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Old 10th November 2008, 02:41 AM   #1
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Default Jeff Rowland Model 9ti clone?

anybody want to try? I believe they use the same LM3886 chips total 8 chips per channel to achieve this..

any ideas? recommendations? how about supply voltage for this.. how much would be fine before rectification?

lets make this if anybody is interested...
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Old 10th November 2008, 08:05 AM   #2
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That would be two bridged groups of four parallel ICs. Although the specs of 70 A continuous and 140 A peak do not sound like four LM3886 in parallel at all. Even eight in parallel couldn't make that. Neither the TDA7293 and TDA7294, which JR uses in some of his designs. Well, let's put that down to marketing.

Adapt TABLE 1 from AN-1192 and you get a recommended 28 V rail to rail for 2 Ohm and 37 V rail to rail for everything above 4 Ohm. That is a 2 x 22 V transformer for the 2 Ohm version and a 2 x 30 V transformer for the standard version.

Transformer size would be around double what AN-1192 uses, that is something around 1500 VA.

Heatsink size will become an issue, if you really want to use that amount of power. Fans will be necessary.

And then there is that CNC-machined front...
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Old 10th November 2008, 08:11 AM   #3
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not lm3886 in parallel
use tda7294 in model 8ti and 9ti
8ti use 12 tda7294 each channel
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Old 10th November 2008, 10:59 AM   #4
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Quote:
Originally posted by arthur
8ti use 12 tda7294 each channel
So the 9ti probably uses 16 TDA7294 per channel.
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Old 10th November 2008, 12:51 PM   #5
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i have no 9ti , so i do not make any comment
may be tomorrow i will post 8ti power board here.
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Old 10th November 2008, 02:32 PM   #6
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first can anybody confirm that is it LM3886 or TDA in that ? but Ive heard that many of them sold off their 9ti and got to 8t any idea why? probably coz of sweet LM3886
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Old 10th November 2008, 03:06 PM   #7
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Had one JRDG model 8 earlier. No LM3886 there.
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Old 10th November 2008, 03:14 PM   #8
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model 8t is a discrete ss power amp
model 8ti is a 100% opamp based amplifier i/p jensen transformer,ina103 balance o/p buffer stage tda7294 , 2 parallel bank as power o/p stage,

i have one 8 ti dessembled completely to play with
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Old 16th April 2010, 12:48 PM   #9
Cuda is offline Cuda  France
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Do you have the chematic of the opamp version ?

thanks
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Old 16th April 2010, 12:53 PM   #10
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by rhythmdiy View Post
anybody want to try? I believe they use the same LM3886 chips total 8 chips per channel to achieve this..

any ideas? recommendations? how about supply voltage for this.. how much would be fine before rectification?

lets make this if anybody is interested...
Quote:
Originally Posted by pacificblue View Post
That would be two bridged groups of four parallel ICs. Although the specs of 70 A continuous and 140 A peak do not sound like four LM3886 in parallel at all. Even eight in parallel couldn't make that. Neither the TDA7293 and TDA7294, which JR uses in some of his designs. Well, let's put that down to marketing.

Adapt TABLE 1 from AN-1192 and you get a recommended 28 V rail to rail for 2 Ohm and 37 V rail to rail for everything above 4 Ohm. That is a 2 x 22 V transformer for the 2 Ohm version and a 2 x 30 V transformer for the standard version.

Transformer size would be around double what AN-1192 uses, that is something around 1500 VA.

Heatsink size will become an issue, if you really want to use that amount of power. Fans will be necessary.

And then there is that CNC-machined front...

Would be very interested myself , has to be able to drive 1 ohm as the H20 amplfiers ...
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