Wayne Firefly Posted March 3, 2017 Share Posted March 3, 2017 (edited) I need a 1x15 combo for rockabilly upright bass. I have access to a 90's Ampeg B-15T, the transistor version. Its 100 watts and fine for rehearsing, but not loud enough for live use and the speaker gets farty. I'm considering buying a minimum 300 watts Trace / Ashdown or similar (I'd LOVE a Fender TV Bassman 1x15 !!) 1x15 combo or is spending the budget on a better, lighter more efficient 15'' driver and possibly maybe uprate the power stage to 300 / 400 or so watts. I like the amp, the pre-amp sounds great with the upright thumping through it, D.I. is fine, looks cool etc etc but I just wondered if a bigger transformer could be fitted and a speaker to match ? Any ideas, thoughts or opinions or am I peeing upriver even thinking about it ? Edited March 3, 2017 by Wayne Firefly Quote Link to comment Share on other sites More sharing options...
Bigwan Posted March 3, 2017 Share Posted March 3, 2017 Afraid you're peeing upriver with this one. I wouldn't attempt this on ANY amp (and I'm an electronic engineer!). Just too much to take into consideration. With the speaker farting out it may be what's holding you back and a more efficient cab would certainly help. I'd start there. You obviously like the Ampeg sound, so if you decide to go for something louder then maybe one of their newer offerings, like the PF500. Saw one sell used locally for £170 quid last week. Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted March 3, 2017 Share Posted March 3, 2017 A common problem with amplified uprights is that the sub-bass as you pluck the string is lower than the speaker can cope with, so it farts. Once you have got rid of that problem, you may find that your existing gear can be turned up to be loud enough. If you search on 'Thumpinator' or 'FDeck' or 'high pass filter' you will find several options to filter out that low frequency content without strangling your sound (FDeck is the designer of one of them). Alternatively, I am based in Warrington, and would be happy to meet up so you can try my high pass filters (based on the FDeck design). David Quote Link to comment Share on other sites More sharing options...
Wayne Firefly Posted March 3, 2017 Author Share Posted March 3, 2017 [quote name='Bigwan' timestamp='1488540868' post='3249781'] Afraid you're peeing upriver with this one. I wouldn't attempt this on ANY amp (and I'm an electronic engineer!). Just too much to take into consideration. With the speaker farting out it may be what's holding you back and a more efficient cab would certainly help. I'd start there. You obviously like the Ampeg sound, so if you decide to go for something louder then maybe one of their newer offerings, like the PF500. Saw one sell used locally for £170 quid last week. [/quote] Ok, lots to take on board there, great answer !! Can I just ask why ? Quote Link to comment Share on other sites More sharing options...
Bigwan Posted March 3, 2017 Share Posted March 3, 2017 You'd basically have to redesign the amp from scratch, it's not just a case of adding a bigger transformer (although that would probably come into it!). Could you add an extension cab the same as what you already have? Sourcing one might be an issue, but you'd be guaranteed to like how it sounded. It'd just be more of what you currently have if the amp supports it... Quote Link to comment Share on other sites More sharing options...
Wayne Firefly Posted March 3, 2017 Author Share Posted March 3, 2017 So the existing pre amp / tone controls would not work then ? Looks like a combo search then !! Quote Link to comment Share on other sites More sharing options...
Bigwan Posted March 3, 2017 Share Posted March 3, 2017 They would if supplied the same voltage they currently have, but I'd doubt you'd get a tech to take on the job. Adding an external power amp would be a cheaper and tidier option. Anything else would be a hack job. A quick google shows these were available with 2 different speakers, either a 100 watt ampeg or an EV EVM 15L. The EV version is 8 ohms so the amp could support a second of those (and if that's the case you're probably only using about half of the available power of the amp). Not sure what impedance the Ampeg version was though... Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted March 3, 2017 Share Posted March 3, 2017 [quote name='Wayne Firefly' timestamp='1488551348' post='3249947'] So the existing pre amp / tone controls would not work then ? Looks like a combo search then !! [/quote] A cheaper interim solution might be to turn down the bass a lot, turn up the volume to find out how loud it gets, then start bringing the bass back in. If you can get enough volume, but with not quite enough bass, then a high pass filter may be all you need. David Quote Link to comment Share on other sites More sharing options...
Wayne Firefly Posted March 3, 2017 Author Share Posted March 3, 2017 Thats good info, cheers mate !! Thats pretty much what I needed to know really. Its the Ampeg speaker not the EV. I also wondered about removing the amp head unit itself and attaching another small, more modern and powerful amp to the 'lid' and just putting a Celestion neo 15'' like a BN15 400X at 8 ohms in the cab. Save a lot of hassle. Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted March 3, 2017 Share Posted March 3, 2017 Third time lucky? So for you have discussed the amplifier and the speaker. Just supposing that it is your instrument that is generating the problem - you could spend quite a lot of money on an amplifier whose power you can not use, and a speaker that farts even more because you have put it a box that was not designed for it. May I suggest that before you spend any money, you do some more testing with other signal sources - conventional bass guitar, MP3s that have a bass solo on them - anything other that a DB with a Piezo pickup - and find out if they fart too, or can be played at the higher volumes that you want. David Quote Link to comment Share on other sites More sharing options...
Bigwan Posted March 3, 2017 Share Posted March 3, 2017 [quote name='Mottlefeeder' timestamp='1488552036' post='3249967'] A cheaper interim solution might be to turn down the bass a lot, turn up the volume to find out how loud it gets, then start bringing the bass back in. If you can get enough volume, but with not quite enough bass, then a high pass filter may be all you need. David [/quote] Excellent suggestion! Quote Link to comment Share on other sites More sharing options...
Wayne Firefly Posted March 3, 2017 Author Share Posted March 3, 2017 (edited) [quote name='Mottlefeeder' timestamp='1488555805' post='3250019'] Third time lucky? So for you have discussed the amplifier and the speaker. Just supposing that it is your instrument that is generating the problem - you could spend quite a lot of money on an amplifier whose power you can not use, and a speaker that farts even more because you have put it a box that was not designed for it. May I suggest that before you spend any money, you do some more testing with other signal sources - conventional bass guitar, MP3s that have a bass solo on them - anything other that a DB with a Piezo pickup - and find out if they fart too, or can be played at the higher volumes that you want. David [/quote] This may make you laugh but it sounds great, really full and punchy, no problems here. I have steel cored Eurosonic Ultralights on it and I made some aluminium mounts to fit Mustang bass pickups to the end of the fingerboard. A Lee Rocker inspired set up but an actual pickup per string if you like, rather than a P. bass pickup across all 4 strings. Theres 3 piezo contacts under the fingerboard for the slap bit, all wired to a Jazz bass style circuit. I dont have a standard style bridge piezo on it. Im doing another bass build with a similar style of pickup mounting but with custom wound Sentell pickups and a John East Stingray replica preamp so that should be fun !! So, the source isnt a problem.[attachment=239520:my old bass pickup mounts (1).JPG] Edited March 3, 2017 by Wayne Firefly Quote Link to comment Share on other sites More sharing options...
Mottlefeeder Posted March 3, 2017 Share Posted March 3, 2017 (edited) If you are playing rockabily on an acoustic instrument, you are probably not playing at pub-rock sound levels. Your gear is not in the budget bracket, so it ought to be working better than it is. When you say that the source is not the problem, you may be equating a 34 inch scale low-action instrument with a 41 inch scale high-action instrument based on them both having magnetic pickups. But the subsonics generated by the longer string, being plucked harder, will be substantially higher and this is where I think your problem lies. If you have access to a mixer with a high pass filter on it, try playing through that and into your existing setup. Those filters are typically set at about 75-80 Hz, and will give you the punchy sound you want while taking out the fundamental that is (probably) distressing your speaker. An MP3 will have bass that has probably been compressed or limited, so this can also be used to identify the problem. Yes is is possible that your amp just doesn't go loud enough, but in my experience, not amplifying stuff you don't want leaves much more power to amplify the stuff you do want. To put that in context, I'm using 150 Watts through a pair of 10 inch speakers and I'm playing a 5-string (low B) on outdoor gigs. It works because I have a high-pass filter. David Edited March 3, 2017 by Mottlefeeder Quote Link to comment Share on other sites More sharing options...
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