Markbass CMD121P replacement tweeter recommendations

[Rusco]

Hi all,

Has anyone replaced their tweeter with a like for like screw in upgrade and can make me a recommendation please ?

I know this is a well discussed topic in general and a lot of people have just disconnect it or mod’d the electronics but I’d like to replace the tweeter with a better non-hiss one. 

The answer may be buried in the many existing threads but thought it easier to just ask :-)

Many thanks.. R

[Bill Fitzmaurice]

Tweeters don't create hiss, they only reproduce hiss created by the electronics. Replacing the tweeter won't get rid of hiss.

[lemmywinks]

I replaced it with a Stageline HT30, on some MB cabs you have to widen the hole (you can make yourself a template from the rubber grommet that comes with the tweeter) but on some of the older ones I think the hole is ok as is. Was a vast improvement over those LeSon piezo things they use(d), no horrible scratchy noises or brittle sounding highs.

 

Really you could just bypass the tweeter anyway, I think someone on here did that a while ago and posted instructions.

[yorks5stringer]

Yep, I bypassed mine, there's a thread somewhere about it.

[King Tut]

I put a Stageline HT30 in mine as did @lemmywinks. I had to use a dremel to slightly reshape the hole but it wasn't too difficult. Imho it made a massive difference for the better. I'd also run it for a while with the tweeter bypassed, but i like quite a bit of high mid in my sound and it wasn't cutting it without the tweeter. I found that with the stage line tweeter, the highs and high mids sound much smoother, less harsh - a very noticeable difference and I'm surprised, given the amount of people who have done the mod, Markbass don't up their game and install something better from scratch.

[lemmywinks]

3 minutes ago, King Tut said:

............. I'm surprised, given the amount of people who have done the mod, Markbass don't up their game and install something better from scratch.

They do/did, quite a few of their cabs have nice little compression drivers in. I think it's just a cost saving measure, those LeSon tweeters will cost MB pennies to buy per unit whereas a better quality alternative with the hardware to make it attenuable will be many times more. 

[Dan Dare]

9 hours ago, Bill Fitzmaurice said:

Tweeters don't create hiss, they only reproduce hiss created by the electronics. Replacing the tweeter won't get rid of hiss.

Bill's correct as usual. Just disconnect the tweeter. Once you're used to the lack of ticking and clattering, fret rattle and general nastiness in your sound, you'll be much happier 

[Al Krow]

The CMD121P, in common with other Markbass heads, has a VLE knob - don't know if you've been finding a use for this?

For folks not familiar, the VLE is a shelf EQ with a gentler slope than a dedicated LPF to give things a 'vintage' feel, and with a frequency range of 250Hz to 20kHz.

This cuts a more dispersed range of high frequencies as you turn it up. Set at about 4/6, it should be cutting at around 5kHz+ and set at 5/6 cutting at 10 kHz+ and therefore reducing the tweeter hiss. If this doesn't reduce it sufficiently and / or you're not a fan of the resultant vintage tone, one alternative would be to use a LPF pedal to provide you with a steeper cut in your 'undesired' frequency range.

Edited April 3, 2018 by Al Krow

[Bill Fitzmaurice]

4 hours ago, Dan Dare said:

Bill's correct as usual. Just disconnect the tweeter.

Depending on the crossover circuit, if it has one, removing the load presented by the tweeter can cause damage to your amp. If you want to ditch the tweeter you need to eliminate all the associated crossover components as well to be safe.

[yorks5stringer]

7 hours ago, Bill Fitzmaurice said:

Depending on the crossover circuit, if it has one, removing the load presented by the tweeter can cause damage to your amp. If you want to ditch the tweeter you need to eliminate all the associated crossover components as well to be safe.

True, it was not just a case of pulling off the wires, one has to cope with the crossover  so it means reattaching them onto different terminals

[Phil Starr]

I'm just a little concerned here. If the original tweeter is a piezo it isn't likely that it has a crossover or that if it does it will match a 'proper' horn driver. People seem to be implying that early Markbass models used a piezo and later ones a coil driven unit, which would have had some sort of crossover. You really need to check before you start swapping things around. Without some sort of crossover the bass will go through the replacement tweeter and destroy it as soon as you play at volume. Piezos have high impedance at low frequencies and so filter out bass by their nature, this saves the cost of a crossover and is one reason why they are so cheap.

If it is a coil/magnet based compression driver and horn  in your speaker then any replacement would need to match the spec of the old unit fairly well in terms of sensitivity, impedance and power handling at least. It looks like others have used the HT30 successfully so I'd copy that mod in your position, but check first.

[Rusco]

Thanks a lot for the replies.

I don’t really want to muck around with the electronics so will check out the tweeters suggested as a direct replacement.

Cheers

[lemmywinks]

When I put the Stageline in my cab I went off information in this thread:

https://www.talkbass.com/threads/installing-new-tweeter-in-markbass-combo.991340/

The fella opened his CMD121P and his accompanying extension cab (the H version with a proper horn) and found they use the same crossover regardless.

 

If you want to disconnect it and are unsure of what to do then have a look at this thread which details which wires go where:

 

Edited April 5, 2018 by lemmywinks
Terrible sentence structure

[Bill Fitzmaurice]

A piezo would not use the same crossover as a dynamic driver unless the piezo was one specifically configured to present a resistive load. Piezos of that sort exist, but they're rare.

While on the subject, there are two issues common with most tweeter equipped cabs, those being the tweeters are crossed over at way too high a frequency, often an octave or more, and the high pass filters have inadequate slope to provide adequate protection. IMO tweeters that don't work down to at least 2.5kHz and high pass filters that aren't at least 3rd order as about as useful as screen doors on a submarine.

[Al Krow]

15 minutes ago, Bill Fitzmaurice said:

and high pass filters that aren't at least 3rd order as about as useful as screen doors on a submarine.

Bill - can you elaborate for us mere mortals on what a 3rd order (or higher) HPF is please?

[lemmywinks]

Two posts where owners of both P and H cabs have discovered the same crossover used in both:

https://www.talkbass.com/threads/installing-new-tweeter-in-markbass-combo.991340/#post-14458666

https://www.talkbass.com/threads/replacing-the-tweeter-in-a-markbass-cmd121p.505727/#post-6812438

Anybody fancy opening theirs up and posting a picture? 

[Bill Fitzmaurice]

4 hours ago, Al Krow said:

Bill - can you elaborate for us mere mortals on what a 3rd order (or higher) HPF is please?

http://www.bcae1.com/xoorder.htm

Quote

Two posts where owners of both P and H cabs have discovered the same crossover used in both

  I already explained that there are piezos that have added circuitry to present a resistive load that allows them to be used with a standard high pass filter, although I've never seen one myself, they are that rare. I use high pass filters with standard piezos, but they're specifically configured for piezos and would not work with a dynamic driver.  There's also the possibility that those cabs used standard piezos with high pass filters when they should not have. I've seen worse foul ups. 

Edited April 6, 2018 by Bill Fitzmaurice

[dannybuoy]

I would just look for a used CMD121H then sell the 121P if that sounds like an option you'd entertain. Slightly bigger, easier to reach controls, deeper lows and sweeter highs.

[lemmywinks]

I'm not arguing a point, just trying to ascertain what is inside the actual cabs the OP owns and whether it would be ok for him to swap out the tweeter for a different one. From memory the piezo tweeters had a habit of blowing (this is what happened to mine) so maybe those P cabs had incorrect configurations.

 

If anyone has either cab and fancies taking internal pictures then that would probably help a lot.

[Muppet]

I have a CMD121P and a NY121 extension cab.  The cab has a Lpad for the tweeter, but the combo doesn't. On both models the tweeter and the crossover are the same.  Rather than just disconnecting the tweeter, I bypassed it and the crossover and connected the amp output direct to the driver. The combo sounds much better without it and if I really need any extra high end I dial it in on the extension cab.