black lion bellari mp105 mod

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puffpastry
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Re: black lion bellari mp105 mod

Post by puffpastry » Wed Aug 18, 2004 11:13 pm

There are two things that everyone can do to cut down on the Bellari's noise:

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 I mentioned in the post above. It's a bit pricey at $10 a pop, so those of you wanting to swap out pots might try a 100k Vishay, ALPS, or something along those lines if you want something cheaper (there's another brand whose name I can't remember). Just make sure you get something with as long of a shaft as the original.

Second--and I think I've actually mentioned this before--get rid of those cheap diodes in the rectifier and multiplier stages. I think they're labeled D6-D9 and D15-D22. Diodes are noisy as rectifiers, and they don't really supply current as well as they should. I'm a fan of General Semiconductor or Vishay UFRED diodes. Try a UF4001 as a sub.

This won't give you a noise floor of -120dB, but it will clean things up.

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theinfamousfish
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Re: black lion bellari mp105 mod

Post by theinfamousfish » Thu Aug 19, 2004 8:33 am

Hmm.. It sounds like you could keep modifying forever. :) Hmm... Well, I still think this will be the way to go.

*edit* I put a lot of stuff here about having a noise problem with my current system, but I think I have limited it using gain control to decrease the SNR. Actually, how I did it goes against traditional SNR reduction theory, but it works. I turned down the level in my pre and turned it up on my level input for my soundcard. The result is a good level with low noise threshold. listen to my file in my next post and see what you think...
Last edited by theinfamousfish on Thu Aug 19, 2004 11:04 am, edited 2 times in total.
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theinfamousfish
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Re: black lion bellari mp105 mod

Post by theinfamousfish » Thu Aug 19, 2004 11:01 am

here is a link to a recording of my setup. How does it sound? I say I have altered it, but I have not, save volume. It is a turner 700 mic (vintage) and my at4462 pre. There is not a lot of noise, I guess, but it doesn't sound very good, I don't think. Maybe I'm wrong. Maybe it is very good. Opinions?

http://www.motagator.co.uk/jamroom/bands/43/music.php

fish
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brianb
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Re: black lion bellari mp105 mod

Post by brianb » Fri Aug 20, 2004 7:40 pm

puffpastry wrote:There are two things that everyone can do to cut down on the Bellari's noise...

This won't give you a noise floor of -120dB, but it will clean things up.
Thanks. Just to clarify. On vocals there wasn't much noise at all, only when I was using it as a bass DI. Even there I seemed to hear the noise when I was tracking but it was barely audible when I played it back even when I soloed the track-which I don't quite understand. I noticed that when I was actually tracking the bass I was only aware of the noise when I stopped playing. Even in those places I couldn't really here it on playback the next day. Would be nice to know why -maybe I'm getting progressively deafer.

Anyway I hope it didn't sound like I was complaining. I really appreciate the generosiy of people that pass on this kind of information for free. Makes it possible for slobs like me to get some better sounds.

Brian

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bantam
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Re: black lion bellari mp105 mod

Post by bantam » Sat Aug 21, 2004 6:41 pm

WOW... I don't think there is anything I enjoy more than getting better sound for close to nothing. I did this mod and i was floored!! :o

About the noise... I had a hell of a problem until i switched from the 1/4 " out to the xlr out. i assumed the 1/4" was trs balanced but it isn't. When i went to the xlr out it was CONSIDERABLY quieter. Just in case anyone overlooked this...

puff please keep these coming...

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sad iron
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Re: black lion bellari mp105 mod

Post by sad iron » Sat Aug 21, 2004 8:04 pm

Ok, so I just got the power supply for my mp105. it is not the original wall wart and says the output is 16VAC. does this matter?

At any rate I swapped out the op amps and threw a JJ Tesla toob in there and, although I haven't tracked anything with it yet I have A/B'd with phones against my Allen and Heath 20:8:2 pres. The 105 is dark and wooly by comparison, which might be a nice flavor to mix in. I won't really know until I track with it, but I'll never know if the PS it too hot, right?
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puffpastry
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Re: black lion bellari mp105 mod

Post by puffpastry » Tue Aug 24, 2004 9:38 am

Ok, so I just got the power supply for my mp105. it is not the original wall wart and says the output is 16VAC. does this matter?
No, not really. The only part of the supply that's regulated is the tube heaters, which is what really matters in this case. The opamps are run on single sided supply, and can handle the additional voltage easily, as can the tube.

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greatmagnet
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Re: black lion bellari mp105 mod

Post by greatmagnet » Tue Aug 24, 2004 10:01 am

As an update on the RP503 mod I did, last night mine started making this hellacious mega-loud hum outta nowhere. When I first did the mod it sounded 100% better AND quieter than stock, and worked fine for a week or so. Now this...who knows what's up. Could be the used Telefunken tube I guess. I'll have to yank out some of the mod parts and replace 'em with the stock stuff to see if it goes away. Kinda spooky.
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theinfamousfish
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Re: black lion bellari mp105 mod

Post by theinfamousfish » Tue Aug 24, 2004 11:43 am

Yeah, keep me updated on that. Mine will come in soon. I want to know if something isn't working for you. Also, btw. When ordering those opamps, how did you know which type to order? There are several versions of the model number listed with varying suffixes. :?:

fish
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-Switchfoot

"I get your point. You're so sharp."
-Television

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greatmagnet
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Re: black lion bellari mp105 mod

Post by greatmagnet » Tue Aug 24, 2004 12:01 pm

When ordering those opamps, how did you know which type to order? There are several versions of the model number listed with varying suffixes.
Here's the skinny from Bob Widenhofer:

Both types of op-amp should be available online from Digi-Key. Burr-Brown merged with Texas Instruments, so the OPA2604 will be listed as a Texas Instruments part in the Digi-Key catalog. The OP275 is an Analog Devices part. The package type you'll need is "8-pin DIP".

The 8-pin DIP thing was the part you really needed to know. I hope this problem I'm having isn't associated with the mod, 'cuz I was really stoked on how it sounded. Then again, if it's NOT the mod, then I'm having to fix the preamp or get a new one, which sucks even more, since we're talking about a $200 preamp vs. a $50 mod. All my studio gear seems to be taking a big dump on me at the same time. Fuck. Grrr. Vent, vent. :evil:
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theinfamousfish
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Re: black lion bellari mp105 mod

Post by theinfamousfish » Wed Sep 01, 2004 4:22 pm

I have received my bellari finally! It is already a great improvement. I will do the mod and let you guys know.

Fish
"If you're a rose, then I'm the thorn in your side."
-Switchfoot

"I get your point. You're so sharp."
-Television

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sad iron
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Re: black lion bellari mp105 mod

Post by sad iron » Wed Sep 01, 2004 4:38 pm

I got my mod done and took the bellari to a session last week. It was a drum session so I used it on a 57 for scratch vox. some of it came out pretty ok. Been tracking some bass w/ it: Bass Pod in m105. So far, I like.
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theinfamousfish
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Re: black lion bellari mp105 mod

Post by theinfamousfish » Wed Sep 01, 2004 6:09 pm

Yeah. I tracked my electric through it (my fender M80 pre into the bellari) and it sounded very, VERY good clean. The tube added a real nice warmth to it and the fender preserved the "fender sound".

mmm..... *drools*

fish
"If you're a rose, then I'm the thorn in your side."
-Switchfoot

"I get your point. You're so sharp."
-Television

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bantam
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Re: black lion bellari mp105 mod

Post by bantam » Sun Sep 05, 2004 9:17 pm

anyone compare the older light blue ones with the newer dark blue ones????

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