henry norton Posted June 25, 2009 Share Posted June 25, 2009 Here's a pic of my Marshall 4150 4x10 combo. It's a good amp and very loud but it isn't hugely bassy. I presume that's something to do with the cabinet design (an open box). I don't like boosting the bass up too much as it's 30 years old and quite rare, so I thought I might buy (or build) a 15 to give it that extra depth and volume. Thing is, will a modern, ported, neowhatever bass cabinet just dominate and drown out the 4 10s I already have? Quote Link to comment Share on other sites More sharing options...
joegarcia Posted June 25, 2009 Share Posted June 25, 2009 Isn't that a guitar combo? Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 25, 2009 Share Posted June 25, 2009 [quote name='joegarcia' post='523945' date='Jun 25 2009, 05:59 PM']Isn't that a guitar combo?[/quote] You're a guitar combo. I think running an extension cab instead of its own speakers is best plan. Means you can rag it and not worry about the extension cabs drowning out the breaking speaker sounds. Quote Link to comment Share on other sites More sharing options...
umph Posted June 25, 2009 Share Posted June 25, 2009 [quote name='Mr. Foxen' post='524000' date='Jun 25 2009, 06:47 PM']You're a guitar combo. I think running an extension cab instead of its own speakers is best plan. Means you can rag it and not worry about the extension cabs drowning out the breaking speaker sounds.[/quote] +1 Quote Link to comment Share on other sites More sharing options...
henry norton Posted June 25, 2009 Author Share Posted June 25, 2009 (edited) No it's a proper bass amp. It's like Marshall's version of the Fender Bassman but bigger and louder. It was from a range called 'club & country', pretty short lived and quite expensive in the late seventies / early eighties but actually rather good - except for the lack of real rumble. It's probably the perfect amp for 'tic tac' bass lines on a Bass VI. Edited June 25, 2009 by henry norton Quote Link to comment Share on other sites More sharing options...
escholl Posted June 25, 2009 Share Posted June 25, 2009 honestly not trying to sound like a complete a**, but: it seems this amp really best suits a certain style of music, and that perhaps that isn't the same style that you play? So the most efficient solution may be to get something else, in this case. Failing that, I would agree with Mr Foxen and say that the best bet is to bypass the internal drivers and just use external cabs -- however i'd imagine that would leave an awful lot to carry round. Quote Link to comment Share on other sites More sharing options...
henry norton Posted June 25, 2009 Author Share Posted June 25, 2009 [quote name='escholl' post='524072' date='Jun 25 2009, 08:58 PM']honestly not trying to sound like a complete a**, but: it seems this amp really best suits a certain style of music, and that perhaps that isn't the same style that you play? So the most efficient solution may be to get something else, in this case. Failing that, I would agree with Mr Foxen and say that the best bet is to bypass the internal drivers and just use external cabs -- however i'd imagine that would leave an awful lot to carry round.[/quote] That's OK, I don't know what an 'a**' is.... It's a good sounding amp and suits me fine for most situations. It doesn't even weigh that much considering it's a 4x10 valve amp! I did consider trading it in for a Markbass a while ago, but thought I'd ask this question first. Quote Link to comment Share on other sites More sharing options...
escholl Posted June 25, 2009 Share Posted June 25, 2009 [quote name='henry norton' post='524093' date='Jun 25 2009, 08:27 PM']That's OK, I don't know what an 'a**' is.... It's a good sounding amp and suits me fine for most situations. It doesn't even weigh that much considering it's a 4x10 valve amp! I did consider trading it in for a Markbass a while ago, but thought I'd ask this question first.[/quote] haha it's a rude word for one's bum. if you really love the amp, then give Alex Claber a PM (alexclaber) and see what his thoughts are on it -- it's likely that one of his cabs, such as the Big Sub or whatever it's called, might do the trick for you in terms of adding to the bass response. Quote Link to comment Share on other sites More sharing options...
JTUK Posted June 26, 2009 Share Posted June 26, 2009 [quote name='henry norton' post='523923' date='Jun 25 2009, 05:35 PM']Here's a pic of my Marshall 4150 4x10 combo. It's a good amp and very loud but it isn't hugely bassy. I presume that's something to do with the cabinet design (an open box). I don't like boosting the bass up too much as it's 30 years old and quite rare, so I thought I might buy (or build) a 15 to give it that extra depth and volume. Thing is, will a modern, ported, neowhatever bass cabinet just dominate and drown out the 4 10s I already have?[/quote] I expect an extn to take over the 4 x 10 as you will not be able to balance the sound..... and being a valve output stage you will have to be careful with your impedance load, IMV.. You will be adding bottom so if that does the job then ok..but personally I'd check out how desirable these are and maybe knock this on.. and get something newer that will probably be better in all things, all round.. Quote Link to comment Share on other sites More sharing options...
Adrenochrome Posted June 26, 2009 Share Posted June 26, 2009 I'm no expert but... I gigged a Marshall Superbass head and even through a sealed Marshall 4x12 bass cab it was shy in the bottom end at gigging volume with a loud band. Very entertaining in most other respects though. Would it be an option to upgrade the 4x10 drivers to something more efficient? It'd keep your rig to a manageable size at least. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted June 26, 2009 Share Posted June 26, 2009 I wonder if you could make a panel to seal the back with some tuned ports in it? The problem with open-backed cabs is the sound cancels out below a certain frequency so in addition to the speaker's 12dB/octave roll-off below resonance (probably about 60Hz) you get another 6dB/octave on top of that, in this case probably starting at about 200Hz. Seal the back and add some ports and you'll get a ton more bottom end. However, how is the amp cooled? Alex Quote Link to comment Share on other sites More sharing options...
henry norton Posted June 26, 2009 Author Share Posted June 26, 2009 [quote name='Adrenochrome' post='524666' date='Jun 26 2009, 11:20 AM']I'm no expert but... I gigged a Marshall Superbass head and even through a sealed Marshall 4x12 bass cab it was shy in the bottom end at gigging volume with a loud band. Very entertaining in most other respects though. Would it be an option to upgrade the 4x10 drivers to something more efficient? It'd keep your rig to a manageable size at least.[/quote] It's very similar to the Superbass, and I've heard quite a few owners of the guitar version change the drivers - I'm not so sure it'll give me much extra low end because of the open back to the cabinet, although at least I won't be shy of turning the bass up a bit. [quote name='alexclaber' post='524765' date='Jun 26 2009, 01:14 PM']I wonder if you could make a panel to seal the back with some tuned ports in it? The problem with open-backed cabs is the sound cancels out below a certain frequency so in addition to the speaker's 12dB/octave roll-off below resonance (probably about 60Hz) you get another 6dB/octave on top of that, in this case probably starting at about 200Hz. Seal the back and add some ports and you'll get a ton more bottom end. However, how is the amp cooled? Alex[/quote] Yeah, that's an interesting idea as there is a ridge around the back of the cabinet which could be used to attach an entire panel, or even a box like extension. Unfortunately, the valves rely on the open air for cooling. Perhaps the movement of the air and the porting could provide a kind of cooling air pump effect? Quote Link to comment Share on other sites More sharing options...
alexclaber Posted June 26, 2009 Share Posted June 26, 2009 Could you measure the internal volume of the cab (best way is to measure the outside and subtract the wall thicknesses) and also the width and height of that slot along the top rear edge? Am thinking it might be possible to close the main back panel and then let that ventilation slot along the top act as a tuned port. Just need to work out what frequency it'll roughly be tuned to. Alex Quote Link to comment Share on other sites More sharing options...
jonny-lad Posted June 26, 2009 Share Posted June 26, 2009 Maybe it would be worth building a separate cabinet for just the amp, so you could use it as just a head into any cabinet you fancy...keep the combo cabinet as it is so you can just put the amp back in if or when you decide to sell it on. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted June 26, 2009 Share Posted June 26, 2009 Yep, if you take those two back panels off, replace them with a single large panel that covers that whole area, and mount a piece of wood on the front of that panel so once screwed into place it pushes on the baffle and stops the front and back panels from resonating too much, then you should get loads more bottom. If it sounds too boomy, make the panel taller so it overlaps more of the exposed back of the amp (this should extend the port length and thus lower the tuning). If that's still too boomy then extend the panel to full height on the right hand side (making the port area smaller will also lower the tuning frequency). Alex Quote Link to comment Share on other sites More sharing options...
henry norton Posted June 26, 2009 Author Share Posted June 26, 2009 (edited) [quote name='alexclaber' post='524923' date='Jun 26 2009, 04:17 PM']Could you measure the internal volume of the cab (best way is to measure the outside and subtract the wall thicknesses) and also the width and height of that slot along the top rear edge? Am thinking it might be possible to close the main back panel and then let that ventilation slot along the top act as a tuned port. Just need to work out what frequency it'll roughly be tuned to. Alex[/quote] Thanks Alex - the internal dims are 25" x 22" x 7.5", so 2.4 cubic feet or .068 cubic meters - smaller than it looks in the photos. I've got plenty of ply and OSB kicking around so I could try making a ported back panel. Oh, the slot's 15mm high by 635mm wide. Edited June 26, 2009 by henry norton Quote Link to comment Share on other sites More sharing options...
alexclaber Posted June 26, 2009 Share Posted June 26, 2009 Cool. Well based on that I would simply replace those two panels with single large panel that leaves exactly the same slot at the top. That should effectively make it a ported cab (with the long thin horizontal gap acting as a slot port) tuned to about 65Hz, which although high for a bass cab is going to give you damn sight more bass than the current open-backed cab. Cover the back panel with a thick layer of foam, polyester batting or fibreglass to prevent nasty midrange reflections messing up the response. Squeeze that front to back brace in to make it more rigid. And if it sounds too boomy try blocking up some of the port, the more you block, the lower the tuning will go. Look forward to hearing how it works! Alex Quote Link to comment Share on other sites More sharing options...
henry norton Posted June 26, 2009 Author Share Posted June 26, 2009 Thanx Alex - I'll give it a go and let ya know. What with yourself and Bernie Goodfellow it looks like the City Of Brighton & Hove is becoming the bass capital of the UK. Quote Link to comment Share on other sites More sharing options...
JTUK Posted June 26, 2009 Share Posted June 26, 2009 I wouldn't do any of the cab mods if the combo is in anyway collectable.... If you must mess around ..then build two boxes, one for the amp and one for the 4x10 ported... so you can puit it back to original. For example..I have an old Selmer combo which is scrap and people are falling over themselves to buy the peice of junk...??????????// Chances are tho that the speakers in a 30 y old combo are poor anyway... by todays standads Unless the amp is dynamite.....get a cab with decent speakers in a config that is useable... It sounds like too much messing around to make an inadequate situation ok.IMV.. Quote Link to comment Share on other sites More sharing options...
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