Is the halfway position on tone controls actually the 'flat' setting?

[walpurgis]

Well? Question as above. Bet it's not necessarily the case, but how do you tell without measuring equipment? I'm sure you can't!

Potentiometers will I reckon vary depending on how good they are or how the maker decides they want them to operate.

And of course there's the 'Lin' or 'Log' thing. How does that influence the situation?

And then there's the amplifier circuit. Does it necessarily give a flat response at an anticipated control position?


Yes. I'm asking 'cos I'm using an amplifier with tone controls (a rare experience :)).

[Primalsea]

If the pots and other components in the tone circuit are 100% accurate then yes. In reality no.... you can check using a computer quite easily, if you have a good soundcard. Just find an online signal generator and sweep through the frequencies while measuring the (attenuated) output.

I imagine that there are very few dual gang pots that are matched well between channels. The better option are separate tone controls for each channel.

[Shovel_Knight]

Some better amps use stepped tone controls. And several hi-end Sony and Yamaha models have a set of relays that remove the tone controls from the signal path when they're set to the middle position.

[walpurgis]

At the moment I'm playing with a seemingly well regarded classic British integrated amp from the seventies. A Cambridge Audio P80 that I bought for a bit of fun. I must admit, the sound quality comes as a surprise. It's remarkably good! But, I feel the tone controls are not exactly accurate. They are pots by the way.

I bought this recently 'cos when I first got involved with Hi-Fi the Cambridge P50 was hailed as being exceptional and when the P80 arrived a few years later it was considered to be even better.

[Primalsea]

Tone controls are a bit of a funny one. If you have a tone defeat you can usually tell that the tone circuit has a detrimental effects. However, overall the tone corrections can be less detrimental that the effect of the room, which can pften be the worst offender.

[Jazid]

Those of us who have moved to the dark side (digital) regard tone controls as a primitive throwback. We expect gain and Q, also frequency centre, impulse response equalisation, and even assymmetry as starting points in a system.
So saying, who's to say that the frequency response of a vintage amp at 'flat' might have been intended to be neutral by the designer? Amps of that vintage were often purposefully skewed across their frequency range one way or another by a few fractions of a decibel to work as intended where intended, and no shame in that. If it sounds good it is good!

Sent from my GT-I9195 using Tapatalk

[Macca]

Distortion levels might also vary with FR. So you've got more than one thing to measure :D

[walpurgis]

who's to say that the frequency response of a vintage amp at 'flat' might have been intended to be neutral by the designer?

That's one of the questions I was asking. No doubt there is no agreed standard.

[Pharos]

If we use a tone control amp, we accept that it is a valid procedure to adjust FR to ameliorate other factors, and therefore, since we do it by ear, any verification of the resulting response is relatively irrelevant, and only of academic interest.

Regarding channel balance, Quad used a tilt system in which as one channel gained top, the other lost it, and so channel balance becomes an irrelevance with this also.

[Firebottle]

Quad used a tilt system in which as one channel gained top, the other lost it, ..........

You've got that a little wrong Dennis, the tilt is applied to both channels. A very effective system to give a small change in presentation.

[Idlewithnodrive]

You've got that a little wrong Dennis, the tilt is applied to both channels. A very effective system to give a small change in presentation.

Exactly that and easily the most usable tone control implementation that I have used or know of.

[Pharos]

I've never had or even used one, so were they just normal boost/cut controls then?
(What was tilted?)

[Firebottle]

No, normal tone controls work on the extremities of the frequency range, the Quad tilt control affects the whole bandwidth by making the response slightly uphill or slightly downhill as it were.

It can very effectively tame a bright sounding or bottom heavy system.

[Pharos]

Last night I looked up several pages on the 34, and they were vague about what the tilt control does, and even the manual was.
But it seems that the tilt literally boosts or cuts bass in one channel whilst doing the reverse in the other with the treble, thus presenting either a downhill or uphill slope from left to right, 20 to 20k.

My difficulty is not in understanding Baxandall circuits, which I have built and used since the 60s, but what the tilt control actually does to the frequency responses of each channel, this largely because it seems that no one can explain it in clear English, even in manuals.

[jandl100]

Quad 34 tilt control action ...

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fkenrockwell.com%2Faudio%2Fquad%2Fi mages%2F34-preamp%2Fmeasurements%2Ftilt-5-dB.gif&f=1

[jandl100]

Back to the OP.

I recall some tests done by a hifi mag back in the day showing that even at the 'flat' position there was some bumpiness to the FR of the amp under test, it was never possible to get them completely out of circuit except if the amp had a bypass button.

[hifi_dave]

A non flat response is the reason for a bypass switch or button.

[GrahamS]

Tone controls are a bit of a funny one. If you have a tone defeat you can usually tell that the tone circuit has a detrimental effects. However, overall the tone corrections can be less detrimental that the effect of the room, which can pften be the worst offender.

There were never truer words!

[GrahamS]

No, normal tone controls work on the extremities of the frequency range, the Quad tilt control affects the whole bandwidth by making the response slightly uphill or slightly downhill as it were.

It can very effectively tame a bright sounding or bottom heavy system.

It would make no sense if the tilt control adjustment was not applied to both channels equally. Who would want to brighten the left channel while boosting the lows of the right channel? I have always believed that the Quad tilt control is used to adjust the character of the whole system. Very useful when matching a particular set of speakers to a system or room, but only to be used with subtlety. Not to be used in lieu of conventional tone controls. This is what I was told by Quad.