'Budget' MC's ??

[Werner]

" The circuit
diagram implies the use of film coupling capacitors."

Trust me. All coupling caps in the phono stage and at the entrace to the power amp were bipolar elcaps. Shall I go home and look in the parts waste bin? (Haven't emptied it in years so they probably are still in there)? The small-pitch Siemens MKS caps I replaced them with 10 years ago cost back then 2 euro/each. Not something to be used on the production line of a budget amp.


"Actually no I did mean the 540P, I think i'm staying with MM for the foreseable future."

FWIW, as I see it the 540p is not a 640p minus the MC input.

The circuits seem similar indeed, but the component selection and (presumably) the tolerances are to a lower level. So even someone using only MM is better off buying a 640p.







It is an exceedingly nice design for the budget sector. My main worry really would be to get rid of the input coupling caps.

[sreten]

Hi,

Presuming they are elcaps as you say they are then for a 20 year
old amplifier they should be changed, new elcaps are going to be
better than just leaving them as is.

Replacing the coupling elcaps and feedback elcaps should be
regarded as a minimum, and I'm not talking "upgrading" them.

But likely sourced replacements will be higher than original quality.

/sreten.

[freefallrob]

Old thread popped up again .

It sure looks like i'm sticking with MM for the foreseable(Sp?!) future. I've been reading the massive cartridge loading thread on here with some interest, it got me wondering if there was anyway I could 'simply' upgrade my Cyrus inbuilt phonostage for use with MM? Removing components (like the 100p loading caps!?), replacing/improving them ??

I'm up for some careful soldering, i've printed off the circuits .

[sreten]

Old thread popped up again .

It sure looks like i'm sticking with MM for the foreseable(Sp?!) future.
I've been reading the massive cartridge loading thread on here with some
interest, it got me wondering if there was anyway I could 'simply' upgrade
my Cyrus inbuilt phonostage for use with MM? Removing components
(like the 100p loading caps!?), replacing/improving them ??

I'm up for some careful soldering, i've printed off the circuits .

Hi,

On inspection there does not seem anything you can simply do to "improve"
the phono stage for "normal" MM 's. High/mediam output MC's as already
discussed are a diffrent matter.

C11 the loading capacitor can be freely varied, as could the 47K R19.
R17 and C13 are a radio frequency filter and likely best not removed.

This thread already covers some modifications, unfortunately there is
no "right" or "ideal" way of modding, to a degree you have to work
out your own philosophy (of what is worthwhile) for upgrading.

At a mimimum replace all electrolytics with good new ones. Pay attention
to coupling capacitors, decoupling capacitors for the op-amps and the
supply capacitors, use IC data sheets if uncertain of value ranges.

C31 and C43 in the power amp should be considered. IMO bypassing
C43 (after replacing it) may be worthwhile. Also note fitting the "biggest"
capacitors for film types is a trade-off between size and voltage rating.
In some positions increasing either will reduce distortion.

One thing not suggested is capacitors across supply diodes, like here :
http://home.computer.net/~pritch/shortwav.htm
Note that the capacitors should be purposefully "poor" quality ceramics.

/sreten.