Exhibit 4.9

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                       AMERICAN RADIO SYSTEMS CORPORATION
                                     Issuer


                     THE SUBSIDIARY GUARANTORS NAMED HEREIN
                                    Guarantor


                               FLEET NATIONAL BANK
                                     Trustee





                                ----------------

                             Supplemental Indenture

                           Dated as of October 1, 1996

                                       to

                                    Indenture

                          Dated as of February 1, 1996

                                ----------------




                                  $175,000,000


                      9% Senior Subordinated Notes due 2006


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         SUPPLEMENTAL  INDENTURE,  dated as of October 1, 1996,  among  American
Radio Systems  Corporation,  a corporation duly organized and existing under the
laws of the State of Delaware  (herein  called the  "Company"),  American  Radio
Systems License Corp., a corporation  duly organized and existing under the laws
of the  State of  Delaware  (herein  called  "License  Corp."  or a  "Restricted
Subsidiary"),  ARS Acquisition II, Inc. (formerly known as Marlin  Broadcasting,
Inc.), a corporation  duly organized and existing under the laws of the State of
Delaware (herein called "Marlin" or a "Restricted Subsidiary"), Radio Systems of
Miami,  Inc.  (formerly  known  as  Marlin   Broadcasting  of  Miami,  Inc.),  a
corporation  duly organized and existing under the laws of the State of Delaware
(herein called "Marlin  Miami" or a "Restricted  Subsidiary"),  Radio Systems of
Philadelphia,   Inc.  (formerly  known  as  Franklin  Broadcasting  Company),  a
corporation  duly organized and existing under the laws of the  Commonwealth  of
Pennsylvania (herein called "Franklin" or a "Restricted Subsidiary"),  and Fleet
National Bank (formerly known as Fleet National Bank of Connecticut), a national
banking  association  duly  organized and existing  under the laws of the United
States of America,  as Trustee  (herein  called the "Trustee") to the Indenture,
dated as of February 1, 1996,  among the Company,  License Corp, and the Trustee
(herein called the "Indenture").


                             RECITALS OF THE COMPANY

         The Company, License Corp. and the Trustee have heretofore executed and
delivered  the  Indenture,  pursuant  to which the  Company  has duly  issued an
aggregate of $175,000,000  principal amount of its 9% Senior  Subordinated Notes
due 2006 (herein called the "Securities").

         The Company,  each of Marlin, Marlin Miami and Franklin and the Trustee
have heretofore executed and delivered a Supplemental  Indenture dated as of May
31, 1996,  pursuant to which each of Marlin,  Marlin  Miami and Franklin  became
parties to, and Restricted  subsidiaries under, the Indenture and guaranteed the
Securities.

         The Indenture  provides that  indentures  supplemental to the Indenture
may be entered  into  without the  consent of any Holders in order,  among other
things,  to cure any ambiguity and to correct any provision thereof which may be
inconsistent with any other provision.

         All  things  necessary  to make  this  Supplemental  Indenture  a valid
agreement  of  each  of  the  Company  and  each  Restricted  Subsidiary,   this
Supplemental  Indenture is executed by it, the valid obligations of such parties
in accordance with its terms, have been done.

         NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH:

         For and in  consideration  of the premises and the terms and conditions
of the  Indenture,  it is  mutually  covenanted  and  agreed,  for the equal and
proportionate benefit of all Holders of the Securities, as follows:


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                                   ARTICLE ONE

                                   Amendments

         SECTION 101.  Amendments.

                  (a) Amendment of Section  1011.  Section 1011 of the Indenture
         is amended to restate  paragraph (c) thereof to read in its entirety as
         follows:

                           "(c)  Indebtedness  represented by (1) the Securities
                  and the Subsidiary Guarantees and (2) guarantees by Restricted
                  Subsidiaries of (i) Senior Bank Debt and (ii) any other Senior
                  Debt  permitted to be incurred by the Company  under the terms
                  of this Indenture;"


                                   ARTICLE TWO

                        Definitions and Other Provisions
                             of General Application

         SECTION 201.  Definitions; Incorporation of Provisions.

         Terms used herein without definition shall have the meanings prescribed
therefor in the  Indenture.  The  provisions  of Sections 107 through 114,  both
inclusive,  are incorporated herein with the same force and effect as though set
forth hereat in their entirety.

         SECTION 202.  Indenture Provisions.

         Except as  specifically  amended by this  Supplemental  Indenture,  the
Indenture shall remain in full force and effect.



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         IN WITNESS  WHEREOF,  the parties hereto have caused this  Supplemental
Indenture  to be duly  executed,  and  their  respective  corporate  seals to be
hereunto affixed and attested, all as of the day and year first above written.

                                           American Radio Systems Corporation

Attest:
                                           By /S/ Joseph L. Winn        
                                              ------------------------------
                                              Name: Joseph L. Winn
/S/ Michael B. Milsom                         Title: Chief Financial Officer
                               
                                           American Radio Systems License Corp.

Attest:
                                           By /S/ Joseph L. Winn
                                              ------------------------------
                                              Name: Joseph L. Winn
/S/ Michael B. Milsom                         Title: Chief Financial Officer
                              
                                           ARS Acquisition II, Inc.

Attest:
                                           By /S/ Joseph L. Winn
                                              ------------------------------
                                              Name: Joseph L. Winn
/S/ Michael B. Milsom                         Title: Chief Financial Officer
                             
                                           Radio Systems of Miami, Inc.

Attest:
                                           By /S/ Joseph L. Winn
                                              ------------------------------
                                              Name: Joseph L. Winn
/S/ Michael B. Milsom                         Title: Chief Financial Officer
                            
                                           Radio Systems of Philadelphia, Inc.

Attest:
                                           By /S/ Joseph L. Winn
                                              ------------------------------
                                              Name: Joseph L. Winn
/S/ Michael B. Milsom                         Title: Chief Financial Officer

                                           Fleet National Bank, as Trustee

Attest:
                                           By /S/ Kathy A. Larimore
                                              ------------------------------
                                              Name: Kathy A. Larimore
/S/                                           Title: Assistant Vice President





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COMMONWEALTH OF MASSACHUSETTS )   ss.:
COUNTY OF SUFFOLK )

         On the 8th day of October,  1996,  before me personally  came Joseph L.
Winn, to me known,  who,  being by me duly sworn,  did depose and say that he is
Chief  Financial  Officer of  American  Radio  Systems  Corporation,  one of the
corporations  described in and which executed the foregoing instrument;  that he
knows the seal of said corporation;  that the seal affixed to said instrument is
such  corporate  seal;  that it was so  affixed  by  authority  of the  Board of
Directors  of said  corporation,  and that he signed  his name  thereto  by like
authority.

                                                     /S/ Kathryn B. Haley
                                                     ---------------------------


COMMONWEALTH OF MASSACHUSETTS )   ss.:
COUNTY OF SUFFOLK )

         On the 8th day of October,  1996,  before me personally  came Joseph L.
Winn, to me known,  who,  being by me duly sworn,  did depose and say that he is
Chief  Financial  Officer  of ARS  Acquisition,  Inc.,  one of the  corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation;  that the seal affixed to said instrument is such corporate
seal;  that it was so affixed by  authority  of the Board of  Directors  of said
corporation, and that he signed his name thereto by like authority.

                                                     /S/ Kathryn B. Haley
                                                     ---------------------------


COMMONWEALTH OF MASSACHUSETTS )   ss.:
COUNTY OF SUFFOLK )

         On the 8th day of October,  1996,  before me personally  came Joseph L.
Winn, to me known,  who,  being by me duly sworn,  did depose and say that he is
Chief Financial Officer of Radio Systems of Miami, Inc., one of the corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation;  that the seal affixed to said instrument is such corporate
seal;  that it was so affixed by  authority  of the Board of  Directors  of said
corporation, and that he signed his name thereto by like authority.

                                                     /S/ Kathryn B. Haley
                                                     ---------------------------


COMMONWEALTH OF MASSACHUSETTS )   ss.:
COUNTY OF SUFFOLK )

         On the 8th day of October,  1996,  before me personally  came Joseph L.
Winn, to me known,  who,  being by me duly sworn,  did depose and say that he is
Chief  Financial  Officer of Radio  Systems of  Philadelphia,  Inc.,  one of the
corporations  described in and which executed the foregoing instrument;  that he
knows the seal of said corporation;  that the seal affixed to said instrument is
such  corporate  seal;  that it was so  affixed  by  authority  of the  Board of
Directors  of said  corporation,  and that he signed  his name  thereto  by like
authority.

                                                     /S/ Kathryn B. Haley
                                                     ---------------------------


                                       -4-

<PAGE>


COMMONWEALTH OF MASSACHUSETTS )   ss.:
COUNTY OF SUFFOLK )

         On the 8th day of October,  1996,  before me personally  came Joseph L.
Winn, to me known,  who,  being by me duly sworn,  did depose and say that he is
Chief  Financial  Officer of American Radio Systems  License  Corp.,  one of the
corporations  described in and which executed the foregoing instrument;  that he
knows the seal of said corporation;  that the seal affixed to said instrument is
such  corporate  seal;  that it was so  affixed  by  authority  of the  Board of
Directors  of said  corporation,  and that he signed  his name  thereto  by like
authority.

                                                     /S/ Kathryn B. Haley
                                                     ---------------------------


STATE OF CONNECTICUT )   ss.:
COUNTY OF HARTFORD   )


         On the 29th day of  October,  1996,  before me  personally  came  Kathy
Larimore,  to me known,  who, being by me duly sworn, did depose and say that he
is an Assistant Vice  President of Fleet National Bank, one of the  corporations
described in and which executed the foregoing instrument; that he knows the seal
of said corporation;  that the seal affixed to said instrument is such corporate
seal;  that it was so affixed by  authority  of the Board of  Directors  of said
corporation, and that he signed his name thereto by like authority.



                                                  /S/ Karen R. Felt
                                                  ---------------------------
                                                  Karen R. Felt
                                                  Notary Public
                                                  My Commission Expires 02/28/99


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