Customizing Harley Benton HB-40 combo

[Jannibal42]

Hi there.

 

I currently own a Harley Benton HB-40B combo https://www.thomann.de/nl/harley_benton_hb_40b.htm

And recently acquired a Markbass Little Mark 250 Blackline: https://www.thomann.de/nl/markbass_little_mark_250_black_line.htm

 

I rather like the idea of maintaining the small combo form factor, so I'm thinking about building the Mark Bass head into the HB40.

I've done some measuring and came to the conclusion that I can build the Markbass head into the combo quite easily. So now I'm just looking for a replacement speaker. Can anyone here help me figure out what to look for? Would this be a good option for example?

https://www.thomann.de/nl/eminence_legend_bp1024.htm

 

Thanks in advance for any advice you can give me!

[BassmanPaul]

Unless you are very lucky, whatever driver you pick is unlikely to work at it's best in your combo's cabinet. This is especially true for use with a bass. You could quite possibly damage the replacement.

[Jannibal42]

Hi Paul,

Thanks for your response. Could you elaborate on why this could lead to damage?

[Phil Starr]

One of the effects of the cab is to damp the movement of the speaker cone. That is a function of both the volume/mass of air in the cab  and the tuning if the cab is ported. If the cone flaps around at certain frequencies it can reduce the power handling of the speaker to a fraction of it's rated power.

 

However it isn't that bleak in practice. Speakers designed for bass tend to hover around very similar specifications and often 'work' in a wide range of cabs. As said above you may not get the best out of a speaker but that doesn't mean nothing is possible or that you cannot tweak. As a broad guide a volume of around 30litres will suit a number of common 10" drivers. Indeed we have offered one design on BassChat BassChat 110T If the internal volume of this cab is around 30l then you could simply use your box as a ready finished cab and try out your idea with little risk of failure. If it isn't 30l then measure the internal volume and we can calculate any tweaks for you. If it helps I've gigged that cab for a while during testing and it is great for small venues (up to 100 people) and rehearsals. It's a good match for your amp too. 

 

You have to decide first of all what your aims are, You could just build our cab and use it with your Blackline which would make a fine solution. This could be done to improve the sound, to squeeze a little more out of what you have or as a fun learning experience, like me you could get hooked on building so look out. The only thing we can't guarantee is what it will sound like when it is done, you only ever really find that out when you finally plug in your completed project, but that is half the fun

[Dan Dare]

I agree with Phil. Why bother to replace both amp and driver in a small budget combo? Wouldn't it be simpler to just sell it and get a suitable cabinet to go with the Markbass head? If you don't want to build one, you could buy a used one and replace the driver if you prefer. It shouldn't be much more expensive and you'll get a much better result. 

[Pea Turgh]

5 hours ago, Dan Dare said:

If you don't want to build one, you could buy a used one and replace the driver if you prefer. 

That’s the same thing though?!

[Pea Turgh]

If you make the mods reversible (keep all the original bits, stick to the same port widths, etc), you can always return it to standard spec to sell on if you don’t get on with it.

 

I did this with a small combo just because I had it and fancied a change.

 

Ended up selling the combo on and building a cab to put the new driver in (with lots of help from @Phil Starr).

 

As Phil says, it can be addictive!

[yorks5stringer]

There's a MB CMD121P in the ads here with a knackered amp, it may be cheap?. Maybe  the LM Blackline would fit and you'd have a decent combo?  I swapped the MB Ninja 250 head  into a CMD 121P and it worked fine....( as I put the LMIII into the Ninja cab).

 

Just seen you are in Germany so that probably rules things out (due to costs and duties)

Edited June 20, 2022 by yorks5stringer

[Jannibal42]

Yeah buying something that big from the UK and importing it to the continent is no longer viable since Brexit took full effect  

 

I’ve already taken the HB40 apart to see what the construction is like, and i could quite easily swap out the speaker and test its performance in a reversible way. I also read up on the theory behind cabinet building, checked the specs of the speaker and on paper it should at least ‘work’. Though that doesn’t guarantee that it’ll sound amazing of course.

The cabinet is about 34L in volume, so with the speaker installed i should end up pretty close to the 30L mark. It’s a relatively cheap and easy experiment so i think i’ll just give it a go. If the sound isn’t an improvement at all, i’ll just reverse the process. At least i can then say that I tried.

[BassmanPaul]

Well I wish you luck with that.

 

Perhaps it might meld harmoniously.  

[gjones]

13 hours ago, Jannibal42 said:

Yeah buying something that big from the UK and importing it to the continent is no longer viable since Brexit took full effect  

 

I’ve already taken the HB40 apart to see what the construction is like, and i could quite easily swap out the speaker and test its performance in a reversible way. I also read up on the theory behind cabinet building, checked the specs of the speaker and on paper it should at least ‘work’. Though that doesn’t guarantee that it’ll sound amazing of course.

The cabinet is about 34L in volume, so with the speaker installed i should end up pretty close to the 30L mark. It’s a relatively cheap and easy experiment so i think i’ll just give it a go. If the sound isn’t an improvement at all, i’ll just reverse the process. At least i can then say that I tried.

I experimented with replacing a 200watt 8 ohm speaker with a 400 watt 4 ohm speaker, into an Ashdown EB 150 combo . I also replaced the 150 watt amp, in the combo, with a 500 watt one. I was told that I was mad and that it wouldn't work but I did it anyway.

 

It sounded great and I played it in various bands, with great success, for a couple of years.

 

So go for it.......what's the worst that could happen?

Edited June 21, 2022 by gjones

[stewblack]

On 21/06/2022 at 20:07, gjones said:

go for it.......what's the worst that could happen?

This . A hundred times this. Don't listen to the naysayers. You've had an idea, you want to follow it through, it sounds fun, so crack on.

I took the speakers out of a crazy heavy cab once and bunged one into a smaller cab of a different make and it sounds, to my ears, way better than it used to. 

You take way more pleasure out if something you've created.

 

[Phil Starr]

On 21/06/2022 at 06:50, Jannibal42 said:

Yeah buying something that big from the UK and importing it to the continent is no longer viable since Brexit took full effect  

 

I’ve already taken the HB40 apart to see what the construction is like, and i could quite easily swap out the speaker and test its performance in a reversible way. I also read up on the theory behind cabinet building, checked the specs of the speaker and on paper it should at least ‘work’. Though that doesn’t guarantee that it’ll sound amazing of course.

The cabinet is about 34L in volume, so with the speaker installed i should end up pretty close to the 30L mark. It’s a relatively cheap and easy experiment so i think i’ll just give it a go. If the sound isn’t an improvement at all, i’ll just reverse the process. At least i can then say that I tried.

This is brilliant, you have a plan and the best reason for doing it. I'll have a look at the Legend later but you might want to look at using the Celestion Pulse 10 also available from Thomann and considerably cheaper https://www.thomann.de/nl/celestion_pulse_10.htm. The Eminence speaker has a distinctive midrange suckout which you might like but the Celestion has a slightly brighter tone. More importantly we've tried the Celestion in a 30l net volume cab and it has been gigged. We also have a design for a simple horn and crossover so you could potentially add that later. 

[Phil Starr]

Brief bit of modelling and I didn't enter the BP102-4 manually trusting the WINISD figures. The eminence is Green and the Celestion in Red. Both with a 33V (roughly 200W) signal as the Celestion is 8ohms. The Celestion is more sensitive (louder) despite being 8ohms with the Eminence giving more output below 50Hz. The eminence has a smoother response but only a little that I wouldn't worry about.