SDA-2A Tweeter Trouble
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acerrato
Posts: 15
Hello, I have a pair of SDA-2A's. I'm using a Technics SA-700 receiver to power them. If I move the volume past halfway my tweeters fade out and become muffled. I swiftly lower the volume and they play perfect. They are all original except the tweeters were replace in 1993 with new sl2000. Any Thoughts? Please Help.
Comments
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Poly switch is cutting the tweeters off. That sda2a is a 4ohm speaker and dips much lower. The Technics just does not have the power needed and is more than likely clipping especially past half way. Eventually you will let the magic smoke out of the receiver those speakers need a high current amp for sure.
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First off, never turn the volume up past halfway as the level of distortion rises rapidly sending clipped signals to the speakers. Your tweeters are protected by a thermal reset device called a polyswitch, which you are tripping due to the fact you've turned the volume up way too high.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I assumed the polyswitch in both were tripping. My receiver I upgraded and recapped and putting out 125 watts a channel. Is that not enough power?
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Sa 700 was originally 110watts a channel at 8omhs
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Sa 700 was originally 110watts a channel at 8omhs
Once again those are 4ohm speakers and in all likelihood your Technics was never built to power a set of 4ohm speakers.
Look at it this way
Your garden hose works great on the house faucet, now put a larger fire hose on it. How well does it work now? IT DON'T ... You shut it off let it fill then turn it on whooosh then nothing a dribble..... that is the 4ohm speaker on your Technics it simply runs out of juice to push it. -
I assumed the polyswitch in both were tripping. My receiver I upgraded and recapped and putting out 125 watts a channel. Is that not enough power?
It is enough power to get sound out of them it is not near enough to jam for any period of time. -
Here are the published specs.
20 Hz ~20 kHz continuous power output
both channels driven 2x110W (4 ohms), 2x 100W (8 ohms)
As you can see the 4 ohm rating is only slightly more than the 8 ohm. Ideally, the 4 ohm rating would be double. That indicates the power supply isn't all that beefy.
The bottom line is you are asking too much from that receiver and I'll repeat, you should never go past halfway on the volume control.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
How much power do you recommend?
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200w of high current power Is the typical goal.
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ok, would a DYNACO ST 416 0r 400 be a good match. They are 200watts at 8ohms. Not sure on 4ohm output.
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Is it common ground?
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yes they both are common chassis ground
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what amp did you guys have in mind?
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It's a damn shame that 200wpc crap keeps being repeated because ALL WATTS ARE NOT CREATED EQUAL.
For example, your Technics is rated at 100wpc @ 8 ohms, the same as a BAT VK-200 power amp except the BAT doubles at 4 ohms. It can also outperform amps with higher power ratings.
I like this guy's description because it's on the money,I once owned a quality 200w/ch amp that cost somewhat less than the modest 100w/ch BAT VK-200. I figured the 200w/ch amp at less money than the 100w/ch BAT had to be the better buy. WRONG! Very very wrong!! Even at half the power rating of the larger amp, the BAT VK-200 is the better buy. In fact, this modest 100w/ch VK-200 is more detailed, transparent, and robust than the 200w/ch or larger 300w/ch amps I've owned in the past.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
I can remember a time when the word "robust" was only used to describe coffee.
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ok, would a DYNACO ST 416 0r 400 be a good match. They are 200watts at 8ohms. Not sure on 4ohm output.
The damping factor of either amp is 30, which is pretty dismal. They would not be a good choice for SDA's.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
F1nut what would you recommend
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What's your budget?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
500 or so
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How is the parasound hca 1200 or 1000a
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It's a damn shame that 200wpc crap keeps being repeated because ALL WATTS ARE NOT CREATED EQUAL.
Then why is it so prevalent on this site? It's to keep noobs from look at amps that are not up to the task (untill they get some experience under their belt). Hell, you know I'm the first to admit that not all watts are the same... My NAD proved that to me instantly as it's only rated at 25wpc and blew away the 100wpc pioneer I was using.
Anywho, when driving a load like the SDAs, high current is the key phrase here. Headroom and damping are things to look for if you really want to push them. -
I'm taking recommendations
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That Parasound 1200 will do the trick.I ran one with my.1.2tl's and enjoyed it until moving on to a McCormack Dna 0.5 deluxe.2 Channel
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It's a damn shame that 200wpc crap keeps being repeated because ALL WATTS ARE NOT CREATED EQUAL.
Then why is it so prevalent on this site? It's to keep noobs from look at amps that are not up to the task (untill they get some experience under their belt). Hell, you know I'm the first to admit that not all watts are the same... My NAD proved that to me instantly as it's only rated at 25wpc and blew away the 100wpc pioneer I was using.
Anywho, when driving a load like the SDAs, high current is the key phrase here. Headroom and damping are things to look for if you really want to push them.
Because a certain person latched onto that notion and has been repeating it for years without a full understanding of the multitude of variables involved.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
How is the parasound hca 1200 or 1000a
Might be your best bet in that price range, but you still can't turn it up past halfway.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
If you're looking to make your ears bleed get a pair of Cerwin Vega's or Klipsch.afterburnt wrote: »They didn't speak a word of English, they were from South Carolina.
Village Idiot of Club Polk -
As in never turn any amp past halfway?
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My DCM qed's will do that with the technics sa 700
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Yes, that is the general rule of thumb with very few exceptions.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Well, aside from F1NUTS explanation, it's the easy answer instead of having to explain the ins and outs of power and how that all relates. Which can take a few pages and confuse people even more.
We've said it many times before, throw out your notion of watts and pay closer attention to current, which is represented in amperes peak to peak in specs. Also don't pay attention to "recommended watts" on the back of speakers. Pay closer attention to the efficiency ratings, and 4 or 8 ohm. That will give you a general idea of how ballsy of an amp you'll need.HT SYSTEM-
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