We have looked at the audio system today, after it was behaving extremely mysteriously: the volume control on the receiver doesn’t control the bass, so the bass remained too loud when we turned it down.
We observed surprise Loud when playing Spotify from the TV, since although the receiver was set to a reasonable volume, the TV output started at 100% volume before Spotify set a lower volume (should not be necessary! inputs should be able to be at 100%), which the subwoofer turned into a loud noise in spite of the receiver’s reasonable volume setting.
We would really like to have a single hardware volume control that actually works.
We found out:
The right speaker buzzes really badly on some songs, due to 4~10KHz sounds. Seems like a physical speaker problem. Repro: of Montreal - Cato as a Pun
The reason the bass isn’t controlled by the volume control on the receiver is that the subwoofer is attached through the receiver using the tape recording output (!!). This obviates the receiver and its controls (EQ, volume) (we checked the schematic, it’s directly attached to the input) but is reasonable because it is a workaround for:
The receiver only has a 2 channel output, for speakers, with no pre-amp out (post volume, post EQ) for the subwoofer.
The subwoofer doesn’t have a crossover for high level signal, so we cannot use it to derive a subwoofer signal from the amplified speaker signal (without losing the speaker outs to the subwoofer, or putting them in parallel (Bad)).
The Good solution:
The receiver should probably be hacked, with a custom PCB/perfboard and proper engineering (is it @TyIsI’s? I note the “do not hack” tape, we will have to figure out whose it is to ask them) to have a pre-amp out (take a high impedance tap of the receiver’s own pre out and give it an impedance buffer and a jack)
The Ugly solutions:
Take a tap off of the speaker outs with some resistors to get some high impedance low level signal to the subwoofer.
or
Write a sign that explains the jank of the system, that there are two volume knobs, one on the receiver and one on the back of the subwoofer (this sucks). sign written
Preface: while looking through the setup it is evident that the project of putting up speakers encountered several difficulties that could have kept speakers from being put up. We really appreciate that these were worked through, and that there are speakers! Please keep janking things if it gets it over the finish line and is not a hazard.
Bonus jank zone; these are eminently and pretty easily fixable in a couple hours and would improve the space:
One of the speaker cables is a hacked up RCA cable that is really thin. This should probably be replaced with proper speaker wire but is not a fire hazard with this receiver at any volume (math was done).
Overall cable management is quite bad, especially the power bar could use some extensions and mounting to the wall.
The binding post plates could use to be attached to something instead of hanging in free air.
I used the power of instant reversibility to circumvent the ‘do not hack’ sign when I added a janky usb-powered Bluetooth adapter. I can’t negate the whole sign though, but I so do love your vigorous enthusiasm for a much better stereo setup and thereby put my utterly ineffective voice behind this idea! (But only in theory because the sign remains and I’m also not versed in ‘no-magic-smoke’ electronics work)
My interpretation of the sign is that anything besides the actual receiver insides and probably the speakers is relatively fair game to hack as long as it’s respectfully done.
Yep that would solve the problem indeed. Feels a little bit overkill and would lose the feature of having the EQ in a nice spot there but might also be sweet for if we put games consoles there and such. Could definitely be used.
sign written
