JapanAxe Posted October 18, 2018 Share Posted October 18, 2018 Does anyone have a schematic for the Ashdown Little Bastard 30? Or at least the output section. I have a project in mind... Quote Link to comment Share on other sites More sharing options...
Bigwan Posted October 18, 2018 Share Posted October 18, 2018 I have. I'll retrieve it from my hard drive at home this evening. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2018 Author Share Posted October 18, 2018 48 minutes ago, Bigwan said: I have. I'll retrieve it from my hard drive at home this evening. Thanks @Bigwan Quote Link to comment Share on other sites More sharing options...
Twincam Posted October 18, 2018 Share Posted October 18, 2018 2 hours ago, JapanAxe said: Does anyone have a schematic for the Ashdown Little Bastard 30? Or at least the output section. I have a project in mind... May I ask what's the project? Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2018 Author Share Posted October 18, 2018 33 minutes ago, Twincam said: May I ask what's the project? You may! I have just acquired (as scrap) a Carvin Vintage 33 combo. The cabinet is more than a little distressed, the speaker is blown, but both transformers work. My plan is to take the existing chassis and transformers (and some other useful working parts e.g. switches, pilot light) and convert it to a 30W bass head with the following features: Output section based around four EL84 valves, because that's what the OT is suited for - hence my interest in the LB30 schematic; Preamp based on a 1964 Amped B15 channel; That's about it! I need to make sure that the pre-amp will work with the power amp (i.e. that phase splitter has enough beans to drive all the EL84s), so I will be working on my understanding of push-pull amps and hitting up the forums . Here's the innards as I got the amp, and the almost-gutted chassis: 1 Quote Link to comment Share on other sites More sharing options...
Merton Posted October 18, 2018 Share Posted October 18, 2018 Sounds like a fun project! I’ll be keeping an eye on this Quote Link to comment Share on other sites More sharing options...
Twincam Posted October 18, 2018 Share Posted October 18, 2018 Excellent! So will there be a thread on this. I would be very interested to see how this turns out. I was reading about phase inverters last weekend. My lass seen what I was reading rolled her eyes and called me sad 😂 haha! Quote Link to comment Share on other sites More sharing options...
Bigwan Posted October 18, 2018 Share Posted October 18, 2018 Here you go LB30_Schematic.pdf 2 Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2018 Author Share Posted October 18, 2018 2 minutes ago, Bigwan said: Here you go LB30_Schematic.pdf Thanks @Bigwan, you are a star! Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2018 Author Share Posted October 18, 2018 Just had a quick look at that schematic. The PI/driver is a 12AU7, and it will probably be simplest if I keep that in and follow the circuit from the wiper of the volume pot - before that will be my 6SL7-based B15-style pre-amp. Solid state rectifier for the HT - works for me, as I have no 5V secondary on my PT, and there is enough power available on the 6V heater secondary for four EL84s and four 12AX7s. Am I right in thinking that is cathode biased like an AC30? 23 minutes ago, Twincam said: Excellent! So will there be a thread on this. I would be very interested to see how this turns out. Yes there will, but first there will be a design-based thread in the Repairs & Technical forum, and in the Tube Amp DIY Builders Facebook group to which I subscribe (where you get people like Rob Robinette and Bruce Egnater chipping in with advice!) 1 Quote Link to comment Share on other sites More sharing options...
Ashdown Engineering Posted October 18, 2018 Share Posted October 18, 2018 Sounds a fun project, if you give us a call and chat to Dave Green(who designed the LB30)he will more than likely give you some advice(he normally does even when not asked...) on how to tie everything up... I’m fairly sure he won’t mind you being ‘inspired’ by his output stage... but sometimes he can be a tad grumpy so you takes your chances 😉 3 4 Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 18, 2018 Author Share Posted October 18, 2018 8 minutes ago, Ashdown Engineering said: Sounds a fun project, if you give us a call and chat to Dave Green(who designed the LB30)he will more than likely give you some advice(he normally does even when not asked...) on how to tie everything up... I’m fairly sure he won’t mind you being ‘inspired’ by his output stage... but sometimes he can be a tad grumpy so you takes your chances 😉 Thanks! Another option was the AC30 output stage - I found the schematic for the 'bass' version on the Dr Tube website. Quote Link to comment Share on other sites More sharing options...
Bigwan Posted October 19, 2018 Share Posted October 19, 2018 14 hours ago, Ashdown Engineering said: Sounds a fun project, if you give us a call and chat to Dave Green(who designed the LB30)he will more than likely give you some advice(he normally does even when not asked...) on how to tie everything up... I’m fairly sure he won’t mind you being ‘inspired’ by his output stage... but sometimes he can be a tad grumpy so you takes your chances 😉 A fine job he did too. Awesome wee amp! Quote Link to comment Share on other sites More sharing options...
Merton Posted October 19, 2018 Share Posted October 19, 2018 1 hour ago, Bigwan said: A fine job he did too. Awesome wee amp! Agreed Quote Link to comment Share on other sites More sharing options...
TheGreek Posted October 19, 2018 Share Posted October 19, 2018 19 hours ago, Ashdown Engineering said: Sounds a fun project, if you give us a call and chat to Dave Green(who designed the LB30)he will more than likely give you some advice(he normally does even when not asked...) on how to tie everything up... I’m fairly sure he won’t mind you being ‘inspired’ by his output stage... but sometimes he can be a tad grumpy so you takes your chances 😉 More great service from a British company we are learning to value and trust. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted October 26, 2018 Author Share Posted October 26, 2018 Sorry to disappoint, but an incoming Ampeg PF-50T has somewhat disincentivised the bass amp project. When I do get round to a build, it is now more likely to be based on a Supro guitar amp like this. Quote Link to comment Share on other sites More sharing options...
Twincam Posted October 27, 2018 Share Posted October 27, 2018 16 hours ago, JapanAxe said: Sorry to disappoint, but an incoming Ampeg PF-50T has somewhat disincentivised the bass amp project. When I do get round to a build, it is now more likely to be based on a Supro guitar amp like this. Enjoy the pf50t I have the pf20t it's fantastic, so I imagine the 50 is even more awesome. 1 Quote Link to comment Share on other sites More sharing options...
Nightmares99 Posted March 10, 2022 Share Posted March 10, 2022 On 19/10/2018 at 01:44, Bigwan said: I have. I'll retrieve it from my hard drive at home this evening. Hi, do you have this on file to share via email to me. My little bastard 30 amp is having a few issues with the output stage. Really keen of you can help Quote Link to comment Share on other sites More sharing options...
Dood Posted March 10, 2022 Share Posted March 10, 2022 3 hours ago, Nightmares99 said: Hi, do you have this on file to share via email to me. My little bastard 30 amp is having a few issues with the output stage. Really keen of you can help The link above still works - but, you should drop a line to @Ashdown Engineering anyway via their website, they'll be able to help for sure. 1 Quote Link to comment Share on other sites More sharing options...
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