Dood Posted February 11, 2015 Author 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] Yeah! Brian May used to have dead straight hair until he started playing AC30's!! Quote Link to comment Share on other sites More sharing options...
scalpy Posted February 11, 2015 Share Posted February 11, 2015 Aguilar db359? Looks 2 or 3u to me, and the one for sale in here is really tempting! Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 11, 2015 Share Posted February 11, 2015 [size=5]I wondered about basing something on the Carvin Legacy 100W guitar head ([color=#000000][font=Arial, Helvetica, sans-serif]17" wide x [/font][/color][color=#000000][font=Arial, Helvetica, sans-serif]9" deep x [/font][/color][color=#000000][font=Arial, Helvetica, sans-serif]8.5" high, [/font][/color][color=#000000][font=Arial, Helvetica, sans-serif]Weight: 29 lb) [/font][/color]but that would be way beyond my DIY skills:[/size] Quote Link to comment Share on other sites More sharing options...
Dood Posted February 11, 2015 Author Share Posted February 11, 2015 That's in the right ball park for sure JapanAxe - and to be honest the preamp only need be a simple Marshall tone stack (cathode follower?) rather than lots of gubbins on board. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 11, 2015 Share Posted February 11, 2015 [quote name='dood' timestamp='1423692555' post='2688094'] That's in the right ball park for sure JapanAxe - and to be honest the preamp only need be a simple Marshall tone stack (cathode follower?) rather than lots of gubbins on board. [/quote] Anyone fancy buying one, gutting it, and putting in a simple bass-oriented preamp? Quote Link to comment Share on other sites More sharing options...
Subthumper Posted February 11, 2015 Share Posted February 11, 2015 I have the transformers for a 120watt head. Making a physically smaller head would be possible although it would still be a reasonable weight. With the transformers I have it would still be a 3U height. Mesa made the 290 a 2u by having custom transformers that fit that height and laying the power valves horizontally, although I have worked on a few of these that have suffered from heat warping the pcbs. However it does interest me as a project/challenge to squeeze it all into as small a box as possible and it was one of the suggestions made to me when i unveiled my 200 watt head. I'll have measure up of things tomorrow and see what can be done. Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 Putting the overall height thing to one side for a moment the one thing that bugs me is the width of many valve amps. Many cabs are now even narrower than a 19-inch rack case so most valve amps overhang both sides. Very ugly. Quote Link to comment Share on other sites More sharing options...
Subthumper Posted February 11, 2015 Share Posted February 11, 2015 Ok, so what sort of width are we talking? The 200 watt head I built used a 19" rack case which with the wooden case is just over 20.5" wide. I'm sure with a bit of deviance it can be squeezed down in size although will rely on forced fan cooling. Using aluminium for the chassis and case will reduce weight. Any other features anyone would want to include? Quote Link to comment Share on other sites More sharing options...
obbm Posted February 11, 2015 Share Posted February 11, 2015 All the popular Bergantino 1x12 and 2x12 cabs are 18.5" wide. Quote Link to comment Share on other sites More sharing options...
Subthumper Posted February 11, 2015 Share Posted February 11, 2015 Ok we'll go with 18". Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 11, 2015 Share Posted February 11, 2015 200w valve watts is enormous..! Wouldn't 100w be easier to reduce in size (a bit...)..? Quote Link to comment Share on other sites More sharing options...
Subthumper Posted February 11, 2015 Share Posted February 11, 2015 Sorry I've misled that a bit. I have the bits for a 120 watt amp. I gave the 200 as an example of using a 19" case. Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted February 11, 2015 Share Posted February 11, 2015 [sharedmedia=core:attachments:167485] Quote Link to comment Share on other sites More sharing options...
Swingong1979 Posted February 12, 2015 Share Posted February 12, 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] I did a studio recording last week using a Countryman 85 DI from the "ex. speaker" out of a fender bassman 100 silverface and it sounded great. The engineer was pleased with the results. Have not tried it live yet but will soon. Quote Link to comment Share on other sites More sharing options...
wateroftyne Posted February 12, 2015 Share Posted February 12, 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's what the Mesa Walkabout and MPulse stuff does (albeit with a solid state final stage, rather than Class D) Quote Link to comment Share on other sites More sharing options...
badboy1984 Posted February 12, 2015 Share Posted February 12, 2015 [quote name='obbm' timestamp='1423680260' post='2687907'] 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] Thats why I like my Ashdown LB30. The DI comes out after the valve power stage. Only problem with that amp is the DI signal could be too hot sometimes. Quote Link to comment Share on other sites More sharing options...
obbm Posted February 12, 2015 Share Posted February 12, 2015 [quote name='badboy1984' timestamp='1423729547' post='2688284'] Only problem with that amp is the DI signal could be too hot sometimes. [/quote] That's easily fixed by a competent sound man (mixers do have gain controls and faders) or judicious use of an in-line attenuator. Far better to have it too hot than too low where it can introduce noise and interference. Quote Link to comment Share on other sites More sharing options...
badboy1984 Posted February 12, 2015 Share Posted February 12, 2015 So so true. I haven't met any sound guy that actually know what his doing so far lol. I bring my LB30 and said I want my valve tone coming through the DI and they are so resist of doing it. End up playing my valve amp onstage as monitor and lineout the DI on my MXR M80 ....... Quote Link to comment Share on other sites More sharing options...
solo4652 Posted February 12, 2015 Share Posted February 12, 2015 (edited) I'm following this thread out of idle curiosity. I have absolutely no idea how valves, transformers and such stuff work. Just maybe, that might enable someone as ignorant as me to suggest something outwardly daft that could possibly work. Top-of-head musings; 1. Are some valves physically smaller than others? 2. Do some valves produce less heat than others? 3. Do you [i]have[/i] to have fan cooling, with the associated fan, motor, thermostat, wires and noise? How about valve dampers - would they eliminate, or at least reduce the size of fans+gubbins? My home radiators have loads of fins behind them to increase surface area for heat release. [url="http://vintageaudiovalves.com/eat-tubes"]http://vintageaudiov...s.com/eat-tubes[/url] and [url="http://www.guildfordaudio.co.uk/store/category.php?category=Valve%20Dampers§ion=Accessories&cattitle=Accessories&page=category"]http://www.guildford...s&page=category[/url] 4. Do the valves [i]have[/i] to be next to each other? If they were separated inside the box, would that help prevent localised heat build-up? Indeed, do the valves have to be inside the box at all? In the best tradition of home decorating, if you can't hide something, make a feature of it. Put the valves on full display with just a minimalist (heat-resistant plastic?) cage/cover for protection? Arab tents use the shape of the funnel-roof to encourage air exhaust and thus cooling. 5. Perhaps the cover could be circular with the airflow sent round a spiral (Dyson vacuum cleaner) to increase the airflow. So; small, cool-running valves placed on their side with heat-dissipation fins/jackets (maybe with a smaller fan system with some sort of venturi-effect airflow accelerator?), placed apart, and placed outside of the main box under some sort of circular minimalist plastic cover that doubles as a clever air-exhaust chimney. I'm sorry. I'll shut up now. Edited February 12, 2015 by solo4652 Quote Link to comment Share on other sites More sharing options...
Happy Jack Posted February 12, 2015 Share Posted February 12, 2015 Dood knew there was something wrong, but he couldn't put his finger on it ... [URL=http://s1128.photobucket.com/user/h4ppyjack/media/Just%20Stuff/Sundry/Valve_zps329a2c58.jpg.html][IMG]http://i1128.photobucket.com/albums/m496/h4ppyjack/Just%20Stuff/Sundry/Valve_zps329a2c58.jpg[/IMG][/URL] Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted February 12, 2015 Share Posted February 12, 2015 It baffles me why nobody has done switch-mode power supplies for the HT and heaters, then a toroidal o/p transformer and you'd be looking at a pretty big size and weight saving. And if you read what Stewart Ward (Session amps) writes about valve sounds and tone, it turns out you don't really need valves at all, just better informed transistor design... Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted February 12, 2015 Share Posted February 12, 2015 [quote name='MoonBassAlpha' timestamp='1423748435' post='2688562'] It baffles me why nobody has done switch-mode power supplies for the HT and heaters, then a toroidal o/p transformer and you'd be looking at a pretty big size and weight saving. And if you read what Stewart Ward (Session amps) writes about valve sounds and tone, it turns out you don't really need valves at all, just better informed transistor design... [/quote] isnt that what markbass or mesa or soneone did? Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 12, 2015 Share Posted February 12, 2015 [quote name='MoonBassAlpha' ='1423748435' post='2688562'] It baffles me why nobody has done switch-mode power supplies for the HT and heaters, then a toroidal o/p transformer and you'd be looking at a pretty big size and weight saving. And if you read what Stewart Ward (Session amps) writes about valve sounds and tone, it turns out you don't really need valves at all, just better informed transistor design... [/quote] It's been done in Hi-Fi DIY circles, though I don't know if that has filtered through to instrument amps. There are SMPS modules like this one, though it wouldn't be sufficient for a 100 watt amp. [url="http://www.siliconray.com/rtp-15-switching-mode-power-supply-smps-for-tube-amplifier.html"]http://www.siliconray.com/rtp-15-switching-mode-power-supply-smps-for-tube-amplifier.html[/url] Quote Link to comment Share on other sites More sharing options...
Musky Posted February 12, 2015 Share Posted February 12, 2015 [quote name='LukeFRC' timestamp='1423749861' post='2688584'] isnt that what markbass or mesa or soneone did? [/quote] I think Peavey did with the VB3. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted February 13, 2015 Share Posted February 13, 2015 [quote name='Musky' timestamp='1423771806' post='2688942'] I think Peavey did with the VB3. [/quote] If they did, consider me un-baffled! Quote Link to comment Share on other sites More sharing options...
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