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Old 28th April 2011, 01:24 PM   #31
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I am still looking for commercial audio amplifier brands, where are in use a bunch of small or medium signal transistors in the output power stage instead only one or only few BjT power device in each half.
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Old 28th April 2011, 05:21 PM   #32
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Perhaps not exactly the same, but a few years ago meier audio (http://www.meier-audio.homepage.t-online.de/) used to sell a power amplifier with like 40 accurate small signal opamps paralelled in the power stage.
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Old 21st August 2011, 02:16 AM   #33
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How about a 10 Toshiba 2SA1930/2SC5171 in stead of a gazillion little ones? these things are fast like smaller transistors but with 10 times the current capacity.
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Old 21st August 2011, 09:42 AM   #34
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Quote:
Originally Posted by Cyberschelm View Post
Perhaps not exactly the same, but a few years ago meier audio (http://www.meier-audio.homepage.t-online.de/) used to sell a power amplifier with like 40 accurate small signal opamps paralelled in the power stage.
Thank you for this advice - this could be also an approach, which promises good results. I will ask there, which model it was.
Was it the amp showed about
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Originally Posted by analog_sa View Post
This idea is not even crazy enough.
???

Quote:
Originally Posted by idlehands View Post
How about a 10 Toshiba 2SA1930/2SC5171 in stead of a gazillion little ones? these things are fast like smaller transistors but with 10 times the current capacity.
Also good, but I would prefer non isolating outline like 2SA968/2SC2238 about
http://cdn.head-fi.org/e/ef/ef5e9c88_IMG_1444.JPG
for more rugged applications like Class-A.
The thermal transition resistance by the ISOWATT-220 (SC-67) outline about
http://bg-electronics.de/catalog/ima...1930%20PMC.jpg
is much more larger than by usual TO-220.
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Originally Posted by forr View Post
There was at least a commercial amplifier having an output made of dozens of medium power transistors, in TO220 package or similar with no heatsink. It was about fifteen years ago; I don't remeber the name except it was european and had no success at all.

Using a huge amount of devices for an output stage, problems can arrise because of parasitic capacitors and inductors.
~~~~~~~~ Forr
Can you try to find out this with help of a forum in your language like this:

Last edited by tiefbassuebertr; 21st August 2011 at 09:57 AM.
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Old 7th January 2013, 10:37 AM   #35
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Quote:
Originally Posted by forr View Post
There was at least a commercial amplifier having an output made of dozens of medium power transistors, in TO220 package or similar with no heatsink. It was about fifteen years ago; I don't remeber the name except it was european and had no success at all.

Using a huge amount of devices for an output stage, problems can arrise because of parasitic capacitors and inductors.

~~~~~~~~ Forr

maybe this brand: GTE Audio Trinity Class A
TRINITY Electronic Design GmbH
High End 2009. Hifi Anlage. GTE Trinity. Lansche Audio. | Audiodoo.de Hifi-Blog
World's expensivest Audio Power Amplifiers - $100.000 - $600.000 (post #6)
Apogee Scintilla - Information about the Efficiency wanted (post #17+#18)

The amp about
Dan d'Agostino MOMENTUM: Sonic Character like pure ClassA/SE despite low Idle Power ?
uses also a lot of power devices in parallel mode.

Here various diy projects:
http://www.elektroda.pl/rtvforum/topic985463-0.html

Last edited by tiefbassuebertr; 7th January 2013 at 10:53 AM.
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Old 7th January 2013, 08:52 PM   #36
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This is the Momentum output stage, there is nothing special with the numbers of transistors. It has local decoupling dought. The Sanken BJT transistors are low cost.
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Old 7th January 2013, 09:05 PM   #37
Telstar is offline Telstar  Italy
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Quote:
Originally Posted by idlehands View Post
How about a 10 Toshiba 2SA1930/2SC5171 in stead of a gazillion little ones? these things are fast like smaller transistors but with 10 times the current capacity.
This thread is interesting
I have got a bunch of the above and similar, which would be very nice for a headphone amp.
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Old 8th January 2013, 12:54 AM   #38
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Actually every LAPT is basically a collection of small transistors in parallel with their own emitter resistors, on the same silicon die. Which is precisely why they can go up to and over 50-70MHz and have large SOA - but being integrated on the die, have less stray capacitance and inductance.
Also, most MOSFETs are cell-based designs, albeot without source resistors (as efficiency is the name of the game), in this case for reasons of efficient scaling - basically change te die size and hence the number of cells, but the behaviour is still like a collection of many small MOSFETs in parallel.
Before the dvent of LAPTs using smaller devices in parallel was the only way to get high speed (however this also depends on the actual technology used for the small devices). Also, it's a case of 'nneds must' - for instance, what if you wanted a JFET with Idss=500mA? There are no current production units like that, hence, use what you have and parallel it
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Old 17th July 2013, 01:53 AM   #39
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Quote:
Originally Posted by tommy1000 View Post
This is the Momentum output stage, there is nothing special with the numbers of transistors. It has local decoupling dought. The Sanken BJT transistors are low cost.
Hi, tommy1000 thanks the picture.

Sanken bjt has good reputation at their good sounded amps from the past like luxman amps, sony, etc. And my 1st good sounded amp using sanken bjt both driver and ops, but most the driver blow in ~3years and changing the driver to toshiba make it sounds worse.
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Old 8th February 2014, 06:58 PM   #40
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tHIS VINTAGE MODEL ALSO USE THE APPROACH OF PARALLEL MODE OF MEDIUM OUTPUT POWER DEVICES
Thule Audio Vintage Integrated Amplifier IA-120 (IA120) Schematic wanted
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