But that way you can't toggle stereo/mono, you must disconnect the cable from the tape outs, or? Regardless, are you suggesting tape loop should be avoided, y or non-y cabled?
One must review exactly how the tape loop is driven, and what features your receiver has. If you have a "tape monitor" button, which would allow you to hear a 3-head deck, as well as insert an EQ there, then that's really the only case where it would be useful. However, be surprised that you might not need the "loop", just plugging a cable into the tape outs can render near mono - while causing problems for external devices. Here's the first schematic I had handy and opened. Analog audio comes in from the internal phono stage on green (for the right channel). It goes through the analog switch IC, and emerges as red. That goes left to both tape outputs and also right to the tone controls and then amp. Now what happens if you simply connect a cable between left and right on either "tape rec out"? You've bridged the left and right channels together with 940 ohms total output resistance. How would that affect the internal phono preamp? It is the direct output of an op-amp, with only DC blocked by output capacitors. It sees a load of 1M (not pictured), plus the load of any tape decks connected. However, any difference signal sees a load of under 1k, which is where op-amps start to get challenged. Most mixer circuits combining op-amps have higher output resistances on the op amps. However, because of those protection resistors on the tape out, it's not enough to completely collapse internal signals to mono, you'd still use the tape monitor loop. But same thing happens when you switch the input to CD, except we don't know how the external CD player operates. If it has an output (source) resistance of 470 ohms, and you connect the inputs together with another 470 ohms, you are collapsing the stereo image that you hear, even when you've not chosen to monitor tape. If it has low output impedance and a minimum tolerated load of 5kohm, bigger problems. What if we have a completely different receiver, one with op-amps that directly drive the tape outs? A buffer amp instead of just a resistor. When there is stereo difference, such as the rumble we are trying to cancel, one amp might output +0.1 volt, while the other outputs -0.1 volt. A difference of 0.2 volts. 0.2 volts across an extremely low resistance delivers how many watts? So basically, don't do it unless you can make the same determination about all your hardware. An external mono switch from tape out to tape in might be acceptable if it also has resistor padding and voltage dividing in it, before combining to the single wire. And you still might have to turn it off for fidelity of other sources. We know that a turntable cartridge, even shorting all the wires together, the worst you get is no sound from the turntable.
This is an ancient thread, and even our honoured host probably would agree that the main purpose in monophonic reproduction (of LPs) is to avoid surface noise. You can do that if, and only if, your cartridge is able to ignore vertical motion of the stylus. If you have a chunk of crud™ sitting in a groove, it will move your stylus vertically, and if the pickup is insensitive to that, you have a silent LP! Y-connectors do exactly what a mono switch on a pre-amp does. Both channels are summed, each speaker plays the same signal, no stereo image is possible, and all the surface noise is there in both channels. If you want your mono LPs to sound different to the way they do through your stereo cartridge, you have to get a mono cartridge that ignores vertical stylus movements. (Hint: not all of them do. If it is a stereo pickup built as normal but wired to sum the channels you just paid for nothing. You need one with the coils on the cantilever rotated 45º, and only one coil is wired up. The other coil is either disconnected - if it is cheaper to build it that way as usual - or isn't present at all, which rather oddly costs more).
I’ve been wanting to try the y-cable trick lately but I’ve been putting it off because the constant swapping of cables sounds so tedious. ..But today I made a startling discovery: my Denon PRA-1500 pre-amp has a mono output (actually TWO, one labelled SUPER BASS and one labelled NORMAL). So, if I go out and buy a single 1 male RCA to 2 male RCA cable, plug the single RCA plug end to the ”Mono NORMAL” output and the two RCA plug end to one of the TAPE inputs (PB or REC?) I should be able to switch between stereo and summed mono by using the tape monitor button? Would it really be that simple or am I missing something? Edit: If for some reason this doesn’t work, my ”plan B” would be to go out and buy another y-cable, plug the other end to tape pb and the other to tape rec and the tape monitor button would switch between stereo and summed mono? I think this method was mentioned in this thread somewhere.
..I forgot to mention that I have a separate phono stage so I won’t be using the Denon pre-amp’s phono input. Also, I see that discussion about tape out/tape monitor solutions can be found right here in this thread. Sorry about that, I’ll do some more reading. That said, the fact that my pre-amp has a single-RCA ”mono normal”-output is a bit of twist. That is IF it works, even if the only benefit versus ”dual y-cables in a tape loop” is saving a few bucks and less cable clutter since theoretically a single cable would be all that is needed.
Regarding connecting the y cables to the tape monitor input and output, I found that the stereo separation is audibly reduced on my equipment even when the tape monitor switch is off to listen in stereo.
I just looked at the back panel layout of you PRA-1500. It is one of the most unique I have every seen. You correct that you can use an RCA single male to two females connector to get two mono outputs from the single Normal RCA jack. I would then take that output into the "PB" jacks on one of the tape loops. You would then switch between between what ever input you use for your phono preamp ( an Aux input ) and the Tape PB input. I am not sure how your Tape Monitor switch works.
^ Thank you! I went out and bought a couple of y-cables, together with some regular RCA-cables I already had I should be able to test three different methods now: ”Mono Normal into tape loop”, ”regular tape loop” and (if all else fails) the OG double y-cable method as suggested by our host. I’ll test all three tomorrow and see what happens.
I'm not sure that method would work, you are taking the output of the preamp and routing it back to the input, seems it would be a feedback loop. And you can't normally connect the tape outputs together since that affects all the inputs, even though the tape outputs are sometimes buffered to prevent the powered off tape deck from loading the inputs, it is often just with resistors so separation may suffer a lot. Anyway, maybe I don't quite understand the method, so keep us posted
I don't think it will work that way. It's pre out for subwoofer. Use the tape loop. edit: Davey beat me to it. Except the tape loop method was reported to work by some users. You should try.
OK, I did some testing already: First: Single RCA/2 RCA Y-cable from ”Mono Normal” into ”Tape PB” —> No sound. Then: Single RCA/2 RCA Y-cable from ”Mono Normal” into ”Tape REC” —> No sound. Yep, you guys were right. That’s a no go! Luckily, this does seem to work: Dual Y-cable from ”Tape PB” into ”Tape REC” (or is it from REC to PB? Same difference I suppose..). I tested this with Die Beatles LP and headphones. Pushing the Tape Monitor-button makes the vocals etc. go dead center. I think I’ll skip testing the third method (the original SH method) for now since I have some mono listening to do! Thanks everyone!
This would have been my last option but it seems I can now avoid all the cable-swapping that comes with it. I think I like my Denon even more than before. Sure, I could just use my H/K 730 and it’s mono button but by using the H/K 730 as a power amp I get remote control over volume, input selection, muting AND now I don’t even have to get up to push the mono button! Oh, and I get some extra inputs and I can still use the H/K’s tuner too. Edit: NOTE: I listened to the stereo Die Beatles for testing purposes only, I do not intend to listen to stereo records in fake mono!
I have now listened to a bunch of mono records: *60’s UK Beatles albums (AHDN, WTB, H!) all seem to sound better with the mono button (in this case the tape monitor button) ON. Scratches, pops and ticks are less audible and overall these albums are more enjoyable to listen to. *The Kinks - s/t (late 70’s/early 80’s PYE, I think), same as above though mine is a very clean copy with not much ticks/noise to begin with. I think the bass is a bit wider and boomier with the mono button OFF, the bass is tighter but maybe not as loud with the mono button ON. *John Coltrane - My Favorite Things (the recent release with both stereo and mono discs), I think mono button OFF is preferable here. With the mono button ON the highs become muffled. *John Coltrane - Blue Train (Tone Poet), this is a tough one.. Sounds good to me with the mono button OFF and ON. With the mono button ON, I think the cymbals lose some of their airiness and sizzle so mono button OFF might be preferable. Then again, mono button ON sounds smoother. Both of the Coltrane albums mentioned are of course NM so I can’t say much about pops and ticks. I not sure if my findings are consistent with what I ”should” be hearing but this is all very interesting. The cleaner presentation for the 60’s Beatles albums is a big plus. On the downside, I think I’ll have to do a test run to see if mono button ON or OFF sounds better to me for every modern mono album I buy in the future before actually listening to it!
Did you notice if the y cable thing affects the sound of any source when it's connected but tape monitor is not engaged?
No, but I didn’t really (A/B) compare. I’ll try to remember to compare later but if it does affect the sound it can’t be very drastic since everything else I listened to (CDs for instance) after putting the cable in sounded perfectly fine to me.
