<SUBMISSION>
<ACCESSION-NUMBER>0001144692-11-000007
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20110808
<FILING-DATE>20110810
<DATE-OF-FILING-DATE-CHANGE>20110810
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BRONSON STEVEN N
<CIK>0001000383
<STATE-OF-INCORPORATION>FL
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-30083
<FILM-NUMBER>111024407
</FILING-VALUES>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>QUALSTAR CORP
<CIK>0000758938
<ASSIGNED-SIC>3695
<IRS-NUMBER>953927330
<STATE-OF-INCORPORATION>CA
<FISCAL-YEAR-END>0630
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3990-B HERITAGE OAK COURT
<CITY>SIMI VALLEY
<STATE>CA
<ZIP>93063
<PHONE>805-583-7744
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3990-B HERITAGE OAK COURT
<CITY>SIMI VALLEY
<STATE>CA
<ZIP>93063
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>BKF CAPITAL GROUP INC
<CIK>0000009235
<ASSIGNED-SIC>6282
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-30083
<FILM-NUMBER>111024408
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>ONE ROCKEFELLER PLAZA
<CITY>NEW YORK
<STATE>NY
<ZIP>10020
<PHONE>2123328400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>ONE ROCKEFELLER PLAZA
<CITY>NEW YORK
<STATE>NY
<ZIP>10020
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>BAKER FENTRESS & CO
<DATE-CHANGED>19970829
</FORMER-NAME>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>BAKER FENTRESS & CO ET AL
<DATE-CHANGED>19940714
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-08-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000758938</issuerCik>
        <issuerName>QUALSTAR CORP</issuerName>
        <issuerTradingSymbol>QBAK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000009235</rptOwnerCik>
            <rptOwnerName>BKF CAPITAL GROUP INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>225 N.E. MIZNER BOULEVARD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>BOCA RATON</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33432</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001000383</rptOwnerCik>
            <rptOwnerName>BRONSON STEVEN N</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-08-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>19259</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.66</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1601659</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-08-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>15480</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.648</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1617139</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares of Qualstar Corp. (Qualstar) common stock were purchased by BKF Captial Group, Inc. (BKF Capital) in an open market transaction.</footnote>
        <footnote id="F2">BKF Capital is the owner of 1,543,959 shares of Qualstar common stock.  Steven N. Bronson, as the Chairman and President of BKF Capital, may be deemed to benefically own the shares of Qualstar common stock held by BKF Capital.  Mr. Bronson as the sole owner of BA Value Investors, LLC is the beneficial owner of an additional 57,700 shares of Qualstar common stock held by BA Value Investors, LLC.</footnote>
        <footnote id="F3">These shares of Qualstar common stock were purchased by BKF Capital in an open market transaction.</footnote>
        <footnote id="F4">BKF Capital is the owner of 1,559,439 shares of Qualstar common stock and Mr. Brosnon as the Chairman and President of BKF Capital may be deemed the beneficial owner of such shares.  Mr. Brosnon, as the sole owner of BA Value Investors, LLC is the beneficial owner of an additional 57,700 shares of Qualstar common stock held by BA Value Investors, LLC.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Steven N. Bronson, President</signatureName>
        <signatureDate>2001-08-10</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Steven N. Bronson</signatureName>
        <signatureDate>2011-08-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
