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Pioneer SPEC-1 Missing Loudness Function

1mike161

1mike161

New Member
I am considering the purchase of a Pioneer SPEC-1 preamp. I have discovered that one of my favorite preamp features, Loudness, is not included in the SPEC-1's functionality. Does anybody know of a work around? Maybe Loudness can be simulated with EQ or maybe a circuit modification can be easily employed. Any thoughts?
 
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Adjust the tone controls to replicate what you like. When you turn up the volume, turn the tone controls off (loudness controls have an intentional roll-off as volume increases).
 
I like EchoWars description. Can work either way.

The spec-1 preamplifier has a 3 position switch on the front that says "attenuator". It has -30db, -15db, and 0db which I believe acts like a variable loudness control........or does that act like a muting control? :dunno:

Never seen a Pioneer without a loudness control of some kind. o_O
 
The Pioneer SA-9500 and SA-9900 are also without a loudness control. The attenuator switch on these amps drops the level of the the entire spectrum by either 15 dB or 30 dB for muting and does not contour the spectrum as does a loudness function. I would imagine that the Spec-1 is the same.

Les.
 
You can get pretty close to the Fletcher-Munson curve with a ten band EQ. You can look it up on wiki for the curve, but how much effect you want is another story.

Fact is, while the ideal is to have all the input levels matched and the loudness contour gradually leave effect as the volume is increased, almost no design actually does that. I know how to do it, and it requires no taps on the volume control at all. but it does require extra circuitry. I have never seen it implemented properly.

Most of them just have a tap at like 50 % and put their components there. It is supposed to lose effect gradually but in reality most of them have full effect up to like 40 % and are completely out ay 60 %. Not very smooth.

So if you listen usually with the loudness on, you are simply listening to a better bass and slight treble boost than most tone controls will give you. Tone controls in most equipment are shelving, the loudness contour actually keeps boosting more as you reach the frequency extremes. If you want to boost the extremes, turn on the loudness and turn down the bass and treble.

When you get the EQ, you don't just "put a smile" or a "V" on it. Sounds like ****. Really not that bad but nothing like audiophile. More like a car stereo. Look at the Flectcher-Munson curve and adjust to something that looks like that.
 
Thanks guys! Looks like the best way to add the loudness function is to put a 10 band EQ on one of the tape monitors and adjust for the Flectcher-Munson (loudness) curve. The attenuator has the same effect as decreasing the volume -- it's completed flat with respect to EQ.
 
fletcher_munson_-2.jpg
 
Couple things to remember about those curves. for one, they are the inverse of what you hear.

Also, as you can see it is not flat even up beyond 100 dB, so even what you hear live has that curve impressed. that is not to be corrected. The DIFFERENCE between the top curves and the bottom curves is what is to be corrected.

That is if you're a purist. I just set the thing so I like the sound.
 
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