Vintage Luxman integrated amplifier Bass & Treble query*

[mschool]

I understand the tone defeat button disables the bass & treble functionality. If the bass & treble knobs are set on flat and tone defeat is pressed in, then all I’ve done is engage circuitry but the sound has not changed.

If I turn either knob left or right, the sound quality changes work in a pleasing way, but do they raise or lower sound + or - 8bB? They are not volume controls are they? What happens here and what is the reason for +/- 8dB as it pertains to bass and table and the overall sound performance from an engineering or an amplifier design POV.

*Only the service manual us available for the Luxman L400 online and it does not address operational Q&A

 

[Blue Shadow]

https://learnabout-electronics.org/Amplifiers/amplifiers42.php

The blue graph shows the boost or cut in volume based on the position of the tone controls. Yes they are volume controls but they work on only the low or high frequencies. Your amp states a limit of boost or cut is 8dB. Different from the graph linked.
That is very similar to the graph on your amp between the tone controls. It just shows more info and will be easier to read.

 

[cademan]

When "tone defeat" is active, it is the same as not having any tone controls. When "tone defeat" is inactive, controls set at "flat" are the same as not having any tone controls.

 

[Akustic]

When you defeat the tone controls, the signal does not flow through the associated wiring and knobs of the tone control circuits regardless of their setting...
It's routed direct..
You are are providing a cleaner more direct path for the signal ..
Typically you're going to hear better dynamics and perhaps a bit more detail with the tone controls defeated ... musical notes sounding sharper and more detailed.

Everything in the signal path affects the music to a greater or lesser degree .. and usually less is more in this case...
And I would be curious to know if your "high cut" or "low cut" buttons have any effect on the music when the tone controls are defeated ...

If setting the tone controls to flat was all that was being accomplished, there would be no point in providing a tone defeat button ..
If you look at higher end electronics they invariably don't have tone controls .. They're all about keeping that signal path as direct and as high quality as possible.

 

[mschool]

If you look at higher end electronics they invariably don't have tone controls ..

Thank you. As an aside, I've been wondering about that distinction of higher end equipment. What tonal adjustment can those owners use with, for instance, popular records with dubious recording? I cite examples of "Layla", "Blind Faith", and Meatloaf's "Bat Out of Hell" which are documented to have recording qualities on many of the pressings over the years that can only be alleviated with tone controls.

 

[cademan]

If the tone controls are truly flat then you should not hear any difference when tone defeat is on or off. My Pioneer silver faced integrated amplifiers are built like this. If they are tuned properly, you should hear no difference. A truly good built EQ should be the same way if the sliders are all set flat straight across, you should hear no difference when the EQ is in or out.

I think the tone defeat option is for purests who like to listen to their music flat or straight through like an amplifier which has no tone controls. If your tone controls are boosted or declined, you can just flip the switch without having to adjust them.

Just my .02

 

[peterp1]

Thank you. As an aside, I've been wondering about that distinction of higher end equipment. What tonal adjustment can those owners use with, for instance, popular records with dubious recording? I cite examples of "Layla", "Blind Faith", and Meatloaf's "Bat Out of Hell" which are documented to have recording qualities on many of the pressings over the years that can only be alleviated with tone controls.

Tone controls (or equalizer or subwoofer crossover/level settings, etc.) are normally intended to be "set and forget" to compensate for the specifics of the room/speakers. Even if the speakers you own measure perfectly flat in the lab, they won't be flat at all in your individual listening space, so the tone controls and EQ are normally used to bring them back as close to flat (or whatever your goal is) as possible in your room. So they are typically set once (usually with significant iteration (or REW analysis) to find the right settings) and then never touched again. Tone controls aren't generally intended to adjust for individual recordings, though anyone can do whatever they want with them.

For high-end equipment that doesn't have tone controls, part of the goal is to minimize what is in the signal chain, and the expectation is that the room will be acoustically treated so that room interaction is minimized. Practically speaking, it's kind of nonsensical to eliminate tone controls given that its impossible to treat any room perfectly and that a tone defeat switch can be used to bypass the extra circuitry, but it has become the norm for high end, and the idea is to leave the sound totally unaltered and to work around that with room and speaker choices.

Much as I struggle with the logic of eliminating tone controls, I'm happy that my main 2-channel tube amp does not have them and it sounds amazing in that room. All of my other systems have tone controls, and I typically use them because the rooms are far less ideal acoustically.

I do adhere to the "never touch once set" rule, not because of some audiophile "Vulcan mind meld" philosophy, but because I actually do find that setting them once for a given room is the best approach (rather than tweaking for individual songs). I don't think I've touched a tone control or a sub setting in years (and I have at least 10 subs in the house). The only time I touch the tone/EQ/sub controls is when I change a piece of equipment (which makes it necessary to adjust the settings).

 

[mschool]

Tone controls (or equalizer or subwoofer crossover/level settings, etc.) are normally intended to be "set and forget" to compensate for the specifics of the room/speakers. Even if the speakers you own measure perfectly flat in the lab, they won't be flat at all in your individual listening space, so the tone controls and EQ are normally used to bring them back as close to flat (or whatever your goal is) as possible in your room. So they are typically set once (usually with significant iteration (or REW analysis) to find the right settings) and then never touched again. Tone controls aren't generally intended to adjust for individual recordings, though anyone can do whatever they want with them.

For high-end equipment that doesn't have tone controls, part of the goal is to minimize what is in the signal chain, and the expectation is that the room will be acoustically treated so that room interaction is minimized. Practically speaking, it's kind of nonsensical to eliminate tone controls given that its impossible to treat any room perfectly and that a tone defeat switch can be used to bypass the extra circuitry, but it has become the norm for high end, and the idea is to leave the sound totally unaltered and to work around that with room and speaker choices.

Much as I struggle with the logic of eliminating tone controls, I'm happy that my main 2-channel tube amp does not have them and it sounds amazing in that room. All of my other systems have tone controls, and I typically use them because the rooms are far less ideal acoustically.

I do adhere to the "never touch once set" rule, not because of some audiophile "Vulcan mind meld" philosophy, but because I actually do find that setting them once for a given room is the best approach (rather than tweaking for individual songs). I don't think I've touched a tone control or a sub setting in years (and I have at least 10 subs in the house). The only time I touch the tone/EQ/sub controls is when I change a piece of equipment (which makes it necessary to adjust the settings).

Interesting. OK, I have been approaching the somewhat incorrectly, but I’m coming round to better understanding.

I recently went through the process of master set speaker placement (sumiko method) and I also eliminated standing waves with bass traps and used absorption at first reflection points. As a result, I find myself reverting to tone defeat because most of my recordings do not demand the intervention of tone control. The sound in my listening room is once again, the best it has ever been

Now, I understand your description and definitions as to why people don’t need tone control because of room treatment, speaker placement, and matched components, but alas like so many others, it was ass backwards in the beginning.

 

[peterp1]

Interesting. OK, I have been approaching the somewhat incorrectly, but I’m coming round to better understanding.

I recently went through the process of master set speaker placement (sumiko method) and I also eliminated standing waves with bass traps and used absorption at first reflection points. As a result, I find myself reverting to tone defeat because most of my recordings do not demand the intervention of tone control. The sound in my listening room is once again, the best it has ever been

Now, I understand your description and definitions as to why people don’t need tone control because of room treatment, speaker placement, and matched components, but alas like so many others, it was ass backwards in the beginning.

Sounds like you are far ahead of me on room treatment. If you are happy with the sound with tone defeat, that's as good as it gets.

With regard to tweaking tone controls for individual recordings, the general thought is that the engineer that mastered the track did the best that was possible for the medium it was targeted for -- so it's best to leave the signal unaltered. That sounds like a theoretical BS concept that would have a million holes in it because quality of recordings (and engineers!) are all over the map, even across the various remasters of the same album.

In practice, I've found that concept to be generally true (to the extent that I never touch tone controls). I haven't really found that I can improve a bad recording with tone controls or EQ. I can add some sparkle to a dull track with EQ or treble, but I'm not sure that improves it -- the track presents itself with "spruced up" sonics but is less true to the original. Someone else might find that the "spruced up" sonics is better and not give a damn about being true to the original. Neither camp would be right or wrong -- whatever works for us is right for us (as long as we've given all options full consideration).

 

[Akustic]

Thank you. As an aside, I've been wondering about that distinction of higher end equipment. What tonal adjustment can those owners use with, for instance, popular records with dubious recording? I cite examples of "Layla", "Blind Faith", and Meatloaf's "Bat Out of Hell" which are documented to have recording qualities on many of the pressings over the years that can only be alleviated with tone controls.

Bad recordings are a curse.. if needed then it's best to use an equalizer or software processing that can be switched back out when it's no longer needed ..

That necessity is the reason that the manufacturers started including tone defeats ..
It was an evolution that began with tone controls on everything 60's-70's and a slow procession ..80's.. to better pieces including a tone defeat ..
The high enders during the 70's were pointing out, that the tone control circuitry was having a negative effect on sound quality ..

To a degree it's possible to use cables and room treatment to balance out the system, but that's not an effective way to compensate for a bad recording ..
I just listen through the warts to those few that are genuinely bad sounding ..

 

[sqlsavior]

As a minimalist, a term I prefer to 'purist', I've adopted a philosophy that a recording is what it is, to coin a phrase.

At one point, I could boast of having nothing but tubes and transformers between my cartridge and my speakers, not even a potentiometer, but rather 24-tap transformers for volume control. That personal system apogee sounded extraordinarily clear, and to my ears, 'natural' rather than 'impressive'. I'm lucky to have an oddly-shaped living room with sloping absorptive ceilings at one end of an open floor plan running all the way to the end of the house - dining room, kitchen, family room. Pretty much the whole house is a giant bass trap, so much so that when I tried mono'ed, DSP'ed bass, it was a loss, to my ears, so I went back to stereo subs.

Since I own several phono stages, I really can't take sides in the EQ debate, can I? Run whatever floats your boat, I say.

Still, on odd occasions, I'll suggest that somebody take their EQ out for a while and see if they can hear more.

 

[Akustic]

What happened when you pushed the high cut or low cut with the Tone defeat button pushed in ???

Was there less treble when you pushed the high cut ??
Was there less bass when you pushed the low cut ??

 

[mschool]

What happened when you pushed the high cut or low cut with the Tone defeat button pushed in ???

Was there less treble when you pushed the high cut ??
Was there less bass when you pushed the low cut ??

The two filter buttons work independently of tone defeat. When tone defeat is out, the filters work. When tone control is in, the filters work. They have a substantial diminished effect once treble and bass are turned either direction from flat.

 

[Akustic]

The two filter buttons work independently of tone defeat. When tone defeat is out, the filters work. When tone control is in, the filters work. They have a substantial diminished effect once treble and bass are turned either direction from flat.

Makin me crazy ..
Those are the strangest filter frequencies,
I don't understand why they chose them.. normal high would be abve 12khz .. low would be about 45-50 hz..
They're too far into the music ..
They're the right frequencies for tone controls to be working at if they were switchable tone controls, but apparently they're not ..
And if that schematic read was correct they're low slopes, but I'm at a loss for why you would inhibit the music like that.
Got me scratchin my memory for answers ..
Enjoy the music ..

I do recall reviews where an amp was criticized for having filters that were too far into the musical range, so maybe this is just one of those instances ..
This is an older piece, and that's pretty much how the gear evolves ..

 

[Akustic]

This website describes those buttons as switchable tone controls .. so I'm not the only one who's confounded ..
Obviously an English translation of an Asian language .. but switchable turnover frequency expression for the tone controls is what I was referring to as hinge frequencies for the tone controls ..

That makes far more sense from Luxman than filters, and the L-400 was produced in the era when selectable tone controls were being introduced. (1982) ..

https://audio-database.com/LUXMANALPINE-LUXMAN/amp/l-400-e.html

When your tone control button increases or decreases the signal it does so at a given frequency that's been engineered into the amp ...
The high cut and low cut buttons should be changing from the engineered frequency that the tone control operates at,.. to the frequency that's listed on the button .. 70hz for the bass knob, and 7khz for the treble knob.

Luxman shouldn't be one of the companies that's cutting into the music with inappropriate filters .. they're too high quality for that.
They were probably one of, if not the first company's to introduce selectable tone controls ..

Don't remember if I ever actually heard that amp, (probably at Steketee's Audio in Grand Rapids) but I read every audio magazine that the library's subscribed to from the
mid 70's thru 1990 or so, so I certainly read the reviews.

 

[Akustic]

High cut filters were common and were used as scratch filters for records .. got rid of the pops and ticks ..but also cut in to the music a bit.
The trick was to keep them as high as possible to mask the noise but still hear the music..

Some amps also had a low cut filter to reduce interference from rumble which was caused by record warps ..
Warps cause mostly subsonic frequency resonances which can interfere with audible bass reproduction ..
Low cuts were typically below 40hz to avoid cutting the bass from the music..

If an amp had a subsonic filter it typically did not include a low cut filter ... just subsonic and a high cut ..
Neither of them is very useful in the days of digital music .. they're for vinyl.
The filters were a use them or not option ..just depended on the condition of the record.

 

[Akustic]

I call them hinge freq. because the tone control knob is increasing or decreasing the volume of the freq. above the hinge for high cut (treble),
or below the hinge for low cut (bass), the hinge frequency...

 

[Lapslah]

A couple clarifications:

This is an admittedly picky distinction, but one that could be causing some confusion. So we're all on the same page - when you say "tone defeat is pressed in" it sounds like you mean tone defeat is engaged, but pressing the button in activates the tone controls.

I agree that the filter frequencies are a little strange, but the Service Manual makes it clear that they are exactly what they say they are. From the specifications section -

Filter:
Hi Cut 7kHz (-6 dB/oct)
Low cut 70Hz (-6dB/Oct)
Phono Subsonic 15 Hz (-6dB/oct)

There are separate specifications for the Tone controls, confirming that they are not switchable and have nothing to do with the filter buttons -

Treble +- 8 dB @ 10 kHz
Bass +- 8 db @ 100 Hz"

I couldn't find an Owner's Manual for the L-400 online, but the Owner's Manual for the L-405 talks about the 7 kHz filter on that unit as "convenient to remove tape hiss, disc scratch noise, etc.", so it's clear that the Luxman engineers did, in fact, intentionally choose that frequency. It appears the 405 doesn't have the low-cut filter, but I own a Luxman CX-100 preamp that is a 2-channel preamp with a rear-mounted, frequency selectable subwoofer output. Maybe the L-400's 70 Hz filter would make sense with a sub/sat configuration if it has a similar sub-out.

 

[Akustic]

A couple clarifications:

This is an admittedly picky distinction, but one that could be causing some confusion. So we're all on the same page - when you say "tone defeat is pressed in" it sounds like you mean tone defeat is engaged, but pressing the button in activates the tone controls.

I agree that the filter frequencies are a little strange, but the Service Manual makes it clear that they are exactly what they say they are. From the specifications section -

Filter:
Hi Cut 7kHz (-6 dB/oct)
Low cut 70Hz (-6dB/Oct)
Phono Subsonic 15 Hz (-6dB/oct)

There are separate specifications for the Tone controls, confirming that they are not switchable and have nothing to do with the filter buttons -

Treble +- 8 dB @ 10 kHz
Bass +- 8 db @ 100 Hz"

I couldn't find an Owner's Manual for the L-400 online, but the Owner's Manual for the L-405 talks about the 7 kHz filter on that unit as "convenient to remove tape hiss, disc scratch noise, etc.", so it's clear that the Luxman engineers did, in fact, intentionally choose that frequency. It appears the 405 doesn't have the low-cut filter, but I own a Luxman CX-100 preamp that is a 2-channel preamp with a rear-mounted, frequency selectable subwoofer output. Maybe the L-400's 70 Hz filter would make sense with a sub/sat configuration if it has a similar sub-out.

Close as it gets so far ..
The Lux is from 1982 .. far before home theater and subwoofers became common ..
If memory serves very few subs were even available at that date ..a couple of the early ones maybe ..they certainly weren't commonplace.yet .
M&K and Volkswoofer maybe a couple others ..

Did you look at the schematic to see if that leg had any possible acess to the tone knob ??

 

[mschool]

So we're all on the same page - when you say "tone defeat is pressed in" it sounds like you mean tone defeat is engaged, but pressing the button in activates the tone controls.

CORRECT