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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 6:50 pm
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You only need to check the bias when changing output tubes. Preamp and PI tubes are plug and play. There is no bias adjustment on the PJr, so you might have to change a resistor in the bias circuit, or add an adjustment pot if you change output tubes.

Using lower gain tubes in V1 and/or V2 will generally get you a cleaner sound, the trade-off being loss of volume, more-or-less depending on which tubes are used.

If you want slightly cleaner sound, try a 12AT7 in V2, and leave a 12AX7 in V1. For even more clean, add a 5751 or 12AY7 in V1.

Yes, collecting tubes can cost a lot of money, but you don't have to buy them all at once. Pickup a couple every now and then and try them. You should have spare tubes anyway, and most of us with tube amps have amassed collections over the years.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 7:04 pm
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shimmilou wrote:
You only need to check the bias when changing output tubes. Preamp and PI tubes are plug and play. There is no bias adjustment on the PJr, so you might have to change a resistor in the bias circuit, or add an adjustment pot if you change output tubes.

Using lower gain tubes in V1 and/or V2 will generally get you a cleaner sound, the trade-off being loss of volume, more-or-less depending on which tubes are used.

If you want slightly cleaner sound, try a 12AT7 in V2, and leave a 12AX7 in V1. For even more clean, add a 5751 or 12AY7 in V1.

Yes, collecting tubes can cost a lot of money, but you don't have to buy them all at once. Pickup a couple every now and then and try them. You should have spare tubes anyway, and most of us with tube amps have amassed collections over the years.


12AT7 in V2 can improve the clean headroom?


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 7:11 pm
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FenderMotsesim wrote:
12AT7 in V2 can improve the clean headroom?


Yes, it does...... Another fine tweak for these units - put in a negative feedback loop switch (carling "on/off" switch between the purple wire and the output jack, simple and effective). There's room to drill a small mount for the switch under the chassis, next to the output jack.


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 7:57 pm
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http://home.comcast.net/~machrone/bjr/bjtubes.htm


Last edited by FenderMotsesim on Mon Jun 09, 2014 10:12 am, edited 1 time in total.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 8:34 pm
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I decided to put 12AT7 in the V2, i think is a good choice for the PRO Because the 'Breaks up early'

i dont know what to put in V1 12AY7 or 12AX7 :?


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Fri Jun 06, 2014 8:56 pm
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FenderMotsesim wrote:
I decided to put 12AT7 in the V2, i think is a good choice for the PRO Because the 'Breaks up early' i dont know what to put in V1 12AY7 or 12AX7 :?


I would start with a 12AX7 preamp tube (V1) if you're going to put a 12AT7 in the PI section (V2). Stick to short plate tubes in V1, no 17mm long plates (those function MUCH better in the phase inverter section), which will help to keep noise levels down. And work you way backward, reducing gain until you are happy, 5751-12AY7-12AU7-12AT7 (although I've actually tried this, putting a 12AT7 into that position-V1- is taking it to extremes, and most would think it a bit nutty).... You could also try a 7025, although those are so similar to the 12AX7's it's hardly worth the effort (largely because good 7025's are getting much harder to find, but dam a good RCA 7025 is a wonderful preamp tube)....


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sat Jun 07, 2014 3:30 pm
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what do you think about


Last edited by FenderMotsesim on Sun Jun 08, 2014 1:27 pm, edited 1 time in total.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sat Jun 07, 2014 5:45 pm
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I think I'll choose

JJ 12AX7/ECC83 in V1


Last edited by FenderMotsesim on Sun Jun 08, 2014 1:26 pm, edited 1 time in total.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sat Jun 07, 2014 6:35 pm
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They sound fine. I'm not very big on the re-issue or new tubes, but they are getting better, JJ and GT tubes are fairly quiet, they're ok for the job!!


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sun Jun 08, 2014 1:31 pm
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Which one is better:


Last edited by FenderMotsesim on Mon Jun 09, 2014 10:11 am, edited 1 time in total.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sun Jun 08, 2014 1:53 pm
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That is always subjective. The JJ is a bit brighter, whereas the GT, being Chinese, is a bit warmer. I have used both in a few different amps, and generally prefer the GT. I couldn't fault anyone else's preference for the JJ though.

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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sun Jun 08, 2014 2:18 pm
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If I am going to replace just one of the 12AX7's with a lower gain tube does it matter if it's the V1 or V2?


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Sun Jun 08, 2014 5:14 pm
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FenderMotsesim wrote:
If I am going to replace just one of the 12AX7's with a lower gain tube does it matter if it's the V1 or V2?


Yes, V1 is the preamp tube and V2 is the PI (phase inverter) tube. Stick to your above decisions, or else you'll get all mixed up.....just focus on the V2 change to the 12AT7 for now, one thing at a time ;) If you don't, you'll find you'll end up with a pile of un-used tubes (like many of us here).....


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Mon Jun 30, 2014 7:17 am
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What a mistake :shock:

I bought the amp from USA and forgot about the 120v i need Europe 230v

what to do?


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Post subject: Re: Pro Junior Owners Club - sign in here
Posted: Mon Jun 30, 2014 8:09 am
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Ebay, search "230-110V step down", that should find you a decent enough step-down converter/transformer....they are a LOT cheaper now than they were a few years ago. It's no big deal.


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