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Old 27th June 2006, 08:14 PM   #1
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Default T-amp stealth mod in passive biwiring

T-amp stealth mod in passive biwiring

Hi folks,

Iím running a pair of SI T-amps in passive biwiring (one for the tweeters one for the woofers) to Mirage 390is speakers. Iím planning to do the stealth mod with Wima 2,2uF 250V MKS caps ( hope they are ok, because I canít get better ones ). Iím wondering whether to mod both amps or just the one running the woofers. Not sure if moding only one would lead to sonic differences between the amps, which would be bad because they are both running the same speakers. On the other hand I donít want the tweeter amp wasting power on low frequencies which the tweeter wonít play anyway, as the power is not abundant with the t-amp
Your thoughts on the subject?
Iím also thinking of replacing the tank cap with a 1000uf 63V one, would that be ok ?

Iím also considering buying a Monica2 from diyparadise. Iíve read it has a low output ( 0.7V? ) and Iím concerned as my current cd-player ( H/K HD-710 ) has a 2V output. Will the difference in volume be as large as numbers suggest ( more than twice) ? I also own a MF X10-D tube buffer which is connected between the cd and the amps. Iíve read that a buffer is supposed to help Monica2 drive the amp.
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Old 27th June 2006, 09:35 PM   #2
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Post Re: T-amp stealth mod in passive biwiring

[QUOTE]Originally posted by Mr.Mekulic
[B]T-amp stealth mod in passive biwiring

I meant passive biamping not passive biwiring
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Old 28th June 2006, 05:12 AM   #3
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Hey,
if you are going to bi-amp, no need for the bigger cap on the tweeter amp. The stock 0.33uF cap is all you need. You could use a better cap, but a bigger one is not needed.

You will be bypassing the stock volume controls, right? You'll want split off after a single volume control so that the 2 amps track together.

By "tank cap" do you mean the cap onboard? Then yes, 1000uF will be great. You can go with 16V or 25V, no problem.

Let us know how it works out.
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Old 28th June 2006, 06:19 AM   #4
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Default A question of power

A power question remains hanging and I would like to address this. The crossovers will prevent any out of band power from being wasted. Essentially this means that the low frequencies going to the tweeter will be decoupled and not see much of a load therefore will not waste power.
A bigger issue is the difference in caps at crossover where both amps are working. I would recommend that at least both channels, high and low, have the same brand and type of cap even if not the same value. This will insure sonic consistency across the crossover region.
Roger
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Old 28th June 2006, 11:08 AM   #5
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Quote:
Originally posted by panomaniac
Hey,
if you are going to bi-amp, no need for the bigger cap on the tweeter amp. The stock 0.33uF cap is all you need. You could use a better cap, but a bigger one is not needed.


Any thoughts on the Wima-s Iím planning to use ? Should I put a Wima 0.33uF on the tweeter amp? Is the stock one 3,3uF or 0,33uF ?

Quote:
You will be bypassing the stock volume controls, right? You'll want split off after a single volume control so that the 2 amps track together.
Iím currently using stock volume controls, syncing them by hand which is clumsy. How could I wire both amp to a single pot? Do I need to change the pot for that? I know I should change the pot for a quality one but Iím still looking for one.


Quote:
By "tank cap" do you mean the cap onboard? Then yes, 1000uF will be great. You can go with 16V or 25V, no problem.

Let us know how it works out.
Will do

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Old 28th June 2006, 04:35 PM   #6
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Hi Mr Mekulic,
I'm currently using a pair of 2.2uF Wima MKP i think... rather huge fellow, when compared with the sonic pcb.

Anyway, I think they sounded fine to me.. can't really compare coz i have not tried the more exotic stuff like auri or obliagatos...

But I do notice they seems to pick up loads of noise! I was having some "ringing" noise problem. The minute I swap it out with a pair of tiny oscons (2.2uF as well, smaller than a regular fuse), it seems to clear up quite a fair bit. I cannot confirm this 100% coz I did not run it like hours to verify this. Anyway, I think I did read somewhere that big caps pick up noise.

Anyway, I did put back the Wima-s and made some shielding+grounding for it. In my case, it did help to reduce the ringing noise.

PS> Btw, my onboard cap is a 2200uF... problem with the bigger ones is the limited "real estate" on this tiny little board...

Cheers!
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Old 28th June 2006, 08:25 PM   #7
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Poozbrear is right, big caps will pick up noise. My big Obbligato copper tube caps will pick up hum if I touch them, or get AC near them. But once there are inside a metal enclosure, no problem.

To use 1 volume pot for 2 amps, just connect the inputs of each amp (including the new cap, if there is one) to the output of the pot. You are simply splitting the signal. Easy!
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