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Pioneer SX-737 clipping with KEF Reference Series 101/2

JayPare

JayPare

Active Member
My amp is cutting on high volume! Let's say we watch a movie, when the sound goes higher, it cuts out.

Can these be paired together? Are those speakers too demanding for my amp? Or maybe my amp needs to be serviced or cleaned?
 
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Most likely the "cutting out" you describe is the protection circuit kicking in saving you from killing your Pioneer.

This is probably happening because the impedance is too low for the Pioneer to handle effectively. The KEF's are rated at 4 ohms but that is nominal meaning that at certain frequencies it can be higher or lower.

http://us.kef.com/explore-kef/kef-museum/1990s/reference-series-model-1012-1990-92

Also if you are running more than one pair of speakers at once the total load is below the Pioneers rating and will certainly cause the protection circuit to kick in. Your Pioneer is rated for a minimum 4ohm load.

https://www.hifiengine.com/manual_library/pioneer/sx-737.shtml
 
I agree with wmgwizard above. I’ve had a 737, and I’m very partial to Kef speakers. But, Kef like lots of power. The 737 just doesn’t have it. The only Pioneer I’ve used that I wouldn’t worry about is the Spec 2. Certainly none of the receivers, except maybe 1050 and up. I’ve no experience with them. I do have an sx-850 that I am planning on trying with my Tangent RS8s, but I’m not expecting there will be any synergy. It is really more a test of my understanding.
 
wmgwizard said:
Also, if you are running more than one pair of speakers at once the total load is below the Pioneers rating and will certainly cause the protection circuit to kick in. Your Pioneer is rated for a minimum 4ohm load.
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No I'm not. But I guess this is still not enough power! :(

BilboBaggins said:
I agree with wmgwizard above. I’ve had a 737, and I’m very partial to Kef speakers. But, Kef like lots of power. The 737 just doesn’t have it. The only Pioneer I’ve used that I wouldn’t worry about is the Spec 2. Certainly none of the receivers, except maybe 1050 and up. I’ve no experience with them. I do have an sx-850 that I am planning on trying with my Tangent RS8s, but I’m not expecting there will be any synergy. It is really more a test of my understanding.
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So surprising. Those speakers are so small! :o
I guess I'll have to revert back to my BIC Venturi Formula 4 by the time I find a more powerful amp! :(
 
While the 939 is more powerful than your 737, it is still rated at a 4ohm minimum load and I believe the protection circuits are similar. Without access to an impedance curve for your speakers it's tough to definitively say the 939 will solve your problems.

If you only activate the protection circuit on your 737 on a "rare occasion" then maybe, but if the protection circuit kicks in with some regularity than probably not. Sadly maybe/probably aren't very clear answers, sorry.

If you're already committed to spending some money there are many options that might make a better choice than buying a 939, although they might not be as pretty.
 
Just to give you a comparison, I have a pair of 103.2s. Same generation, but a little bit bigger. One afternoon, I decided to try these out with 3 very nice integrated amps I have. Sansui AU-9900, Pioneer SX-9500, and a McIntosh MA-6200. The McIntosh had been fully restored and optimized by leestereo. The Kef’s sounded terrible with the MA-6200. So bad I quickly changed to the Pioneer. Better but still not good. They sounded pretty good with the Sansui. But I could sense they would sound better with something bigger.

However, I was looking for a match with my ma-6200, so I decided to try EPI 100Ms with the ma-6200, and there was a huge improvement in sound. The problem isn’t so much how much power the amp can supply, but how much current it can supply. And to do that, it needs a good transformer and output transistors that can handle the demand. Kef 101.2 are excellent speakers, but they need to be matched with the right amp to sound their best.

Good luck! I know what you are going through as I have done it, and I finally found happiness with big power amps.
 
Most of the amp I see are (from hifi engine) saying:
Power output: x watts per channel into 8Ω (stereo)
But:
Speaker load impedance: 4Ω to 16Ω

Therefore, how can I know if an amp is gonna be powerfull enough in term of current for those speakers? Should I be looking for something with a minimum speaker load impedance of 2Ω?
 
One telltale sign of a high current amplifier is the power increases as the load decreases:
50wpc @ 8 ohms becomes 75wpc @ 4 ohms. Some amplifiers will even double their output into a 4 ohm load.

There are receivers that are capable of this but they are usually TOTL and can get expensive.

It may be time to consider upgrading to separate components or different speakers.
 
Of the units you listed, the Pioneer is the top of the heap.

None of the units are more powerful nor are they high current capable. You run the risk of damaging any of them and/or your speakers.

You may consider "thinning the herd" and allocating the funds toward something more suitable.

You might also consider becoming a subscriber so you can access Bartertown. There are always some good deals from people who know and enjoy the equipment thereby reducing the potential for disappointment dealing with CL or eBay.
 
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wmgwizard said:
Of the units you listed, the Pioneer is the top of the heap.

None of the units are more powerful nor are they high current capable. You run the risk of damaging any of them and/or your speakers.

You may consider "thinning the herd" and allocating the funds toward something more suitable.

You might also consider becoming a subscriber so you can access Bartertown. There are always some good deals from people who know and enjoy the equipment thereby reducing the potential for disappointment dealing with CL or eBay.
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Thanks for you info. I will follow your advice. This morning I came accross some amps on Facebook Marketplace I don't know if some could do the job:

Yahama R-S300
Yamaha AX-450
Sansui 1000X
Sansui AU-6600

If so I will post in dollar sense if the price is right for them.

Thank you again @wmgwizard !
 
wmgwizard said:
You might also consider becoming a subscriber so you can access Bartertown. There are always some good deals from people who know and enjoy the equipment thereby reducing the potential for disappointment dealing with CL or eBay.
Click to expand...

Just saw your edit. The thing is I'm in Canada so I don't know if that would be useful?
 
There are many members in Canada. Put in a wanted to buy ad explicitly aimed at Canadian members. There is Barter Town North, but I’m not sure how well that works. I don’t look there very often. You have to be a subscriber to post there. The subscription is well worth the $25 annual fee.

Certain Yamaha, NAD, and Harman Kardon work well with 4 ohm speakers. I’m using an HK 495i right now with a pair of Ohm L. These speakers sound crappy with most receivers I’ve tried. They are sounding quite good with the 495i. Something like that or an NAD of about 100 WPC or higher should work well.

There is also the Pony express. If you find something in Ottawa, I will be in Montreal on New Years Eve.
 
BilboBaggins said:
There are many members in Canada. Put in a wanted to buy ad explicitly aimed at Canadian members. There is Barter Town North, but I’m not sure how well that works. I don’t look there very often. You have to be a subscriber to post there. The subscription is well worth the $25 annual fee.

Certain Yamaha, NAD, and Harman Kardon work well with 4 ohm speakers. I’m using an HK 495i right now with a pair of Ohm L. These speakers sound crappy with most receivers I’ve tried. They are sounding quite good with the 495i. Something like that or an NAD of about 100 WPC or higher should work well.

There is also the Pony express. If you find something in Ottawa, I will be in Montreal on New Years Eve.
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This is really kind to offer. I think I will give a try to AK Suscriber. Thanks for your help! :)
 
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My pleasure Jeremy!

I’ve already helped one AK member in Toronto with the pony express thing. Well half of it, anyway. The other half will be when the work has been completed here.
 
I've received an offer for a HK3270 (need to pay shipping from USA to Canada), a NAD 7600 and a Yamaha CR1000 (tbh, I don't like the look of the CR1000). I also found a HK3390 locally. I still don't have a price for the NAD as the guy needs to fix it, but the HK3390 is ~100$ and HK3270 ~135$ + shipping and taxes. Two questions:

Are those type of unit great for a Thorens TT? Will I see a difference (better or inferior) in the sound with my Pioneer SX-737?

Also, is the HK3390 comparable to HK3270? Better? Inferior?
 
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