Attempting to improve the bass on my DD walkman

I saw a post on the tapeheads forum where mihokm posted his guide for improving the bass response on the DD walkman. He pointed out that many DD models had thin bass and it can be fixed by replacing the tantalum capacitor (potentially aging and faulty) between the NF pin and the bias pin of the BA3304F preamp chip. He said if that capacitor was faulty due to its age, it could lead to a weird peak around 100 Hz, which I has experienced before. Also, he said increasing the capacitor from 10uF to 47uF could improve the bass response.

While my DDII does not have the same bass issue he described (20+dB drop at 20Hz), my D3 does, so I replaced the tantalum caps on my D3. I also replaced the electrolytic capacitors (from 220uF to 560uF polymer) before the headphones socket as instructed to lower the cutoff of the high-pass filters and thus further improve the bass response (kind of a shame because the "original" ones were Nichicon gold). 220uF is fine for high-impedance headphones but cut the bass too high for lower-impedance ones (check) [f_c=1/(2*pi*R*C)].

The mod does appear to improve the bass but certainly not night and day. Measurement with audacity still showed more than 12dB of bass drop at 20Hz and >6dB drop at 30Hz. I did not write down the value before the mod though (I remember seeing a very significant drop) (I thought changing the cap would basically flatten the response curve like mihokm described).

I did not replace the tantalum caps on my DDII, but I replaced the ones before the headphone out to 560uF. Subbass is improved slightly (I think?). Hard to say without more serious measurement. But at least I know it on longer has a bass cutoff at like 25Hz.

The tantalum capacitors (new)

The 560uF polymer capacitors (before headphone out)

10/16/2022

I don't like the 560uF change for DDII. It seems to make it sound harsh and distorted at mid high frequency (could be due to the lower voltage. Or it might simply don't like the capacitance). I removed the 560uF cap at the output. It sounds a lot more natural after the removal. I tried replacing the tantalum cap, which again made it sound distorted. So I changed it back.

BTW, with either the old (10uF) or new (47uF) tantalum cap, the walkman has the same bass response according to audacity (lack of impedance load might affect the result) (drop by slightly less than 3dB at 30Hz; have only tested 30Hz).

DDII chip capacitor.

Comments

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cliz305

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