hi, im new so let me start. i have an existing sound system(chinese clone amp thingie) which has separate tuner, tone control and power amp boxes. im planning to change the amp into chipamp and reuse things i can from the amp-box and the transformer. the transformer is a toroid with 150va 30-0-30vac(42v when rectrified). so i was wondering what chipamp would be ideal to replace the old solid-state(based on C4468/A1695 pair).
i have the old speaker @ 4 ohms rated 50 watts, but i am planning to re-used a speaker system(model L90VH from sony) for the new amp.
i was planning to go with LM3886 but @ 42v i am at limit. thanks for the suggestions.
i have the old speaker @ 4 ohms rated 50 watts, but i am planning to re-used a speaker system(model L90VH from sony) for the new amp.
i was planning to go with LM3886 but @ 42v i am at limit. thanks for the suggestions.
TDA7294 states the absolute maximum voltage as ±50v. It recommends ±40v as the sane maximum, so you should be just fine. The problem is that chipamps hate high voltage and low impedance loads like the original speakers... Thankfully that sony speaker system states 8 ohms in its manual. Have some beefy heatsinks doing the job, maybe even helped with a 80mm computer fan at 5-7v which equals silent.
edit: reading further into the datasheet
It's the same situation as the LM3886... my bad.
I think there are some LME series chips that can withstand the voltage, but then require discrete output transistors to do the job and complete the amplifier.
edit: reading further into the datasheet
It's the same situation as the LM3886... my bad.
I think there are some LME series chips that can withstand the voltage, but then require discrete output transistors to do the job and complete the amplifier.
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Hello altogether, i am new here to.
Last month i finished a small Stereoamp with the TDA 7293- each one wih a 30 - 0 -30 V / 80VA torodial transformer. they each drive a 4 ohms Visaton WS 17 E - Speaker. The System works fine. In the Datasheet the absolute Voltage Maximum is described as 120V ! Of course you Need a big Heatsink cause the Chip gets rerally HOT. The Circuit Diagram of this Amp is in the Datasheet or you can find it on sound-westhost.com (Rod Elliot).
Please excuse my English, i am in Germany...
Regards, Jörg
Last month i finished a small Stereoamp with the TDA 7293- each one wih a 30 - 0 -30 V / 80VA torodial transformer. they each drive a 4 ohms Visaton WS 17 E - Speaker. The System works fine. In the Datasheet the absolute Voltage Maximum is described as 120V ! Of course you Need a big Heatsink cause the Chip gets rerally HOT. The Circuit Diagram of this Amp is in the Datasheet or you can find it on sound-westhost.com (Rod Elliot).
Please excuse my English, i am in Germany...
Regards, Jörg
thanks for the replies guys.
@vodka; your right, most chipamps suggests at +/- 35v for continuous operations. my sony l90vh speakers are indeed 8 ohms as specified at its back cover. based on service manual this speaker is rated at 100-120 watts. im doubtful to use th eold speaker coz its just too small (4" woofer cone) and dont do good high freq.
Basslastig67 - im looking at TDA7293's datasheet and it indeed falls to my requirements but datasheet shows about THD @ 10% when running 8 ohms at 38+ volts.
Derfnofred - yes, probably bridging might do but still needs voltage to be just about 35-38volts which would mean i will change my toroid(they are hard to find where i am and costs 2-3 times more of the cost of building 2 lm3886;s w/o power caps). but bridging will cost me more space unless i place amp boards sideways or facing upside-down each other. the box is just 12"x8.5"x4.5"(LxWxH) and the toroid is 4.5" at its outer diameter.
thanks all.
@vodka; your right, most chipamps suggests at +/- 35v for continuous operations. my sony l90vh speakers are indeed 8 ohms as specified at its back cover. based on service manual this speaker is rated at 100-120 watts. im doubtful to use th eold speaker coz its just too small (4" woofer cone) and dont do good high freq.
Basslastig67 - im looking at TDA7293's datasheet and it indeed falls to my requirements but datasheet shows about THD @ 10% when running 8 ohms at 38+ volts.
Derfnofred - yes, probably bridging might do but still needs voltage to be just about 35-38volts which would mean i will change my toroid(they are hard to find where i am and costs 2-3 times more of the cost of building 2 lm3886;s w/o power caps). but bridging will cost me more space unless i place amp boards sideways or facing upside-down each other. the box is just 12"x8.5"x4.5"(LxWxH) and the toroid is 4.5" at its outer diameter.
thanks all.
Wertz--not bridging, parallel 7294's. You're sitting close to the edge SOA of these devices, so paralleling chips will help minimize risks with power handling (since each chip is ultimately running at ~1/2 the global current). The 7294's can handle 42V, but not at any sort of low impedance. You'll want to have a input buffer (unity gain) sitting in front of these two chips in order to present a nice, high, input impedance.
30-0-30Vac will almost certainly blow a 3886, if not immediately, then eventually.
The internal protections will probably not work properly/effectively when the supplies are higher than that absolute 84V limit.
Do you have the transformer?
Have you measured the capacitor voltage?
Have you calculated/predicted the maximum worst case supply rail voltage?
The internal protections will probably not work properly/effectively when the supplies are higher than that absolute 84V limit.
Do you have the transformer?
Have you measured the capacitor voltage?
Have you calculated/predicted the maximum worst case supply rail voltage?
Hi Werts,
i think that you are afraid of the THD 10% is at every listening Level bui it is not ! in my Datasheet is the THD of 10% while it is running at +-40V rails and delivers 100 Watts at a 8 ohms load. That is quite clear because clipping starts at this Voltage by driving 100 Watts at 8 ohms.
just a Little below 100 Watts the THD will less than 1%.
i think that you are afraid of the THD 10% is at every listening Level bui it is not ! in my Datasheet is the THD of 10% while it is running at +-40V rails and delivers 100 Watts at a 8 ohms load. That is quite clear because clipping starts at this Voltage by driving 100 Watts at 8 ohms.
just a Little below 100 Watts the THD will less than 1%.
Caution: There is no chip available to replace your high end Sanken outputs with better performance.
However, replacement with a chip is doable.
To do that with your specified transformer (there are some limitations!) I'd like to know if you want concert realistic party sound with an amplifier that is great only when loud (doesn't work well used quietly), OR an amplifier that does fine quality 3d/realism at the cost of very little output power. With the specified transformer, you won't get both from a chip, but you may have one or the other. Specify?
I'm very sure which one I'd choose, but I'd love to know what your preference is?
You know, after making statements like that, the thought occurs that it could be better and possibly less expensive to buy the transformer suited to the amp that you wanted to use?
However, replacement with a chip is doable.
To do that with your specified transformer (there are some limitations!) I'd like to know if you want concert realistic party sound with an amplifier that is great only when loud (doesn't work well used quietly), OR an amplifier that does fine quality 3d/realism at the cost of very little output power. With the specified transformer, you won't get both from a chip, but you may have one or the other. Specify?
I'm very sure which one I'd choose, but I'd love to know what your preference is?
You know, after making statements like that, the thought occurs that it could be better and possibly less expensive to buy the transformer suited to the amp that you wanted to use?
I have made a thread with schematic of the current amp in Sokid State section maybe you couldcheck how this amp really is. I was just thinking of rrplacing this with chipamp because i dont really know how really capable this amp is. The disco music was just test, i usually just listen to acoustics or live music and some metal stuffz...
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