<PAGE>   1
                                                                    EXHIBIT 10.6

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                                  ODWALLA, INC.


                      PREFERRED STOCK CONVERSION AGREEMENT




                           Dated as of April 24, 2000


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<PAGE>   2
                                TABLE OF CONTENTS


<TABLE>
<CAPTION>
                                                                                                Page
                                                                                                ----
<S>     <C>                                                                                     <C>
1.      Conversion of Preferred Stock and Cancellation of Warrant...........................      1

2.      Tax Treatment.......................................................................      2

3.      Closing.............................................................................      2

4.      Closing Conditions..................................................................      2

5.      Representations and Warranties of Catterton.........................................      3

        5.1    Authorization................................................................      3

        5.2    Disclosure of Information....................................................      3

        5.3    Status.......................................................................      3

        5.4    Investment Intent; Certain Restrictions......................................      4

        5.5    Restricted Securities........................................................      4

6.      Representations and Warranties of the Company.......................................      4

        6.1    Authorization................................................................      4

        6.2    Private Placement............................................................      5

7.      Other Matters.......................................................................      5

        7.1    Limitation on Conversion of Preferred Stock..................................      5

        7.2    Restrictive Legend...........................................................      5

        7.3    California Securities Laws...................................................      5

8.      Termination.........................................................................      6

        8.1    General......................................................................      6

        8.2    Effect of Termination........................................................      6

        8.3    Exclusivity of Termination Rights............................................      6

9.      Miscellaneous.......................................................................      6

        9.1    Further Assurances...........................................................      6

        9.2    Fees and Expenses............................................................      6

        9.3    Attorneys' Fees..............................................................      6

        9.4    Governing Law; Arbitration...................................................      6

        9.5    Successors and Assigns.......................................................      7

        9.6    Entire Agreement.............................................................      7
</TABLE>


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<PAGE>   3
<TABLE>
<CAPTION>
                                                                                                Page
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<S>     <C>                                                                                     <C>
        9.7    Separability.................................................................      7

        9.8    Amendments...................................................................      7

        9.9    Notices......................................................................      8

        9.10   Publicity and Use of Confidential Information................................      8

        9.11   Counterparts.................................................................      9

        9.12   Delays or Omissions; Waivers.................................................      9

        9.13   Remedies Cumulative; Specific Performance....................................      9

        9.14   Headings.....................................................................     10

        9.15   Construction.................................................................     10
</TABLE>


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<PAGE>   4
                                  ODWALLA, INC.
                      PREFERRED STOCK CONVERSION AGREEMENT


        THIS PREFERRED STOCK CONVERSION AGREEMENT (the "Agreement") is entered
into as of April 24, 2000, by and between ODWALLA, INC., a California
corporation (the "Company"), and CATTERTON-SIMON PARTNERS III, L.P., a Delaware
Limited Partnership ("Catterton").

                                    RECITALS

        A.      The Company, Orange Acquisition Sub, a Maine corporation and
                wholly owned subsidiary of the Company ("Merger Sub"), Fresh
                Samantha, Inc., a Maine corporation ("Samantha"), and the other
                signatories thereto, have entered into that certain Agreement
                and Plan of Merger, dated as of February 2, 2000 (the "Merger
                Agreement"), to effectuate the merger (the "Merger") of Merger
                Sub with and into Samantha, with Samantha as the surviving
                corporation and wholly owned subsidiary of the Company.

        B.      Pursuant to that certain Stock and Warrant Purchase Agreement,
                dated as of January 29, 1999 (the "Purchase Agreement"), by and
                between the Company and Catterton, Catterton purchased (i)
                1,000,000 shares of the Company's Series A Preferred Stock (the
                "Preferred Stock") convertible into the Common Stock of the
                Company (the "Common Stock") on a 1:1 basis, and (ii) a Warrant,
                dated as of February 10, 1999, to purchase 75,000 shares of the
                Company's Common Stock at $10.00 per share (the "Warrant").

        C.      Pursuant to the dividend preference of the Preferred Stock,
                Catterton has received stock dividends in the amount of 74,666
                shares of Preferred Stock.

        D.      In connection with the Merger, Catterton and U.S. Equity
                Partners, L.P. (and its affiliates) have entered into that
                certain Stock Purchase Agreement, dated as of February 12, 2000,
                pursuant to which Catterton shall purchase an additional 160,128
                shares of Common Stock.

        E.      Pursuant to the terms of the Merger, the obligation of the
                parties to consummate the Merger is subject to, among other
                things, both the conversion of the Preferred Stock into Common
                Stock and the cancellation of the Warrant.

                                    AGREEMENT

        The Company and Catterton, intending to be legally bound, agree as
follows:

1.      CONVERSION OF PREFERRED STOCK AND CANCELLATION OF WARRANT.

        In consideration of both the conversion of the Preferred Stock into
Common Stock and the cancellation of the Warrant pursuant this Section 1, and
subject to the terms and conditions hereof, the approval of the shareholders of
the Company and the amendment of the Certificate of Determination, filed January
26, 1999, setting forth the preference and rights of the Preferred Stock (the
"Certificate"), at the Closing (a) the 1,074,666 shares of Preferred Stock
presently


                                       1


<PAGE>   5
held by Catterton shall be converted into 1,333,333 shares of Common Stock
pursuant to a conversion ratio of 1:1.2407, and (b) the Warrant shall be
cancelled and be of no further force and effect.

2.      TAX TREATMENT.

        For tax purposes, the parties hereto acknowledge and agree that the
transactions contemplated by this Agreement (the "Transactions") shall be
treated as a recapitalization in accordance with Section 368(a)(1)(E) of the
Internal Revenue Code of 1986, as amended.

3.      CLOSING

               (a) The closing (the "Closing") shall take place at the offices
of Morrison & Foerster LLP, 425 Market Street, San Francisco, California 94105,
at 10:00 a.m. (Pacific time) contemporaneous with the Merger Closing Date (as
defined below) or on such other date or at such other place or time as the
Company and Catterton may mutually agree (such date is hereinafter referred to
as the "Closing Date").

               (b) At the Closing:

                      (i) Catterton will deliver: (i) the stock certificate(s)
representing the Preferred Stock; (ii) the Warrant, marked "CANCELLED;" and
(iii) any other documents and agreements reasonably requested by the Company to
be delivered at the Closing; and

                      (ii) the Company shall deliver: (i) certificates
representing the Common Stock to be issued to Catterton pursuant to this
Agreement in proper form for transfer; and (ii) the other documents and
agreements required hereunder to be delivered by the Company at the Closing.

               (c) The "Merger Closing Date" shall refer to that date upon which
all of the conditions set forth in Sections 4.1 and 4.2 of the Merger Agreement,
other than the condition requiring the conversion of the Preferred Stock held by
Catterton into Common Stock, are satisfied or waived.

4.      CLOSING CONDITIONS.

        Each of the Company's obligation to issue the Common Stock at the
Closing, and Catterton's obligations to convert the Preferred Stock into Common
Stock and cancel the Warrant at the Closing, are subject to the satisfaction of
the following conditions:

               (a) the amendment to the Certificate, substantially in the form
attached hereto as Exhibit A, shall have been accepted for filing by the
Secretary of State of the State of California;

               (b) the Merger shall have been consummated pursuant to all of the
material terms and conditions contained in the Merger Agreement, except (i) for
the condition requiring the conversion of the Preferred Stock held by Catterton
into Common Stock, and (ii) with the consent of Catterton (which consent shall
not be unreasonably withheld), to the extent (A) any


                                       2


<PAGE>   6
change in the terms and conditions of the Merger Agreement benefit the Company,
or (B) the waiver or non-satisfaction of a condition contained in the Merger
Agreement is for the benefit of the Company; and

               (c) neither the consummation nor the performance of the
Transactions will, directly or indirectly (with or without notice or lapse of
time), contravene or conflict with or result in a violation of, or cause a
material adverse effect on the condition (financial or otherwise), assets,
liabilities, obligations, business, properties, prospects or results of
operations of the Company as presently conducted or as proposed to be conducted,
together with its subsidiaries taken as a whole, as a result of, specifically,
(i) a change in any applicable legal requirement after the date of this
Agreement or any federal or state judgment, order, writ, decree, statute or
regulation of any court, regulatory body or administrative agency or other
governmental body applicable to the Company (an "Order") issued after the date
of this Agreement, or (ii) any legal requirement or Order that is proposed after
the date of this Agreement by or before any governmental body.

5.      REPRESENTATIONS AND WARRANTIES OF CATTERTON.

        Catterton hereby represents and warrants to the Company that:

        5.1     AUTHORIZATION.

        Catterton has full power and authority to enter into this Agreement, and
this Agreement constitutes the valid and legally binding obligation of
Catterton, enforceable against Catterton in accordance with its terms, except
(i) as limited by applicable bankruptcy, insolvency, reorganization, moratorium,
and other laws of general application affecting enforcement of creditors' rights
generally, and (ii) as limited by laws relating to the availability of specific
performance, injunctive relief, or other equitable remedies.

        5.2     DISCLOSURE OF INFORMATION.

        Catterton further represents that it has had an opportunity to ask
questions and receive answers from the Company regarding the terms and
conditions of the conversion of the Preferred Stock and the business,
properties, prospects and financial condition of the Company.

        5.3     STATUS.

               (a) Catterton is an "accredited investor" as that term is defined
in Rule 501(a) of Regulation D of the Securities Act.

               (b) Catterton, by reason of its business and financial experience
has such knowledge, sophistication and experience in financial and business
matters and in making investment decisions of this type that it is capable of
(i) evaluating the merits and risks of an investment in the Common Stock of the
Company and making an informed investment decision, (ii) protecting its own
interest, and (iii) bearing the economic risk of such investment for an
indefinite period of time.


                                       3


<PAGE>   7
        5.4     INVESTMENT INTENT; CERTAIN RESTRICTIONS.

               (a) Catterton is acquiring the Common Stock for investment for
its own account, not as a nominee or agent and not with the view to, or any
intention of, a resale or distribution thereof, in whole or in part, or the
grant of any participation therein. Catterton understands that the Common Stock
has not been, and will not be, registered under the Securities Act or state
securities laws by reason of specific exemptions from the registration
provisions of the Securities Act and applicable state securities laws that
depend upon, among other things, the bona fide nature of Catterton's investment
intent and the accuracy of Catterton's representations as set forth in this
Section 5. Catterton has not been formed for the specific purpose of acquiring
the Common Stock. Catterton further understands that, other than pursuant to
that certain Shareholders' Rights Agreement, to be entered into on the Merger
Closing Date by and among the Company, Catterton and the other signatories
thereto, the Company shall have no obligation to register the Common Stock under
the Securities Act or any state securities laws or to take any action that would
make available any exemption from the registration requirements of such laws.
Catterton hereby acknowledges that because of the restrictions on transfer and
assignment of the Common Stock, Catterton may have to bear the economic risk of
the investment in the Common Stock for an indefinite period of time.

               (b) Catterton will observe and comply with the Securities Act and
the rules and regulations promulgated thereunder, as now in effect and as from
time to time amended, in connection with any offer, sale, pledge, transfer or
other disposition of the Common Stock.

        5.5     RESTRICTED SECURITIES.

        Catterton understands that the shares of Common Stock issuable by the
Company upon conversion of the Preferred Stock are characterized as "restricted
securities" under the federal securities laws inasmuch as they are being
acquired from the Company in a transaction not involving a public offering and
that under such laws and applicable regulations such securities may be resold
without registration under the Securities Act only in certain limited
circumstances. In this connection, Catterton represents that it is familiar with
Rule 144, as presently in effect, and understands the resale limitations imposed
hereby and by the Securities Act.

6.      REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

        The Company hereby represents and warrants to Catterton that:

        6.1     AUTHORIZATION.

        The Company has full power and authority to enter into this Agreement,
and this Agreement constitutes the valid and legally binding obligation of the
Company, enforceable against the Company in accordance with its terms, except
(i) as limited by applicable bankruptcy, insolvency, reorganization, moratorium,
and other laws of general application affecting enforcement of creditors' rights
generally, and (ii) as limited by laws relating to the availability of specific
performance, injunctive relief, or other equitable remedies.


                                       4


<PAGE>   8
        6.2     PRIVATE PLACEMENT.

        The offer, sale and issuance of the Common Stock upon conversion of the
Preferred Stock as contemplated by this Agreement is exempt from the
registration requirements of the Securities Act of 1933, as amended (the
"Securities Act") and state securities "blue sky" laws, and neither the Company
nor any authorized agent acting on its behalf will take any action hereafter
that would cause the loss of such exemptions.

7.      OTHER MATTERS.

        7.1     LIMITATION ON CONVERSION OF PREFERRED STOCK.

               The parties hereto agree and understand that they are entering
into this Agreement in connection with the Merger, and therefore Catterton
covenants and agrees that, notwithstanding the acceptance by the Secretary of
State of the State of California of the aforementioned amendment to the
Certificate, Catterton shall only convert the Preferred Stock at the higher
conversion ratio contained in such amendment pursuant to the terms of this
Agreement in connection with the consummation of the Merger.

        7.2     RESTRICTIVE LEGEND.

               All certificates representing the Common Stock deliverable to
Catterton pursuant to this Agreement, and any certificates subsequently issued
with respect thereto or in substitution therefor, shall bear the following
legend:

        THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
        UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), AND MAY NOT BE
        SOLD, TRANSFERRED, ASSIGNED OR HYPOTHECATED UNLESS PURSUANT TO THE TERMS
        specified in thAT certain SHAREHOLDERS' rights agreement, dated as of
        APRIL __, 2000. copIES of such Agreements may be obtained froM ODWALLA,
        INC. without charge, by the holder of this certificate upon written
        request therefor.

        7.3     CALIFORNIA SECURITIES LAWS.

        THE SALE OF THE SECURITIES THAT ARE THE SUBJECT OF THIS AGREEMENT HAS
NOT BEEN QUALIFIED WITH THE COMMISSIONER OF CORPORATIONS OF THE STATE OF
CALIFORNIA AND THE ISSUANCE OF SUCH SECURITIES OR THE PAYMENT OR RECEIPT OF ANY
PART OF THE CONSIDERATION FOR SUCH SECURITIES PRIOR TO SUCH QUALIFICATION IS
UNLAWFUL, UNLESS THE SALE OF SECURITIES IS EXEMPT FROM QUALIFICATION BY SECTION
25100, 25102 OR 25105 OF THE CALIFORNIA CORPORATIONS CODE. THE RIGHTS OF ALL
PARTIES TO THIS AGREEMENT ARE EXPRESSLY CONDITIONED UPON SUCH QUALIFICATION
BEING OBTAINED, UNLESS THE SALE IS SO EXEMPT.


                                       5


<PAGE>   9
8.      TERMINATION.

        8.1     GENERAL.

        This Agreement may be terminated prior to Closing by the mutual consent
of the Company and Catterton.

        8.2     EFFECT OF TERMINATION.

        If this Agreement is terminated pursuant to Section 8.1, all further
obligations of the parties under this Agreement shall terminate provided,
further, that Sections 9.2, 9.3, 9.4, 9.9 and 9.10 shall survive the termination
of this Agreement.

        8.3     EXCLUSIVITY OF TERMINATION RIGHTS.

        Except to the extent termination occurs due to the bad faith of the
other party, the termination rights and obligations provided in this Section 8
shall be deemed to be exclusive. The parties shall not have any other or further
liabilities to or with respect to one another by reason of this Agreement or its
termination.

9.      MISCELLANEOUS.

        9.1     FURTHER ASSURANCES.

        Each party hereto shall execute and/or cause to be delivered to each
other party hereto such instruments and other documents, and shall take such
other actions, as such other party may reasonably request (prior to, at or after
the Closing) for the purpose of carrying out or evidencing any of the
Transactions.

        9.2     FEES AND EXPENSES.

        The Company shall bear the reasonable costs and expenses with respect to
the negotiation, execution and delivery of this Agreement and in connection with
the Transactions, including any transfer, recording or similar taxes levied as a
result of the consummation of the Transactions.

        9.3     ATTORNEYS' FEES.

        If any legal action or other legal proceeding (including arbitration)
relating to the Transactions or the enforcement of any provision of any of this
Agreement is brought against any party hereto, the person presiding over such
action or other proceeding may award reasonable attorneys' fees, costs and
disbursements to the prevailing party (in addition to any other relief to which
the prevailing party may be entitled).

        9.4     GOVERNING LAW; ARBITRATION.

               (a) This Agreement is to be construed in accordance with and
governed by the laws of the State of California (as permitted by Section 1646.5
of the California Civil Code or


                                       6


<PAGE>   10
any similar successor provision), without giving effect to any choice of law
rule that would cause the application of the laws of any jurisdiction other than
the State of California to the rights and duties of the parties.

               (b) Any controversy or claim arising out of or relating to this
Agreement, or breach thereof, shall be settled by arbitration administered by
the American Arbitration Association in accordance with its then existing
Commercial Arbitration rules and judgment upon the award rendered by the
arbitrator may be entered in any court having jurisdiction thereof. The
arbitrator shall be appointed by mutual agreement of the Company and Catterton
involved in such controversy or claim, but, if the Company and Catterton fail to
agree, the arbitrator shall be appointed by the American Arbitration Association
in accordance with its then existing rules. The place of the arbitration shall
be San Francisco, California and the governing law shall be the laws of the
State of California in accordance with Section 9.4(a) of this Agreement.

        9.5     SUCCESSORS AND ASSIGNS.

        Except as otherwise expressly provided herein, the provisions hereof
shall inure to the benefit of, and be binding upon, the successors, assigns,
heirs, executors and administrators of the parties hereto and shall inure to the
benefit of and be enforceable by each person who shall be a holder from time to
time of the Common Stock to be issued pursuant to this Agreement. None of the
parties hereto may assign any of its or their rights or obligations hereunder to
any other party (by contract, operation of law or otherwise) without the prior
written consent of the other, which consent shall not be unreasonably withheld,
and any attempted assignment in violation thereof shall be void and of no
effect.

        9.6     ENTIRE AGREEMENT.

        This Agreement constitutes the full and entire understanding and
agreement among the parties thereto with regard to the subjects hereof and
supersede all prior agreements and understandings among or between any of the
parties relating to the subject matter hereof and thereof.

        9.7     SEPARABILITY.

        In case any provision of this Agreement shall be invalid, illegal or
unenforceable, the validity, legality and enforceability of the remaining
provisions shall not in any way be affected or impaired thereby, unless such
provision is material to the terms of this Agreement, in which case the Company
and Catterton shall in good faith agree upon such amendments as are necessary to
restore the original intent and arrangement between the parties.

        9.8     AMENDMENTS.

        This Agreement may be amended or modified only upon the written consent
of the Company and Catterton. Any amendment or modification effected pursuant to
this Section 9.8 shall be binding upon the Company and Catterton.


                                       7


<PAGE>   11
        9.9     NOTICES.

        Any notice or other communication required or permitted to be delivered
to any party under this Agreement shall be in writing and shall be deemed
properly delivered and given (a) on the date delivered or given, when delivered
or given by hand or by telecopier during business hours, (b) one business day
after being delivered or given by courier or next-day express delivery service,
or (c) two business days after being delivered or give by registered mail to the
address set forth beneath the name of such party below (or to such other address
or telecopier number as such party shall have specified in a written notice
given to the other parties hereto):

if to the Company:

        Odwalla, Inc.
        120 Stone Pine Road
        Half Moon Bay, CA  94019
        Attention:  D. Stephen C. Williamson
        Telecopier: (650) 712-5967

        with a copy to:

        Morrison & Foerster LLP
        425 Market Street
        San Francisco, California 94105
        Attention: Robert Townsend, Esq.
        Telecopier: (415) 268-7522


if to Catterton-Simon Partners:


        Greenwich Office Park
        Greenwich, Connecticut 06830
        Attention:  Craig Sakin
        Telecopier:  (203) 629-4903

        with copies to:

        Morgan, Lewis & Bockius LLP
        101 Park Avenue
        New York, NY 10178-0060
        Attention:  Philip H. Werner
        Telecopier:  (212) 309-6273

        9.10    PUBLICITY AND USE OF CONFIDENTIAL INFORMATION.

               (a) Notwithstanding anything to the contrary contained in any
agreement among the parties hereto, the Company shall have the right to disclose
the terms of this Agreement through the use of printed offering materials or
otherwise or as otherwise required by applicable legal requirements, in
connection with the preparation of a proxy statement (the "Proxy


                                       8


<PAGE>   12
Statement") in connection with the solicitation by the Board of Directors of the
Company of the affirmative vote of a majority of the outstanding Common Stock
and Preferred Stock to approve the Merger and related matters.

               (b) Neither Catterton, on the one hand, nor the Company, on the
other hand, shall issue or disseminate any press release or other publicity
concerning any of the Transactions, or permit any press release or other
publicity concerning any of the Transactions to be issued or otherwise
disseminated on its behalf without the prior written consent of Catterton, in
the case of the Company, or the Company, in the case of Catterton; provided,
however, that the Company and Catterton may disclose or disseminate such
information as required by any applicable law or rule to which the Company or
the Catterton are subject, including the Securities Exchange Act of 1934, as
amended, and the rules of the National Association of Securities Dealers.

        9.11    COUNTERPARTS.

        This Agreement may be executed in any number of counterparts, each of
which shall be an original, but all of which together shall constitute one
instrument.

        9.12    DELAYS OR OMISSIONS; WAIVERS.

               (a) No failure on the part of any person to exercise any power,
right, privilege or remedy under this Agreement, and no delay on the part of any
person in exercising any power, right, privilege or remedy under this Agreement,
shall operate as a waiver of such power, right, privilege or remedy; and no
single or partial exercise or waiver of any such power, right, privilege or
remedy shall preclude any other or further exercise thereof or of any other
power, right, privilege or remedy.

               (b) No person shall be deemed to have waived any claim arising
out of this Agreement, or any power, right, privilege or remedy under this
Agreement, unless the waiver of such claim, power, right, privilege or remedy is
expressly set forth in a written instrument duly executed and delivered on
behalf of such person; and any such waiver shall not be applicable or have any
effect except in the specific instance in which it is given.

        9.13    REMEDIES CUMULATIVE; SPECIFIC PERFORMANCE.

               (a) All remedies, either under this Agreement or by law or
otherwise afforded to the parties hereto, shall be cumulative and not
alternative.

               (b) Each of the parties hereto agrees that if the conditions to
such party's obligation to consummate the Transactions have been satisfied as
set forth in Section 4, as the case may be, and such party nonetheless refuses
to consummate the Transactions, then the other party shall be entitled (in
addition to any other remedy that may be available to it) to (i) a decree or
order of specific performance or mandamus to enforce the observance and
performance of such obligation to consummate the Transactions, and (ii) an
injunction restraining such non-performance.


                                       9


<PAGE>   13
        9.14    HEADINGS.

        The headings contained in this Agreement are for convenience of
reference only, shall not be deemed to be a part of this Agreement and shall not
be referred to in connection with the construction or interpretation of this
Agreement.

        9.15    CONSTRUCTION.

               (a) For purposes of this Agreement, whenever the context
requires: the singular number shall include the plural, and vice versa; the
masculine gender shall include the feminine and neuter genders; the feminine
gender shall include the masculine and neuter genders; and the neuter gender
shall include the masculine and feminine genders.

               (b) The parties hereto agree that any rule of construction to the
effect that ambiguities are to be resolved against the drafting party shall not
be applied in the construction or interpretation of this Agreement.

               (c) As used in this Agreement, the words "include" and
"including," and variations thereof, shall not be deemed to be terms of
limitation, but rather shall be deemed to be followed by the words "without
limitation."

               (d) Except as otherwise specified, all references in this
Agreement to "Sections" are intended to refer to Sections of this Agreement.


                                       10


<PAGE>   14
        IN WITNESS WHEREOF, the parties hereto have executed this PREFERRED
STOCK CONVERSION AGREEMENT as of the date set forth in the first paragraph
hereof.



COMPANY:                           ODWALLA, INC.,
                                   a California corporation

                                   By:
                                      -------------------------------------
                                         Name: D. Stephen C. Williamson
                                         Title:   Chief Executive Officer


                                   CATTERTON-SIMON PARTNERS III, L.P.,
                                   a Delaware limited partnership

                                   By:
                                      -------------------------------------
                                         Name:  Craig Sakin
                                         Title:    Authorized Person


                                       11


<PAGE>   15
                                    EXHIBIT A

                    AMENDMENT TO CERTIFICATE OF DETERMINATION
                           OF SERIES A PREFERRED STOCK


                                       12