Sony Tube Pre SRA-3

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musical5
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Sony Tube Pre SRA-3

Post by musical5 » Thu May 21, 2009 10:18 pm

acquired one of these recently. I love the thing except for there is very little headroom on the input before distortion. I have heard of folks modding these. Anyone have any info on how to increase the headroom? Or who may have the knowledge to mod it?


Thanks,
Justin

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Blade
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Post by Blade » Sat May 23, 2009 10:36 am

I have 3 of them......

What I did was swap out the 12AX7 tubes for 12AU7's.

If the mic input is distorting, then send it into the line input. It will give you cleaner headroom.

I have to do this on my Scully 280's as well sometimes.

musical5
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Post by musical5 » Sat May 23, 2009 9:10 pm

Thanks Blade. I will swap the tubes. Even a passive bass can quite easily distort the mic input on the Sony, if the Bass volume is at full. Is this not your experience? I do use it for all my bass tracks now. I just have to roll off 40% of my pickups volume.

Thanks,
Justin

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Blade
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Post by Blade » Sun May 24, 2009 11:57 am

Anything I plug in that has a hot input, I run through the line in. But if you like the sound of the mic input and you can't get enough gain because of distortion, then just record it low and normalize it after the fact. Or, just run something after it that has clean gain.

musical5
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Post by musical5 » Mon May 25, 2009 2:49 pm

Blade,

What brand tubes did you put in yours? Did you notice a difference? Also, did you use all 12AU7's? I thought there was other some funky tube in there.

Thanks,
Justin

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Blade
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Post by Blade » Tue May 26, 2009 12:24 pm

I said 12AX7 before, but it's actually a 12AT7.
What I stepped down to was a 12AU7.

I put old RCA tubes in one side, and old GE's in the other.

The line tube is a 6AU6 and the mic tube is a 12AU7.
Those are the only 2 tubes you have to change out, if you so desire.

Tubes don't make that much of a difference in my book, but I definitely don't like the NEC brand that are in the unit. It's all about the transformers!!!!

You could change out one side of tubes in the unit, so that you could do a comparison.

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infiniteposse
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Post by infiniteposse » Sat May 30, 2009 6:34 pm

Just a voyeur on this topic, but one thought. Have you tried a pad before hitting the front end to lower the input gain? I have Shures I use around here all of the time that seem like they might help your problem...

Congrats on the find. Sounds great!
Lee
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??It doesn't matter if you can play a scale. It doesn't matter if your technique is good. If you have feelings that you want to get out through music, that's what matters.? Neil Young

musical5
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Post by musical5 » Sun May 31, 2009 5:01 pm

Funny thing is the mic inputs just have a very small window for use, as far as the gain staging goes(unless you want cool tube distortion). The aux inputs much the unit very useable for me now.
Thanks Blade!


Justin

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infiniteposse
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Post by infiniteposse » Sun May 31, 2009 5:14 pm

Interesting. If you've got a good tech in your area perhaps they can play with pot values or perhaps changing something on the front end to offer more sweep range from the pot.

You've totally got me on the hunt for these now. I had no idea they were still so cheap when you could find them.
Lee
www.mysterymachinestudio.com
??It doesn't matter if you can play a scale. It doesn't matter if your technique is good. If you have feelings that you want to get out through music, that's what matters.? Neil Young

Schmolze
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Post by Schmolze » Sun May 31, 2009 7:46 pm

I've collected a few of these over the last couple years. They seem to go for about $120 on evilBay these days. I find that mine have a bit of a midrange accent compared to the Sebatron vmp-4000, makes for a nice compliment tonally. At some point I will have them modded to add phantom, phase, pad, and balanced inputs.
Wait...why are we in this handbasket? And where are we going?

musical5
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Post by musical5 » Mon Jun 01, 2009 8:33 pm

One more note..... My unit was built to get power from a reel to reel so the plug I converted has no ground :( I have a gnarly 60 cycle hum. Is this from the lack of a ground? How would one add a ground? I have it plugged into a power strip though. Wouldnt this act as one for it?


Thx
Justin

Schmolze
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Post by Schmolze » Tue Jun 02, 2009 7:17 am

Sounds like a ground loop. For some background on the subject, google "eliminate ground loops". Try placing the unit on a wood table (or other non-conductive surface) by itself, connect it and see if it still hums. If so, attach one end of a wire to the sra-3 chassis and the other end to an equipment ground. If you are not proficient in single phase ac electrical systems, then just stick the other end of the wire into the ground...the actual dirt outside. Also try touching it to the chassis of whatever amp you have connected to the sra-3, don't be afraid to investigate as identifying ground loops can be elusive. Whatever you do, though, do not come in contact with or allow your equipment to come in contact with a "hot" or "live" 120v ac wire. This will destroy your equipment and possibly kill you. But connecting chassis to chassis or to ground plugs is perfectly safe.
Wait...why are we in this handbasket? And where are we going?

musical5
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Post by musical5 » Tue Jun 02, 2009 10:19 pm

Thanks for that info. Much appreciated.

JJ

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