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Post subject: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 3:44 pm
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Hi All,

First off, I am completely new to the forum, and also new to tube amps.

I purchased a used BDRI last week and love it. Only, within minutes of use and cranking it up, slightly, I noticed the 'glassy rattle' kicking in. So, after reading a few things within this forum I have found the rattle to be coming from one of the pre amp tubes, (using the rubber end pencil test).

I haven't yet removed it as I have nothing to replace it with, so my question is. Inside the amp there is a label stating the pre's are 12AX7-A's. I am looking online to buy new tubes, and don't see any 12AX7-A's, only others like 12AX7-C 12AX7-R. Can I use these without having to rebias? What is the difference? If a 12AY7 was put in, does it mean a rebias? Basically I want a simple straight swap, that I can do myself.

Another thing is, I notice one tube has like a plastic spacer or something on the upper part of the tube, while the other two don't, but they have a foam type damper or something.

The person I bought it from is willing to help me get it back to proper working order and said he has spare tubes, but I'd like to stick new ones in it, and get a bit of knowledge on it myself, instead of just letting someone else do it.

Thanks for taking the time to read this, and I look forward to any advise that comes my way.

Cheers.


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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 4:21 pm
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Hi seveaghead,

Welcome to the forum.

First, tapping the tubes, especially V1 will produce some sound, this is normal, all tubes are microphonic to some extent, that's how they work. What you seem to be describing is tube rattle and that only happens when playing, so try to grasp each preamp/phase inverter (PI) tube one at a time while it is rattling and see if the noise subsides. It sounds like one tube has a damper ring and the other two have the factory foam which is to try and prevent tube rattling in the same way as a damper ring.

Any 12AX7 type/brand will be interchangeable with any other 12AX7 type/brand, the different suffixes are just variations in either the place that the tube was made, or variation in gain.

A 12AY7 is just a lower gain tube, as is a 12AT7 or 5751 or 12AU7, and all are interchangeable, the differences being in gain or type of tone produced.

No bias adjust is required when changing preamp (V1 and V2) or PI (V3) tubes. Changing output tubes requires a bias check/adjustment.

Here is some handy info about tube numbers and associated gain factors. Lots of other useful info on this site, they are a great tube supplier, but you can find a little misinformation on their site, so don't take this as the authority on all things tube. :wink:

http://www.thetubestore.com/Resources/Guitar-Amp-Info/Gain-Factor

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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 4:50 pm
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Hi shimmilou,

Thanks so much for the quick reply.

Ok, so to determine which one is causing the rattle I should grasp each one. I suspect it is the one far right when facing the rear of the amp (don't know if that's P1, P3), as there does be a difference when I push the rubber of the pencil slightly against it, when hitting a lowish note, while the other two don't affect the rattle, but I will do the grab test.

I watched a You Tube vid of a HRD tube replacement & biasing, after I posted, which explained no need to bias pre's, which was one part of my list of questions. And now I know that the pre's are variations. Would I be right in saying that 12ax7 C=Chinese, R=Russian? So the variants are personal taste.

What a difference 15 mins can make to ones confidence of diving into the deep.

Thanks for the reply.


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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 5:08 pm
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Facing the rear of the amp, from right to left, V1, V2 are preamp tubes, V3 is the PI, V4, V5 are output tubes.

Yes, pushing on the tube with the eraser can have the same results as grasping, and it sounds like you have found it, V1. You can substitute any 12AX7 (or any equivalent that we've mentioned, such as 5751, 12AY7), and yes the -C could be Chinese and the -R could be Russian.

Yep, lots of choices in tube types and brands, as you noted it's all about personal preference. There are many, many brands such as, Tung Sol, Sovtek, Mullard, Svetlana, Gold Lion, EH, JJ, RCA, GE, etc, etc, etc.

For example, my HRDlx is similar to your BDRI, and I have a 5751 in V1, a 12AX7-C in V2, and a 12AT7 in V3.

It can be very interesting to try several different tube types in each preamp/PI position to get your preferred type of tone. Just as an example, a Tung Sol might not sound good in V3, but might sound great in V1 or V2. Or an EH might only sound good in V2 when also using a 5751 in V1........the possibilities are nearly endless.

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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 5:19 pm
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Once again shimmilou, thanks for being so informative. I was going to stick with the same, 12AX7, but maybe I will buy a few variations and try them out, when I'm on the case.

Looking forward now to a bit of trial and error on the old tone front.
It's time to go order some tubes!!

Cheers


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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 5:38 pm
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I have a few hundred tubes, several of each of many brands, and I do a lot of tube rolling with each amp to find the perfect combination. Search this forum, and the web, to learn as much as you can about the types of tones produced from different brands, and the affect on breakup that different gain factors can produce. It is always a good idea to have plenty of spare tubes, so try as many as you can and get extras of the ones that you like best. You can really change the voice and response of your amp with different tube combinations.

There are lots of knowledgeable and helpful people on this forum, with many varied opinions about tone and tube types, so check in often and ask questions, you can learn a great deal here. Have fun! 8)

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 6:09 pm
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I most certainly will be checking in..... regularly. This is big exciting step forward for me, not so much for others, but, I can't wait to re-tube and get this amp mic'd up and recording, instead of via pc software, which wasn't doing it anymore, tone wise. Amazing the difference my tele sounds through this amp as it is.
Tubes and pedals in the post later, so, bring it on!!!
Once again, thanks for the usefull knowledge.


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Post subject: Re: BDRI Valve Replacement
Posted: Thu Nov 13, 2014 10:54 pm
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If you use the search function at the top of the page and enter Blues Deluxe RI and author bluesky636, you will find a ton of info on tubes and the amp in general. :D


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Post subject: Re: BDRI Valve Replacement
Posted: Fri Nov 14, 2014 3:01 am
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Cheers for that joe. Had a look, and there certainly is a good amount of info to digest. What a forum, already I know a lot more about the amps workings, rather than just turning it on and plugging a jack into input 1! Fantastic. So glad I joined, instead of giving the amp back to the seller to sort the problem out.
Really appreciate the replies.


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