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Post by drew on Jul 23, 2018 7:56:19 GMT -7
Hi, I just serviced my SRZ-65r and want to know, do I need to install the preamp tube retainers/covers? I played an outdoor 4 set gig without them and it performed as good as ever. Do they serve a performance purpose other then securing the preamp tubes? I'm thinking the tubes would run cooler without the covers on and if needed I can use tube rings to control vibrations.
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Post by Maddog on Jul 23, 2018 9:21:46 GMT -7
Depending on the amp, Drew, some higher gain amps especially pick up interference from radio stations, cell phones, lighting, and other radio frequency (RF) generating devices.....These tube shields create an electronic barrier for the plates of the tubes from unwanted, external interference just like the shielding in instrument cables and guitar control cavities. If your not recording, and the amp sounds just fine for gigs (and that's all you care about), they offer no great benefit beyond protection from mechanical breakage and help retain the tubes in their sockets...
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Post by drew on Jul 23, 2018 13:21:23 GMT -7
Thanks Lee. From a non technical standpoint all of the pre-amp tubes run at what I would call a normal heat generating range. Except for one that runs very hot for a 12ax7, IMHO. I think the hottie is in the reverb circuit but it's hard to tell without a tube layout. Which led me down the path of thinking no cover less heat. There are 5 preamp tubes, no effects loop, and it's in a V3 position - left to right from V1. I've replaced that tube twice since i've owned the amp, 3 1/2 years, for noise reasons. Once when I got the amp and then last week. The SRZ gets a lot of playing time. Maybe it's not supposed to be a 12ax7 but that's what was in there when I received the amp. And it sounds so good I keep plugging in what was there. I don't think it can hurt anything by trying an AT7? I only use a smidge of reverb.
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Post by Maddog on Jul 23, 2018 18:36:28 GMT -7
Yeah, it might be a good idea to call home and ask Doc what the actual tube compliment is supposed to be.... Most reverb units use both a 12aT7 and a 12aX7 IIRC....I don't think you can hurt anything with using a 12aT7 in place of a 12aX7 ....it's just that they are much lower in gain and biased very coldly....(your amp may sound flat or dead-ish if you use one in V1.....but should work well in a reverb driver slot...) Found this on the web: The 12AT7 has better plate dissipation, which, for example, makes them a better reverb driver. A 12AX7 in the reverb driver position could burn up prematurely, depending on the circuit. Probably sound like crap, too.
Found that^^^^^ here:
www.lespaulforum.com/forum/showthread.php?118461-Are-12AT7-and-12AX7-tubes-just-a-direct-swop
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Post by drew on Jul 23, 2018 20:23:48 GMT -7
Makes sense Lee. Interesting read you provided, it just might be why i'm going thru 12ax7s in the reverb circuit. I'll check with the shop and a couple of SRZ65R owners to see what they are running in V3.
Thank You Lee
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Post by drew on Jul 25, 2018 17:15:12 GMT -7
Lee, you nailed it. :-) I got the Tube layout from Mike's SRZ65-RC. It should be a 12AT7 in V3. I'll put the tube sleeves back on.
Thank You
For anyone interested; SRZ65-RC preamp tube config V1 = ECC 83s V2 = ECC 83s V3 = 12AT7 V4 = 7825/12AX7 V5 = 12AX7
Thanks, Drew
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Post by Maddog on Jul 25, 2018 19:07:38 GMT -7
I bet that hot V3 socket is saying, "Whew....thanks, Drew!" LOL
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Post by sharkboy on Jul 25, 2018 19:21:34 GMT -7
I’m also not convinced that some tube shields don’t provide some heat sinking. With a mechanically connected aluminum shield in place and a large aluminum (aluminium) cylinder, it seems likely that it would help with heat dissipation.
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Post by Ridgeback on Jul 25, 2018 20:04:27 GMT -7
Hi Drew. Hope all is well with you.
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Post by drew on Jul 25, 2018 23:15:45 GMT -7
Hi Drew. Hope all is well with you. Hey Nick, Doing good, thx. It's been a while, hope you and yours are doing well. And that Charlene is behaving and not bringing the police to your place. ;-) The band is rockin' the Lake Stevens AquaFest Beer Garden Stage Fri and Sat night if you're looking for something different to do.
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Post by Ridgeback on Jul 26, 2018 3:21:52 GMT -7
Hi Drew. Hope all is well with you. Hey Nick, Doing good, thx. It's been a while, hope you and yours are doing well. And that Charlene is behaving and not bringing the police to your place. ;-) The band is rockin' the Lake Stevens AquaFest Beer Garden Stage Fri and Sat night if you're looking for something different to do. Everything is fine here. No more visits from the local constabulary since I stopped hanging out with Z-Talk reprobates. Have a good gig.
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Post by premiumplus (Dave) on Jul 26, 2018 5:20:35 GMT -7
Any time there is a tube shield installed by the maker I keep them in place. I think they protect the tube and no doubt keep them well seated in the socket.
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