Speaker switching box and "protection mode" ...?

[toddalin]

Ok... Thanks for all of the advice and support here. I decided to pull the trigger and I managed to get a "buy it now" one of these things (the same Niles model that I mentioned before) on Ebay for just $22, including shipping. I saved myself some money (the local Craigslist seller wanted $50 for the thing) and some hassle as the location was a fair drive from where I live.

I figure that for $22 I don't have much to loose because even if I don't end up likening the way that this thing works, I haven't wasted that much money on it and I can probably even sell it on Craigslist and make some of my money back anyway (not that $22 is much of a hardship). I do like the elegance of being able to access any function on my stereo with a button or knob on the amp, but at this point I already have a component switcher box and separate phone pre-amp box... so what's one more thing?

Any time you introduce L-pads into the equation, you loose damping. My selector has the ability to attenuate the two speakers either at the line source (potentiometers) and/or at the speakers (Lpads). When the Lpads are switched in, bass takes a definite hit as it looses its "tightness" on the JBL L300s. Will you hear this on your speakers using that system...

 

[spark1]

Feeling victi

Yes, but in the case of parallel connection the resistor is wasting power at all times.

It seems to me that this would be the case only when protection is activated...which of course only needs to be done when both pairs are being used simultaneously.

 

[quiet]

The eight speaker AR box here protects full time. I use two of them parallel and can run up to16 pair at a time. I have at least one receiver that can run a 4 ohm load.
With each pair of speakers added after the first pair the volume DOES increase with "no" volume knob adjustment. And the 16 pair will ultimately play "much" louder with max usable receiver power than any one pair. The sound quality from the speakers "themselves" doesn't deteriorate, I don't think.
It's not my intention to start a contentious comb filtering debate in the middle of Arron's thread. But yes, I hear substantial comb filtering. Very nice with organ solo. Not good for acoustic guitar solo.

I'm not having power loss operational problems from a load matching box. To the contrary. I can now mow 2 acres to any tune I want. I use 30 to 80 watts here.

 

[RunOutGroove]

Any time you introduce L-pads into the equation, you loose damping. My selector has the ability to attenuate the two speakers either at the line source (potentiometers) and/or at the speakers (Lpads). When the Lpads are switched in, bass takes a definite hit as it looses its "tightness" on the JBL L300s. Will you hear this on your speakers using that system...

Not sure what the term "L pads" refers to..? I wonder when you say that "bass takes a hit" if you are talking about only when the two pairs are set to play together or simply either pair on it's own as long as it's plugged into a box like this? I guess that I could live with a little less quality when the two are playing together as I don't often do that anyway... though I do of course like the option to do so here and there (why I want the damn box!).

 

[toddalin]

I am saying that any speaker that runs though an Lpad looses a "tightness" in the bass unless you crank it to "full" which will by-pass the internal windings.

If you are assessing two speakers and one is louder than the other so you use an Lpad to make them the same, you compromise the bass response in that speaker throwing off the comparison.

Every now and then I'll play the L300s (B speaker) simultaneously with another set of speakers (A) and inevitably end up turning down the L300s using 100 watt stereo Lpads to better match their volume.

Then I may listen to the A speakers without the B speakers (as I do most often). Then if I switch to the B speakers and forget that I still have the Lpads engaged to the L300s, I'll wonder why the bass sounds like crap until I realize what's going on and need to turn off the Lpads.

I have no idea how others wire their selector switches, but an adjustable volume control means that something is going through an Lpad unless they do it at the line level (i.e., attenuate the signal level when a certain speaker is selected). But that would require another set of cords between the preamp and amp or in a tape monitoring circuit.

 

[RunOutGroove]

I am saying that any speaker that runs though an Lpad looses a "tightness" in the bass unless you crank it to "full" which will by-pass the internal windings.

If you are assessing two speakers and one is louder than the other so you use an Lpad to make them the same, you compromise the bass response in that speaker throwing off the comparison.

Every now and then I'll play the L300s (B speaker) simultaneously with another set of speakers (A) and inevitably end up turning down the L300s using 100 watt stereo Lpads to better match their volume.

Then I may listen to the A speakers without the B speakers (as I do most often). Then if I switch to the B speakers and forget that I still have the Lpads engaged to the L300s, I'll wonder why the bass sounds like crap until I realize what's going on and need to turn off the Lpads.

I have no idea how others wire their selector switches, but an adjustable volume control means that something is going through an Lpad unless they do it at the line level (i.e., attenuate the signal level when a certain speaker is selected). But that would require another set of cords between the preamp and amp or in a tape monitoring circuit.

I'm pretty un-technical so I'll admit that I don't understand everything that you've said. I do get though that something like a volume control that's passive, as in this unit, is only going to pull something out, rather than make anything louder than the original signal. Perhaps this then effects the bass frequencies to a greater degree than everything else. My instinct when using something like this would be to keep the volume all the way up and to make any adjustments of volume with the amp. Of course if I'm running both sets of speakers simultaneously I might want to turn down one of the volumes to adjust the proportion of each. I'd be using both sets simultaneously pretty rarely and even then I doubt I'll be all that into changing the volume as it wasn't something that I ever even thought about when I used to have 2 sets of 8 ohm speakers and run those together (without the possibly of separate volumes). Mostly when I'm running both sets of speakers together, I'm cleaning my house and cranking up rock and roll, not doing anything like careful listening so a bit of a hit in sound quality won't be too much of a drag...

Just to reiterate, if I'm to understand you, the issues with sound degradation come primarily with turning the volume on the speaker-switcher box down from 100%, right?

 

[spark1]

You've got it. And as soon as you get yours hooked up, you can come to your own conclusions! Good luck with it.

 

[RunOutGroove]

OK... here's the followup... I got my $22 (including shipping) Niles speaker switcher from UPS the other day. The thing seems to be very well made... Anyway, I just hooked it up and what folks had said about it is 100% correct. It does seem that running both of the speakers together with the "protection" switch engaged (which is really the only way that one should use the thing) does cause a bass drop. It's not subtle either and turning up the bass on the amp doesn't quite restore what's lost as it does bring back some of the bass, but in a muddier, less punchy way. The speakers do seem to sound as good as ever when they're played one set at a time though. The protection switch doesn't seem to have any effect if both speakers aren't played together, which I guess is how it's designed. Oddly my one set of speakers the Elac Debut 6.2s that run with an Energy subwoofer seem to be much more affected by the running both sets together with the protection switch on than my other pair of speakers, Wharfedale Diamond 10.1s. There's a difference with the Wharfedales but it's more subtle.

Anyway, I guess that it's all worth it for the occasional times that I want to crank up both sets of speakers at the same time. In that case I can dial in a bit of extra bass, even if it doesn't quite restore the bass lost by the whole protection circuit thing...

In other news, I've noticed that if I crank it beyond a certain point in my main listening room and I'm playing something on the turntable, I get a nasty bass feedback loop going. I noticed a bit of that before, but since upgrading my speakers it seems to be happening at a lower volume that it was before. I've also added a pho-preamp that I wasn't using before, though I can't imagine that this is likely to be the issue wit. The way that my room is set up means that I can't really move the speaker that's closest to the turntable very far away. I wonder if it might have to do with some kind of thing that can be remedied on the turntable end...?

 

[spark1]

Perhaps your new speakers go lower, or have less attentuation in the low frequencies, than your old speakers. Or your subwoofer and your mains together are over-amplifying the offending frequencies.

In any case, you have a feedback problem. First verify that the turntable's VTF is correct, and that the table is level.

Do you have a subsonic filter on your preamp? See if it addresses the problem. Alternatively, if the sub has a high-pass filter built into it, wire your main speakers to it.

If neither of those is available, figure out if it is the subwoofer causing the issue. Turn it off and run the speakers only, at a volume that was causing the issue. If the problem is gone, drop the crossover point, and perhaps the volume as well, on the subwoofer. I find that a lot of folks have their sub turned up too loud...my belief is that you should not hear it distinctly; rather you notice it primarily when it is turned off.

Now turn off the main speakers and play only the sub, again at the same point on the preamp's volume control. If no feedback, go to next step. If still having feedback problem, further adjust sub.

Finally, run both the speakers and the sub to verify that problem is gone.

Oh, and as best as possible, get the speaker away from the table, and the table of out the speaker's line of fire.

After all this, if you still have the problem, it will be time to try and better isolate the turntable. Lots of approaches to this...I think I've tried most of them over the years. By far most effective is an isolation shelf. Unfortunately, it is often impractical unless you have dedicated listening space.

 

[gkimeng]

The Marantz 2270 had an issue that was reported in several publications of the time. For most amplifiers that can handle 4 ohm loads, the power rating is higher at 4 ohms than at 8 ohms, but for some unexplained reason the 2270 tested lower, clipping at 55 wpc at 4 ohms vs 70 wpc at 8 ohms. This was corrected in the 2275, but no fix was ever offered for the 2270.

Running two sets of 8 ohm speakers at the same time on the 2270 is not such a great idea. Two sets of 6 ohm speakers can only be worse.

 

[David_NC]

Personally, I'd just buy a cheap, used power amp, add a Y-splitter to the receiver's main-out / pre-in jacks, and connect the second set of speakers there. You'll know it'll be safe for your receiver this way. The last power amp that I bought was a Parasound HCA-1000A at 125 wpc at 8 ohms / 200 wpc at 4 ohms for the high price of $125.

 

[RunOutGroove]

Personally, I'd just buy a cheap, used power amp, add a Y-splitter to the receiver's main-out / pre-in jacks, and connect the second set of speakers there. You'll know it'll be safe for your receiver this way. The last power amp that I bought was a Parasound HCA-1000A at 125 wpc at 8 ohms / 200 wpc at 4 ohms for the high price of $125.

That's an interesting idea... I wonder if I could find something cheap that's also pretty low profile, that I could add to my stack of components without making it too much taller...?

 

[David_NC]

That's an interesting idea... I wonder if I could find something cheap that's also pretty low profile, that I could add to my stack of components without making it too much taller...?

If you want something really small, look for a Parasound Zamp. They look a bit like toys, but are tiny and well-reviewed. I keep looking at them, along with the matching Zpre preamp for my work system. Otherwise, most lower wattage power amps are relatively low profile. I believe mine is around 3"

 

[RunOutGroove]

The Marantz 2270 had an issue that was reported in several publications of the time. For most amplifiers that can handle 4 ohm loads, the power rating is higher at 4 ohms than at 8 ohms, but for some unexplained reason the 2270 tested lower, clipping at 55 wpc at 4 ohms vs 70 wpc at 8 ohms. This was corrected in the 2275, but no fix was ever offered for the 2270.

Running two sets of 8 ohm speakers at the same time on the 2270 is not such a great idea. Two sets of 6 ohm speakers can only be worse.

I didn't know any of that... but I there's a lot of stuff that I don't know! I will say that before I got these couple of sets of 6 ohm speakers I had two 8s and I regularly used them together with seemingly no ill effects. I was probably just lucky though. I feel like as much as I dig the 2270, I am starting to understand the limitations of it. I like the sound that I'm getting with the newer pairs of speakers much better and yet them being 6 ohm and likely less efficient means that they don't seem to want to go as loud without distorting as my old speakers. I'd still trade the quality that I'm getting now for raw volume, but here and there it's nice to be able to shake the house, you know...

 

[gkimeng]

During the 70s the FTC rolled out a power rating requirement that was more stringent than the method previously used by most audio manufacturers. Amplifiers that had previously claimed 100 watts of "dynamic power" were suddenly testing at 40 watts FTC, and a lot of manufacturers just removed 4 ohm ratings from their amps altogether. Your 2270 is probably just fine in an average room at average listening levels with a pair of today's more efficient bass-reflex speakers. But wire up a pair of 4 ohm acoustic suspension speakers from the 70s whose impedance can fall as low as 2 ohms at certain frequencies and crank up the volume and you can easily reach tweeter-toasting levels of clipping.