Follow up to my last post… I did a thing.
Firstly, theoretical measurements show stock a 5.48dB loss at 10Hz compared to only 1.83dB modified. The -3dB point shifts from around 17Hz to under 8Hz. A big improvement. Measurements taken from around the web show an output impedance of 3.5 ohm, volume pot is 10k ohm, stock cap 1.0uF, upgrade cap 2.2uF. I've set volume to 100% for purpose of the caps as it shows clearest the fall off.
Secondly, be careful ordering the WIMA caps, it seems some newer batches of the previously posted part number are using the 63v shell so will not fit. Check with your supplier, they should measure 7x4x10mm, not 7x7x13! (Width x depth x height)
Ok, on to some pictures, first the charts, courtesy of ampbooks.com and using the values stated above. a 3.3uF cap would be even better but space is TIGHT!
Look at that drop off starting right up at 50Hz or so, that’s no good!
Secondly lets take a look with 2.2uF caps instead, now we can see that 10Hz -5.48dB loss reduced to a much more preferable -1.83dB and the drop off starting much lower at around 25Hz. That's a lot of bass regained!
And a few photos of the modification itself, this one before, sizing up the new caps, yep, they're pretty close to stock size! If anything slightly deeper but of no concern.
During... plenty space to work with now the stock 1uF caps are gone.
After... Those lovely red WIMA's soldered in place. CARE POINT: The pins are about 1mm too long, they protrude too far out the back to fit into the case so trim them before you fit them then carefully fold the pins 90 degrees as per the stock part before soldering and you'll have no issue fitting it in the case.
Finally, gotta test it out, easier to do so with the case off just in case... yup, all working fine and sounds great! improved sub bass rumble, sounds clearer and more forward and dynamic range seems to be improved. Overall very pleased with the result. I haven’t got means of measuring the result and with any mod, some of the improvement could be in my head…
Cost wise capacitors were from eBay UK and £1.35 each plus postage. I ordered 4 'just in case'. Didn't need the two extras so now I have spares. They'll go into my odds and ends box 'forever'..
Took 15 minutes. Worth it? Hell yeah, I mean, why not, I like to tinker and soldering is very relaxing. You could simply bypass the caps, DC is low enough but this seems a better technical solution. Now. What to modify next...