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Old 27th March 2005, 09:20 AM   #11
BWRX is offline BWRX  United States
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i actually haven't seen those projects before, but thanks for letting me know about them! they look easy enough to construct, the problem is finding more money to buy parts we all know how that works
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Old 28th March 2005, 10:06 AM   #12
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Default Biamping

You may want to try driving the bass with one anp and the high, mids with another. The vertical method is usually better, but you will have a problem if the neg connections in the speaker are tied together in the crossover.

George
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Old 28th March 2005, 03:41 PM   #13
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Thanks for all the help folks!

I've decided to run 1 amp for the minute (even though I've sourced another 1.5A power supply free!) and I must admit that I am enjoying the sound alot.

Seeing as this is my first DIY audio project, I've decided that DIY is definately the way to go! No more buying cables, amps, speakers etc - all upgrades will hopefully be done by me!

Anyway - the little T-amp isnt even run in yet, but I decided to play it through my fathers B&W 802 Matrix 3's and Arcam 6 CD player (using a standard interconnect and Nordost Blue Heaven speaker cable) and I was stunned. On Pink Floyd's "Breathe" (track 2 Dark Side of the moon), you can hear his breathing so much clearer as he runs and the general detail is just astonishing.

Compared to his Meridian 101 Pre/ 2x 105 Monoblock amp set up, I personally preferred the detail, but the tonal balance didnt seem perfect (hopefully due to it only being run for about 10hours at this stage). The monoblocks are 100wpc and they give much stronger bass.. I found the T-amp to be much brighter then the meridian set up. It wasnt fatigueing however, but I like a smooth, rich sound (hence the love affair with arcam) so I'm hoping the T-amp loosens up and becomes more revealing on the bassy side.

Oh - and for anyone wondering how to get the front knob off the pot on the t-amp, it's not glued, all you have to do is get a nail behind it and pull!

I'm still contemplating going down the bi-amp route, but the impedance thing worries me.. How can I solve this issue?

Also - If i just wanted to run them as power amps (with no volume control) - Which im currently doing with my 8r as a pre-amp - would it be sufficient just to put a 10k resister in place of the potentiometer?
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Old 28th March 2005, 05:15 PM   #14
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Quote:
Originally posted by Commited
Thanks for all the help folks!

..........................................
Compared to his Meridian 101 Pre/ 2x 105 Monoblock amp set up, ..........

Care to post a picture of those. They were way ahead of their time when they first came out.. I guess they should be re-cap by now..not that they have many I do not think. Yes I remeber how powerful they were when driving the Tannoy Super Reds

Miss them so much
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Old 28th March 2005, 10:29 PM   #15
Pano is online now Pano  United States
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Committed,
Looks like you've got a really nice rig going there. Love the light-up switches on the box.

Your bi-amp should work nicely, but there are a few things you should know, some mentioned here already.

Power:
Yes, you will need more. I suggest a minimum of 2A per unit. Be sure your PSUs have good, large caps. Average draw will be about 300mA on each unit, but peaks will need more.

Wiring:
Be certain that your speakers do not have the ground (or anything else) in common. The S.I. is a bridged amp and will not tolerate having the ouputs tied to any common point.

Signal flow:
You can use a Y cable to drive the 2 amps, but your CD player may not have what it takes to drive 2. A preamp most likely will. If using a preamp, run the S.I. volumes up to max, or bypass them altogether.

Bi-amping:
As explained earlier in this thread, you aren't fully bi-amping, or at least not in the way commonly referred to. You'll need an active crossover between the source and the power amps.

That said, you should still find benefit in "simple" bi-amping. A little more power, perhaps, but mostly the fact that the tweeter amp won't be "polluted" with the back EMF of the woofer amp.

The down side to no active crossover will be that each amp will get the entire signal, it will be the passive crossover that dumps the unneeded portion. An active crossover will send only the part of the signal needed to each amp. No wasted power there.

So go ahead with your bi-amp plan, keeping in mind the above.
It should sound very nice. Move up to an active crossover later, you'll enjoy the improvements.

Be sure to change out those input caps, that's the best thing you can do for the Sonic. Replace the electrolytic power cap on the PCB, too. A Panasonic FM series electrolytic works well here.

Happy listening!
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Old 21st November 2006, 03:38 AM   #16
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Quote:
Originally posted by panomaniac
Wiring:
Be certain that your speakers do not have the ground (or anything else) in common. The S.I. is a bridged amp and will not tolerate having the ouputs tied to any common point.
With a passive crossover (as in most speakers) how do you ensure this?

Quote:
Originally posted by panomaniac
Bi-amping:
The down side to no active crossover will be that each amp will get the entire signal, it will be the passive crossover that dumps the unneeded portion. An active crossover will send only the part of the signal needed to each amp. No wasted power there.
Would using different value input caps for each amp hel with this - something like 0.2uF for the amp that will power the tweeters and 2.2uF for the amp that will power the woofers?
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Old 21st November 2006, 11:09 AM   #17
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Quote:
Originally posted by Fin
With a passive crossover (as in most speakers) how do you ensure this?
Check with your ohm meter to see if there is a connection between the Hi & Lo grounds. They should NOT be connected.


Quote:
Would using different value input caps for each amp help with this - something like 0.2uF for the amp that will power the tweeters and 2.2uF for the amp that will power the woofers?
Yes, but you don't want to go too small with the input caps or you will be adding another pole to your filter that may push the cutoff higher than you want. Or do strange things to phase. But 0.2uF is probably safe.
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Old 21st November 2006, 11:15 AM   #18
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Thanks Michael

The speakers I thinking of using are not currently bi-wireable....but I would like to add a second set of terminals.

0.2uF was sort of just a guess.
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Old 22nd November 2006, 02:33 PM   #19
ruaneg is offline ruaneg  Ireland
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Hi Committed!!!

fellow paddy modder here...Im doing a very similar thing to yourself ,im biamping two charlizes..Im using a MDHT Constantine Dac and a Ming Da Mc3 preamp.. Its very impressive to my novice ears and very happy with how its sounding.

Im biamping passively at the moment but was hesitant at doing this initially as theyre so much contracdictory information on the web on the benefits of passive baimping. But I can say without doubt it makes a big difference on mine. All muddyness disapears in the mids lows...in audiophool speak.

btw i have one hooked up to highs and the other for mids/lows
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Old 22nd November 2006, 07:24 PM   #20
vex0rg is offline vex0rg  Ireland
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Another Irish modder here, have the SI T-amp just trying to work up the courage to order some caps and heat up the soldering iron.

Also have a pair of Fostex FE166e to go in a BIB when I can find some void free ply.
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