electrolytic with a 10uF Dayton Audio film foil capacitor wired in parallel The reason NP electrolytics are very cost effective but exhibit high ESR Equivalent Series Resis tance and also have some inductive components Using a small value high quality capacitor placed in parallel with the electrolytic will also p2. Off Axis 30 Off Axis 45 Off Axis 60 Off Axis Frequency On Off Axis Response of BR 1 System Note that even 60 degrees off axis the woofer is producing a reasonably flat response without deep nulls or cancellations throughout the crossover region Page 6 LRE Loudspeaker Measurement System U3 72 C 19 57 LinearX Systems Inc dB spl Magni tude gt Sound Pressure Level lt Phase LA TT ALA A E EI SL en E 85 Pa ar N A a x En 90 R C hed A hd 7 135 e Le 3 f So 300 Frequency Individual Driver and Summed System Response The above graph was produced with the microphone at a distance of 45 on the tweeter s axis It was preferred to use the slightly farther then 1 meter 39 37 distance to be more in the far field to get a better representation of how the drivers will blend The response is within the 2 0 dB window to 12KHz In fact the response is commendably flat from 300 Hz to 3 5KHz It can be seen that the acoustic crossover occurs at 2 1KHz These curves have been smoothed 1 6th octave The woofer s peak at 3 200 Hz is still present and it should be noted that a parallel notch filter could be used in the low pass circuit to reduce it s effect One was omitted to keep in the spirit of a low cost design since this would add three more crossover components per speaker The peak s audibility was found to be relatively benign however lts
3. Inductors L TCUP BR 1 2 Terminal Cups 16 Ga 6Ft 1 6 long 16 Ga Sound King Wire 205 16 14 24 205 16 14 F Disconnect 50 PCS Foam 2 Acoustic Foam 1 1 2 24 x18 8X34 8 8 x 3 4 Phillips Pan Head for woofer 6X34 14 6 x 3 4 Phillips Pan Head for tweeter amp cup MANUAL 1 BR 1 Instruction Manual Background and Objectives The objective when designing this system was to offer customers a great sounding low cost kit that can be quickly and easily assembled while offering a basic lesson in speaker design Although cost was a factor the design must offer excellent performance In short a Budget Reference system Hence the name Dayton Audio BR 1 Many of you have a strong interest in building inexpensive loudspeakers but do not possess the necessary test equipment to design from scratch The BR 1 is an effort to provide an inexpensive kit that gets the most out of the chosen drivers Even though cost was a factor in the choice of components and in the final crossover design the end result is quite satisfying The design objective was met with flying colors The overall sound is smooth and detailed with a wide soundstage that belies their smallish size The tonal balance is on the warm side of neutral which is pleasing with most types of music Bass also is impressive for a 6 5 driver the F3 Half power frequency in Hz being around 43 Hz Your BR 1s will perform well for living room family room or dorm room music listening
4. or in your high end home theatre surround system Page 2 The Drivers Included in your kit are two each of the 6 1 2 Dayton Audio woofer and the Dayton Audio 1 1 8 silk dome tweeter Both units are good candidates for this project The woofer incorporates a treated paper cone coupled to a rubber surround The response is generally well behaved but does exhibit a peak centered around 3 3KHz The Dayton Audio 1 1 8 silk dome tweeter is hands down one of the finest tweeters available in it s price range The response exhibits some peakiness and the driver seems to have a wandering Fs but the sound is on a par with tweeters that cost far more LRE Loudspeaker Measurement System Mar 28 2001 LMS Library U3 72 C 1997 LinearX Systems Inc Wed 8 25PM DAY6_A LIB ggas spl lt Magni tude gt Sound EEE Level lt Phase 6 5 On Axis Frequency Response Loudspeaker Measurement Suste Feb 17 2001 LMS Library U3 72 C 1997 LinearX Systems ne Sat 9 40PM 2935 305 LIB Parameters as derived by Leap are as follows Le 1 87 mH Re 6 5 ohms Vas 21 3 liters Mms 24 29 grams Oms 3 85 Qes 365 Ots 333 SPL 86 5 dB 1W 1m eR tude gt Impedance Measurement lt Phase a eo Y EE a GEE AFH g NEE Het i a aen 6 5 Impedance Swee The impedance is smooth but due to the rather large amount of voice coil inductance commonly known as a driver s L e rises sharply Note in the 2KHz area where th
5. worth discussing the parallel notch filter because it is a handy circuit that is used to control frequency response peaks A parallel notch filter consists of a capacitor an inductor and a resistor all wired in parallel with each other then this circuit is placed in series with the driver For a 8 ohm woofer with a typical peak about 5 dB use the following formula for a starting reference C 1 33 freq of peak L 025 freq of peak squared With the 6 1 2 woofer mounted on the BR 1 baffle the peak is centered at 3 200 Hz So C 17133 3200 C 0000094 farads or 9 4 uF L 025 10240000 0000094 L 000259 henries or 259 mH To find the value of R you first must find the Q of the peak Do this by finding the 3dB points on both sides of the peak For the 6 1 2 woofer these 3dB points are 2 500 Hz and 3 700 Hz Now use this formula to calculate the peak s Q Q freq of peak Fh FI Q 3200 3700 2500 Q 2 67 We can now calculate the resistor value by R Q square root of C L R 2 67 square root of 0000094 000259 R 14 05 ohms Page 7 So the values for our proposed parallel notch filter is a 9 4uF capacitor 26mH inductor and a 14 ohm resistor Un like the impedance compensation filter discussed earlier this filter is harder to generate from just design formulas It is best to use some means of measurement to validate the result Please note that addin
6. DAYTONALDIS 2 WAY REFERENCE MONITOR SYSTEM Model BR 1 Construction Workbook Congratulations on your purchase of the Dayton Audio BR 1 2 Way Reference Monitor Speaker System Features of this kit include an elegant design quality components detailed assembly instructions and an in depth design tutorial The BR 1 Speaker Kit can be built in only a few hours using basic hand tools and electronic supplies Once you ve completed this speaker project you will have learned the basics of speaker design and construction and have speakers that will provide you with fantastic sound for years to come Parts Inventory Carefully unpack the kit take inventory of all parts and make sure that nothing was damaged during shipping Your BR 1 Reference Monitor System should include the following Model Qty Description BR 1CAB 1 Dayton Audio BR 1 Cabinet Pair DC160 8 2 Dayton Audio 6 1 2 Woofers DC28F 8 2 Dayton Audio 1 1 8 Silk Dome Tweeters BR 1XO 2 Crossover Boards 47uF 100V 2 47uF 100V Non polarized Capacitors C3 DFFC 0 10 2 Dayton Audio 1uF 400V By Pass Capacitor C3 DNR 8 0 2 Dayton Audio DNR 8 0 8 Ohm 10W Non Inductive Resistors R1 DMPC 3 0 2 Dayton Audio 3 0uF 250V Polypropylene Capacitors C2 1 5mH IND 2 1 5mH 18 Ga Perfect Layer Inductors L2 DMPC 6 2 2 Dayton Audio 6 2 250V Polypropylene Capacitors C1 4 Ohm 5W 2 4 Ohm 5W Resistors R2 6 2 Ohm 5W 2 6 2 Ohm 5W Resistors R3 4mH ACI 2 4mH 20ga Air Core
7. The tweeter is flush mounted to the baffle while the woofer is recessed only to the top of the basket This was done due to the 5 8 thickness of the enclosure material The Cabinet The Dayton Audio BR 1 cabinet uses 5 8 thick MDF and has an net internal volume of 52 cubic feet It utilizes a EBS extended bass shelf alignment and is tuned to 38 Hz with a rear mounted port This tuning results in a F3 of 43 Hz The box dimensions are 8 5 8 wide 14 1 4 high with a depth of 11 giving ita small footprint suitable for stand mounting It is recommended to place the tweeter at or slightly below ear height of a seated listener The center to center driver spacing is 5 3 4 which is an important consideration When ever you have two drivers combining output as is encountered around the crossover frequency there will be some interference patterns This interference will create dips and peaks to the frequency response The greater the distance between the two drivers the more intense this undesirable interaction The generally accepted maximum center to center distance between the two drivers is equal to one wavelength 13 560 at the proposed crossover frequency Max center to center distance 13560 crossover frequency So in the case of the BR 1 Max CTC 13560 2100 or 6 45 Since the tweeter to woofer distance is 5 3 4 the BR 1 is well within the one wavelength tolerance and will provide a uniform radiation pa
8. arallel the undesirable resistance and inductance thus reducing them greatly This method is called bypassing The high pass filter is comprised of C1 and L1 and is also a electrical 2nd order yet it yields approximately a 3rd order acoustic response R2 and R3 attenuates the tweeter s output 6 dB to match the woofer s level Page 5 Most loudspeakers including the BR 1 use drivers mounted on a flat baffle One problem encountered here is the fact that the tweeter s relative acoustic center is set ahead of the woofer s relative acoustic center In general a flush mounted tweeter s acoustic center is aligned with the front baffle A typical 6 1 2 woofer s relative acoustic center is set about 1 1 2 behind the tweeter This means that when fed a signal at the crossover frequency the woofer s output will be delayed 110uS relative to the tweeter For successful filter summation this must be dealt with The method used to compensate for this delay in the BR 1 is the use of asymmetrical filters Normally one would use the same crossover topology for both high pass and low pass filters A 3 order high pass acoustic slope is used with a 2 order low pass acoustic slope to allow for the time delay This technique takes advantage of the phase delay differences between the two filter types and results in a flat summation and allows both drivers to be acoustically in phase with one another at the crossover frequency The crossover fil
9. arge wall But speakers are usually mounted in boxes with varying degrees of baffle width At a given frequency determined by the baffle dimensions the lower frequency wavelengths start to wrap behind the baffle This is called a 2 pi to 4 pi transition and will result in a 6 dB loss in an anechoic chamber A typical two way speaker in a normal listening room will exhibit a 3 to 4 dB loss in the bass region If left unchecked most speakers will sound too thin with too much midrange output The BR 1 was designed with 4 dB of baffle step compensation which results in surprising bass output for a 6 1 2 diameter woofer The midband is rolled off to match the woofer s natural in room response to achieve the excellent bass performance The trade off is a loss of some midband sensitivity with an overall sensitivity of about 83 dB In most rooms you will find the BR 1 to sound best placed approximately 3 feet from the rear wall and mounted on ap propriate speaker stands Ideally you want to place the speakers so they are at least 3 4 ft from side walls if possible Warranty Information Dayton Audio products are constructed by industry experts and are thoroughly tested before shipment Dayton Audio products are warranted for the period of one year This warranty is limited to manufacturer defects either in materials or workmanship Dayton Audio is not responsible for any consequential on inconsequential damage to any other unit or component or t
10. g this notch filter to the existing BR 1 crossover will change the filter roll off and will necessitate a low pass filter redesign LRE Loudspeaker Measurement System Mar 29 2001 U3 72 C 1997 LinearX Systems Inc Thr 7 56AM Curve 6 REV NUL gone spl lt Magni tude gt Sound Pressure Level HA I AT EEEN TARV ON Frequency Reverse Tweeter Polarit Reversing tweeter polarity is a quick check performed with even order filters to test the overall phase relationship that exists between the tweeter and woofer The goal is to achieve a fairly deep symmetrical null at the crossover fre quency when the tweeter polarity is reversed If one is witnessed when the tweeter polarity is reversed then it can be assumed that a good phase relationship exists when the tweeter is connected with normal polarity LRE Loudspeaker Measurement System Mar 28 2001 LMS Library U3 72 C 1997 LinearX Systems Inc Wed 7 35AM DAY6_A LIB Curve 16 gt ACTUAL IMPEDE eee tude gt 2 npe dance Heasurenent ES hase Dum mn CA a A ie System Impedance and Phase Page 8 The system impedance and electrical phase is quite smooth with a nominal 8 ohm impedance This loudspeaker will be an easy load to drive for most any amplifier However due to the 82 5 dB sensitivity a minimum of 75 watts per channel is recommended The center to center driver spacing is 5 3 4 with the tweeter being offset 1 in a mirror image pair
11. he cost for installation or extraction of any component of the audio system In the rare case of a product failure please contact your place of purchase or call our Customer Support Department at 937 743 8248 Warranty Limitations There are no other warranties either express or implied which extend the foregoing and there are no warranties of merchantability or fitness for any particular purpose The warranty will not cover incidental or consequential damage due to defective or improper use of products This includes but is not limited to burnt voice coils overheating bent frames holes in the cone or broken lead wires This warranty gives you specific legal rights and you may also have other rights which vary from state to state Non Warranty Service If non warranty service is required the product may be sent to the Company for repair replacement transportation prepaid by calling 937 743 8248 for details complete instructions and service fee charges daytonaudio com 705 Pleasant Valley Dr ORD DAY TONAUDIO tel 937 743 8248 Springboro OH 45066 A info daytonaudio com USA ORF Dayton Audio Last Revised 2 10 2015
12. inductor should be mounted on its side to minimize the interaction between the two coils on the board You can trim the length of the leads on the L1 inductor without effecting its value Using a utility knife scrape off the enamel coating on the trimmed lead ends so it will accept solder DAYTON MPT 3 0uF 250V K ATID D N A DRAKON PTOI AOV w 1 PPTA 74FK 250 j AUDIO GRADE IVA fi 7 Y MEE MG 5 A h ried 100 v j Page 10 3 To help reduce the risk of components rattling on the p c board especially the inductors use RTV sealant or hot glue to mount the components to the p c board We recommend using hot glue due to its faster setup time If you use RTV sealant you may need to let it setup over night before proceeding with the assembly 4 Solder all component connections on the p c board using silver or electronics grade 60 40 solder At this time you should also solder the riveted 205 terminal connections A properly soldered connection appears shiny and smooth We recommend using a soldering iron with a wattage rating between 20 30watts Using wire cutters trim off all excess component leads 5 Cut the supplied wire into 6 pieces approximately 12 long Strip the insulation on all wires back about 3 8 1 2 6 Using acrimp tool crimp the 205 terminals on the wire leads To ensure a tight connection gently squeeze the push on terminals with a small pair of pliers Note If you prefer y
13. is driver will be crossed over the impedance is 25 ohms For this reason an impedance compensation network will be used commonly known as a Zobel Network Page 3 About Zobels C This simple circuit consists of a single resistor and capacitor It is commonly referred to as a Zobel network named for the Bell Laboratories engineer whom invented it An excellent starting point can be calculated by using 7 D this formula Lt R 1 25 x Re C Le R squared Re is measured voice coil DC resistance in ohms 8 Le is measured voice coil inductance in henries R is in ohms C is in farads The 6 1 2 woofer parameters were measured using the ZO bel LMS Loudspeaker Measurement System a PC based package for measuring loudspeaker systems and the Le was found to be 1 87 millihenries Using an accurate ohm N etWO rk meter the Re was 6 5 ohms Using the above formula R 1 25X6 5 R 8 125 ohms SO C 00187 66 C 0000283 farads or 28 3 uF Although these values will give a good result actual in box impedance measurements indicated an even better com pensation can be had with a 47uF capacitor and a 8 ohm resistor 2 Lende ak Measurement System Feb 18 20 LMS Library U3 72 gt 1 3 e er e r 01 H C 1997 LinearX Systems Inc Sun 7 33AM 2935 305 LIB gonne lt Magnitude gt Impedance Measurement lt Phase OEE ME BE ED BES Kanten nnn mn nn nat mmm 6 5 Impedance w Zobel Network
14. n top and bottom The bottom piece of foam will simply lay on top of the crossover 4 Position the labeled woofer and tweeter lead wires through the foam and run to their respective driver openings Page 14 C Installing Drivers Put sealing caulk around the woofers prior to mounting When applying caulk it is a good idea to first roll the caulk between your fingers to thin out the caulk bead The tweeter is supplied with a gasket so it does not need sealing caulk Putting sealing caulk on the tweeters mounting flange may not allow the faceplate to mount flush with the baffle 1 Attach each wire to the appropriate driver terminals while observing proper polarity positive to positive negative to negative The tweeter has a red paint dot on the positive terminal If you decide to solder be careful not to apply too much heat to the driver terminals especially the tweeters 2 Install the drivers using the 8 large screws for the woofers and the 6 small screws for the tweeters Be careful not to over tighten the screws and strip the wood Page 15 Speaker Placement Many loudspeakers are designed without regard to baffle step loss If a woofer has a midband sensitivity of 88 dB for example and is mounted on a large infinite baffle like your living room wall it will maintain the 88 db sensitivity right down to it s rated F3 All frequencies even the large low frequency wavelengths are supported by the l
15. ou can solder the wires directly to the p c board and drivers instead of using the connectors Page 11 7 The locations where the input and driver output wires connect are clearly marked on the p c board While observing proper polarity attach all input and driver wires to their respective mounting terminals Example To attach the input wire take the positive input wire and connect it to the IN terminal Next take the negative input wire and connect it to the In terminal Repeat this step for the woofer tweeter and other crossover Again it is very important to observe the proper polarity 8 At this point it is a good idea to label each wire to ensure proper hook up Masking tape and a marker will work fine 3 Cabinet Assembly Instructions A Installing the Crossovers To mount the crossovers we recommend using hot glue due to its faster setup time If you use RTV sealant you may need to let it setup overnight before proceeding with the assembly You could also use screws but they can be a little difficult to install and you run the risk of driving the screw through the finished side of the cabinet No crossover mounting screws are included 1 Position the crossover board on the inside bottom of the cabinet against the back wall with the wiring facing outward 2 Glue the crossover in place Page 12 3 Pull the labeled input wire through the terminal cup hole and while observing p
16. roper polarity connect the wire to the terminal cup The positive input wire should be connected to the red binding post 4 Orient the terminal cup with the binding posts toward the bottom and install using the small 6 screws and a phillips screwdriver 5 Repeat these steps for the other speaker cabinet B Install Acoustic Damping Foam We ve included two 2 sheets of acoustic foam one sheet for each speaker Acoustic damping foam absorbs internal standing waves inside the cabinet and prevents reflections to the woofer cone You can install the foam using hot glue RTV sealant or spray adhesive 3M Super77 if available A simply way to cut the foam is to leave the two sheets nested together while cutting Place the foam on a flat surface and cut the foam with a straight edge and a utility knife Make medium depth cuts with several strokes Do not try to cut through the entire depth of foam with one cut 1 The foam must be cut to fit internally on the right left side walls rear top and bottom panels Do not apply it to the front baffle Cut the foam to the dimensions shown in Fig 1 18 gt 13 7 5 1 2 Top Rear 5 1 2 Bottom Yv 1 lI o FIGURE 1 Foam Cutting 2 Install the foam on the back of the cabinet first and trim around the port tube Make sure it does not obstruct the airflow to the port tube as this will alter the tuning of the box 3 Next install both sides and the
17. ters were designed to achieve a flat overall resoonse The BR 1 measures on axis within 2 0dB from 100 Hz 12 KHz Flat frequency response is desirable so that all frequencies are reproduced with the same loudness over the loudspeaker s bandwidth In itself flat frequency response does not ensure a good sounding loud speaker But targeting flat on axis performance is the first step in designing a high performance loudspeaker Another arguably more important goal is flat off axis frequency response Many times a speaker can measure flat on axis but the off axis curves suffer from dips in the response This is due to insufficient driver overlap usually caused by using too high of a crossover point for the low frequency driver Good off axis performance will avoid the so called Venetian blind effect What is the Venetian blind effect When the seated listener moves horizontally from directly in front of the speaker the treble or high frequency response drops off dramatically A loudspeaker which exhibits good off axis response can be listened to well away from directly in front of the speakers and excellent performance will still be enjoyed Louds peak Measurement System Mar 18 2001 LMS Library U3 72 CC 1 57 LinearX Sds tams Inc Sun 8 25PM DAYBUD LIB On axis 15 degrees 30 degrees 45 degrees and 60 degrees off axis Curves offset for clarity All measured at a distance of 45 ppg gt Sound Pressure an lt Phase On Axis 15
18. ttern Page 9 BR 1 Assembly Instructions 1 Installation Tools Needed e Phillips screwdriver e Wire cutter stripper e Hot glue gun or RTV sealant e Small pliers e Soldering iron e Crimp tool e Silver or electronic grade solder e Utility knife Crossover Assembly Note Warning The correct assembly and wiring of the crossovers is critical to the proper operation of this speaker system In a worst case situation an improperly wired network can damage your receiver or amplifier Please double and triple check all values and wiring Assembling the Crossovers 1 Install all components on the boards in their proper location When installing R1 position it so that air can circulate around its body Before mounting C3 to the p c board it needs to be bypassed C3 is actually two capacitors one 47mfd electrolytic bypassed with a 10mfd Dayton Audio poly film foil This was done to improve the acoustics of the electrolytic capacitor To bypass the capacitor simply parallel the two capaci tors together and wrap the smaller poly cap leads around the larger electrolytic cap leads and solder Trim excess poly cap leads and use the electrolytic leads to mount the bypassed cap to the p c board Jj f OAKVLVON J PPT 0 15 A000 rT sy Ad AUDIO GR j j f mn be bas OI dd bel a 2 When positioning components try to keep lead lengths to a minimum Note The L1 40mH
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