Undertone Posted March 19 Share Posted March 19 I wonder if anyone could assist please. This power adapter seems to say AC / AC Adapter. It has the usual pedal pin (centre negative) attachment. Does this make sense? Is it AC / AC (ie. just voltage change) or AC / DC? I googled the brand & model number and it seems to say AC / DC, but why does it say AC / AC on the unit? Typo? Thanks Quote Link to comment Share on other sites More sharing options...
neepheid Posted March 19 Share Posted March 19 (edited) If it says AC/AC, I'd go with that. There is no centre negative, it's AC, that's why there's an absence of the symbol. Please don't plug this into anything that expects DC. Edited March 19 by neepheid 1 Quote Link to comment Share on other sites More sharing options...
tauzero Posted March 19 Share Posted March 19 As it says "Output 12V ~", that's AC. It would be something like "Output 12V ......" if it was DC, and as @neepheid says, would show the polarity of the connector. 1 Quote Link to comment Share on other sites More sharing options...
Undertone Posted March 19 Author Share Posted March 19 Great, thankyou. So next question is then something like: Does tube gear more generally need AC power ? That is, this power unit normally powers a Reussenzehn BassMax tube pre-amp (12-15V), which is kind of a pedal (has stomp switches etc.). But pedals usually take DC. So is it the tube nature of this product that causes it to require AC, or something else do you think? I've contacted the guy in Germany who makes these but he's not responding and forum searches seem to suggest he's known for being cantankerous. The label on the pre-amp has worn so as to be illegible. This power supply came with it but it's and EU plug (I know I can use an adapter) but I was hoping to replace with with a UK plug version. Finally, it needs 12-15V; am I likely to get better performance from 15V vs 12V? (I'm assuming there's no internal voltage doubling / step-up going on). Thanks again Quote Link to comment Share on other sites More sharing options...
BigRedX Posted March 19 Share Posted March 19 If this is the correct PSU for the Reussenzehn BassMax then it most likely means that the bridge rectifier that converts the AC from the PSU to DC is in the pedal rather than the PSU. There are plenty of devices that do this and have AC PSUs. 2 Quote Link to comment Share on other sites More sharing options...
Suburban Man Posted March 19 Share Posted March 19 I would just cut off the EU plug and replace it with a Uk 13A version - 3A fuse inside. Only needs a screwdriver and a pair of cutters. Quote Link to comment Share on other sites More sharing options...
neepheid Posted March 19 Share Posted March 19 (edited) 4 minutes ago, Suburban Man said: I would just cut off the EU plug and replace it with a Uk 13A version - 3A fuse inside. Only needs a screwdriver and a pair of cutters. If it's the adaptor in the picture above then what are you cutting off? It looks like a single moulded unit to me - PSU and plug in one. Edited March 19 by neepheid Quote Link to comment Share on other sites More sharing options...
Suburban Man Posted March 19 Share Posted March 19 5 minutes ago, neepheid said: If it's the adaptor in the picture above then what are you cutting off? It looks like a single moulded unit to me - PSU and plug in one. Ah, me making a naff assumption again... I didn't realise it was a wall wart and thought that it had a separate plug. Doh! Quote Link to comment Share on other sites More sharing options...
nekomatic Posted March 19 Share Posted March 19 3 hours ago, BigRedX said: If this is the correct PSU for the Reussenzehn BassMax then it most likely means that the bridge rectifier that converts the AC from the PSU to DC is in the pedal rather than the PSU. There are plenty of devices that do this and have AC PSUs. The most obvious (to me) reason for doing this is so you can have positive, ground and negative power rails for your circuit without needing an odd custom 3-pin connector. Without knowing the exact details of the pedal, and taking on trust what it says on the label you’ve posted, any 12 volt AC/AC adapter rated 400 mA or more should do the job. If the power rails are regulated inside the pedal then choosing a 15 volt adapter will make no difference. Quote Link to comment Share on other sites More sharing options...
Undertone Posted March 19 Author Share Posted March 19 Thanks everyone. Super useful. Case closed. Quote Link to comment Share on other sites More sharing options...
obbm Posted March 19 Share Posted March 19 4 hours ago, Undertone said: Great, thankyou. So next question is then something like: Does tube gear more generally need AC power ? That is, this power unit normally powers a Reussenzehn BassMax tube pre-amp (12-15V), which is kind of a pedal (has stomp switches etc.). But pedals usually take DC. So is it the tube nature of this product that causes it to require AC, or something else do you think? I've contacted the guy in Germany who makes these but he's not responding and forum searches seem to suggest he's known for being cantankerous. The label on the pre-amp has worn so as to be illegible. This power supply came with it but it's and EU plug (I know I can use an adapter) but I was hoping to replace with with a UK plug version. Finally, it needs 12-15V; am I likely to get better performance from 15V vs 12V? (I'm assuming there's no internal voltage doubling / step-up going on). Thanks again Certain Electro-Harmonix pedals that use valves, English Muff'n and Black Finger Compressor, use 12-volt AC Adaptors. Inside they use a small step-up transformer to generate 300-volts for the valves' anodes so they can work as originally designed. It could well be that your BassMax does something similar. One would need to check the circuit schematic. BTW It is possible to get 13A based 240v AC to 12v AC plug in adaptors. Quote Link to comment Share on other sites More sharing options...
Undertone Posted March 19 Author Share Posted March 19 Interesting. Thanks Quote Link to comment Share on other sites More sharing options...
Undertone Posted March 19 Author Share Posted March 19 Does the 4.8VA (units of Watts) matter? Quote Link to comment Share on other sites More sharing options...
obbm Posted March 19 Share Posted March 19 12 minutes ago, Undertone said: Interesting. Thanks Just found a picture of the inside of it and the input socket is wired directly to a small transformer. I can also see a rectifier and smoothing capacitors so it definitely needs AC. If it came with a 4.8VA adaptor then that should be a minimum requirement. If you find something with a higher rating then that will be fine. Quote Link to comment Share on other sites More sharing options...
tauzero Posted March 20 Share Posted March 20 I would imagine it'll have a transformer doing a step up for the main power (which will be rectified) and a step down for the heater power (which IIRC isn't). 1 Quote Link to comment Share on other sites More sharing options...
Undertone Posted March 20 Author Share Posted March 20 Thankyou again. Quote Link to comment Share on other sites More sharing options...
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