Beymer SM212 issues

[Beer of the Bass]

The "unsuitable for bass guitar" line is a bizarre approach to take. Looking at the small number of 12" speakers they [i]do[/i] list as bass guitar drivers, all of them have specs that indicate that they would all be rather less robust than the Beyma when handling the low end of a bass. They have the Celestion BN12-300S and BL12-200x and the Eminence Basslite S2012. Other than having "bass" in the model name, I can't see what would make any of those a better choice.

[stevie]

What's even more bizzare is that they are saying there's nothing wrong with the speaker and that the cabinet is the problem.

[Chienmortbb]

Re Blue Aran, they are not the UK distributor. The distributor is LMC http://www.lmcaudio.co.uk.

[JohnDaBass]

Here are the latest comms with Blue Aran.
John DaBass wrote:

Dear Mr Kos,
May I propose, as a remedy, that you acquire a re-cone kit (BEYMARESM212-08) and your technicians re-cone the driver and carefully removing the defective voice coil and cone assembly for analysis?
Clearly until this data is available no one knows the root cause of the fault mode. Indeed as Beymer is ISO 9000 accredited it is vital that they have access to the defect analysis to meet the ‘Continuous Improvement’ pillar of their Quality Management System.
I am sure that you would agree with me that Blue Aran also need to review their Test capability tolerance limits to improve your ability to trap defects and protect your customers from receiving defective products.
Within your supply contract with Beymer there would be a ‘Warranty provision’ clause which would set out the terms of the warranty provided by Beymer. This provision, which could be a monetary value or a FOC quantity of drivers, would be used by your organisation to cover any costs faced by Blue Aran in dealing with warranty claims. At the end of the financial year, with agreement of your Auditors, any unused warranty provision built up throughout the year would be released to the bottom line.
May I therefore propose that the cost of the re-cone and the re-cone kit be split 50/50?
I get back a fully functioning SM212, Beymer get all the data they need to review their manufacturing processes, Blue Aran get to improve the capability of their Test systems and it is cost neutral to Blue Aran.

Regards
John
Andy Kos replied today:

[font="Arial"][size="2"]Thank you for your email.[/size][/font]

[font="Arial"][size="2"]As previously explained, from the information we have, there does not appear to be any warranty defect. The driver is fully functioning.[/size][/font]

[font="Arial"][size="2"]The problems you are experiencing are due to the driver being used incorrectly.[/size][/font]

[font="Arial"][size="2"]Reconing the driver will not fix the problem, a new reconed driver will exhibit the same problems if put into a cabinet tuned at 51 Hz and significant frequencies below 50hz are applied to it.[/size][/font]

So I think the next step is to give up on Blue Aran, ask for the speaker to be returned.
I will now look at modifying the cabinets to tune at 40 Hz.

Any views anyone?
Are you out there SKIDDER??

[stevie]

I'm a bit confused about what's going on here, John: you say the driver is blown, Blue Aran say it's fine.

Did you swap the drivers in your two cabinets?

On the tuning frequency thing, ports provide support for the driver not just at the tuning frequency but also either side of it. A port tuned to 50Hz reduces the excursion of the speaker between 40Hz and 60Hz (and a bit beyond). Tuning to 40Hz means your driver will have less support from the port and 60 to 70Hz, where you really need it.

[Phil Starr]

Hi John, I'm confused too. In your original post you said the driver was blown, which i took to mean completely non functional. Blue Aran are saying it is perfectly OK. What was the original fault exactly? If it was making no sound at all was it potentially a wiring fault? maybe even a dodgy speaker lead/plug/socket.

If Blue Aran return it and it works than that is a bit strange but you will have a working driver. Their answers to you have been over aggressive/ill informed but I find it hard to believe they would say it is working if it isn't at all.

[JohnDaBass]

The fault mode was that the speaker was not dead (Voice coil open circuit) just very distorted with loud random 'clicking' noise from open A downwards, 55hz down to 41Hz. The fault mode was first observed in the Mk1 cabinet but was evident in both Mk1 & Mk 2 cabinets, as I swopped the speaker to try to eliminate cabinet characteristics. The fault mode was evident using different basses and the online Tone generator using flat EQ settings.
The second SM212 I had DID NOT display the fault mode when used under the same conditions so I was able to A/B the two speakers.
It is interesting to note that Blue Aran's test regime was unable to reproduce the fault mode, indeed it would be helpful to understand what exactly their Test capabilities actually are? They claim to 'Test' every speaker before dispatch but if the test capability limits are insufficient to trap defects then the customer will be left to try to obtain recourse from an organisation who appear to unhelpful.
I have to say that I am disappointed with the response from Blue Aran. While the Beymer does not generate a substantial margin for Blue Aran compared to more expensive speakers I do feel that they should have a more balanced approach to customer service whatever the price of the product purchased. If it is defective then they should honour their warranty policies.
I have asked for the speaker to be returned to me and I will feedback any further news in the coming days.

[Phil Starr]

Did it click at all power levels or just at high powers?

[6v6]

Fwiw I made my sm212 loaded cab (similar but not same design as the bc 12) with an adjustable shelf port and gigged with both 50 and 41hz tuning.

IMHO the 50hz tuning handled the lows of my 4string bass better and I did provoke a few ugly sounds from the driver with the lower tuning. So I also don't think it will necessarily help to tune lower unfortunately.

[JohnDaBass]

Fender Rumble 500 head
settings
gain 7 o clock (minimum) for Fender Active PJ and 12 o clock for Passive Fender Jazz
Bass 3 o clock
Low Mid 12 o clock - flat
High Mid 12 o clock - flat
Treble 12 o clock - flat
Master 9 o clock

[LukeFRC]

I can kinda see Blue Arran's response - someone buys a driver, bolts it into a home-made box and then uses an unknown (to them) amplifier with unknown compression or effects added to make live bass guitar noise and an unknown number of gigs and load-in and load outs..... there are so many variables there that I can understand their reticence to make it their problem.

Just a wee question - the driver is rated for 350w, and from reading the bass cab build thread the cabs built with it have a flat response and a surprising amount of low end. In a gig situation IME, unless you have brilliant sound tech, and good stage noise dicipline, that flat response and bottom end gets lost a bit.
From the sound desk turning up a mid freq to let the bass cut through, cutting bottom on keys, and guitars and making sure the kick and bass arn't compete in is how I would solve it. But from the bass players position it makes sense to not be able to hear yourself and turn up a bit.
If you respond by turning up you make the mush worse and work your speakers harder.

How much power do you think you've been putting into the speakers? Stevie says you can put 350w through without problem.
Reason I ask is looking up the spec sheet of the amp module in your amp it's rated for 8ohms at 500w [size=4]@ 1%THD+N typical. With class D would we expect the burst power figures to be higher than that? If the amplifier is loud enough to start distorting it puts out typical 630w [font=Flama]@ 10%THD+N.

Now that [/font][/size][font="Flama"]doesn't tell us what limiting Fender have added and I don't claim to fully understand spec sheets - but is it possible you were just putting too much power into it? [/font]

[Chienmortbb]

[quote name='LukeFRC' timestamp='1481364269' post='3191741']
I can kinda see Blue Arran's response - someone buys a driver, bolts it into a home-made box and then uses an unknown (to them) amplifier with unknown compression or effects added to make live bass guitar noise and an unknown number of gigs and load-in and load outs..... there are so many variables there that I can understand their reticence to make it their problem.

Just a wee question - the driver is rated for 350w, and from reading the bass cab build thread the cabs built with it have a flat response and a surprising amount of low end. In a gig situation IME, unless you have brilliant sound tech, and good stage noise dicipline, that flat response and bottom end gets lost a bit.
From the sound desk turning up a mid freq to let the bass cut through, cutting bottom on keys, and guitars and making sure the kick and bass arn't compete in is how I would solve it. But from the bass players position it makes sense to not be able to hear yourself and turn up a bit.
If you respond by turning up you make the mush worse and work your speakers harder.

How much power do you think you've been putting into the speakers? Stevie says you can put 350w through without problem.
Reason I ask is looking up the spec sheet of the amp module in your amp it's rated for 8ohms at 500w @ 1%THD+N typical. With class D would we expect the burst power figures to be higher than that? If the amplifier is loud enough to start distorting it puts out typical 630w [font=Flama]@ 10%THD+N.

Now that [/font][font=Flama]doesn't tell us what limiting Fender have added and I don't claim to fully understand spec sheets - but is it possible you were just putting too much power into it? [/font]
[/quote]Good points and Stevie is right, the Beyma will be within its XMax figure over most of the frequency spectrum even at 350 watts. However if you are driving it hard, power compression will start to limit the power and if you start to put more power in, it gets hotter, the power compression gets worse and you are in an upward spiral. Gradually the speaker is working harder and harder. Add the cone unloading at frequencies below tuning and it is easy to see how the speaker could start complaining.

Having worked in the After Sales dept of a major manufacturer, I know that many times we got stuff back for repair that worked to spec. As I see it the problem Blue Aran have is that, rather than ask for more info and telling JohnDaBass that they had found no fault, they went on the attack. No way to keep customers happy.

JohnDaBass, as BA say the driver is working, can you ask them to do a specification spec? Also have you contacted Beyma about this.

Finally, and this is a note to everyone. JohnDaBass has bought an HPT, The Thumpinator. It has tightened up his sound and is protecting his speakers. Please use a High Pass Filter. There are several available, the Thumpinator is a UK one, on the Other Place, FDeck makes a few different ones that have variable filters. These stop low frequency rubbish getting to the driver, give you much more headroom, a better sound and protect your speakers. I have no commercial interest and in either product I just know they are a great idea.

Edited December 10, 2016 by Chienmortbb

[Beer of the Bass]

[quote name='Chienmortbb' timestamp='1481370694' post='3191803']
Finally, and this is a note to everyone. JohnDaBass has bought an HPT, The Thumpinator. It has tightened up his sound and is protecting his speakers. Please use a High Pass Filter. There are several available, the Thumpinator is a UK one, on the Other Place, FDeck makes a few different ones that have variable filters. These stop low frequency rubbish getting to the driver, give you much more headroom, a better sound and protect your speakers. I have no commercial interest and in either product I just know they are a great idea.
[/quote]

Another thing worth mentioning is that for the DIY inclined (which presumably anyone building their own cabs will be), Francis Deck has kindly put the schematic for the earlier version of his HPF in the public domain. This version is aimed at double bass use, with a less steep 12dB/octave filter, but it should still be useful with electric bass.
[url="https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxocGZ0ZWNobGxjfGd4OjQyNGJhOWE3YzdjMDY0ODg"]https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxocGZ0ZWNobGxjfGd4OjQyNGJhOWE3YzdjMDY0ODg[/url]

Someone else has made a neat stripboard layout for it too. I keep meaning to build one for myself...

[url="http://tagboardeffects.blogspot.co.uk/2015/01/hpf-technology-hpf-pre-2.html"]http://tagboardeffects.blogspot.co.uk/2015/01/hpf-technology-hpf-pre-2.html[/url]

[LukeFRC]

why don't they put a HPF as standard on bass amps?

[VTypeV4]

[quote name='LukeFRC' timestamp='1481377455' post='3191852']
why don't they put a HPF as standard on bass amps?
[/quote]

I've always wondered this too..

[Passinwind]

[quote name='LukeFRC' timestamp='1481377455' post='3191852']
why don't they put a HPF as standard on bass amps?
[/quote]

There are substantial tradeoffs at play and the vast majority of players either "don't need" one or don't realize that they do. Note that I do include one as a standard feature on most of my DIY builds these days though...

[Phil Starr]

[quote name='LukeFRC' timestamp='1481377455' post='3191852']
why don't they put a HPF as standard on bass amps?
[/quote]

Just about all amps, bass or otherwise, have a low frequency cut off. Within the preamp stages capacitors are often used to link the signal and these act as filters for bass. That's not universal though. Even if it isn't an inherent part of the design putting in an HPF should really be standard and you could always make it switchable. Building it in would cost pence as opposed to an expensive add on.

With the bass control at 3 o'clock you could be applying 1/4 to 1/2 bass boost. Assuming you have 12dB of boost available every 3dB of boost will double the power and the speaker excursion so that could be the problem, it is certainly taking the speaker right up to it's limits.

As the idiot who did most of the design I worked on the assumption that the fundamental makes up only about 25% of the signal from the bass. I used the only information I had to hand which was from some testing TKS were generous enough to share. It's impossible for any designer to have control over how their design will be used but if 6dB of bass boost (much less than doubling the amount of bass subjectively) was used then that 25% assumption means 100% and I'd have to assume the speaker was working right up against its limits for considerable amounts of time.

I've never claimed this as a 350W speaker. Beyma give out the figure of 350W thermal but that involves a test signal which is constant but with bass and treble filtered according to AES specs. I used 300W max in all my calculations.

All ported cabs suffer from this problem and all commercial designs could be damaged in this way. I suppose this should be more widely shared on BC. I'll start a new thread next week, not everyone will be interested in the Beyma.

[Passinwind]

[quote name='Phil Starr' timestamp='1481446201' post='3192267']
As the idiot who did most of the design I worked on the assumption that the fundamental makes up only about 25% of the signal from the bass. I used the only information I had to hand which was from some testing TKS were generous enough to share. It's impossible for any designer to have control over how their design will be used but if 6dB of bass boost (much less than doubling the amount of bass subjectively) was used then that 25% assumption means 100% and I'd have to assume the speaker was working right up against its limits for considerable amounts of time.
[/quote]

There was a long and sometimes contentious thread on Talkbass several years ago where many bases were tested with an eye toward spectral distributions. It's archived in the Amps Forum FAQ: [url="https://www.talkbass.com/threads/bass-frequency-waterfall-plots-what-they-mean-to-rigs.510749/"]https://www.talkbass...to-rigs.510749/[/url]

I provided some of the first few analysis examples, which from my perspective basically worked out to [i]let no good deed go unpunished[/i], which seems like something you might relate to right about now. It's not all that hard to do your own testing and draw your own conclusions, which I would highly recommend. My personal takeaway was and is that as usual, it just depends. Room EQ Wizard is one bit of free software that does an excellent job analyzing bass recordings. In any case, boosting the fundamental in the way you mention most likely won't take that hypothetical 25% number to 100%, because the overtones still all have energy and therefore have to take up part of that 100% ceiling, and depending on what note you are looking at the bass control may well be boosting the first overtone or two just as or nearly as much as the fundamental. I'll be happy to illustrate this with an actual measured example or two when you start your new thread if you like. I don't do DIY speaker cabs any more myself, but I still enjoy doing the math.

I reckon that the adjustable HPF I build into my amps would add right around $100 at retail, given the standard markup typically needed to make a successful go of commercial production. But that also just depends, and as you say, most amps already have at least a rudimentary low order filter response built in. IMO, in many cases that is plenty, and may represent the best balance of tradeoffs for many users.

Edited December 11, 2016 by Passinwind

[Phil Starr]

[quote name='Passinwind' timestamp='1481450162' post='3192299']
There was a long and sometimes contentious thread on Talkbass several years ago where many bases were tested with an eye toward spectral distributions. It's archived in the Amps Forum FAQ: [url="https://www.talkbass.com/threads/bass-frequency-waterfall-plots-what-they-mean-to-rigs.510749/"]https://www.talkbass...to-rigs.510749/[/url]

In any case, boosting the fundamental in the way you mention most likely won't take that hypothetical 25% number to 100%, because the overtones still all have energy and therefore have to take up part of that 100% ceiling, and depending on what note you are looking at the bass control may well be boosting the first overtone or two just as or nearly as much as the fundamental. I'll be happy to illustrate this with an actual measured example or two when you start your new thread if you like. I don't do DIY speaker cabs any more myself, but I still enjoy doing the math.


[/quote]

I'll have a look at that thread later, thanks.

OK guilty as charged I over simplified my argument to make it clear to the OP. Percentage of what? Obviously not of sound as stated, what I should have said was if the speaker was making 25% of the allowable excursion with the tone control flat then it would probably be doing 100% of the allowable excursion with the sort of bass boost he was applying.

Tone controls are tricky things, there are a lot of different circuits used to control tone. Passinwind will vouch for that. A lot of tone controls are still based on the traditional Baxendall design. The trouble is this circuit will boost sound most the further you get away from it's first frequency of action, extreme bass is boosted more than upper bass. http://www.learnabout-electronics.org/Amplifiers/amplifiers42.php This means that when you boost bass to get a bit more warmth the subsonics are boosted even more than the bit you are interested in.

Turning the bass control to 3 o'clock as the OP did is hardly extreme, but he may well have ended pumping four times as much power as he thought into his speakers. I want to help him get good results and to understand what may have happened but most of all I want to be able to offer the best possible advice to people who build these speakers. It's hard to explain situations where there are many variables in simple ways to the non-techy reader.

Let's hope that when it gets back it is working as Blue Aran say it is.

[Passinwind]

[quote name='Phil Starr' timestamp='1481617010' post='3193664']
I should have said was if the speaker was making 25% of the allowable excursion with the tone control flat then it would probably be doing 100% of the allowable excursion with the sort of bass boost he was applying.

Tone controls are tricky things, there are a lot of different circuits used to control tone. Passinwind will vouch for that. A lot of tone controls are still based on the traditional Baxendall design. The trouble is this circuit will boost sound most the further you get away from it's first frequency of action, extreme bass is boosted more than upper bass. [url="http://www.learnabout-electronics.org/Amplifiers/amplifiers42.php"]http://www.learnabou...mplifiers42.php[/url] This means that when you boost bass to get a bit more warmth the subsonics are boosted even more than the bit you are interested in.

Turning the bass control to 3 o'clock as the OP did is hardly extreme, but he may well have ended pumping four times as much power as he thought into his speakers. I want to help him get good results and to understand what may have happened but most of all I want to be able to offer the best possible advice to people who build these speakers. It's hard to explain situations where there are many variables in simple ways to the non-techy reader.

Let's hope that when it gets back it is working as Blue Aran say it is.
[/quote]

Agreed to every bit of that. I could say much more, but I'll save that for some more overtly tech oriented thread.

[vinceom]

On 29/09/2016 at 14:59, stevie said:

John, I think you'll find your cabinet is tuned too high. My calculations say you've tuned to around 60Hz. With that tuning, you'll be exceeding xmax at 40Hz with an input of 200 watts. As you have also applied bass boost, this figure could easily drop to 100 watts or less.

Tuning to our recommended 50 Hz will give you an extra 3dB at 40Hz, perhaps making bass boost unnecessary. The speaker will then also handle an input of 350 watts without exceeding xmax (at least in theory).

You might like to check the tuning frequency using the rice grain test. Use your good driver obviously. This works on the principle that driver movement is greatly reduced at the cabinet tuning frequency, because that's where the port is doing most of the work. Turn your speaker on its back and sprinkle a few grains of rice in the centre of the cone. Then go to this site (or something similar): <http://onlinetonegenerator.com/subwoofer.html>, play the frequencies and you will see the rice dancing up and down along with the movement of the cone. As you approach the tuning frequency, movement will slow down. The point at which the rice moves least is your tuning frequency, and this will be shown on your display.

Then get back to us.

PS Try this with your good cab with the round ports first. You should get a tuning frequency of 54Hz.

Hi

can you explain how you calculate tune frequency of your cab ? With Winisd ?

Thanks !

[stevie]

Yes, with Winisd or any similar program.

[vinceom]

Thanks !