Celestion Pulse XL 10.40 Cab

[LeighOnSea]

This sounds great!
Cab out of Ext Speaker, and Harmon Kardon Onyx Studio 2 out of Line Output/Phones

 

[LeighOnSea]

Hi,

I got my Markbass Marcus Miller CMD 101 Micro 60
Wow

Also, runing my DIY cab via the Markbass combo amp was very satisfying!

So, I am thinking of putting a tweeter into my cab

Since I have the Celestion PULSE XL 10.20 Bass Speaker, I want to use the PULSE XL 1.10 Supertweeter

https://celestion.com/productpdf.php?id=9507

Presumably they will work well together and the roll off (I very recently found out what that means!) is around 2 kHz I think

There is room for it in the cab

I am presuming I need a crossover at around 2 kHz?

Would anyone have any recommendations for one, please?

A search for 'crossover' came back with 25 pages, and I dont know enough to refine it!

Reasonably priced would be preferable if not over restricting
Preferably available UK / Europe

EDIT: Presumably I could put in a simple switch to isolate the crossover and tweeter for when I didnt want them to work?

Cheers

 

[LeighOnSea]

OK, I am going to forge ahead,
I ordered the PULSE XL 1.10 Supertweeter (25% off at €37)
I sent an email to Celestion and they advised a simple capacitor resistance crossover, with bass and tweeter in parallel
Capacitor 2 to 3 uF (The larger the capacitor value the more low frequency you will get from the tweeter). Any higher than 4 uF risks damaging Tweeter
Resistance (always be positioned before the capacitor to avoid changing crossover frequency), between 6 to 16 Ohm (16 Ohm tweeter quieter)

I dont know how loud I want the tweeter and would like to be able to control it (and turn it off if required) so I made up the following:
The potentiometer can be linear in this case, I think

 

[LeighOnSea]

Or, I could put a logarithmic Pot in and replace the 10 ohm with a 100 ohm one and then half turn on the pot would give me 16 ohm (approx) and full turn 106 ohm, effectively turning the pot off - ish and removing need for switch

(Invalid Link Removed)

or log pot plus 200 ohm instead of 10 then 1/4 turn is 16 ohm ish and full turn is 206, turning tweeter down to very low indeed

 

[agedhorse]

There are proper ways to accomplish the same thing without all the pitfalls:

Link Removed

 

[6thplanet]

You want what's called an L-pad. If the tweeter is 8ohm, then get an 8ohm 50Watt L-pad. Put the cap in the circuit before the L-pad.

 

[LeighOnSea]

There are proper ways to accomplish the same thing without all the pitfalls:

Link Removed

Thanks! What are the pitfalls? - Pesky impedance?

 

[LeighOnSea]

You want what's called an L-pad. If the tweeter is 8ohm, then get an 8ohm 50Watt L-pad. Put the cap in the circuit before the L-pad.

Thanks!
Something like this?

L-Pad Attenuator 1" Shaft 8 Ohm

Explore L-Pad Attenuator 1" Shaft 8 Ohm. Check the main specifications and product details to see whether it fits your audio project at SoundImports.

www.soundimports.eu

 

[LeighOnSea]

Welcome to the forum! I'm a fellow Clash fan and I'm also working (slowly) on a DIY cabinet ... a sealed 2x10 in my case. I'm certainly not an expert in either design or build, but I've learned a lot from some of the resident experts on this forum, a variety of other online resources, and a few of my own mistakes so my comments are well-intentioned, perhaps somewhat useful, and hopefully not completely incorrect! My suggestions assume that you will not be changing the size of the box or the diameter of the port as you've given very valid reasons for those choices.

I've used WinISD for a few years and have become rather familiar with it even though I understand that its results should not entirely be trusted to be accurate. In fact, I've verified this to be the case when I compared the measured tuning frequency of two cabinets to those predicted by WinISD using the same box and port dimensions and found them to be considerably different than the measured frequencies. This doesn't concern me a great deal as I'm building a sealed cabinet, but I still like to check its results against something else. So, I recently began using a free online calculator at Speaker Box Lite and I've based my comments on those results.

The tuning frequency of almost 62 Hz seems quite high and both WinISD and Speaker Box Lite (SBL) show that it results in a very large peak (about 6 dB) around 75 to 80 Hz. This would certainly be quite noticeable and likely difficult to work around with typical eq controls. I'd suggest a much lower tuning frequency and I've attached two plots from SBL showing the effect of lower tuning frequencies on the frequency response and the port air velocity. It looks like lowering the tuning frequency will reduce the sharp peaking, extend the low end response, and slightly reduce the port air velocity. Although your specific Celestion driver is not available in the SBL database, you can simply select another model and then alter its parameters to those published by Celestion for the Pulse XL 10.20.
View attachment 6996325

As for the build of the cabinet, I tried cutting the baffle hole with a jigsaw at first and was not happy with my result. Your result may be quite different than mine as this is entirely dependent on the skill (and patience) of the operator. I ended up remaking the baffle and used a 230 mm hole saw that I bought online. It's not a great quality cutting tool, and will likely never be used again, but working slowly in a drill press and cutting from both sides of the board, it produced a much nicer opening than I was able to with the jigsaw. I also installed threaded inserts for the mounting holes which I marked, drilled, and installed prior to cutting the large driver hole as they come rather close to the edge of the cutout and I was concerned that they might break through during installation.

As for the polarity convention, I believe the tip is typically connected to positive.

My only other comment is that, based on Celestion's published frequency response graph, this driver does will not have a lot of top-end extension and this may result in a rather dark-sounding cabinet. But since you already have the driver, give it a try and see how you like it. Best of luck and enjoy the journey!

Would the differences in the Transfer function responses between 40 and 50 Hz shown in the plot above actually make a noticeable difference to the sound? And if so, in which way. Perhaps converting quantitative into subjective I guess, but just an indication?
I could alter the cab tuning by shortening the pipe from 136 to 89 or even 56 mm to increase the Fb from 40 to 45 or even to 50 Hz.

Presumably the cab Fb has nothing to do with the speaker parameters except for the volume it takes up? SubBox Pro seems to very accurately predict Fb (for me, predicted 40 Hz, rice test ~ 40.5 Hz) and there is no other input of driver parameters in subbox pro except for size and volume.

Also, @Dino Boreanaz , when you say, 'does will not have a lot of top-end extension', do you mean above around 2 kHz, and hence addition of a tweeter could 'remedy' this?

 

[6thplanet]

Thanks!
Something like this?

L-Pad Attenuator 1" Shaft 8 Ohm

Explore L-Pad Attenuator 1" Shaft 8 Ohm. Check the main specifications and product details to see whether it fits your audio project at SoundImports.

www.soundimports.eu

Yup

 

[LeighOnSea]

Yup

Thanks, you have been really helpful!!
That's now ordered, along with this 2 uF capacitor
I got the lowest tolerance just cause they were not expensive and foil since I believe these are the ones to go for?
I also got the 2.7 and 3 uF versions whilst at it in case I need to change capacitance

Order Dayton Audio PMPC-2.0 capacitor

Buy the PMPC-2.0 online at SoundImports ✓ Same day shipping ✓ Low shipping rates

www.soundimports.eu

 

[6thplanet]

That's fine. It's kinda hard to tell exactly what your doing without some sorta measurement equipment. Good luck

 

[Dino Boreanaz]

Would the differences in the Transfer function responses between 40 and 50 Hz shown in the plot above actually make a noticeable difference to the sound? And if so, in which way. Perhaps converting quantitative into subjective I guess, but just an indication?
I could alter the cab tuning by shortening the pipe from 136 to 89 or even 56 mm to increase the Fb from 40 to 45 or even to 50 Hz.

Based on my limited experience with a few different ported combo amps, I found that the ones with higher tuning frequencies (around 55 to 60 Hz) sounded less defined in the lows (from low E to A). On two combos that had multiple ports, I tried closing one port and found that I preferred the sound. To me, it sounded more defined, tighter in the very lowest notes. Cutting the port area in half has the effect of reducing the tuning frequency by a factor of 1.4, so this would have reduced their tuning frequencies to somewhere around 40 Hz. Being aware that this "experimentation" had the potential to affect the cone excursion, I always kept the volume home-friendly so I have no idea whether my subjective results would have been the same had I repeated this at higher volumes. If you're OK with shortening the pipe to try different tuning frequencies, I definitely suggest trying it to see what you actually prefer. One difficulty you might have though is accurately assessing the difference in sound (for me it was fairly subtle, perhaps due to the low volume I played at) since there is likely to be significant time between the various trials. I was able to simply insert a small, round plastic container with a few turns of vinyl tape around it into the port, so I could very quickly change between one port and two.

Presumably the cab Fb has nothing to do with the speaker parameters except for the volume it takes up? SubBox Pro seems to very accurately predict Fb (for me, predicted 40 Hz, rice test ~ 40.5 Hz) and there is no other input of driver parameters in subbox pro except for size and volume.

That is my understanding as well.

Also, @Dino Boreanaz , when you say, 'does will not have a lot of top-end extension', do you mean above around 2 kHz, and hence addition of a tweeter could 'remedy' this?

Exactly.

 

[LeighOnSea]

Since I impatiently glued the pipe into the cab side I will not now mess around with the pipe length.
Especially since I am sure that with my untrained ear such changes as fo 40 to 45 Hz wont be 'measurable'.
I will put the tweeter in with the 2 uF cap and L-Pad and see how it goes.
I am using the amp of the Markbass combo which they say has a frequency response down to 45 Hz. I am not sure how this relates exactly to Fb, but perhaps the amp has a 45 Hz HPF?
I am already sensing that I will want to add a bass amp for my cab soon

 

[David Morison]

Probably wise re the re-tuning, unless you're just an inveterate tinkerer

A quick & dirty sim (ie I use WinISD cos it's easy, albeit not the most accurate program) shows the 45Hz tune would have a little less level at the deepest frequencies, and ~1/2 to 1dB more in the 50-150Hz region.
If you had the chance to A-B those back to back you'd hear it, but it would still be fairly subtle.
Without a direct A-B comparison, it'd be even harder to tell the difference.

Re the Markass, the odds are the speaker in the original combo was the limiting factor in how deep it might have reached, rather than the head.
Given how deep the PulseXL is reaching in these sims, I don't think you'll find it lacking in depth.
HTH,
David.

 

[LeighOnSea]

Probably wise re the re-tuning, unless you're just an inveterate tinkerer

A quick & dirty sim (ie I use WinISD cos it's easy, albeit not the most accurate program) shows the 45Hz tune would have a little less level at the deepest frequencies, and ~1/2 to 1dB more in the 50-150Hz region.
If you had the chance to A-B those back to back you'd hear it, but it would still be fairly subtle.
Without a direct A-B comparison, it'd be even harder to tell the difference.

View attachment 7007004

Re the Markass, the odds are the speaker in the original combo was the limiting factor in how deep it might have reached, rather than the head.
Given how deep the PulseXL is reaching in these sims, I don't think you'll find it lacking in depth.
HTH,
David.

Thanks David!

My moto is normally, 'Fix it till its broke'

But in this case I am going to leave it as is with the (glued in tube) tube at present length and tuned for 40 HZ.
If any changes are going to be very subtle, then I am not going to hear them (lack of trained ear and lots of scaring due to learning by crashing windsurfing forward loop perforated eardrums in the mid 80's), and I like the idea of keeping the deeper frequencies.
With a signal generator at 40 Hz you can definitely hear (& feel) the cab.

I am quite excited to put in the tweeter. Celestion told me that a 2 to 3 uF cap would be about right, with 3 letting lower frequencies through to the tweeter, but higher cap values increasing the risk of damage to the tweeter, so to stick with 2. I am wondering how far down this 'crossover' would be, more or less, in terms of frequency, and how much (ball park) the change in frequency of this would be from 2 to 3 uF?

Sorry for all the questions, I'm afraid it's in my nature to be inquisitive, always has been.

The most important thing is that, (as well as this sciency stuff being exactly my cup of tea) the amazing sound coming out of my cab and MarkBass are an absolute pleasure and give me great joy and lots of enthusiasm for playing. I'm still and probably always will be crap, but I dont care. @Dino Boreanaz - loving Police on my Back!

 

[LeighOnSea]

You want what's called an L-pad. If the tweeter is 8ohm, then get an 8ohm 50Watt L-pad. Put the cap in the circuit before the L-pad.

@6thplanet - Just to be sure, by 'Put the cap in the circuit before the L-pad.' you mean to just replace my amateur arrangements of resistances in the figure below with the L-Pad, so cap is between tweeter and L-Pad? (I wont put the switch in the diagram in)

 

[David Morison]

Nope; 6thplanet is advising to stick with the conventional layout of input>cap>L-pad>tweeter.
This accomplishes two things: 1; it shields the L-pad from much of the (potential) power output of the amp, allowing the use of an L-pad with lower total power rating and 2: by putting resistance in between the cap and tweeter we get less variation in impedance w.r.t. frequency as seen by the cap, so the actual shape of the roll-off created by the cap becomes closer to the theoretical target.

Herewith 1uF (red), 2uF (green) & 3uF (blue):
I adjusted the L-pad values (shown as the 2 resistors in the schematic view) to keep the levels roughly equal at the top end of the response, with all of them padded down to approximately the level of your 10".

 

[LeighOnSea]

Nope; 6thplanet is advising to stick with the conventional layout of input>cap>L-pad>tweeter.
This accomplishes two things: 1; it shields the L-pad from much of the (potential) power output of the amp, allowing the use of an L-pad with lower total power rating and 2: by putting resistance in between the cap and tweeter we get less variation in impedance w.r.t. frequency as seen by the cap, so the actual shape of the roll-off created by the cap becomes closer to the theoretical target.

Herewith 1uF (red), 2uF (green) & 3uF (blue):
I adjusted the L-pad values (shown as the 2 resistors in the schematic view) to keep the levels roughly equal at the top end of the response, with all of them padded down to approximately the level of your 10".

View attachment 7007033

Great, Thanks, extremely clearly explained and a great help!

I will try 2 uF and see how it sounds

 

[LeighOnSea]

OK, next questions!

I have read that the fundamental range is around 40 to 400 Hz, but that Harmonics go up to 4 to 5 kHz.
Is that correct?

And if so, does that mean that, in the context of @David Morison 's tweeter plots, that above 5 kHz, it really doesn't matter for a Bass guitar?

And, what are the advantages of decreasing the capacitance in terms of sound? I think the disadvantages are that this can overdrive the tweeter causing damage? But I cant see what the advantages are when I can 'turn the tweeter up' with the L-Pad

I realise that all the above are probably very badly informed questions, since I do not know what I am talking about, but I am still finding my way, so I apologise in advance.

I love the phrase, " 'I'm English', I appologised' "