Distortion and popping from new speakers

Fernando, I will try that tomorrow. I have thought about that possibility also.

Sounds to me like your AC line is below the 120 V reading with so many gear plugged to it, try to disconnect everything and just plug one source at the time, or feed your amp from other AC outlet which is not in the same route of the rest of the system.

Fernando

Thank you Plato for you research and analysis.

I will enjoy my new system and it does sound great to me.

Dave,

I just checked the specs on the CD Player's output level and the amplifier's input sensitivity. Basically, the amplifier only needs to see 250 mV at the inputs to drive the power section to the full 115W rated output. Your CD player puts out 2.14VRMS at 1kHz at the digital 0dB level (this is a typical figure for a CD player). So it would appear that the CD player is capable of putting out way more voltage than your amp needs in order to produce its full rated power. This suggests that the amp would reach clipping (point where distortion skyrockets) at a fraction of the volume knob's maximum rotation.

So I believe the distributor is correct in saying that your units are working as intended. Your situation is actually common. Manufacturers want to know that you could drive your amp to full power even in the worse case scenario of having a much lower output source component. The numbers on the volume control are merely arbitrary indicators that will not tell you where maximum volume will occur with a given source component and a particular recording.

If you took your amp to a tech for a bench test, I'm fairly sure he'd find that your amp is meeting it's full output power spec. It just reaches full power at a lower position on the volume knob than might be typical, since the amp's input sensitivity is on the high side... By the time you recognize distortion (gross distortion as you observed) the amp is well past its maximum safe output level.

Since many components have different output voltages, the point on the dial where the amp clips will vary from source to source and from recording to recording. For instance, in my system, I have to turn my volume knob considerably higher when using my turntable than I do when using the CD player to get the same volume level... Plus, not all recordings are made at the same output level (they can vary quite a bit). I know I can clip my power amp well below its maximum volume setting with any combination of source and recording. This is normal.

Enjoy your new system -- but watch that volume level! If you hear obvious distortion, it's way too loud. Be aware: excessive distortion can make the amp unstable and can harm both the amplifier and the loudspeaker(s). Many manufacturer's warranties will not cover damage caused by overdriven amplifiers... They consider it abuse and misuse.

Talked to the musical fidelity distributor and he said that turning the volume up 50% is full power for an amp ??? He didn’t think there was any problem with my Amp.
I also checked and my speakers are 4 ohms with Sensitivity 90 dB Recommended amplifier power: 30-180 watts Nominal impedance: 4 Ohms and my amp has Power 115 Watts per channel into 8 Ohms (20.5dBW) 185 Watts per channel into 4 Ohms.
I’m not sure what to think but I don’t have any other ideas except I shouldn’t turn it up to loud.

I could definitely live with it this way but it seems to me that something is wrong. I will contact Musical Fidelity about the possibility of a bad transistor. Thanks for the input guys. Any other ideas would be appreciated.

You may want to post a question directed to Musical Fidelity owners here and at Audio Asylum and see if they have the same problem.

I really can't see this as being a clipping issue with the volume control only a little above 11:00.

I had a similar problem with a Jolida amp that would make a popping sound as it was turned up to about the same position as yours. It like Alfredo's had a bad transitor.

Dave, my guess is that it is normal in this case. The amp is probably hitting full volume at around the 11 O'clock position. The only reason I find that a bit unusual is because your CD player is part of the same series from the same company and usually same-series components work very well together. Nevertheless it appears to be the case.

So relax and enjoy it. If you need to play it that loud, you'll need a much bigger amp; and at that point you may be taxing the power handling capacity of your speakers.

Distortion like you've experienced can harm/blow your speakers and you don't need to impress your friends at that cost and bother. High-end systems are not normally designed for rock-concert output levels. Heck, if you want really LOUD playback levels buy a pair of Klipsch Cornwalls and a high-powered amp... Then you'll be damaging your hearing -- not your system.

Frank :)

Davef, I had a similar problem but with a Hafler DH-200 power amp. The problem with mine was that it had a bad output transistor.

In your situation however, it could be different. I would call Musical Fidelity and tell them the situation.

Thanks
Alfredo

Depends on a lot of factors, including CD output voltage power rating of amp, and sensitivity of speakers.

The cd is plugged into the cd input.

Yes it is very loud and I would not listen to it for more than about one song at that volume. When I first noticed it was when a friend come over and we listen to the intro to Hotel California. the "bass" and Acoustic Guitar into. didn't cause the problem it was after they started to play the song. So then it might be normal for a system to only play distortion free up to about 40% of full volume?

Hey Dave, I just thought of something else -- make sure the CD player is NOT plugged into the phono input! That would definitely cause the symptoms you've outlined above. The input level would be way too high with the bass boosted out of proportion as well -- surefire recipe for overload.

You may be overdriving your amp -- since it sounds good when you turn it down. Is it VERY LOUD at the point where it starts to distort and pop?

11:30 on the volume control does not indicate 45 percent power -- in your particular case it could be closer to 150 percent at that setting. You don't get bad distortion and popping unless you are clipping an amp excessively. The fact that it doesn't distort until the volume is raised past a certain threshold indicates the distortion is probably in the amplifier. If the volume level is not loud and the speakers are distorting badly then there may be something wrong with the amplifier. Try a different, more powerful amp if possible and see if the problem persists. Also, check your speaker cables and make sure none of the positive and negative connections are touching/shorting.