[geoffmartin]

Hi Keith,

A big “thank you” from me for the years of work you’ve put in here!

Cheers
– geoff

[geoffmartin]

Hi,

I’ve been thinking about analogies for a system with a Beolab 8 on the left and a Theatre on the Right. The best ones I can come up with is wearing a pair of sunglasses where only one of the two lenses is tinted. Or driving a car with 15″ wheels on the left side and 16″ wheels on the right, maybe…

and no – you currently can’t have two Theatres playing in sync in a multichannel (i.e. one-room) system.

Cheers
-geoff

[geoffmartin]

Hi @Lavie,

thanks for the nice comments about the Theatre.

I’m afraid that your plan for an “asymmetrical” setup won’t work for “real” stereo listening, since the Beolab 8 and one of the outputs of the Theatre are not a matched pair of loudspeakers. Although the two are designed to work together in a surround system (e.g. Theatre in the front and Beolab 8s as surrounds), they are certainly not matched enough to produce a reliable phantom centre or good imaging.

[geoffmartin]

@tph

nice to see someone reads the guide. 😉

[geoffmartin]

@Yossi:

If you are ONLY measuring two Beolab 50s, then it doesn’t matter where you measure from, since the software is calculating the difference between the two. For example, if you tell the software that one loudspeaker is 1.5 m away and the other is 1.75 m away, you get the same result as if you said 0.0 m and 0.25 m. The DSP is finding the closest of the two loudspeakers and delaying it by the difference.

HOWEVER, if you have a mixed system, then you need to be a little more careful – or be willing to make changes based on how it sounds rather than what your laser says. The acoustic centre of a Beolab 50 is closer to the tweeter than the midranges or speaker grille. So, measuring from the tweeter (or the middle of the circle at the top of the speaker if it’s closed) will deliver a closer better result. But the distance value can really be considered to be a quick, but slightly imprecise setup that can, in most cases, be tweaked to sound “better” to the listener.

As for your nose, since the distance is imprecise (my definition of “precise” when setting up loudspeakers means millimetre-scale) then measuring from your nose is good enough (that also what I do…). However, if you’re going to be as geeky as possible, you should measure from the centre of where your head would be. Unfortunately, your ears are about 7 cm away from that point, but it’s the best you can do…

Cheers
-geoff

[geoffmartin]

Of course, it’s hard to diagnose the issue with back-and-forth text on a forum thread.

However, try this:

• Create a new preset
• Do not enable the room compensation filters
• Set both Speaker Distances to 0 m
• Set both Speaker Levels to 0 dB

Sit in the middle, the same distance from each loudspeaker, and listen to something coming in on the optical connection (to isolate the loudspeakers from the Power Link and Wireless Power Link sources) in mono or almost-mono (I use early Aretha Franklin and Ray Charles a lot… 🙂 )

Where do you hear the voice?

And, since this is probably an isolated problem, we should take the discussion to a private message thread. That way I can also get some more detailed info from you about your setup.

[geoffmartin]

The room compensation is a different thing, independent of the Speaker Level and Speaker Distance adjustments.

Also, I’ve seen some people make the Room Compensation measurements, but never enable the filters in the Preset. I’m not implying that you’ll make this mistake. I’m just saying that I’ve seen other people make this mistake more than once. 🙂

Good luck and please keep me/us up to date with your progress!

[geoffmartin]

Cool – so we know we are talking about the same thing.

In MOST situations, it’s safe to do the following:

• set both Levels to 0 dB
• Adjust the Speaker Distances to the correct values for both loudspeakers. Be as accurate as possible, since a small error here can have a big effect.
• Have a seat in the listening position and listen for the location of the voice.
• If the voice is not in the middle, then start by making small adjustments to the distance. To move the voice towards the LEFT loudspeaker, make the LEFT distance a little bigger. This will cause the sound to come out earlier.
• At some point, you will not be able to fine tune the distance enough (you’ll notice that the voice position jumps when you adjust the distance).
• At this point, use the LEVEL to do a final tuning of the voice location.

 

 

NOTE that if you are using the Power Link or Wireless Power Link input from most Bang & Olufsen sources, then the Beolab 50s DISTANCE and LEVEL processing is disabled, since it is done in the source itself.

However, if you do the adjustments in either the source or the loudspeakers, you can just manually duplicate the values to the other. It’s normal to do them in both places, since (for example) you’ll want them to work for the Power Link source (probably a Beovision television) and a third-party source (like whatever you have connected on your Optical input).

[geoffmartin]

In order to ensure that the the loudspeakers are correctly calibrated at the listening position, the Speaker Distance and Speaker Level must be adjusted for each loudspeaker.

The Speaker Distance is the distance from the loudspeaker to the listening position.

The Speaker Level is used to adjust the output level of the loudspeaker so that both loudspeakers have the same output level at the listening position.

I, like Mr10Percent, am a little confused, since this is called “Speaker Level” (or perhaps just “Level”) but not specifically  “Output Level” – so the explanation above may not be for the parameter you’re asking about. If not, I’d be happy to help if I can get a little more information about your question to clarify.

Cheers
-geoff

[geoffmartin]

Am I right in guessing that there’s muffler tape on the tonearm?

I wonder how much extra that adds to the tracking force…

[geoffmartin]

Personally, I don’t worry too much about the stylus shape when playing my 78s, but I’m just putting them on for fun, not to digitise them.

There are some things to consider when playing 78 rpm records on a “modern” turntable (I use the word “modern” to mean anything younger than about 60 years old…)

The stylus (because it’s much smaller) will sit down in the very bottom of the groove. This means that it is down there with the dust and dirt, so it will have more high frequency noise than, say, using a sharpened Burmese Colour needle in a wind-up gramophone.

On the other hand, if you’re playing a well-loved disc, then the modern needle is sitting in the groove wall in a different place than all of the steel needles that have been there before. So you might be playing on a “virgin” surface. (The same thing can happen when switching to a stylus of a different lateral grind radius on a new turntable.)

Another possible issue with the different stylus radius is that you’ve got a (comparatively) tiny needle sitting down in a big trough. (Imagine a marble travelling down a human-sized waterslide for a gross exaggeration for intuition’s sake.) Since there isn’t as much lateral control of the needle from the sidewalls of the groove, you will lose high frequency content. I’ve attached a scale drawing from the Beogram 4000c manual that shows the difference between the grooves on a 78 rpm and a 33 1/3 microgroove LP. A steel needle has a typical tip diameter of about 150 µm, whereas an early spherical tip stylus for an electrical record player would be in the range of something like 20 to 50 µm.

However, many / most 78 RPM records were made before the RIAA equalisation curve was standardised. Later 78s would have used some kind of equalisation, but there’s no real way of knowing for sure what the EQ curve should be. Some early electrical phono preamps had two dials for manually selecting the low frequency boost and high frequency roll-off that sounded most appropriate for a given record. Early 78s had no pre-emphasis at all, since it wouldn’t have been possible with a fully mechanical recording system.

So, given the uncertainties associated with these issues, combined with the level of production quality of the discs themselves, I would suggest an informed level of strategic apathy.

Of course, one thing you MIGHT choose to worry about in earnest is the wear on your stylus. 78s were usually made of a combination of shellac and clay, which made them tough enough to stand up to a steel needle with a 0.5 – 1 kg tracking force. However, this also makes pretty good “sandpaper” that might be less than friendly to your pickup.

Cheers
-geoff

 

[geoffmartin]

@Millemissen and @AdamS,

I’ve started writing the explanation on tonmeister.ca/wordpress.

However, I’ve decided to take the long way, so settle in for an extended series of postings about closed and ported cabinets…

[geoffmartin]

Hi Stuart50_1,

The possible issue of slave-drivers (of BL2) cancelling the low end of a closed cabinet (of BL20) cannot explain your issue, since your 20s and 9s are all closed cabinet design.

So, if you are lacking bass, then the issue must be caused by something else. You have a number of options available to you in the setup menus of the BV11, but this takes the thread to a completely different topic.

You could start by adjusting the Bass Redirection levels so that the 9s and 20s have the same value, and then if you want more bass, turn them all up by the same amount (go slowly…)

Another option is to turn UP the 20s and set the 9s lower.

A third option is to try turning off Bass Management to see if this better matches your preference.

Hopefully this helps (a little…)

Cheers
-Geoff

[geoffmartin]

Totally agree with MM, but I would even go so far as to say that adding the Beolab 2 might make some frequencies QUIETER when you combine it with the Beolab 20s. This is because of the frequency-dependent phase differences caused by the fact that Beolab 2 has slave drivers and the Beolab 20s have closed cabinets.

If anyone wants a more technical explanation of this, let me know and I’ll start writing a blog post. 😀

[geoffmartin]

If you’re mixing the Beolab 18s with non-B&O loudspeakers (like KEF) with a non-B&O surround processor, then you also need to worry about latency. In the case of the 18s, this can probably be compensated using a small addition to the loudspeaker distance calibration in the processor’s setup menus.

There’s a blog posting about how to do this here:

https://www.tonmeister.ca/wordpress/2017/12/06/bo-tech-beolab-loudspeakers-and-third-party-systems/

[geoffmartin]

There is no industry-wide standard for specifying the Frequency Range of a loudspeaker, so each manufacturer uses their own definition which allows (potential) customers to compare within a single brand. B&O has not changed its definitions for at least as long as the 20 years that I’ve worked here. (Note that this is not a new specification – I guess that it’s just been newly added to the Beolab 8 page.)

While it might be arguable that a single standard for passive loudspeakers is a good idea, this would not be applicable to active loudspeakers due to dynamic processing, which immediately raises the issue of which output level to use for such a measurement. (For example, when ABL starts protecting a B&O loudspeaker, it reduces the frequency range, if only temporarily.)

I would argue that it’s a bad idea to make an industry-wide standard unless it’s generalised so much that it’s useless. Consider, for example, the difficulty of creating a single standard that would be applicable to loudspeakers with very different directivity patterns: a dipole electrostatic and an omnidirectional loudspeaker.

I certainly agree with your implication that it would be difficult/impossible to correlate loudspeaker sales with these technical specifications, which also would indicate that these technical specifications are not important factors for most of our customers. However, this does not mean that we should not make them public – we definitely should, in the same way that car manufacturers publish horsepower (despite the fact that most people only care about torque in most day-to-day driving).

If our dealers (or their sales staff) don’t understand what these specifications mean, then it means that there is a weak link in our internal education. I am one of the people who educate the trainers and develop the training materials to teach the sales staff. Of course, there are links in this chain, but our sales staff should either know what these specifications mean, OR they already have the resources to find that information quickly.

That said, I completely agree with you that the biggest problem here is that our customers might make assumptions about what these numbers mean and assumptions are frequency incorrect. This means that I have a job this week to contact our marketing department to start figuring out how we can put an easily-accessible glossary on our website that explains the specifications so it’s easy to find out what the numbers mean, and how they can be used correctly. This isn’t as simple as it sounds due to the necessity of ensuring that it’s available in a number of languages – so don’t expect something to show up next week.

However, I’m happy to spend some time here explaining how the measurements are done if there are any questions. That’s exactly why I’m “allowed” to contribute to beoworld – to clear up technical questions and confusion.

Cheers
-Geoff

[geoffmartin]

There may be some incorrect assumptions about what the terms “Frequency Range” and “Bass Capability” mean.

I explained “Frequency Range” a long time ago in this blog posting:

https://www.tonmeister.ca/wordpress/2014/10/15/bo-tech-reading-specifications-part-1/

Note that a graph in a magazine is probably / usually created by doing one measurement in one location in front of the loudspeaker. This is equivalent to evaluating a television by measuring a single pixel – in other words, it can be worse than useless (we often say that, when it comes to a loudspeaker, one measurement is typically worse than no measurements). If you’re going to find a reasonably good representation of frequency range, you have to take a weighted average of a number of measurements at different angular directions in order to be fair/representative/useful.

Bass Capability is a measure of the maximum output level for the loudspeaker at a given narrow frequency range for a given amount of time.* This has nothing to do with Frequency Range (in the same way that top speed of a car has nothing to do with its 0 – 100 km/h acceleration time). I touched on this (at least intuitively) in this blog posting:

https://www.tonmeister.ca/wordpress/2013/12/13/bo-tech-what-are-subwoofers-really-for/

Hope that helps clear up any confusion.

Cheers
-geoff

* It’s important to remember that ABL protects the loudspeaker from clipping caused by over-excursion of the loudspeaker driver, or attempting to exceed the limits of the amplifier voltage / current or the power supply current. However, there is also thermal protection that pulls back the output of a loudspeaker driver to prevent it from melting the voice coil. If you play at maximum level for a period of time, the thermal protection starts working and the level will go down. So, the Bass Capability is the output level before that starts happening. If you’re playing a sine wave, you can hear this behaviour as a simple ramping-down. However, since music & movie sound is much more dynamic, the behaviour is much more complex.

[geoffmartin]

a little more information:

I just had a look at the service manual for the Beogram 1202 and 3000. The recommended tracking force stated there is:

• Beogram 1202 with an SP 14 A pickup: 2.0 g equivalent
• Beogram 3000 with an SP 10 A pickup: 1.2 g equivalent

 

 

[geoffmartin]

Hi,
Despite the fact that these are different turntables, the photos on this page should help give you an idea of how things should look

https://www.tonmeister.ca/wordpress/2022/09/11/beograms-side-by-side/

Note that there are some different issues that can cause this angular error:

• as Mark-sf said, tracking force is the first suspect… However, if this looks to be correct, then:
• the height of the platter can be adjusted using an adjustment screw. This might be incorrect if you’ve completely disassembled the turntable
• the suspension of the pickup might be damaged

[geoffmartin]

Nice one! Thanks Keith!

I’m actually surprised that I haven’t seen that issue before.

[Author]

Posts