Nick K Posted April 1, 2007 Share Posted April 1, 2007 I added a set of speakers in the kitchen on the "B" circuit to my Sony receiver (STR-D711). My Klipsch 2.1 satellite speakers (on "A") go nearly comletely quiet when I use the A+B setting, and the tiny in wall Boston Acoustics (on "B") are loud. Is impedence playing a role here?? I have talked to many folks, none of whom seem to have an answer. Help me Obiwan, you're my only hope! Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted April 1, 2007 Share Posted April 1, 2007 Does your Sony amp an impedance switch on the back? To drive both (A+ channels that switch should be in the 4-6 ohm setting, irregardless of your actual speaker iimpedance. Another possibility is issues with the bridge jumpers that some Sony amps have on the rear of some units. HTH WOT Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 1, 2007 Author Share Posted April 1, 2007 No, my receiver doesn't have an impedence switch. What is a bridge jumper and is it something I can address, or are we talking new receiver? Thx for the help! Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted April 1, 2007 Share Posted April 1, 2007 Are you sure? Most Sonys have them. It's kind of hidden with a small "slider" switch you have to move with a screw driver (kind of like the 120/220 switch on a PC power supply) The "jumpers" are also used on some Sony amps and bridge the A/B amp sections together to get full max rated power. They are usually just a pair of U shaped devices that pushes into a pair of holes in the back of the unit. WOT Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 1, 2007 Author Share Posted April 1, 2007 Yes, the D711 doesn't have the impedence switch. The D911 does. The manual says the AB setup is run in parallel if that impacts any potential solution.... Any ideas for a remedy? Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted April 1, 2007 Share Posted April 1, 2007 Hmmm not really Running out of options Does each individual pair of speakers work 100% when connected to A (leaving B disconnected) then B (leaving A disconnected)?? WOT Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 2, 2007 Author Share Posted April 2, 2007 Yes. The A circuit works great on A. The B circuit works great on B. The B circuit also works great on A+B. Its the A speakers when on A+B. They do work buy barely. Not sure if it helps to mention that the little sound that does come from the Klipsch A speakers when on A+B, is very subdued. I have to crank up the volume to hear it and it sounds muffled with lots of reverb. I appreciate you staying w/me on this problem! Quote Link to comment Share on other sites More sharing options...
WopOnTour Posted April 2, 2007 Share Posted April 2, 2007 Well that pretty much eliminates cabling or a major problem with a speaker itself. Given the lack of selectable impedance the pairs of speakers should have at least the same impedance rating. Even if they do the true impedance being reflected to your amp is obviously different (not that unusual) and it's having trouble driving both pairs of them equally.Or maybe more correctly stated, your amp IS driving them equally but the differences in the speakers themselves (impedance, sensitivity etc) is resulting in diffferent output levels.So I would recommend you use 4 identical make/model speakers for this application. If these are in the same room it should be pointed out that this type of connection wasnt really designed for bi-amped (or multi-channel HT?) single room listening, Sorry I cant help much more than that.. Good luck with the system WOT Quote Link to comment Share on other sites More sharing options...
@silverfox@ Posted April 2, 2007 Share Posted April 2, 2007 have you tried revursing the pos&neg on speaker 'a ' never know? Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted April 2, 2007 Share Posted April 2, 2007 Its just a stereo receiver right? If not and its in surround mode, your set of B or A speakers maybe being set aside for surrounds possibly. Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 2, 2007 Author Share Posted April 2, 2007 No, this is a surround receiver. The A and B circuits are completely separate from the Center and Rear speaker inputs. I can toggle these surround speakers with the (surround) Sound Field on/off button. In either case, the front R and L have these symptoms. Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 2, 2007 Share Posted April 2, 2007 What model 2.1 speakers? And are you driving them off the speaker output of the receiver? Gil Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 2, 2007 Author Share Posted April 2, 2007 oops they are the KG 2.5s -- had them forever (and love them). Yes, running these out of the speaker output of the receiver as intended. Receiver is Sony STR-D711. Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 2, 2007 Share Posted April 2, 2007 Okay, we're getting closer. It arises from the fact that your amp puts A and B in series. But let's discuss things. I asked about the 2.1 because speakers with that nomenclature are typically Pro Media which have a line level input. But not knowing more I thought you might have been using the speaker outs of the receiver to drive a line level inputs to Pro Media. This can work if the speaker output is at very low levels. (People here will note that one of the KIipsch mini-box center channels uses the speaker level output.) But you have regular old KGs. Fine. I looked at the Sony site for the manual for your system. It is for the 911 and 711. As reported only the 911 has as an impedance selector switch. This must adjust something in the amp to allow higher current at lower voltage. That area of inquiry by others was a good first guess. This is because most "A or B, and A+B" settings on receivers put the A and B speakers in parallel. It seems that sometimes the combined parallel load is too much for the amp and a current sensing sensor will shut down the amp. Switching to the lower impedence (if you're unit had it) could help, if that was the problem. (It is not.) My first thought was that somehow, the Sony was more sophisticated and shuts off one of the A or B in the case where you're driving both. And that is what you're experiencing. But that is not correct. It pays to look at the manual. On page 12 it says that the A and B speakers are in series (not parallel). Also that A+B will not work unless there are speakers connected to both. Which makes sense. This is certainly the root of the problem you're experiencing. - - - This brings up the problem of connecting speakers in series. There will be issues. My thought is that the KG has an autotransformer which will cause the impedance of the box overall to have a high impedance in the treble horn area. Your in the wall speakers should have a more normal 8 ohm impedance thoughout the frequency range. Armchair reasoning by me is that the KG's should work okay and the in the wall speakers don't because of the above, in the treble area. But your reporting something different, and opposite. I have not experimented and don't have any brilliant thoughts. Is there any chance the in the wall speakers were set up for a 70 volt system? If so, their impedance would be even higher. With the knowledge that the A-B is a series, others may have thoughts or experience. Gil Quote Link to comment Share on other sites More sharing options...
michael hurd Posted April 3, 2007 Share Posted April 3, 2007 I didn't look at the manual but I assume that A+B is in parallel, not series as suggested. My guess is that the inwalls are a much lower impedance and command more of the "shared" power when hooked up in parallel. I have a good chart in a technical book that could help explain this, but no access to a scanner at the moment. It deals with combining speakers of unlike impedance in parallel off one amplifier channel. The lower impedance speaker gets the lion's share of the power, so to speak. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 3, 2007 Share Posted April 3, 2007 You can get a wall mounted volume control to fine tune the level of each speaker. Get one that uses an autoformer instead of resistors or l-pads. These are on ebay all the time. I bought many at 10 bucks each. They come in 60, 100, 150 watt versions. 60 watts is plenty. Quote Link to comment Share on other sites More sharing options...
Nick K Posted April 3, 2007 Author Share Posted April 3, 2007 I did more research: The in wall Boston Acoustics are 8 ohm. Yes the AB is in series. When the switch is on A+B and all 4 speakers are hooked up, the A (Klipsch) speakers are barely audible. When I remove the B speakers, the A speakers totally cut out. I guess that just confirms the series setup. More details on the in wall speakers are below. If the impedence difference is the problem, is there a way to hook up some sort of speaker switch to the inputs to level this out? Or do I need a receiver with AB in parallel? Details: » 3/4" dome tweeter » 5-1/4" woofer » handles up to 90 watts » frequency response 75-20,000 Hz (±3dB) » sensitivity 90 dB » 8-ohm impedance » paintable speaker grilles » cutout dimensions: 6-3/4" diameter » mounting depth: 3-1/8" » warranty: 5 years Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 4, 2007 Share Posted April 4, 2007 The wall mount autoformer folks sell a black box version. Basiclly, the black box takes over the A, B, A+B function and controls the speakers and their volume level. In your case, all the speakers need an autoformer volume adjustment....a black box product will do that. if speakers A are 4 ohms, and speaker B are 8 ohms, that would mean that 66% of the power are going to speaker A and 33% going to speaker B. Other factors are the SPL ratings of the speakers. If one had an SPL of 87, and the other 90, the gap widens. Quote Link to comment Share on other sites More sharing options...
Klipsch Employees Trey Cannon Posted April 4, 2007 Klipsch Employees Share Posted April 4, 2007 IF your a math person this may help... http://www.aikenamps.com/VoltageDividerRule.htm Quote Link to comment Share on other sites More sharing options...
Klipsch Employees Trey Cannon Posted April 4, 2007 Klipsch Employees Share Posted April 4, 2007 Oh yea, get a new receiver or an impedance matching speaker switch to solve your problm. Quote Link to comment Share on other sites More sharing options...
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