Ultimate ECC for Class B from Thule Audio? Topology also used by Teac - diyAudio
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Old 7th February 2010, 06:28 PM   #1
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Default Ultimate ECC for Class B from Thule Audio? Topology also used by Teac

Are this an ultimate approach for an error correction topology for Class B and getting sound like pure Class A at the same time?
This topology from Anders Thule also inside by some amplifiers from Teac (go to the first PDF attachement) as I note today.

In my old folder from Thule Audio there is to read follow:

One topic of key interest is to reduce the switching distortion and output impedance without compromising the time response performance at a complex load. The switching distortion appears when the power output transistors are switching and sounds particular hard and unmusical.
For this reason Thule Audio has developed a special error correction circuit, which convert the power output transistors to an near perfect buffer, to eliminate nearly all switching distortion. The remaining distortion is a more "musical" type.
The damping factor is increased (= low output impedance) to about 80 for unbalanced and about 150 for balanced products and is identical for low and high frequencies, which are very good values.
Therefore the Spirit amplifiers have:

None global feedback for good stability
Reasonable low distortion (THD < 0.08%, 20-20k Hz).
High damping factor, for both high and low frequencies, for good drive capability

This combination has the wanted dynamic, open and detailed sound, which on the other hand never becomes hard.


Because I discover this topology also by Teac - thus Anders Thule also developed for Teac
A power amp schematic sample of TEAC A-BX10 you will find in the first PDF attachement and some other images of the devices in follow attachements.

The complete schematic of TEAC A-BX10 you can download there:
ftp://ftp.vegalab.ru/%D1%C5%D0%C2%C8...C0%CB%DB/TEAC/
The whole circuit topology is close to his own IA-50/IA100 amplifiers

Are this error correction topology really developed from Anders Thule?
Except by Thule and Teac devices I haven't see this topology.
Who knows more?
Attached Images
File Type: jpg Teac A BX 10.jpg (53.7 KB, 964 views)
File Type: jpg Teac A-BX10 test I.jpg (179.8 KB, 951 views)
File Type: jpg Teac A-BX10 test II.jpg (184.7 KB, 928 views)
File Type: jpg Thule IA50-CD100.jpg (21.9 KB, 882 views)
File Type: jpg thule IA-50.jpg (145.6 KB, 846 views)
Attached Files
File Type: pdf Thule ECC schem by Teac A-BX10.pdf (71.7 KB, 535 views)

Last edited by tiefbassuebertr; 7th February 2010 at 06:31 PM.
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Old 12th February 2010, 02:37 AM   #2
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What happen to thule audio?
you will find many pictures from a visit in the factory of Thule Audio, that I have found on a Danish website.
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Old 14th July 2010, 12:50 PM   #3
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no informations?
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Old 19th July 2010, 12:08 AM   #4
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Default TEAC A-BX-10 inside, PCB, top view

TEAC ABX-10 inside, PCB, top view
Attached Images
File Type: jpg Thule Teac A-BX10.open.jpg (122.7 KB, 290 views)
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Old 19th July 2010, 06:38 PM   #5
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Default Teac Made in Denmark by Anders Thule

Anders Thule from Thule Audio not only developed for Teac. He even produced for Teac at least the model "ABX-10" from previous post and the A-BX7R (ABX-7R, see pdf attachement)
The A-BX10 ii seems to be close by Thule's model IA-100 (the predecessor of the IA-100 from the "Spirit"-line); and the ABX7R? this I don't know (perhaps the unbalanced and unbridged version of IA-50). Thus I can also offer service for this models and all the other Teac's stereo devices, where Thule Audio components are inside.
Attached Images
File Type: jpg Thule TEAC A-BX7R front.jpg (26.8 KB, 250 views)
File Type: jpg Thule Teac A-BX7R owner's and package.jpg (40.7 KB, 67 views)
File Type: jpg Thule Teac A-BX7R test .JPG (258.8 KB, 103 views)
Attached Files
File Type: pdf Thule Teac A-BX7R open + front (IA50).pdf (126.4 KB, 190 views)

Last edited by tiefbassuebertr; 19th July 2010 at 06:43 PM.
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Old 20th July 2010, 06:27 PM   #6
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What am I missing here?

It just looks like ramming some one-sided current into the pre-driver to create some DC off-set (to be corrected by the front-end). I guess this would insure that one half of the output stage doesn't turn off.
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Old 21st July 2010, 07:18 AM   #7
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I also see only a triple emitter follower with a bias-adjust and CCS .
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Old 21st July 2010, 02:21 PM   #8
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Default Thule calls their Error Correction "Virtual Class A"

about the Alexis Internet Archive I have found this and have create and attached PDF-Files. The last file is the schematic of Thule Audio's unbal. amp devices with follow PCB: EM1070 Rev 8. Here is to see a current mirror insted a CCM
Attached Files
File Type: pdf Thule Amplifier circuit design considerations.pdf (68.8 KB, 315 views)
File Type: pdf Thule virtual Class A basics.pdf (38.0 KB, 281 views)
File Type: pdf C ...-A-Thule Audio unbal EM1070-8.ckt.pdf (22.3 KB, 272 views)

Last edited by tiefbassuebertr; 21st July 2010 at 02:43 PM.
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Old 21st July 2010, 02:36 PM   #9
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Quote:
Originally Posted by djk View Post
What am I missing here?

It just looks like ramming some one-sided current into the pre-driver to create some DC off-set (to be corrected by the front-end). I guess this would insure that one half of the output stage doesn't turn off.
OK, but I see 10k R's in series with this "one sided current injection", so whatever it's doing current wise, it's not doing much.

Marketing hype, IMO.

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Old 21st July 2010, 07:13 PM   #10
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"OK, but I see 10k R's in series with this "one sided current injection", so whatever it's doing current wise, it's not doing much."

The triple EF stage probably has a current gain of around 100,000 (20x50x100).
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