CD Player line out too hot?

[Barry_Sound]

Friend of mine is using a 90s Rotel Pre-/end combination Rha-10 and Rhb-10. He finds it hard to control CD player volume because its very quickly very loud. (No measurement here but louder than his turntable.) The CD player is connected to the AUX input. The CD player line out is fixed. I have not heard his current setup but I know the CD player was working fine in another system (no signs of being "too loud" at all).

Any idea what could be the issue here?

Speakers are Dynaudio floorstanders with 86db sensitivity.

Thank you

 

[MaxwellsEq]

Friend of mine is using a 90s Rotel Pre-/end combination Rha-10 and Rhb-10. He finds it hard to control CD player volume because its very quickly very loud. (No measurement here but louder than his turntable.) The CD player is connected to the AUX input. The CD player line out is fixed. I have not heard his current setup but I know the CD player was working fine in another system (no signs of being "too loud" at all).

Any idea what could be the issue here?

Speakers are Dynaudio floorstanders with 86db sensitivity.

Thank you

It's a bit odd that the preamplifier is from the 90s. This is a common issue with older preamplifiers and integrated amplifiers, e.g from the 80s and earlier. Tuners, cassette players, tape machines all output 1V. CD players output 2V, so with older gear, CD players are too loud. By the 90s, preamplifiers had CD inputs expecting 2V, so there should be an input that is not too hot.

 

[DVDdoug]

You can get in-line attenuators. With fixed attenuators you'll have to guess what attenuation you want, or get more than one pair. Since the problem is "bad" probably at least -6dB.

You can also get variable attenuators but sometimes left & right don't track "perfectly" (and it's more bulky).

...Unless you're in a pro studio nothing is calibrated. There are "standards" but really they are just guidelines so that most outputs have more than enough signal and most inputs have more than enough gain. Some records are louder than others (also true with digital), cartridge sensitivity varies, and phono preamp gain varies.

 

[staticV3]

The obvious solution is to place a Line level attenuator between CD player and RHA-10, to bring its level down to the turntable.

Something like the Behringer Monitor1 or one of the many Nobsound/Douk Audio/Little Bear products sold on Amazon and eBay would do the trick.

 

[Barry_Sound]

Thanks, that's the workaround, but why is the CD player perceived too loud in the first place? Is there an issue with the amplifier/preamplifier?

 

[Doodski]

Thanks, that's the workaround, but why is the CD player perceived too loud in the first place? Is there an issue with the amplifier/preamplifier?

The voltage is higher coming from the CD player.

 

[RayDunzl]

RHA-10

Input (1-5) Sensitivity/Impedance................ 140 mV/13 kohms

The attenuation from 2 V to 140 mV is approximately 23.1 dB

Try a 20dB attenuator.

 

[staticV3]

Thanks, that's the workaround, but why is the CD player perceived too loud in the first place? Is there an issue with the amplifier/preamplifier?

It's just gain mismatch caused by insufficient Preamp attenuation and excessive Amp gain.

It's not a component defect or anything. Just suboptimal tools for the job.

 

[MaxwellsEq]

Thanks, that's the workaround, but why is the CD player perceived too loud in the first place? Is there an issue with the amplifier/preamplifier?

Nothing is broken or faulty. All the posts in this thread are telling you exactly the same thing - CD player (and DACs) output 2V which is twice as high as everything else in "Aux" land.

If you want a culprit, it's Rotel. By 1991, CD had been around for nearly a decade. I don't understand why one of the preamplifier's inputs isn't labelled CD and has a lower sensitivity.

 

[AnalogSteph]

1991 was the very first year that brickwall limiters were even used at all. There's no way that Rotel could have predicted the loudness war as it happened. CDs got up to 10 dB louder. Originally they were aiming for ~300 mV average levels, not dissimilar from other analog sources.

I had a look at the service docs and calculated the gain of each unit:
RHA-10: 15 dB - not unusual for a preamp.
RHB-10: 34.4 dB - somewhat higher than average but it's also a 200 wpc unit.
Sum total: 49.4 dB.

That's a bit higher than your average 85-100 wpc integrated at 45-46 dB, and those are known to be plenty twitchy enough when confronted with loudness war era CD material. So only a small part of the blame really falls on Rotel, and even that is sort of understandable (twice as much power --> 3 dB more).

If going for a computer-based playback chain with playback volume normalization isn't an option, I would recommend a 12-16 dB attenuator between pre and power amp. (A spare headphone amp would also do.) Should bring down noise levels along the way.