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Old 16th November 2013, 05:31 PM   #1
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Default A tale of three t-amps....

Hi, first post. A year ago I bought the Sure Electronics 20/24 amp, really loved it driving my JBL
L5's (6ohm). This week I stepped it up and ordered two Sure Electronics TDA 7492's, more power same decent build quality I hoped. I installed the first one at work with a pair of A/D/S L720/2 speakers. Sounded great but no volume whatsoever. Thought it was the effiency of the speakers. Then i swapped the Sure for my Lepai at half the cost of the Sure and half the power. Lepai drives the A/D/S speakers just fine, so much louder, and they don't hsve to go so loud. This makes me wonder about gain. I'm perplexed. The Sure sounds good at home with my JBL's, but not appreciably more powerful than the first Sure. Ideas?
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Old 16th November 2013, 06:50 PM   #2
Jsixis is offline Jsixis  United States
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Location: Columbus Ohio
I just ordered one of these from parts express also picked up the volume board.
claims 20watts stereo at 4 ohms. Seems to be under powered according to the spec sheet.
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Old 16th November 2013, 09:11 PM   #3
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These were built amplifiers, not the raw boards. I was wondering if their is an internal gain inside on the board?
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Old 17th November 2013, 09:03 AM   #4
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Location: On a hill, in a wooden shack, next to the woods, in Somerset.
The chip has 4 preset gains, and the lowest is only 21.6dB, which isn't even 20x. I guess the original has probably 30x gain. So the chances are that it's not running out of power, just needs more signal. The gain is set on pins 30 an 31. If those are tied the Ground and there isn't a 3.3V supply, then that's your explanation. If there is a 3.3V supply, then you can set one or both of the pins to 3.3V and vary your gain.

Page 22, here: http://www.st.com/st-web-ui/static/a...CD00205863.pdf
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Old 18th November 2013, 05:55 PM   #5
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Would those have 333 printed on the top? I am so electronics inept.
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Old 19th November 2013, 02:06 PM   #6
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Location: On a hill, in a wooden shack, next to the woods, in Somerset.
Ni idea. You may have to count the pins, if it's not marked on the board. Then measure the voltage on the pins. Otherwise what you are looking for is a small regulator else, or perhaps a test point that says 3.3V (fat chance probably). If you're lucky it might be a 7805 with a zener after if. Maybe an LM317 (at all of 10p) in a TO92 case (so like a transistor.
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Old 29th November 2013, 03:24 AM   #7
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I bought a headphone amp on ebwy. Guy makes them in mint boxes CMOY based. Its between source and amp. Sounds excellent now. Not sure why they would ship them this way.
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Old 31st December 2013, 02:30 AM   #8
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I now love this amp. I use a preamp with it, an interesting pre, handmade in Charlottesville, Va, right up the road from me. Amber is the brand. The gain on this amp is set low, yet it rocks, is deep, clear and sparkly when it gets proper input. I have also added a powered sub(Lab 12 in a sealed 1.5 cu ft box, powered by a Bash 300). Bliss.
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