Post by sandawa on Jul 14, 2005 22:24:08 GMT 7
i have a Yamaha B-4 power amp (Japanese model), which i thought was the same as the M-4 amp (international model). i realized that the B-4 is quite different especially the electronics and amp design inside after i saw the M-4 manual at the Yamaha website: www.yamaha.co.jp/manual/english/index.php.
axel dahl of The Vintage Knob also pointed this out to me but he can't prove it since he has seen only the B-4 in a late '70s Yamaha brochure.
the B-4 and M-4 look like a case of Yamaha cutting corners, producing a significantly inferior similar product for the international market reducing production cost for lower retail price to sell more. i would be posting the photos below at Audio Karma tomorrow for documentation and to prove that the two models are not the same. many members there currently own the M-4 power amp.
bago sa kanila, dito muna:
B-4's front looks similar to M-4's
this amp is rated 120wpc at class AB, and 30wpc class A. tests done in one Jap website showed it could reach 40wpc class A with insignificant distortion.
the left front side of B-4 has the power button, speaker on/off, and class A operation. for M-4, the buttons are for power, and speakers A and B
the right side for B-4 is an impedance adjustment, slider plus or minus one ohm, to calibrate on speakers hooked. for the M-4 this was converted into power output meter
the back panels of the two models are almost the same except B-4 has only one pair of speakers and M-4 has two pairs with cheaper spring connectors
the innard has significant changes, B-4 has two transformers and four 15,000mF power caps while M-4 has only one transformer and two 15,000mF power caps
B-4 also uses different MOS-FET code numbers from those installed in M-4
this is for documentation in case a rare vintage Yamaha B-4 shows up on the surplus market. this is a rarity and a trophy for vintage SS collectors in US and Europe.
axel dahl of The Vintage Knob also pointed this out to me but he can't prove it since he has seen only the B-4 in a late '70s Yamaha brochure.
the B-4 and M-4 look like a case of Yamaha cutting corners, producing a significantly inferior similar product for the international market reducing production cost for lower retail price to sell more. i would be posting the photos below at Audio Karma tomorrow for documentation and to prove that the two models are not the same. many members there currently own the M-4 power amp.
bago sa kanila, dito muna:
B-4's front looks similar to M-4's
this amp is rated 120wpc at class AB, and 30wpc class A. tests done in one Jap website showed it could reach 40wpc class A with insignificant distortion.
the left front side of B-4 has the power button, speaker on/off, and class A operation. for M-4, the buttons are for power, and speakers A and B
the right side for B-4 is an impedance adjustment, slider plus or minus one ohm, to calibrate on speakers hooked. for the M-4 this was converted into power output meter
the back panels of the two models are almost the same except B-4 has only one pair of speakers and M-4 has two pairs with cheaper spring connectors
the innard has significant changes, B-4 has two transformers and four 15,000mF power caps while M-4 has only one transformer and two 15,000mF power caps
B-4 also uses different MOS-FET code numbers from those installed in M-4
this is for documentation in case a rare vintage Yamaha B-4 shows up on the surplus market. this is a rarity and a trophy for vintage SS collectors in US and Europe.
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