WIRELESS NEWS

Press, Volume LXVI, Issue 20092, 22 November 1930, Page 9

WIRELESS NEWS

(By ••Max.")

A short scries of articles or rather, notes, on the principal types of loudspeakers will be given in this column and for a commencement the old horn will be taken. Now the horn speaker is nothing more or less than a modified telephone ear-piece with the addition of a funnel, or horn, to concentrate and direct the sound waves.

If the ebonite cap of an ear-phone piece were to be unscrewed, it would be seen that it held down, around its periphery, a thin disc of iron sheet, terro-type, to give it the correct name. This disc, when removed, discloses the two poles of a small permanent magnet and there is "a small bobbin of fine wire surrounding each pole-piece, as the ends or poles of toe magnet are called. In the ordinary te'.ephone ear-piece, the wire is much coarser than it is in the usual headphones of a wireless set, and th». early r.idio headphones were also wound with this somewnat coarser wire.

The two windings arc connected so that when a current of electricity Hows through them, they affect the two ends of the magnet in a sinnlnr manner, strengthening them if (lowing in one direction, and weakening them when the current flows in the reverso direction. This varying of the strength of the' poles changes the pull of the magnet upon the thin ft-rro-type disc, which just clears the magnet ends and is under a tension as a result of being so close. Again, if a current is flowing through the windings in one direction all the lime, but the strength of the liirrput is altering, then the magnetic field will also be altered in svmpat'iv, again varying the pull on the dis^.

It is always wise to connect headphonos to a receiver of the valve type so that the current will strengthen the magnet, thus tending to preserve it, reverse currents having a demagnetising action in the course of time. Now when a changing current passes through the coils of wire, the pull varies in sympathy and the disc, or diaphragm, vibrates accordingly, sets up corresponding vibrations in the air, and we have speech or music

In wireless headphones the wire used is extrt-mclv fine ami might have a resistance of one or two thousand ohms per ear-piece. The reason for this is that the variations of current as well 08 the steady current flowing through are vary small, being only a few one-thousandths of an ampere. One turn of coarse wire carrying one ampere will have as much effect as one thousand turns carrying one onethousandth of an amp. It is the number of ampere-turns that count, so where currents are very small a-large number of turns are required. It is essentia! to limit the size of the coils so that the depth of winding in each is not much greater than the thickness of the permanent magnet, therefore a fine wire must be used. There is no object in having wire with a hisrh resistance, for resistance takes energy to overcome it, but unfortunately it cannot be avoided, resistance being proportional to the smallness of th© cross section of the wire as well as to thf length.

Tho main disadvantages of a speaker using a unit of the above kind are that tho range of musical frequencies to which it will respond faithfully is limited, especially the low tones; notes which are of the same frequency as tho natural period of vibration of the diaphragm, will be overemphasised. Insufficient volume is another fault. Again, the closer the diaphragm is drawn to the polepieces, the greater is the pull of the magnets, and so a loud tone is apt to be over-emphasised. However, there is one point to be noted and that is that the volume can be very much increased if an exponential horn is used. This horn doubles in diameter at regular distances along its length, and a certain minimum "rate of expansion" as it is termed, will aid in gi%'ing rsspouse to low notes.

We are no used to tho rapid development of wireless that we receive 110 thrill when we read that a radio telephone service is now open between England and New Zealand. A number of listeners have already overheard the stations concerned while testing, and it remains to be seen whether a system will be used which will preserve secrecy.

"New Zealand Radio," in its latest issue gives an illustrated article covering Mr Gerity's receiver, which uses the high amplifying properties of the A.C. screen grid valve as a defector. Complete details should enable any home constructor to build a set along the same lines. It would be interesting to know If a choke coupling could be tried to obviate the extra voltage required for the plate resistance.

A rather novel form of interference has been reported in one of our seaside resorts where the trouble was caused by a flash sign. A bulb was borrowed from the owner of a similar but m re up-to-date apparatus and when this was used the difficulty was overcome.

That modern high ratio step-up audio transformers give stronger signals than a lower ratio was proved lately This was a 9 to 1 transformer, and it about trebled the signals when used to couple a crystal detector to an amplifier, As a rule the quality is not so good with this type, but this particular one evidently suited tho crystal in use. * *

A well-known British musician states that the radio and the gramophone both tend to lower the musical standard of tli*j growing generation. He argues that neither system is perfect enough to give even a moderately true conception of music as played bj an orchestra. Because the radio is becoming universal the attendances at musical recitals, etc., are seriously falling off and we are becoming used to a lower standard of musical reproduction. ■» *

From the United States of America, on the other hand we read that the great facilities of wireless are a big aid,in the development of the musical sense. It is considered that reproduction of the voice and of instruments is of a sufficiently high standnrd and that listeners cannot but bonefit from continually hearing concerts, etc.

There is probably more than a grain of truth in both statements, but tho former applies to, perhaps, those specially gifted with a high developed musical ear while the latter is true where the great majority of people is concerned. Whatever way we consider the question, it cannot be denied that the advent of radio has opened up paths unthought of before as a means of enabling a tremendous number of people to hear music of a high standard as given by modern receivers and gramophones, especially the electrically reproduced type. * * It hag often been argued that the ordinary wound typo of waxed paper dielectric condenser cannot act at its

Notes From Far and 2STear

IYA. AUCKLAND. (900 Kilocycles.)

BROADCASTING.

TODAY'S PROGRAMMES. CHRISTCHURCH. recita? m .l Afternoon session—Gramophone dren a h Q , lr " s -, results. 5.0: Chil<>.o: Dinnnr' * at an d Uncle Charlie. 7 30" Snoi-iu sesj "° n - 7.0; Newa nessio.j. villc' 80: Chimes. Vaudel' ni» M m rh( Optimist Club.'' f'au"'wv, Lawry. Overture— Futurist;! 8 Orcliestra, • 'Caprice (n) "I'arV n shoruse5 horuses —Optimists Party, M"I UP V«ur Troubles" (Anon.): "Vv and , I{ »dishes" (Anon.); (c) r,r,.,fn «• Ke " ,uc . k y Home" (Foster). Soprano— Mwi Marjorie Nelson, (a) "Quiet" (Sanderson); <b) "This Little Pie «<"«» to Market (Holland). 8.20: Comedy—t.othani Comedy Quartet, "King Arthur" . i,p> ' baritone—Mr W. J. Sprntt. (a) <■>. l ..c. Tapper's Song" (Charles); v n E °' le Waggoner" (Brevillo* *m? Jit —Mr Mark Richards, Juda Browning's Account of Rubinstein's ilaying" (Moses Adams). Male quartet- — Optimist Four, "Lullaby" (Brahms). 8.40: Organ-—Stanley Mac Donald, (a) "Was it a Dream 1" (Coslowj ; (b) "Nicolette" (Batten). 8.46: Tenor—Optimißt Jim, "My Dreams" (Toßti). Choruses—Optimists* Party, (a) "Stockriders' Song**' (with chorus) (James); (b) "There is a Tavp.rn in the Town" (Anon.); (c) "The Threo Crows" (Anon.;. 8.58: Plaza Theatre Or ehestra, "My Lady Dainty" (Hesse) o.l*. Weather forecast and station notices. 9.3: Novelty—Gotham Comedy Qnartet, "The Old Sow" (trdtl.). 9.0: Bass-baritone —Mr J. L. Tennant, (a) "Spanish Song—Mule» teer of Malaga" (Trotere) ; (b) "Old Barty" (Douglas Grant). Contralto—Mrs F\ M. Korr, (a) "Fisher Lad" (Day); .(b) "The Songs My Mother Sang" (Grimshaw). 0.20: Banjo and banjoleno trio—Misses E. Churchill and M. and L. Straw, (a) "Circus Parade" (Mortey); (b) "Painting thft Clouds with Sunshine" (from * Gold Diggers") (Dubin Burke). 9.27: L*uet. tenor and bass—Mesprs Jas. Shaw and JL. Tennant, "Flow, Gentle Deva" (Parry;. Recitation—Mr Mark Richards "Pat's x * cclsior" (Anon.). Male quartet—Optimist Four, "A Catastrophe" (Sprague). Comedy—Seamus O'Doherty, "The SVutterm Lovers." 9.40: Baritone —Mr O. M. Jo "*\ (a) "Friend of Mine" (Sanderson) ; (h> "The Carnival" Molloy). Choruses —Opttmists' Party, (a) "Little Brown Jug (Anon.); (b) "My Bonny (Anon.) , (c 1 "Soldiers* Chorus" (from Faust ). O.Sfi Paul Godwin's Orchestra, (a) riretty » Idyll" (I/mcke). Vienna Schrsmmel Qu" tet, (A) "Firefly's Appointment (tsiede;. 10.0: Dance music until 11 p.m. 3ZC, CHRISTCHURCH. (260 Metres.) 10 a.m.: Women's session. 10 a.m.: "Uoartsoase,*' Peerless Orchoatra. 10.5j Tested recipes. 10.25: "On Wings of Son* (Mendelssohn), Vasa Prihoda (violin); * I ro* legue," "Pagliacci/' Arthur Middleton baritone); 'Hoses Remind Me of You,' ( Frederick Kinsley (organ); "Serenade (Gounod), Cecil Arden (contralto); # Itching Fingers/' Roy Schineck (guitar); Maid of the Went." Walter Chapman (tenor); "Semper Fidetis," New York Military Band; "The Low-Backed Car/ 1 Walter Van Brunt (tenor); ''lmpassioned Dream Walts," Peerloss Orchestra; "Songs My Mother Taught Me" and "Poem," Vasa Prihoda (violin); "Largo," Merle Aleock (contralto); "The Little White House," Frederick Kinsley (organ); "Yo Who Have Yearned Alone," Cecil Arden (song) ;"Ttae 12th Street Raff/' Roy (ukulele); "Memory's Oarden," Walter Scanlan (tenor); "Trumpeter's Carnival," New York Military Band. 11.30 a.m.: Close down. 2YA. WELLINGTON. (720 Kilocycles.)

3 p.m.: Chimes. Selected studio 3.30 and 4.30: Sporting results to hand. 5.0: Children's session, conducted by Uncle Toby. 6.0: r-inner music session. 7.0: News session, market reports and sport* results. 8.0: Chimes. A relay from the Town Hall of the Wellington Harmonic .Society's final concert of the 1030 season. Conductor, Mr H. Temple White; accom panist, Mr Clement Howe. Chorus—The Choir. "Beyond the Spanish Main" (Arm-strong-Glbbs). Part song—-Qholr, ,4 I Loved a Lass" (Dyson); "In the Merry Spring.'* Violin—Mr Leon de Manny. "Sonata in A Major" (Handel). Part s^ng—Choir. "The Dawn of Song" (Bairstow). Choral song —Choir, "Seraphic Song" (Rubinstein, arr. Gaines). From the studio: Weather report and station notices. Part son?— Choir, "London Town" (German). Part song— The Ladies, "The Two Clocks" (lingers) Violin—Mr Leon de Mnuny, "Hymn to the Sun." Part song—Choir. "Unto V* a Son Is Given" (Freer): "A Cradle Sons" (Wheeler). Choral Fantasia—Choir, "Faust" (Gounod, arrgd. Challinor). 10.0 (approx.): Dance programme from studio.

11.45 a.m.: Relay—Otahuhu Trottinff Club's Meeting at Alexandra Park, inter spvraed with gramophone item». 6.0: Children's session, conducted by Cinderella 6.0 Dinner session. 7.0: News and market ro ports. 7.40: Talk—Mr A. E. McMahoa "Gardening." 8.0: Chimes. OvertureBand of Ii.II. Grenadier Guards, "A Prin cess of .Kensington" (German). 8.9: Bassbaritone—Mr Arthur Wright, "The Crown of the Year" (Martin), 5.13: SelectionString Oi-tet, under direction of J. Whit ford Waugh, "Firefly" si-lection (Priml). 8.23: Novelty—Mister Ree, "Radio Magic.' 8.38: String Octet, (a) "Flight of the Bumble Beo" (Korsnkov) ; (b) "Humoresque" (Dvorak). 8.44: Soprano—Mrs Hal McLennan, "Sing, Joyous Bird" (Phillips): "I Hid My Jjove" (d'llardelot). 8.51 Comedy—Flotsam and Jetsam. "Schubert's Toyshop." 8.55: Humour —Mr T. T. Garland. "Some Humour." 9.0: Evening weather forecast and announcements. o.'-: Selection—String Octet, "Primrose Seloc tion" (Gershwin). 5).12: Bass-baritone—-Mi Arthur Wright, (a) "Beating up the Chan nel" (Sanderson); (b) "A Chip of thi* Old Block" (Squire). 0.19: Comedy—FlotRam « and Jetsam. 4 'Polonaise in the Mail. 9 23* Soprano—Mrs Hal McLennan, "Loves a Sailor" (Kent): "What's in the Air To dnvf" (Eden). 9.20: String Octet— Mlnm ture Suite" (O'Donnell) ; (a> "CantontM. ; (b) "Piz7.lcato"; (c) "Onpnce 0.3J Humour—Mr T. T. Garland "A F'r"-!" Chat." 9.46: Xylophone—Rudy Starita "The Punch and Judy Show (Black). 0 50- String Octet, three dunces from lom Jones" (German) ' (a) "Morris Pan.; (b) "Gavotte ; (e) "Jig. iro gramme of dance music. 4YA, DUNEDIN. (650 Kilocycles.) 3 p.m.: Chimes. Selected B«m°phone Items. 5.0. Children's hour, conducted by CJncle Sambo. 6.0: Dinner music 7.0: News session. 8.0: Relay of programme from 3YA, Chrislchurch. Dance session. SUNDAY. 3YA, CHRISTCHURCH.

3 p.m: Afternoon session— Gramophone recital. 5.30: Children's song service by children from Presbyterian Sunday Schools. 6.15: Chimes from studio. 6.30: Pl *" o ,, Miss Dorothy navies, "Prelude in A JMa* (Chopin), 6.35: Cbrlstchurch Broadcasting Trio, "Allegro Vlvaee" (Beethoven). Vocal—lrish Male Quartet, "Holy God, wa Praise Thy Nome.'* 6.47: Broadcasting Trio, (a) "Entr'acte" from "Rosemunfl (Schubert): (b) "Waltz" (Heblkof). Duet—liUcrhia Bori and Lawrence T.bbett "Calm as the Night." 7.0: Belay of eveniiiK service from St. Paul's Presbyterian Church. Preacher, Rev. W. Bower Blacß. Oreanist Mr Norman Williams; Choir Conductor, Mr H. BUketey. 8.15 (appro*): Relay of band programme from His Mnientv a Theatre, Ashhurton, by the Silver Band (Conductor, Mr H. J. Osborne). 2VA, WELLINGTON. 3.0 to 4.30 p.m: Afternoon session of selected gramophone items. 6.0: Children a song service conducted by Uncle Qeorgt, assisted bv the Vivinn Street Baptist Sunday School Choir. 7.0: Relay of evening service of St. Thomas's Anglican Church, Wellington Bouth. Preacher: Rev. \V. Bullork, Virnr 01 St. Peter's Church : Organist and Mr W. A. Gntheridge. 8.15 (appro*.): Studio concert by the Salon Orchestra and Etude Quartet: Selection—Salon Orchestra (Conductor, Mr M. T. Dixon). "Lucia ni Lnmmermoor' * (Donizetti). Quartet—-i «® Etude, "See Our Oars With Feathered Spray." Soprano—Miss Oretta Stark, H"** You But Known" (Denza). Band—H.M. Coldstream Guards, (a) ".Pirates of I en-

ratcc. capacity because of the inductance effect of the winding of the strips of tin foil and paraffined paperIt is said that the condenser cannot charge up at radio frequencies. This is probably quite true and accounts for the fact that at least one manufacturer of world renown is now making condensers in a way which will overcome this fault. This difficulty applies only to tho higher capacity by-pass condensers which aro not of the electrolytic kind.

xance"; (b) "lolanthe** (Sullivan). Bari* tone —Mr Kay Kemp, "Thanks Be To God'* (Dickson). Reverie —I'aion Orchestra, (a) •'The Sacred Hour" (Ketelbcy); (b) selection, "Adagietto tralto —Mra Hay Kemp, "He Wipes the Tear" (Lee). Arthur Pryor'a Band, " 'Officer of the Day" (Hall). Weather report and station notices, Selection—Salon Orchestra, "Brahms Memoiren" (Morena). Tenor—Mr Will Hancock, "In a Monastery Garden" (Ketelbcy). Duct—Mr and Mrs Ray Kemp, "The Voyagers" (Sanderson). ChorusRoyal Opera Chorus, (a) "Opening Chorus"; (b) "Pilgrims* Chorus" from "Boris Godounov" (Mouasorgsky ). Selection—-Salon Orchestra, "The Lost Chord" (Sullivan). Bolls—W. E, Jordan, (a) "Spring Song" (Mendelssohn); (b) "Country Dance'' (New* ton). Quartet —The Etude, "Peaceful Slumbering on the Ocean" (Storace). Selection—&*aton Orchestra, "By the Lake of Geneva," Part 1 (Bendcl). IYA, AUCKLAND. 3 p.m.* Relay irom Scott's Hall, lecture op "Christian Science" by Judge Samuel W. Greene, C.5.8., of Chicago, 111., U.S.A., under tho auspices of First Church of Christ Scientist, Auckland. 4.0: Selected gramophone items from the studio. 0.0: Children's song service, conducted by Uncle Bert. 6.55: Relay of Divine Sorvice, Beresford Street Congregational Church. Preacher, Rev. Albert V. Whiting; Choirmaster, Mr William Gemmell; Organist, Mr Arthur Cherry. 8.80: (appro*.)• Johann Strauss and Syropho.ny Orchestra, * * Doctrinen." Contralto —Miss Norma M. Calder, (a) "Here in the Quiet Hills" (Came); (b) "The Wind". (Sprosa). Studio Trio—(a) "Menuet" (Bach); (b) "Prcislied" (Wagner;. Baritone —Mr John Rree, "Aladdy Mine" (Lohr), Piano—-Mr Eric F. B Waters, "Autumn" (Chaminade). Organ —Stanley Roper, "Imperial March" (Elgar). Violin and piano—Messrs J. Whit ford Waugh and Cyril Towsey, "Sonata No. 4" (Handel). Contralto—Miss Norma M. ('aider*, "Summer Rain" (Willeby). Trio—"Scherso and Finale 0 from 'Grand Trio Cfvncertante" (£,*pohr). Baritone —Mr John Bree, (a) "The Rose of Tralee (Spencer); (b) "Simon the Cellarer (Hatton). Johann Strauss and Symphony Orchestra, "When the Lemons Bloom. 4YA, DUNEDIN. 3 p.m: Chimes. Selected gramophone items. 5.30: Children's song service, conducted by Big Brother Bill. 6.45: Relay of evening church service from Salvation Army Citadel Church. Preacher, Captain Chandler; Band Conductor, Mr Millard. 8.15; Relay through 3YA. Christchurch, of concert by the Ashburton Silver Band from His Majesty e Theatre, Ashburton, under the couduetorship of Mr H. J. Osborne.