Accuphase M-60 Love

[User211]

Fair enough, 105°C vs. 85°C might make all the difference.

LOL. Just to say so you know - when I buy stuff I spend literally ages doing the research first. It was a well considered buy.

[User211]

For Barry - why the ELNAs have to go as you said and I also think given the below. I measured all of them at 90-100mOhms.

Here's what Grok said:

**Yes — 100 mΩ is high enough to cause noticeable heating**, and it is a clear sign the original Elnas are well past their best.

### Original (new) ESR estimate
For a large screw-terminal 22000 µF / 100 V 85 °C capacitor of that era and physical size (≈75 mm diameter), a typical new ESR at 100 Hz would have been roughly **10–20 mΩ** (most likely in the 12–18 mΩ range when fresh).

Modern equivalents of similar size and rating sit around 6–15 mΩ. Your measured ≈100 mΩ is therefore **roughly 5–10× higher** than new — classic ageing (dried-out electrolyte + increased internal resistance).

### Will 100 mΩ cause heating?
Yes, potentially quite a bit, depending on the ripple current in your amplifier.

Power dissipated as heat inside the capacitor is:

\[
P = I_{\text{rms}}^2 \times \text{ESR}
\]

- With a healthy new ESR of ~15 mΩ, even several amps of ripple produces only modest heat.
- At 100 mΩ the same ripple current produces **6–7× more heat**.

In a high-power amplifier (especially Class AB with heavy bass content or high continuous power), the original caps can easily run warm or even hot to the touch. That extra heat further accelerates ageing, which is why they degrade faster once ESR starts rising.

### Practical takeaway
100 mΩ is high enough that replacement is fully justified on both performance and reliability grounds. The new TDK/EPCOS B41560A9229M (≈6 mΩ) will run dramatically cooler and deliver much tighter regulation under load.

If you want a quick check before swapping: power the amp, play music with strong bass for 10–15 minutes, then carefully feel the old cans (power off first). If they are noticeably warmer than the chassis, the elevated ESR is definitely contributing to heating.