<PAGE>
 
                                                                   June 24, 1996


Cable TV Fund 14-A/B Venture
c/o Jones Intercable, Inc.
9697 E. Mineral Avenue
Englewood, CO 80112
Attention:  J. Roy Pottle


     Re:  Fourth Letter Amendment 
          -----------------------
          Venture Revolving Credit 
          ------------------------


Gentlemen:

     Reference is made to that certain Revolving Credit and Term Loan Agreement,
dated as of September 30, 1988, by and among Cable TV Fund 14-A/B Venture (the
"Borrower"), The Bank of Nova Scotia and PNC Bank, National Association
(successor by merger to Provident National Bank) (the "Banks") and The Bank of
Nova Scotia, as agent for the Banks (the "Agent"), as amended by that certain
First Letter Amendment, dated June 11, 1990, that certain Second Letter
Amendment, dated May 28, 1992, and that certain Third Letter Amendment, dated
June 30, 1994 (the "Credit Agreement").  Capitalized terms used herein and not
otherwise defined shall have the meanings assigned to them in the Credit
Agreement.

     The Borrower desires the Banks to extend credit in excess of the
Commitments stated in the Third Letter Amendment, allow for a new revolving
period, extend the maturity date of the Term Loans to December 31, 2003, amend
the principal amortization schedule for the Term Loans, amend the Total Debt to
Annualized Cash Flow ratio covenant, extend the Capital Expenditure limitation,
and to make certain other changes to the Credit Agreement.  The Banks are
willing to amend the Credit Agreement for such purposes on the terms and
conditions stated in this Fourth Letter Amendment.

     Effective upon the satisfaction (or waiver by the Banks) of all of the
conditions precedent stated below, the Credit Agreement shall be amended as
follows:

     1.   Section 1.1 is hereby amended:

          (a) by deleting the definition of "Business Day" and replacing it with
     the following language:

                                      -1-
<PAGE>
 
          "'Business Day' shall mean any day other than a Saturday, Sunday,
            ------------
     public holiday under the laws of the State of New York or other day on
     which banking institutions are authorized or obligated to close in New York
     City, New York.";

     (b)  by deleting the definition of "Debt Service";

     (c)  by deleting the definition of "Excess Cash Flow";

     (d)  by deleting the definition of "Expiration Date" and replacing it with
the following language:

          "'Expiration Date' shall mean December 31, 1998.";
            ---------------

     (e)  by adding the following definitions after the definition of "FCC
License":

          "'Fourth Letter Amendment' shall mean that certain Fourth Letter
            -----------------------
     Amendment to Cable TV Fund 14-A/B Venture Revolving Credit and Term Loan
     Agreement, dated as of June 24, 1996, among Borrower, Agent and the Banks.

          "'Fourth Letter Amendment Closing Date' shall mean the date on which
            ------------------------------------
     the amendments contained in the Fourth Letter Amendment become effective
     pursuant to the terms thereof.";

     (f)  by adding the following definition after the definition of
"Indebtedness":

          "'Interest Expense' shall mean for any fiscal period the sum of the
            ----------------
     Borrower's cash interest expense paid on Total Debt for such period.";

     (g)  by adding the following definition after the definition of "Premium
Subscription":

          "'Pro Forma Debt Service' shall mean, with respect to the Borrower for
            ----------------------
     the twelve (12) complete calendar months immediately following the date of
     calculation, the sum of (a) interest scheduled to accrue in respect of
     Total Debt, plus (b) payments of principal scheduled to be paid on Total
     Debt, all in accordance with the documents, instruments and agreements
     evidencing such Total Debt.  For purposes of calculating Pro Forma Debt
     Service (i) where any item of interest on any Total Debt varies or depends
     upon a

                                      -2-
<PAGE>
 
          variable rate of interest (including, without limitation, the Base
          Rate or the Euro-Rate), such rate shall be assumed to equal the rate
          in effect on the date of calculation thereof and (ii) the principal
          amount outstanding under any revolving or line of credit facility
          shall be assumed to be the outstanding principal balance thereunder on
          the last day of the fiscal quarter immediately preceding the period in
          respect of which the calculation of Pro Forma Debt Service is being
          determined or, if less, the aggregate commitment under such revolving
          or line of credit facility as of the date of calculation, in each case
          adjusted to give effect to any mandatory commitment reductions which
          are scheduled to occur during such period in respect of which the
          calculation of Pro Forma Debt Service is being determined."; and

          (h)  by deleting the definition of "Term Loan Expiration Date" and
     replacing it with the following language:

               "'Term Loan Expiration Date' shall mean December 31, 2003."
                 -------------------------

     2.   Section 2.1(a) is hereby deleted in its entirety and replaced with the
following language:

          "(a)  The Commitments.  Subject to the terms and conditions and
                ---------------
     relying upon the representations and warranties herein set forth, each Bank
     severally agrees (such agreement being herein called such Bank's
     "Commitment") to make loans to the Borrower (the "Revolving Credit Loans")
     at any time or from time to time on or after the Fourth Letter Amendment
     Closing Date and to, but not including, the Expiration Date in an aggregate
     principal amount not exceeding at any one time outstanding such Bank's
     Current Commitment at such time.  Each Bank's "Current Commitment" at any
     given time shall be equal to the amount set forth opposite the name of such
     Bank in the table below, as such amount may have been reduced under Section
     2.4 hereof at such time."

<TABLE>
<CAPTION>
                                                     Percentage
     "Name of Bank          Current Commitment        Interest
      ------------          ------------------        --------
      <S>                   <C>                       <C>
 
     The Bank of
       Nova Scotia              $25,000,000             58.82%
 
     PNC Bank                   $17,500,000             41.18%
                                -----------             ------

     TOTAL                      $42,500,000            100.00%"
</TABLE> 

                                      -3-
<PAGE>
 
     3.   Section 2.4(a) is hereby deleted in its entirety and replaced with the
following language:

          "(a)  Commitment Fee.  The Borrower agrees to pay to the Agent, for
                --------------
     the account of each Bank, as consideration for the Banks' Commitments
     hereunder, a commitment fee equal to three-eighths of one percent (0.375%)
     per annum (based on a year of 365 or 366 days, as the case may be) on the
     unborrowed amount of the Current Commitment for each day from and including
     the Fourth Letter Amendment Closing Date to and including the Expiration
     Date.  A commitment fee shall be due and payable for the preceding period
     for which such fee has not been paid (i) on the last day of each March,
     June, September and December after the date hereof, (ii) on the date of
     each reduction of the Current Commitment on the amount so reduced and (iii)
     on the Expiration Date."

     4.  Section 2.6 is hereby deleted in its entirety and replaced with the
following language:

          "2.6  Term Loan Ceiling.
                -----------------

          "At no time shall the aggregate principal amount of Term Loans
     outstanding exceed the Term Loan Ceiling at such time.  The "Term Loan
     Ceiling" shall mean the aggregate principal amount of the Term Loans made
     on the Expiration Date as provided in Section 2.5(a) (the "Initial
     Ceiling"), reduced as follows:

          "(A)  On each March 31, June 30, September 30 and December 31 during
     each period indicated below the Term Loan Ceiling shall be reduced by
     amounts equal to the following percentages of the Initial Ceiling
     (regardless of whether the Term Loan Ceiling shall have been reduced
     pursuant to (B) below):

          January 1, 1999 - December 31, 1999     4%
          January 1, 2000 - December 31, 2000     4%
          January 1, 2001 - December 31, 2001     5%
          January 1, 2002 - December 31, 2002     6%
          January 1, 2003 - December 31, 2003     6%

          On December 31, 2003 the Term Loan Ceiling shall be reduced to zero
     (0)."

          "(B) In addition, if at any time Term Loans are prepaid or Rollover
     Loans are made in a lesser aggregate principal amount than the maturing
     Term Loans being rolled over except to the extent necessary as a result of
     a reduction in the Term Loan Ceiling pursuant to (A) above, the then
     current Term Loan Ceiling

                                      -4-
<PAGE>
 
     shall on such date be reduced by the amount of the prepayment or of such
     difference.

          "Once reduced, the Term Loan Ceiling may not be increased.  If on any
     Mandatory Reduction Date the outstanding Term Loans on such date shall
     exceed the Term Loan Ceiling as reduced on such date, the Borrower shall
     pay or prepay (subject, among other things, to Section 2.13(b) hereof)
     sufficient Loans to reduce the principal amount of the outstanding Loans to
     such reduced Term Loan Ceiling."

     5.  Section 2.8(a)(i) (Base Rate Option) is hereby deleted in its entirety
and replaced with the following language:

          "(i) Base Rate Option:  A rate per annum (computed on the basis of a
               ----------------
     year of 365 or 366 days, as the case may be) for each day equal to the Base
     Rate for such day, plus the percentage set forth below that corresponds to
     the Borrower's then current ratio of Total Debt to Annualized Cash Flow,
     such interest rate to change automatically from time to time effective as
     of the effective date of each change in the Base Rate or the date of the
     Borrower's financial statements evidencing a change in such ratio, as the
     case may be:

                       Ratio                  Percentage
                       -----                  ----------
               2.50  to 1.00 or greater          0.250%

               less than 2.50 to 1.00            0.125%."

     "Base Rate," as used herein, shall mean a fluctuating interest rate per
     annum equal at all times to the rate of interest announced by the Agent in
     New York City, New York from time to time in its sole discretion as its
     base rate.

     6.  Section 2.8(a)(ii) (CD Rate Option) is amended by deleting the first
sentence thereof and replacing it with the following language:

     "A rate per annum (based on a year of 360 days and actual days elapsed) for
     each day equal to the CD Rate for such day, plus the percentage set forth
     below that corresponds to the Borrower's then current ratio of Total Debt
     to Annualized Cash Flow, such percentage to change automatically from time
     to time effective as of the date of the Borrower's financial statements
     evidencing a change in such ratio:

                                      -5-
<PAGE>
 
                          Ratio                     Percentage
                          -----                     ----------
          
                 2.50  to 1.00 or greater             1.375%
          
                 less than 2.50 to 1.00               1.250%."

     7.  Section 2.8(a)(iii) Euro-Rate Option is amended by deleting the first
sentence thereof and replacing it with the following language:

         "A rate per annum (based on a year of 360 days and actual days
     elapsed) for each day equal to the Euro-Rate for such day, plus the
     percentage set forth below that corresponds to the Borrower's then current
     ratio of Total Debt to Annualized Cash Flow, such percentage to change
     automatically from time to time effective as of the date of the Borrower's
     financial statements evidencing a change in such ratio:     

                          Ratio                  Percentage
                          -----                  ----------

                 2.50  to 1.00 or greater          1.250%

                 less than 2.50 to 1.00            1.125%."

     8.  Section 2.11 is hereby deleted in its entirety and replaced with the
following language:

          "2.11 Interest Payment Dates.  Interest on each Base Rate Loan shall
                ----------------------
     be due and payable quarterly in arrears.  Interest on each CD Rate Loan
     shall be due and payable on the last day of the corresponding CD Rate
     Maturity Period and, if such CD Rate Maturity Period is longer than 90
     days, also every 90th day during such CD Rate Maturity Period.  Interest on
     each Euro-Rate Loan shall be due and payable on the last day of the
     corresponding Euro-Rate Maturity Period and, if such Euro-Rate Maturity
     Period is longer than three months, also quarterly during such Maturity
     Period.  After maturity of any Loan (by acceleration or otherwise),
     interest on such Loan shall be due and payable on demand."

     9.  Section 5.8 is hereby deleted in its entirety and replaced with the
following language:

          "5.8 Use of Proceeds.  Except as otherwise provided by Section 2.7
               ---------------
     hereof or the Subordination Agreement, the Borrower shall apply the
     proceeds of all Loans hereunder only to (a) repayment of the Term Loans
     outstanding on the Fourth Letter Amendment Closing Date, (b) repayment to
     Jones of Advances outstanding on the Fourth Letter Amendment Closing Date
     in an amount not to exceed three million eight

                                      -6-
<PAGE>
 
     hundred twenty thousand dollars ($3,820,000), and (c) otherwise for Capital
     Expenditures and other general business purposes."

     10.  Article V is amended by adding the following Section 5.11:

          "5.11 Interest Rate Protection.  On or before the date that is twelve
                ------------------------
     months from the Fourth Letter Amendment Closing Date, the Borrower shall
     enter into an interest rate protection agreement on terms and conditions
     satisfactory to the Banks in their sole discretion covering not less than
     fifty percent (50%) of the principal amount of the Loan outstanding at such
     time for a period of not less than three (3) years."

     11.  Article V is amended by adding the following Section 5.12:

          "5.12 Amendment Fee.  The Borrower shall pay to the Agent, for the
                -------------
     account of each Bank in proportion to their respective Current Commitments,
     as consideration for the agreement of the Banks to enter into the Fourth
     Letter Amendment, an amendment fee equal to one hundred fifty-nine thousand
     three hundred seventy-five dollars ($159,375), with one-half of the
     amendment fee payable on the Fourth Letter Amendment Closing Date and the
     remaining one-half of the amendment fee payable one year from the Fourth
     Letter Amendment Closing Date if the Borrower and a seller have not signed
     a binding purchase and sale agreement for the sale of all the Borrower's
     Systems on terms and conditions reasonably satisfactory to the Banks.  If
     the Borrower and a seller have signed such a binding purchase and sale
     agreement, the remaining one-half of the amendment fee will be due and
     payable nineteen months from the Fourth Letter Amendment Closing Date,
     unless prior to such time all amounts due hereunder, under the Notes and
     any Related Document have been paid in full and the Commitment has been
     terminated."

     12.  Section 6.1(a) is amended by deleting the last two lines of the table
of ratios of Total Debt to Annualized Cash Flow and replacing them with the
following:

     "April 1, 1996 - June 30, 1997           4.00 to 1.00
     July 1, 1997 - June 30, 1998             3.50 to 1.00
     July 1, 1998 and thereafter              3.00 to 1.00"

     13.  Section 6.1(b) is hereby deleted in its entirety and replaced with the
following language:

                                      -7-
<PAGE>
 
     "(b)  Annualized Cash Flow/Pro Forma Debt Service. The ratio of Annualized
           -------------------------------------------
     Cash Flow to Pro Forma Debt Service shall not be less than 1.50 to 1.00 at
     all times after the Fourth Letter Amendment Closing Date."

     14.  Section 6.1 is further amended by adding the following Section
6.1(c)after Section 6.1(b):

          "(c)  Cash Flow/Interest Expense. The ratio of Cash Flow to Interest
                --------------------------
     Expense shall exceed 2.50 to 1.00 at all times after the Fourth Letter
     Amendment Closing Date."

     15.  Section 6.14 is hereby deleted in its entirety and replaced with the
following language:

          "6.14 Capital Expenditures.  Borrower shall not make any Capital
                --------------------  
     Expenditures which in the aggregate exceed $3,000,000 in fiscal year 1988;
     $10,000,000 in fiscal year 1989; $9,000,000 in fiscal year 1990; $4,500,000
     in each of fiscal years 1991 through 1998; $5,000,000 in each of fiscal
     year 1999 through 2001; and $5,300,000 in any fiscal year of the Borrower
     thereafter. No unused portion of Capital Expenditures permitted in any
     given year may be carried forward to any subsequent year or years. The
     cost of Systems purchased by Borrower pursuant to Section 6.11 shall be
     included in Capital Expenditures hereunder."

     16.  Article VI is amended by adding the following new Section 6.18:

          "6.18  Management Fees.  Borrower shall not pay Management Fees which
                 ---------------
     exceed five percent (5%) of total revenue for any fiscal year of the
     Borrower."

     17.  The Credit Agreement is hereby amended to delete each reference to
"San Francisco time" and replace it with a reference to "New York City time."

     On the date upon which the amendments contained in this Fourth Letter
Amendment become effective, the Borrower shall repay all Term Loans outstanding
on such date from funds obtained from Revolving Loans made on such date,
together with all accrued and unpaid interest thereon and all other amounts owed
in connection with such repayment pursuant to the terms of the Credit Agreement.

     The effectiveness of the amendments contained in this Fourth Letter
Amendment is subject to the fulfillment, in form and substance satisfactory to
the Agent, of the following conditions precedent on or before June 24, 1996:

                                      -8-
<PAGE>
 
     (a) The Agent shall have received three counterparts of this Fourth Letter
Amendment duly accepted and executed by the Borrower, three counterparts
executed by The Bank of Nova Scotia, as a Bank, and three counterparts executed
by PNC Bank, National Association.

     (b) As amended by Exhibit A hereto, the representations and warranties
contained in Article III of the Credit Agreement and in the Related Documents
shall be true on and as of the date of execution and acceptance of this Fourth
Letter Amendment by the Borrower with the same effect as though made on and as
of such date, and no Event of Default and no Potential Default shall have
occurred and be continuing or exist or shall occur or exist after giving effect
to the amendments contained herein.

     (c) The Agent shall have received three signed copies of a certificate,
dated the date of the Borrower's acceptance and execution of this Fourth Letter
Amendment, and signed on behalf of the Borrower by the President, Vice
President, Treasurer or Chief Financial Officer of Jones, to the effect that (i)
the representations and warranties described in (b) above are true and correct
on and as of such date and (ii) on such date no Event of Default or Potential
Default has occurred and is continuing or exists or will occur or exist after
giving effect to the amendments contained herein.

     (d) The Agent shall have received three signed copies of certificates dated
as of the date of the Borrower's acceptance and execution of this Fourth Letter
Amendment and signed by the Secretary or Assistant Secretary of Jones, on behalf
of Jones, the Borrower, and each General Partner, certifying as to any changes
since the Closing Date, if any, in the corporate, joint venture or partnership
documents and actions referred to in section 4.2 of the Credit Agreement, of
Jones, the Borrower and each General Partner, respectively and, in the case of
Jones, (i) as to the names, true signatures and incumbency of the officer or
officers or other authorized representatives of Jones authorized to accept,
execute and deliver this Fourth Letter Amendment and the certificate referred to
in (c) above, and (ii) as to the resolution of the Board of Directors of Jones
authorizing such action.

     (e) The Agent shall have received certificates (i) of the Secretary of
State of the State of Colorado certifying that Jones is a corporation in good
standing and that each General Partner is a limited

                                      -9-
<PAGE>
 
     partnership in good standing, and (ii) of the Secretary of State of the
     State of Florida certifying that each General Partner is qualified to do
     business in Florida.

          (f)  The Agent shall have received payment in full of the portion of
     the amendment fee due on the Fourth Letter Amendment Closing Date pursuant
     to Section 11 of this Fourth Letter Amendment, for distribution to the
     Banks in proportion to their respective Current Commitments.

          (g)  Each Bank shall have received a substitute Note, in the form of
     Exhibit B hereto, duly executed by the Borrower, reflecting the amendments
     to the Commitment and maturity dates contained in this Fourth Letter
     Amendment (and thereafter shall return the Notes issued on June 15, 1990 to
     the Borrower).

          (h)  The Agent shall have received all amendments to the Related
     Documents requested by the Banks to reflect the transactions contemplated
     hereby, executed by all parties thereto.

          (i)  All actions necessary or desirable in the opinion of the Banks to
     preserve and protect the first priority lien of Agent established by the
     Security Documentation shall have been taken, including, without
     limitation, recording of an amendment to the Mortgage to reflect the
     transactions contemplated hereby and endorsements to all title policies
     held by Agent confirming the first priority nature of the Mortgage as so
     amended.

          (j)  The Agent shall have received legal opinions from counsel to
     Borrower on such matters related to the transactions contemplated hereby as
     the Banks may reasonably request.

          (k) The Agent shall have received all such other instruments,
     approvals or documents as the Banks may reasonably request.

     Except as amended hereby, the Credit Agreement shall remain in full force
and effect and is hereby ratified and confirmed. This Fourth Letter Amendment
may be executed in two or more counterparts, each of which shall be deemed an
original.

                                      -10-
<PAGE>
 
      If you agree to the foregoing amendments to the Credit Agreement, execute
the enclosed counterparts of this letter in the space provided below and return
them to us prior to June 28, 1996.

                               THE BANK OF NOVA SCOTIA, 
                               as Agent and as a participating 
                               Bank



                               By  [SIGNATURE APPEARS HERE]
                                  ---------------------------------------

                                  Title  Authorized Signatory
                                        ---------------------------------

Accepted:

CABLE TV FUND 14-A/B VENTURE,        Date:
a Colorado general partnership

By  Cable TV Fund 14-A, Ltd., 
    Cable TV Fund 14-B, Ltd., 
    both Colorado limited partnerships

    By  Jones Intercable, Inc., 
        a Colorado corporation, 
        as general partner of each


        By  [SIGNATURE APPEARS HERE]
           ---------------------------------

           Title  VICE PRESIDENT/TREASURER
                 ---------------------------

PNC BANK, NATIONAL ASSOCIATION,
as a participating Bank



By  [SIGNATURE APPEARS HERE]
   ----------------------------------------

   Title  SVP
         ----------------------------------

                                      -11-