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#1
10-17-2020, 11:51 PM
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Stereo speakers far too sensitive
Ok so this is my bedroom setup: https://imgur.com/a/EcJuOFp
The amp/receiver is a Fisher RS-1052, and the speakers are my fathers old Pioneer's that I replaced the crossovers on (I built my own). Before the crossover mod and after, it has one issue with this Fisher, it's just too damn sensitive. I turn the volume just one little speck up and it's already blasting and rattling the room. I'd like to have more control obviously over the volume and not have, off, a little quiet, and omg my eardrums, considering there's an entire range of the knob. I did try connecting my oscilloscope to the speaker terminals with only a dummy load attached to verify the volume knob isn't broken, and no, it has a very linear range, so apparently this amp is just so damn loud I guess, but with these speakers there's no room whatsoever. Considering the amp is 50ish watts, and the speakers "claim" 150 watts, I'm surprised it's this loud at all off one indent on the volume knob. I was figuring maybe on my crossover, I should design an LPAD attenuator for it perhaps? (The stock crossover was garbage, low pass, and two high pass filters, the mid was on a high pass as well, and they were designed with the crossover well above where mids should be, so it always had a built in EQ "V" curve, and I hated it. I redesigned the crossover to be more flat in the response, so my tone controls on the receiver can be in the middle and it actually sound correct, and it does now, because watching movies on it sounds very much like a proper movie theater which is funny, these speakers don't sound that bad for MDF construction and being "Rack" speakers, once it had a properly designed bandpass for the mids, and adjusted the high pass for the tweeter). If I go an LPAD route, about how many dB of attenuation should I be aiming for? To give a better understanding of the limited volume range, the knob goes up to 10, but at 2 it's already rattling windows and making the CD player skip, it's THAT loud. Though, when I look at pictures of other people using a Fisher RS-1052, they seem to have theirs at 2 as well like this is apparently common with this receiver no matter what speakers are used. 
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#3
10-18-2020, 10:28 AM
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Interesting. I think the booster board is there to drive a higher
wattage STK module or whatever it uses. Its a simple amp & cap coupled so a snap to eliminate. If the VC goes to ground on one end be sure it is ! A cracked pot could do it to. Last thing you probably know. If you plug a phono with a ceramic cartridge into the magnetic cart input it will blast you out of the house. This was a common problem when someone added a TT to a stereo & got the wrong one. 73 Zeno  LFOD !
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#4
10-18-2020, 10:59 AM
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Quote:
Even FM and AM are far too loud as well. I'm feeling that the best fix for this really might be to just attenuate the speakers themselves, maybe an inline attenuator on the speaker wire without installing it in the speakers themselves (since it doesn't have this issue with other amps).
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#5
10-18-2020, 11:16 AM
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You say the scope reading shows a linear range. Do you mean that the voltage is 20% at setting 2, 30% at 3 etc.? (Linear?) Variation should be logarithmic, starting out very small for an increment of say 1 to 2 or 2 to 3, but be relatively huge going from 8 to 9 to 10. If it's a similar size steps from 1 to 2 and 8 to 9, there's a problem with the volume control circuit.
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| Audiokarma |
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#6
10-18-2020, 11:47 AM
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Quote:
https://www.youtube.com/watch?v=zISM75LzX9A
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#7
10-18-2020, 11:54 AM
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The speakers are Pioneer CS-G403's, with a crossover installed of my own design since I felt Pioneer really screwed these speakers up by not even having a proper bandpass on the midrange, giving it a massive lack of mid range performance.
This is the schematics to my crossover, unless it's my crossover that's the problem? (I never got to use the original crossover on this speaker, but on the Onkyo receiver in the livingroom my crossover works perfect with).  With the stock crossover, the sensitivity of these speakers are around 93dB. With my crossover I simply don't know, I had an SPL meter once to measure the frequency response to make sure it was flat like I wanted, but I never tested sensitivity at the time.
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#8
10-18-2020, 01:39 PM
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I'm probably just going to install this on the speakers. It'll limit the speakers to 100 watts vs the "150" they claim, but with the small size of the woofers magnet, I don't think it was ever truly 150 watts anyway, and the amp is only 50w, so it's not even close to a loss.
https://www.amazon.com/Eminence-Over...3043713&sr=8-6
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#9
10-18-2020, 04:58 PM
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I don't know of any way a crossover could change the sensitivity unless it was wired entirely wrong and sending the wrong frequencies to the wrong drivers. Plus, in that case, it could only decrease sensitivity, not increase it. So, I'd think your speakers and crossovers are fine.
I don't know if the clipping before you get near max could be a clue, or not. But, what if there's a bad connection in the receiver where something should be loading down the signal more, or should be producing negative feedback to simultaneously reduce distortion and signal level? Do you have other speakers to try and see if they are too loud also?
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#10
10-18-2020, 06:16 PM
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Quote:
Old 70's Panasonic: Not loud, you really have to crank it. 2005ish KLHs: Very loud Both were 8 ohms as well. The pioneer claims it's 6 ohms, but a simple measurement shows 8 ohms are technically at the terminals (DC, since I have no way to measure the impedance across multiple frequencies since I know speakers change impedance based on the frequency). The fisher does state it can handle 6 to 16 ohms on the back.
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| Audiokarma |
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#11
10-18-2020, 08:30 PM
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Interesting, so the difference really is the speaker sensitivity. Well, then, the pad makes sense.
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#12
10-18-2020, 08:54 PM
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If your amp can handle 6 ohms minimum, then you need to put an additional resistor in series with the output before connecting the L-pad and 6 ohm speakers. The minimum resistance load will be with the L-pad set to max, which will be 8 ohms (pad) in parallel with 6 ohms (speaker) = 3.4 ohms. A series 3 ohm 50 watt would do. This also means you would have a minimum attenuation of about 6 dB when the L=pad is set to max, but from your description, you need it.
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#13
10-19-2020, 04:29 PM
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Never had speakers ( 4-16 ohm imp.) act like this. Often when test running
a set we would hang a pair of cheap TV speakers on it & never had a problem except if the PA shorted & popped them. No great loss.... This was on anything from tube amps through STK amps & big discrete component PA's. Since the amp wants to see a given SPKR impedance to be most efficient any SPKR problem should show only reduced volume IMHO. Other thing is you seem to infer the STK has been changed ?? If so its almost impossible to find REAL ones. Almost all are Chi-com bootlegs that barely work. From two sources i trust. https://www.youtube.com/watch?v=EZJjqpDaSZs https://www.youtube.com/watch?v=zvx07QdAoig 73 Zeno LFOD !
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#14
10-19-2020, 04:49 PM
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Quote:
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#15
10-20-2020, 05:07 PM
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Does your receiver have a tape monitor loop? You could build a simple 2-resistor voltage divider/attenuator that connects between tape-out and tape-in. Then activate the tape monitor to switch in the attenuator. Resistors would be in the kohm range. That way you wouldn't have to modify your speakers or change the impedance matching between the amp output and speakers.
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| Audiokarma |
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Linear Mode
