Pioneer VSX-45tx and M&K Speakers (1 Viewer)

[Tommy_C]

I am running a Pioneer VSX 45tx with M&K S-150's front and 4 SS-150 rears with my HT right now. These speakers are a 4ohm system. The receiver has a 6 ohm and 8 ohm settings that I have set to 6.
What has been happening on occasion is this. When I watch a movie at the -10 or -8 area and a powerful scene comes on the receiver shut off. For example when I am watching Sum Of All Fears and the bomb goes off, or Apollo 13 when they are re-entering the earths atmosphere it shuts down.
The person I bought it from, Josh at DocDVD.com ( great to work with by the way) said the combo should run great. I am wondering if this is just to much for the amp or is there something else wrong?
Thanks for the thought
TC
Admit one Basement Bijou

 

[Brae]

Tommy, there is a lengthy thread about this receiver on the AVS Audio Hi-Fi forum.
Aside from that thread, you are asking the receiver to handle a speaker load beyond its published capabilities. First, what speaker impedance setting did you set on the 45TX: '6 to less than 8-ohms' or '8 to 16 ohms'? Nevermind, I re-read what you said.
Next, [email protected] played you for a chump. The 45TX is not designed for 4-ohm load speakers, and even my 8-ohm load speakers have shut the unit down in the past. Not knocking the receiver, but I acknowledge its limitations.
At least you have provided the means for others to avoid Josh, and continue to help you resolve your problem. BTW, have you run the MCACC program yet? Also, are the speakers configured as Large or Small?
No, the problem is two fold: less than startling current storage in the amplification department, and overly sensitive to distortion (both internal, IMHO, and external). Many are mating their 45TX's with external amps on the mains as I will probably be doing, too.

 

[MikeRP]

TC:

I hate to tell you this but the 45 is not designed for 4 ohm speakers. 6 ohm is the minimum.

Now there is a few things you might try to alleviate the problem if you love the 45 as I do.

One is after you run the MCACC - change the eq settings so that the lower freq's are de-emphasized for the front mains and center channel. Also set the crossover to no less than 80 Hz. You might even go to the next level higher ( I think its 120 Hz) and have your sub woofer handle the bass.

Finally, buy a good 3 channel amp and preout the FL FR and CC from the 45 or use the 45 and bi-amp those channels with the 45 handling the upper freq's on the speakers. This depends upon if your speakers are able to be bi-amped.

Again the 45 is only good for 6 ohm loads and above. See AVSForum and the shutdown thread on the 45 and you'll get a lot of good info.

Mike

 

[MikeRP]

Oops:

Sorry Brae:

Didn't know you were answering!

Should have known you'sd be lurking!

Mike

 

[Brae]

Well, sitting hear at work doing nothing makes me a little bored. I thought I would point out a couple of things. I know someone local to me that also got into this combination 45TX & 4-ohm speakers but he has not calibrated it yet for the fnial determination.

 

[Tommy_C]

I don't think Josh set a me up. If you look at THX Ultra specs, for an am to be certified it must be able to handle down to 2 ohms. I know the material says 6 for pioneer but if the stamp something THX ultra it has to follow those lines too. One thing Josh and I brain stormed was the loud button on the amp my be on. I am in my car right now and when I get home will check to see. I am also all set for small on my Mac program, that was the first thing I looked at. I might try the bass tweak too if the loud does not work. Thanks will let you know.
TC
Admit one Basement Bijou
PS love the 45 though.

 

[Brae]

The 45TX is not THX Ultra certified. Were you talking about your speakers? The 45TX is THX Select certified only--unless I am in store for some good news.

 

[Garth]

Tommy,
Nice Basement! If I were you I would send it back. Your room looks great and your speakers should work well in there without the MCACC. The only reason I kept the 45 was to tame my room, I have a BIG ODD shaped room and the MCACC really helped. I did have to add amps to the front LCR to get it to work. I'm very happy with my 45 with separate amps, I think we'll all end up with separates in the end, it's just the question of when do we start?

 

[Brae]

A serious consideration would be something like a QSC DCA-1222/1824 (375x2 or 250x4) and amping via preouts. You could also get away with using the PLX-1202 (325x2). BTW, if you get a chance, do the following:
1. Reset the receiver, place Impedance at '6 to less than 8-ohms' and run the MCACC test.
2. Determine the threshold where the receiver wishes to shut down (dB value on the Master Volume).
3. Disconnect one channel at a time and see if you can exceed the above determined level on the Master Volume. Reconnect this channel and repeat for each channel.
4. If you find that one channel is being somewhat troublesome, then disconnect all channels and connect only the suspect channel. Does it still shutdown at the threshold originally determined in Step 2? If so, this may be your problem (it was for me, a bad surround speaker).
If none of this helps, sorry for wasting your time, hehe.

 

[Tommy_C]

Here is the gremlin. I just watch Ring of Fire last night (BTW WOW on the sound and efx)at levels I would have expected it to shut off, and it performed great. So to test it I put in a disk that I know it shut off at and played it at the same volume and it did not this time? Man I don't know what the deal is. Maybe in the long run I do go with a 3 channel to run the fronts and leave the 45 on the back 4 and sub.

 

[Brae]

The behavior is not one-dimensional. The current storage (capacitor) holds a finite amount of electric charge. As the impedance begins to dip at some frequency the rate of consumption of that electric charge increases. The deeper and or wide the dip the greater the overall amount of rapid charge depletion.

Of course, this may not be a condition of impedance and maybe you have a problem in the area of clipping, distortion, etc.

 

[MikeRP]

I think this receiver needs a little break in time also.. Play it for 5-6 hours on a moderate volume and then check it out and see if you have the problem.

Mike