<PAGE>   1


Exhibit 10(a)
                                     WAIVER

                  WAIVER, dated as of September 29, 1999 (this "Waiver"), to the
Credit Agreement, dated as of May 6, 1997, as amended by Amendment No. 1, dated
as of January 30, 1998 and as amended by Amendment No. 2, dated as of December
23, 1998 ( as amended, supplemented or otherwise modified from time to time, the
"Credit Agreement"), among TELEX COMMUNICATIONS, INC., a Delaware corporation
("Telex" or the "Borrower"), the several banks and other financial institutions
from time to time parties thereto (the "Lenders"), MORGAN STANLEY SENIOR
FUNDING, INC., as documentation agent for the Lenders (in such capacity, the
"Documentation Agent"), and THE CHASE MANHATTAN BANK, a New York banking
corporation, as administrative agent for the Lenders (in such capacity, the
"Administrative Agent").

                              W I T N E S S E T H:

                  WHEREAS, the Borrower has requested that the Administrative
Agent and the Lenders waive certain covenants contained in the Credit Agreement;
and

                  WHEREAS, the Administrative Agent and the Lenders are willing
to agree to the requested waiver on the terms and conditions contained herein;

                  NOW, THEREFORE, the parties hereto hereby agree as follows:

                  1. Defined Terms. Terms defined in the Credit Agreement and
used herein shall have the meanings given to them in the Credit Agreement.

                  2. Waiver of Subsection 8.1(a). The Lenders hereby waive
compliance with the covenant in Subsection 8.1(a) for the period from September
30, 1999 to October 31, 1999.

                  3. Waiver of Subsection 8.1(b). The Lenders hereby waive
compliance with the covenant in Subsection 8.1(b) for the period from September
30, 1999 to October 31, 1999.

                  4. Waiver of Subsection 8.1(c). The Lenders hereby waive
compliance with the covenant in Subsection 8.1(c) for the period from September
30, 1999 to October 31, 1999.

                  5. Conditions to Effectiveness. This Waiver shall become
effective on the date (the "Waiver Effective Date") on which Telex, the
Administrative Agent and the Required Lenders shall have executed and delivered
to the Administrative Agent this Waiver.

                  6. General.

                  (a) Representation and Warranties. In order to induce the
Administrative Agent and the Lenders to enter into this Waiver, the Borrower
hereby represents and warrants to the Administrative Agent and the Lenders that
the representations and warranties of the Borrower contained in the Loan
Documents are true and correct in all material respects on and as of the Waiver
Effective Date (after giving effect hereto) as if made on and as of the Waiver
Effective Date (except where such representations and warranties expressly
relate to an earlier date in which case such representations and warranties were
true and correct in all material respects as of such earlier date); provided
that all references to the "Credit Agreement" in any Loan Document shall be and
are deemed to mean the Credit Agreement as amended hereby.



<PAGE>   2

Additionally, the Borrower represents and warrants that GSCP has consented to
not accept any payment in cash for its management fee (as more fully described
in the agreement between Telex and GSCP for the rendering of management
consulting or financial advisory services described in Section 8.10(ii) of the
Credit Agreement) during the period covered by this Waiver and the Borrower
agrees not to pay such management fee during such period; it being understood
and agreed that such management fee may continue to accrue during such period in
accordance with the terms of such agreement.

                  (b) Affirmation of Guarantees. Each Guarantor party hereto
hereby consents to the execution, delivery and effectiveness of this Waiver and
reaffirms its obligations under the Guarantee and Collateral Agreement.

                  (c) Payment of Expenses. The Borrower agrees to pay or
reimburse the Administrative Agent for all its reasonable out-of-pocket costs
and expenses incurred in connection with this Waiver, any other documents
prepared in connection herewith and the transactions contemplated hereby,
including, without limitation, the reasonable fees and disbursements for a
single law firm of counsel to the Administrative Agent.

                  (d) Counterparts. This Waiver may be executed in two or more
counterparts (including by facsimile transmission), each of which shall
constitute an original, but all of which when taken together shall constitute
but one instrument.

                  (e) Headings. Section headings used in this Waiver are for
convenience of reference only, are not part of this Waiver and are not to affect
the construction of, or to be taken into consideration in interpreting, this
Waiver.

                  (f) Continuing Effect of Loan Documents. This Waiver shall not
constitute an amendment or waiver of any other provision of the Credit Agreement
not expressly referred to herein and shall not be construed as a waiver or
consent to any further or future action on the part of the Borrower that would
require a waiver or consent of the Required Lenders or Lenders, as the case may
be, or the Administrative Agent. Except as expressly amended, modified and
supplemented hereby, the provisions of the Credit Agreement and the other Loan
Documents are and shall remain in full force and effect.

                  (G) GOVERNING LAW. THIS WAIVER AND THE RIGHTS AND OBLIGATIONS
OF THE PARTIES UNDER THIS WAIVER SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

<PAGE>   3


                  IN WITNESS WHEREOF, the parties hereto have caused this Waiver
to be duly executed and delivered by their respective proper and duly authorized
officers as of the day and year first above written.

                                 TELEX COMMUNICATIONS, INC.


                                 By:
                                    ---------------------------------
                                    Title:






                                 TELEX COMMUNICATIONS GROUP, INC.


                                 By:
                                    ---------------------------------
                                    Title:





                                 TELEX COMMUNICATIONS INTERNATIONAL, LTD.


                                 By:
                                    ---------------------------------
                                    Title:









<PAGE>   4


                                 THE CHASE MANHATTAN BANK,
                                 as Administrative Agent and as a Lender


                                 By:
                                    ---------------------------------
                                    Title:





                                 MORGAN STANLEY SENIOR FUNDING, INC.
                                 as Documentation Agent and as a Lender


                                 By:
                                    ---------------------------------
                                    Title:





                                 BANKBOSTON, N.A.


                                 By:
                                    ---------------------------------
                                    Title:




                                 THE BANK OF NEW YORK


                                 By:
                                    ---------------------------------
                                    Title:



                                 U.S. BANK NATIONAL ASSOCIATION



                                 By:
                                    ---------------------------------
                                    Title:




                                 HELLER FINANCIAL, INC.


                                 By:
                                    ---------------------------------
                                    Title:


<PAGE>   5

                                 THE BANK OF NOVA SCOTIA


                                 By:
                                    ---------------------------------
                                    Title:



                                 MERRILL LYNCH SENIOR FLOATING RATE FUND, INC.


                                 By:
                                    ---------------------------------
                                    Title:



                                 MERRILL LYNCH PRIME RATE PORTFOLIO
                                 By:  Merrill Lynch Asset Management, L.P.,
                                      as Investment Advisor


                                 By:
                                    ---------------------------------
                                    Title:



                                 THE ING CAPITAL SENIOR SECURED HIGH
                                 INCOME FUND, L.P.
                                 BY:  ING CAPITAL ADVISORS, INC., as
                                      Investment Advisor


                                 By:
                                    ---------------------------------
                                    Title:



                                 MORGAN STANLEY DEAN WITTER
                                  PRIME INCOME TRUST


                                 By:
                                    ---------------------------------
                                    Title:



                                 CRESCENT/MACH I PARTNERS, L.P.
                                 BY:  TCW ASSET MANAGEMENT COMPANY
                                      ITS INVESTMENT MANAGER

                                 BY:
                                    ---------------------------------
                                    Title:

<PAGE>   6


                                 DEEPROCK & COMPANY
                                 By:  EATON VANCE MANAGEMENT,
                                      AS INVESTMENT ADVISOR

                                 By:
                                    ---------------------------------
                                    Title:



                                 KZH-ING-1 LLC (formerly known as KZH HOLDING
                                 CORPORATION II)


                                 By:
                                    ---------------------------------
                                    Title:



                                 CRESCENT MACH I


                                 By:
                                    ---------------------------------
                                    Title:


                                 THE TRAVELERS INSURANCE COMPANY



                                 By:
                                    ---------------------------------
                                    Title:



                                 KZH PAMCO LLC


                                 By:
                                    ---------------------------------
                                    Title:



                                 INDOSUEZ CAPITAL FUNDING III, LIMITED
                                 BY:  INDOSUEZ CAPITAL, AS PORTFOLIO ADVISOR


                                 By:
                                    ---------------------------------
                                    Title:


<PAGE>   7

                                 PAMCO CAYMAN LTD.
                                 BY:  HIGHLAND CAPITAL MANAGEMENT L.P.
                                      AS COLLATERAL MANAGER


                                 By:
                                    ---------------------------------
                                    Title:



                                 KZH-CRESCENT LLC


                                 By:
                                    ---------------------------------
                                    Title:






                                 KZH-SOLEIL LLC


                                 By:
                                    ---------------------------------
                                    Title:



                                 SENIOR DEBT PORTFOLIO
                                 By:  BOSTON MANAGEMENT &
                                      RESEARCH, AS INVESTMENT ADVISOR

                                 By:
                                    ---------------------------------
                                    Title:



                                 ML CBO IV (CAYMAN) LTD.
                                 BY:  HIGHLAND CAPITAL MANAGEMENT L.P.
                                      AS COLLATERAL MANAGER

                                 By:
                                    ---------------------------------
                                    Title:

<PAGE>   8



                                 NATEXIS BANQUE BFCE


                                 By:
                                    ---------------------------------
                                    Title:



                                 PAM CAPITAL FUNDING LP
                                 BY:  HIGHLAND CAPITAL MANAGEMENT L.P.
                                      AS COLLATERAL MANAGER

                                 By:
                                    ---------------------------------
                                    Title: