{"id":4137,"date":"2024-06-02T03:30:22","date_gmt":"2024-06-02T03:30:22","guid":{"rendered":"https:\/\/solidstatestereo.com\/?page_id=4137"},"modified":"2024-12-10T02:43:17","modified_gmt":"2024-12-10T02:43:17","slug":"ka7002-kt7001","status":"publish","type":"page","link":"https:\/\/solidstatestereo.com\/index.php\/amps-and-tuners\/ka7002-kt7001\/","title":{"rendered":"KA7002 + KT7001"},"content":{"rendered":"\t\t
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Kenwood KA7002 + KT7001<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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sold<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Examples of interior restoration results (click on photos to expand)\n<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Exterior photos<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Restoration notes<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Bench measurements<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Beyond the list of standard restoration steps detailed on the main page<\/span><\/a>, here are some added notes for this unit<\/em> :<\/p>

I bought these as a set from from a small record store in Springfield, MA.\u00a0\u00a0<\/p>

The ka7002 and kt7001 were Kenwood’s “top of the line” in 1971.\u00a0 As a result, they are extremely well built (with extensive use of shielding) and have some unusual features – examples :<\/p>

The ka7002 phono1 has 2 input impedance settings (30Kohm or 50Kohm) while phono2 features an optional extra preamp stage to accept input levels down to 0.06V (very nice as this is compatible with many moving coil cartridges).\u00a0 There is also a “null” button that removes ground from the speaker (-) outputs to enable better R\/L output matching (not as useful and shows how folks were trying out new features and not all being carried forward in later generations).<\/p>

The kt7001 has “multipath” button that repurposes the signal strength meter to instead show multipath reception strength (this was used to optimally orient the FM antenna to minimize multipath).\u00a0 There are also 2 FM muting levels (level 1 has a “normal” muting threshold while level 2 is much higher – and really not that useful IMHO).<\/p>

ka7002 restoration notes :<\/p>

Power cord has gouges exposing the copper conductors – new cord and strain relief installed.\u00a0 Original output drivers present and tested good.<\/p>

Protection relay did not “click on” during power up testing.\u00a0 Examination showed that the original relay was wired to used the “normally connected” terminals to tie the amplifiers outputs to the speakers (this is unique and confused me for a couple days).<\/p>

Long aside follows….\u00a0 The KA7002 protection circuit monitors speaker DC voltages, currents and energizes the relay coil to disconnect<\/span> the speakers if failure excursions are seen.\u00a0 This is “backwards” vs the vast majority of later amplifier protection circuits that energize the relay coil to connect<\/span> the speakers (the “click” heard during power up and power down).\u00a0 For the ka7002, hearing a “click” means there is something amiss and the speakers have been disconnected.\u00a0 Kenwood was an early adopter of “directly coupling” the amplifier to speakers (and therefore the use of a protection relay) vs earlier cap-coupled designs.\u00a0 They applied the “act if an issue” philosophy like earlier cap-coupled protection schemes that cut input stage power to the main amp if an issue was seen.\u00a0 This approach works, but was improved upon over time.\u00a0 The ka7002 captures an interesting moment in stereo amplifier progression.<\/p>

The main amplifier board had 2 overheated resistors (same one in both left and right bias circuits).\u00a0 The pots for DC offset and idle current setting were trash and were replaced along with the 2 fried resistors.\u00a0 I was then able to set the DC offset and idle currents, but basic amplifier output testing showed very early clipping of the negative phase of the test sine wave signal.\u00a0 The left and right channels acted the same, so I looked for a failure that would impact both channels.\u00a0 That turned out to be a shared 14V Zener diode that had failed open.\u00a0 I replaced that, reset the DC offset\/ idle currents and the early clipping issue was resolved.\u00a0 The rest of the recap\/cleaning went normally.\u00a0 It is now a nice sounding, over-achieving amplifier.<\/p>

kt7001 restoration notes:<\/p>

Highly functional after switch cleaning.\u00a0 The 53 year old tuning string was fraying, so I restrung it.\u00a0 This was Kenwood’s best tuner in 1971 with FM sensitivity and channel separation noted as strong points after listening tests.<\/p>

WRT cosmetics, the wood sides had issues, so I applied new veneer which was then stained\/sealed,\u00a0 These came out looking pretty nice (please see photos).\u00a0 I decided to keep the original finish on the metal cabinet tops despite some minor scratches, scuffs.\u00a0 The ka7002 has some minor faded faceplate printing\u00a0 (“tuner” on function switch) but the faceplates are otherwise in good condition.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Kenwood’s spec for the ka7002 amplifier output (all into 8 ohms, both channels driven, 0.05% max distortion\u00a0)<\/p>

\u00a0 \u00a0 \u00a0 \u00a020 Hz to 20,000 Hz\u00a0 : 50 watts per channel,\u00a0<\/p>

\u00a0 \u00a0 \u00a0 \u00a01000 Hz : 55 watts per channel<\/p>

My results :\u00a0<\/p>

\u00a0 \u00a0 \u00a0 \u00a0 20 Hz to 20,000 Hz\u00a0 : 61 watts per channel,\u00a0<\/p>

\u00a0 \u00a0 \u00a0 \u00a01000 Hz : 63 watts per channel<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Some reference links<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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hifiengine\u00a0 :\u00a0 https:\/\/www.hifiengine.com\/manual_library\/kenwood\/ka-7002.shtml<\/a><\/p>

Radio Museum\u00a0 : https:\/\/www.radiomuseum.org\/r\/trio_kenwo_stereo_tuner_kt_7001.html<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Kenwood KA7002 + KT7001 sold Examples of interior restoration results (click on photos to expand) ka7002 top no shields ka7002 right no shields ka7002 right shields ka7002 left no shields ka7002 left shields ka7002 front shields ka7002 front no shields ka7002 bottom kt7001 top no shields kt7001 top shields kt7001 right no shields kt7001 right […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":128,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ocean_front_end_style_editor":"no","ocean_post_layout":"","ocean_both_sidebars_style":"","ocean_both_sidebars_content_width":0,"ocean_both_sidebars_sidebars_width":0,"ocean_sidebar":"","ocean_second_sidebar":"","ocean_disable_margins":"enable","ocean_add_body_class":"","ocean_shortcode_before_top_bar":"","ocean_shortcode_after_top_bar":"","ocean_shortcode_before_header":"","ocean_shortcode_after_header":"","ocean_has_shortcode":"","ocean_shortcode_after_title":"","ocean_shortcode_before_footer_widgets":"","ocean_shortcode_after_footer_widgets":"","ocean_shortcode_before_footer_bottom":"","ocean_shortcode_after_footer_bottom":"","ocean_display_top_bar":"default","ocean_display_header":"default","ocean_header_style":"","ocean_center_header_left_menu":"","ocean_custom_header_template":"","ocean_custom_logo":0,"ocean_custom_retina_logo":0,"ocean_custom_logo_max_width":0,"ocean_custom_logo_tablet_max_width":0,"ocean_custom_logo_mobile_max_width":0,"ocean_custom_logo_max_height":0,"ocean_custom_logo_tablet_max_height":0,"ocean_custom_logo_mobile_max_height":0,"ocean_header_custom_menu":"","ocean_menu_typo_font_family":"","ocean_menu_typo_font_subset":"","ocean_menu_typo_font_size":0,"ocean_menu_typo_font_size_tablet":0,"ocean_menu_typo_font_size_mobile":0,"ocean_menu_typo_font_size_unit":"px","ocean_menu_typo_font_weight":"","ocean_menu_typo_font_weight_tablet":"","ocean_menu_typo_font_weight_mobile":"","ocean_menu_typo_transform":"","ocean_menu_typo_transform_tablet":"","ocean_menu_typo_transform_mobile":"","ocean_menu_typo_line_height":0,"ocean_menu_typo_line_height_tablet":0,"ocean_menu_typo_line_height_mobile":0,"ocean_menu_typo_line_height_unit":"","ocean_menu_typo_spacing":0,"ocean_menu_typo_spacing_tablet":0,"ocean_menu_typo_spacing_mobile":0,"ocean_menu_typo_spacing_unit":"","ocean_menu_link_color":"","ocean_menu_link_color_hover":"","ocean_menu_link_color_active":"","ocean_menu_link_background":"","ocean_menu_link_hover_background":"","ocean_menu_link_active_background":"","ocean_menu_social_links_bg":"","ocean_menu_social_hover_links_bg":"","ocean_menu_social_links_color":"","ocean_menu_social_hover_links_color":"","ocean_disable_title":"default","ocean_disable_heading":"default","ocean_post_title":"","ocean_post_subheading":"","ocean_post_title_style":"","ocean_post_title_background_color":"","ocean_post_title_background":0,"ocean_post_title_bg_image_position":"","ocean_post_title_bg_image_attachment":"","ocean_post_title_bg_image_repeat":"","ocean_post_title_bg_image_size":"","ocean_post_title_height":0,"ocean_post_title_bg_overlay":0.5,"ocean_post_title_bg_overlay_color":"","ocean_disable_breadcrumbs":"default","ocean_breadcrumbs_color":"","ocean_breadcrumbs_separator_color":"","ocean_breadcrumbs_links_color":"","ocean_breadcrumbs_links_hover_color":"","ocean_display_footer_widgets":"default","ocean_display_footer_bottom":"default","ocean_custom_footer_template":"","footnotes":""},"class_list":["post-4137","page","type-page","status-publish","hentry","entry"],"_links":{"self":[{"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/pages\/4137","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/comments?post=4137"}],"version-history":[{"count":56,"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/pages\/4137\/revisions"}],"predecessor-version":[{"id":5412,"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/pages\/4137\/revisions\/5412"}],"up":[{"embeddable":true,"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/pages\/128"}],"wp:attachment":[{"href":"https:\/\/solidstatestereo.com\/index.php\/wp-json\/wp\/v2\/media?parent=4137"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}