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Old 10th April 2003, 06:24 PM   #11
jam is offline jam  United States
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Tbla,

Sorry but mlloyd is correct. The new Jeff Rowland amplifiers do ues transformers at the inputs. Lundals on some models.

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Jam
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Old 10th April 2003, 06:43 PM   #12
mlloyd1 is offline mlloyd1  United States
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Default Re: The other side of the moon...

8. are expensive for good quality

Quote:
Originally posted by Tube_Dude

4. are sensible to magnetic fields..

5.suffer from histerisys of the magnetic material...

6.are sensivel to core saturation if they have a small DC across it...

7. are bandwith limited...
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Old 10th April 2003, 06:56 PM   #13
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Default The eight comandements...

Quote:
8. are expensive for good quality
100% agree!!... Like women!!!!
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Old 10th April 2003, 07:27 PM   #14
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Default jam

do you have any "evidence".....pictures please, model 10, 12 and 112 do not use transformers but another "device".....???
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Old 10th April 2003, 07:45 PM   #15
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Talking Re: The eight comandements...

Quote:
Originally posted by Tube_Dude


100% agree!!... Like women!!!!

Hi Tube_Dude, do you have any evidence, pictures please?
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Old 10th April 2003, 07:46 PM   #16
Philo is offline Philo  United States
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tbla,
Go to http://www.jeffrowland.com/techtalk.htm and scroll down the list. There are several articles in the TechTalk section that address the company's use of input transformers. The models you listed are called out specifically because they don't use input transformers. And it all depends on how you pay for your women. Those of us on the long term plan really have to pay out the nose.
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Old 10th April 2003, 09:31 PM   #17
jam is offline jam  United States
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Tbla,

The new series 300, I think, use transformers. I saw them at the CES show in Las Vegas.

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Jam
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Old 10th April 2003, 10:01 PM   #18
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Default Re: single ended to balanced...

Quote:
Originally posted by tbla
wouldn't you say that using a DRV134 from Ti as the input device, could be a very good idea...? perhaps JEFF ROWLAND is allready doing this in his poweramps - there is certanly no input transformer inside...?
That'd be one way to convert an unbalanced input to a balanced output. Or you could use the more generic and ubiquitous approach using a dual opamp chip.

But the issue here is input transformers, not simply single-ended to balanced conversion.

I believe in their new gear instead of input transformers, Rowland is using InGenius line receivers from <a href="http://www.thatcorp.com">THAT Corporation</a>.

Bill Whitlock (President of Jensen Transformers) patented an amplifier topology which gives high common-mode rejection even when there is an imbalance in the source impedances (the worst case being unbalanced sources). Transformers are very good at this and can give you triple digit common-mode rejection even from unbalanced sources. But typical active circuits can only achieve this level of rejection when the source impedances are precisely balanced.

se
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Old 10th April 2003, 10:02 PM   #19
haldor is offline haldor  United States
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Quote:
Originally posted by Philo
tbla, ... And it all depends on how you pay for your women. Those of us on the long term plan really have to pay out the nose.
I don't know about that, I just bought one of these for my wife so she can stay in touch and and entertain herself wherever the US Navy decides to send her. Could of bought a lot of nice drivers and amp parts for that much money

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Old 10th April 2003, 10:16 PM   #20
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Default Re: The other side of the moon...

Quote:
Originally posted by Tube_Dude
4. are sensible to magnetic fields..
So is any conductive loop. But this is really only an issue with high impedance input transformers, which are typically supplied with magnetic shielding.

Quote:
5.suffer from histerisys of the magnetic material...
Which is why the best transformers use the best core materials with the smallest hysteresis loops. This doesn't become significant except at the lowest frequencies and the highest input levels. Linearity increases with frequency and by the time you get to a couple hundred hertz, is virtually non-existent.

Quote:
6.are sensivel to core saturation if they have a small DC across it...
If your source component is outputting enough DC to actually saturate the core, it's probably time to have your source component repaired.

Certainly DC currents in the primary or secondary can degrade performance. But it's rather trivially easy to keep these down to levels that they're not terribly significant.

Quote:
7. are bandwith limited...
Guess it depends where you draw the line for "limited." The input transformers I use have a bandwidth of 100kHz. I don't see how that's limiting in any meaningful way. And output transformers can have bandwidths into the tens of megahertz.

So what exactly do you consider "bandwith limited"?

se
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