bellari mp105 pot replacements... puff? mr. pastry?

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eeldip
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bellari mp105 pot replacements... puff? mr. pastry?

Post by eeldip » Sun Feb 06, 2005 8:04 am

so, i think i really got to get rid of these pots. anyone who has one of these i am sure has sympathy for me. (poor george)

anyone tried replacing these pots? a little bird said that the clarostat 308NPC100K might work. at $12 a pop.. whew. those gotta be nice pots for a bellari.

but you know. its super bowl sunday, just put the brisket in the oven, about 8 bud lites from now the superbowl will be over and i'll be ready to head over to scratch my head at the digikey website...

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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by ubertar » Sun Feb 06, 2005 8:10 am

Do they really need replacing? I have a mp110-- cleaned the pots with deoxit and it's fine. Are they just scratchy (clean 'em) or do they suck tone?
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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by eeldip » Sun Feb 06, 2005 8:31 am

nah, its the 105. different pots methinks.

they not only are cheapy scratchy and dont clean up well. they seem to have the wrong values, in that the pot movement changes the amp in a very non-linear way. as in, on the gain knob, from all the way off to about 3 o'clock, the gain goes up like 20db. then from 3 to about 3.1 oclock the gain goes up another 20db.

ok, i am exaggerating. but just a little bit, it is really annoying. really hard to get the right gain going, and with a noisy amp like this.. its pretty important.

plus i havent quite reached the point where the cost of modding this box has exceeded the ebay price... MUST MAKE MORE SILLY MODS.

maybe i should just buy a 110...

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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by theistheman » Sun Feb 06, 2005 9:38 am

I hate to tell you,

but that's just how it is. I don't think that changing the pots is going to fix anything. That pre is pretty un-usable when you put it past the 2 o'clock position (unless you're going for total fuzzed-out distortion), and the pots are scratchy in that way right out of the box. I don't think that it's the pots-though I'm not sure.

Besides those shortcomings, I think that it's an AWESOME pre. For the money, you certainly can't beat it, and it's way better than the presonus and art crap.

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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by eeldip » Sun Feb 06, 2005 9:51 am

here is the theory per puff:

"First, as I stated earlier, the potentiometers not only suck, but I think
they're too large. High resistance in a circuit has benefits depending upon
the application, but one of the drawbacks is noise. Also, I suspect that stage to stage impedance may be a factor here, since the AD826's have to deal with these large value pots as their source impedances. Lately, I've been experimenting with the effects of lower value potentiometers in certain applications--this being one of them. I've seen a dramatic decrease in noise and an improvement in the circuit's tracking by using 100k pot--in this case, the Clarostat 308NPC"

also, in no way am i knocking this pre. i just want to improve this little bit...

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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by puffpastry » Sun Feb 06, 2005 11:55 am

Hey--
The Clarostat pot is the only type I've experimented with here, largely due to the fact that it's a good potentiometer and it mounts in the existing design pretty easily. It is expensive, yes. Ultimately, I decided that its cost was a bit too expensive in this application. I'm afraid I don't have any less expensive suggestions, though.

There is a difference in tonality when using a 100K pot instead of the 500K pot in this circuit, yes. Whether or not that difference is better is purely a matter of opinion, I suppose.

If you don't like the way the pot tracks volume changes, a different taper should solve that. I don't remember for sure, but I think that Bellari used a linear potentiometer here. If that is the case, an audio taper would provide a smoother response.

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Re: bellari mp105 pot replacements... puff? mr. pastry?

Post by eeldip » Sun Feb 06, 2005 1:28 pm

puffpastry wrote:
If you don't like the way the pot tracks volume changes, a different taper should solve that. I don't remember for sure, but I think that Bellari used a linear potentiometer here. If that is the case, an audio taper would provide a smoother response.
thanks so much. i think the tracking is sort of the least of my complaints... if the pot was better it wouldnt bug me so i think, its just when you have to find the perfect spot and the pots are scratchy that it gets annoying.

anyway, i dont mind the expense so much. if i am going to spend the time to do this.. why not put an extra $10 into a pot?

thanks again.. you are the best....

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