PULLING TWO POWER TUBES IN MY AD 30 HEAD?

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deanogeorgeproject
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PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by deanogeorgeproject » Wed May 08, 2019 2:39 pm

I did this in the past on mesa amps, marshalls, vht amps but I want to know with my ad30 head can I pull two tubes and what ones to pull as each amp manafture is different. I rememeber my old twin was 1 & 3 instead of say the two inner or two outer ones. Please let me know then of course my 16 orange cab would plus into the 8 ohm on amp. I want to make sure with orange as this amp is so good but I want to ask first, thanks

Jondog
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by Jondog » Wed May 08, 2019 2:53 pm

1+4, 2+3, 1+3, 2+4. As long as you have one in the left most pair, and one in the right most pair. But, you'll also need to change the bias resistors.
Last edited by Jondog on Wed May 08, 2019 4:40 pm, edited 1 time in total.
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deanogeorgeproject
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by deanogeorgeproject » Wed May 08, 2019 4:05 pm

I emailed orange in USA and they said it wont operate doing this ? I think they are wrong. Also I cant get a hold of anyone in UK to ask. So two inner tubes is safe to pull the way you described it ?

Jondog
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by Jondog » Wed May 08, 2019 4:52 pm

deanogeorgeproject wrote:
Wed May 08, 2019 4:05 pm
I emailed orange in USA and they said it wont operate doing this ? I think they are wrong. Also I cant get a hold of anyone in UK to ask. So two inner tubes is safe to pull the way you described it ?
Change the bias resistors. Orange likely won't tell you how to modify their amps in a way they were not designed.
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JJJ
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by JJJ » Tue May 21, 2019 3:35 am

If you do some googling you will see this is not possible without modifying the amp's bias circuit as stated above

This is not like a jcm marshall or something where you can just pull two tubes and swap speaker outs. If you really want to do that, take it to an amp tech and have them modify it for you

a.hun
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by a.hun » Tue May 21, 2019 4:45 pm

Big difference from most Mesa / Marshall / etc amps is that the AD30 is cathode biased, not fixed biased.

With fixed biased amps you can pull 2 (paired) output valves and just bumping the output (speaker) impedance one step keeps everything groovy.

With cathode biased amps, as mentioned, it isn't so simple...

Andy.
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Banned052319c
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Re: PULLING TWO POWER TUBES IN MY AD 30 HEAD?

Post by Banned052319c » Thu May 23, 2019 10:43 am

I am 100% interested to have this device

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