Dood Posted February 11, 2015 Share Posted February 11, 2015 Ok, so this is a crazy question to begin with, so let me flesh it out a bit. I have in my possession a vintage Marshall Super Bass 100W valve amplifier. It has been recently serviced and had a few part upgrades to improve it's response and tone. I have to say, it sounds amazing! It is however a big beast of an amplifier as you all will know. So it got me to thinking. I *know* that the output and power transformers are big and bulky. I know that the valves need room for a bit of fresh air. But has anyone actually tackled making a 100W all valve bass amplifier smaller and lighter? Rack mountable in a 2u box at least! I'm not talking about hybrids here. Everyone is doing that these days! Quote Link to comment Share on other sites More sharing options...
badboy1984 Posted February 11, 2015 Share Posted February 11, 2015 I don't really know will such things exist. I own a Ashdown LB30, is a 30watt all valve head. I won't say is very light and is not too small either. Of course comparing to bigger valve amp the LB30 is tiny and light weight. I can see the size could be smaller but I don't think the weight would be light. Never say never on technology, it may have something in the future that will full fill our requirement. Quote Link to comment Share on other sites More sharing options...
discreet Posted February 11, 2015 Share Posted February 11, 2015 Doesn't the Prodigy go somewhat in that direction? [url="http://www.mesaboogie.com/amplifiers/bass/prodigy--strategy-tube-bass-amp-series/bass-prodigy-four-88/index.html"]http://www.mesaboogie.com/amplifiers/bass/prodigy--strategy-tube-bass-amp-series/bass-prodigy-four-88/index.html[/url] 29lb isn't exactly lightweight, but it's a hell of a lot better than 29kg! Quote Link to comment Share on other sites More sharing options...
sifi2112 Posted February 11, 2015 Share Posted February 11, 2015 EBS T90 ? ... but not 2U Quote Link to comment Share on other sites More sharing options...
No lust in Jazz Posted February 11, 2015 Share Posted February 11, 2015 I think you'd have to manage your expectations of small, as you say, transformers and valves have their own physical needs. Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 The physical size of the transformers, and yes you need transformers, and the height of the power bottles pretty much dictate things. 2U is a tall order. Marshall did manage to shoehorn 2 x 100-watt power amps into a 3u x 19-inch. It's the 9200 and its heavy. If one wanted a project then you could strip out one power amp and build a pre-amp the in there. That would get you a 3U x 100-watt amp Dood. I think I'll just stick with my Mesa Boogie Prodigy. Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted February 11, 2015 Share Posted February 11, 2015 [quote name='obbm' timestamp='1423664424' post='2687622'] I think I'll just stick with my Mesa Boogie Prodigy. [/quote] Which has to be the smallest valve amp I`ve ever seen Dave, plus it sounds great, was knocked out by its sound at the SE Bass Bash. Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 11, 2015 Share Posted February 11, 2015 DV Mark (the guitar amp division of Markbass) do a guitar amp which is impressively small for a valve 100 watter. It has a 2x KT88 power stage and some sort of digital preamp. I don't know how they've made it that small, whether they're using a switchmode supply in place of a conventional power transformer or just using toroidal transformers. No bass version though! [url="http://www.dvmark.it/?/products/79/tube_multiamp"]http://www.dvmark.it/?/products/79/tube_multiamp[/url] Quote Link to comment Share on other sites More sharing options...
No lust in Jazz Posted February 11, 2015 Share Posted February 11, 2015 [quote name='Lozz196' timestamp='1423664709' post='2687634'] Which has to be the smallest valve amp I`ve ever seen Dave, plus it sounds great, was knocked out by its sound at the SE Bass Bash. [/quote] Perhaps I should try another one sometime - the one I owned was a big disappointment. Quote Link to comment Share on other sites More sharing options...
Dood Posted February 11, 2015 Author Share Posted February 11, 2015 I have to admit, I purposely left out some of my own thoughts - but I did wonder what results could be achieved by losing at least one transformer (mains) to power the valve amplifier using an SMPS instead. The other transformer would obviously still be a sticking point given it's role in valve amplification. Quote Link to comment Share on other sites More sharing options...
SubsonicSimpleton Posted February 11, 2015 Share Posted February 11, 2015 I used to use a peavey 50/50 classic when I was playing skinny string - 2u but not particularly lightweight pic of the interior here http://en.audiofanzine.com/guitar-power-amplifier/peavey/classic-series-classic-50-50/medias/pictures/a.play,m.468770.html You could probably convert the innards of any traditional head to rackmount format, but assuming you want the end result to be roadworthy I don't think you would save much(if any) meaningful amount of weight in the process of remounting everything into a 19" rackmount chassis, and the smallest dimension of the transformers is always going to dictate the height. I've always felt that the rectifier and power transformer are important to how valve amps deal with the large transients at the start of a note(and plenty of argumentation about solid state vs valve rectification in guitar amp circles), so using a switched mode power supply might negate a certain amount of what makes playing through a valve amp enjoyable in the first place. Quote Link to comment Share on other sites More sharing options...
JPJ Posted February 11, 2015 Share Posted February 11, 2015 Just a daft question, but as we are told that the 'valve sound' comes from the interaction between the valve preamp and the valve power amp, is it not possible to have say a valve pre driving a low wattage valve power amp driving a class D type amp module with a lightweight switch mode power supply? Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 11, 2015 Share Posted February 11, 2015 [quote name='JPJ' timestamp='1423672793' post='2687795'] Just a daft question, but as we are told that the 'valve sound' comes from the interaction between the valve preamp and the valve power amp, is it not possible to have say a valve pre driving a low wattage valve power amp driving a class D type amp module with a lightweight switch mode power supply? [/quote] That, in essence, is what the FOH PA does. All that's needed is the low-power valve power amp. There are 5w amps out there; no good with a DI out to FOH..? Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 [quote name='Dad3353' timestamp='1423679338' post='2687894'] That, in essence, is what the FOH PA does. All that's needed is the low-power valve power amp. There are 5w amps out there; no good with a DI out to FOH..? [/quote] The only way that would work is if you mic up the cab. The DI from most valve amps comes out before the power stage, and it's the valve power stage that gives the valve amp its uniqueness. Quote Link to comment Share on other sites More sharing options...
pete.young Posted February 11, 2015 Share Posted February 11, 2015 I think you can now get DI boxes which work off a speaker output, though I've never used one. Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 [quote name='pete.young' timestamp='1423681170' post='2687919'] I think you can now get DI boxes which work off a speaker output, though I've never used one. [/quote] Yes after I'd written that I remembered that plus that a few amps take their DI out from an extra winding on the output transformer. Personally a 5-watt amp wouldn't work for me as it wouldn't be loud enough. I prefer to feel the air move. Quote Link to comment Share on other sites More sharing options...
solo4652 Posted February 11, 2015 Share Posted February 11, 2015 (edited) "...and the height of the power bottles pretty much dictate things" Do they[i] have [/i]to stand upright? Edited February 11, 2015 by solo4652 Quote Link to comment Share on other sites More sharing options...
Dood Posted February 11, 2015 Author Share Posted February 11, 2015 [quote name='solo4652' timestamp='1423681830' post='2687935'] "...and the height of the power bottles pretty much dictate things" Do they[i] have [/i]to stand upright? [/quote] No. I was also wondering about the use of different shaped transformers too, such as toroidal types. Quote Link to comment Share on other sites More sharing options...
discreet Posted February 11, 2015 Share Posted February 11, 2015 [quote name='solo4652' timestamp='1423681830' post='2687935'] Do they[i] have [/i]to stand upright? [/quote] No. In the G-K MB500 Fusion they're on their sides. As they are in the Ampeg SVP 1U preamp. Quote Link to comment Share on other sites More sharing options...
Dood Posted February 11, 2015 Author Share Posted February 11, 2015 I owned a Warwick preamp once that was made up of a valve preamp followed by a small valve power amplifier whose output went to DI as well as the connections to feed a normal power amp. The idea being that you'd get the tone and feel of a real valve amplifier in a rack but choose your solid state power section to drive your speakers. Great idea but in reality it wasn't as articulate as I'd hoped. Quote Link to comment Share on other sites More sharing options...
No lust in Jazz Posted February 11, 2015 Share Posted February 11, 2015 To be honest, there are enough technically minded members here to put this together - assumptions can be cretinous though. Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 [quote name='discreet' timestamp='1423682511' post='2687952'] No. In the G-K MB500 Fusion they're on their sides. As they are in the Ampeg SVP 1U preamp. [/quote] Pre-amp valves are fine on their sides but the power valves seem to need to be vertically oriented otherwise the electrons get confused. IIRC the AC30 had them upside down Quote Link to comment Share on other sites More sharing options...
discreet Posted February 11, 2015 Share Posted February 11, 2015 [quote name='obbm' timestamp='1423683156' post='2687965'] Pre-amp valves are fine on their sides but the power valves seem to need to be vertically oriented otherwise the electrons get confused. IIRC the AC30 had them upside down [/quote] What about a small valve combo where the power valves hang down into the speaker enclosure? Oh, wait... Quote Link to comment Share on other sites More sharing options...
Bottle Posted February 11, 2015 Share Posted February 11, 2015 IIRC didn't Dave Hall of DHA fame make a hybrid 2U amp - valve pre stage with an output tap and parallel feed into a 500W Class D power stage? Or am I off the mark? I'm going back a few years here Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 11, 2015 Share Posted February 11, 2015 Our Mesa Simul-Class 2:90 has all the power glass horizontal. As long as the cooling has been thought through, there should be no problem. Yes, there are DI boxes that can connect like a speaker; some can even replace the speaker. I agree with feeling the air move, but then, I wasn't asking for a low-power valve amp..! We use a back-breaking 200w Hiwatt. No 'workarounds' for us, we just suffer the weight..! The sound is worth it, though. Quote Link to comment Share on other sites More sharing options...
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