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Can I swap a 5U4GB and 5AR4 rectifier tube in a Deluxe Reverb?


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So today I got a '76 Deluxe Reverb to replace my '01 DRRI. It's all original as far as I know except for tubes and a replacement '67 Jensen speaker with the original cone.

 

So my questions is. This amp doesn't seem as loud and punchy as the DRRI. It sounds great don't get me wrong, but I want to get that punch and little bit more headroom back. I've noticed that the rectifier tubes are different and I know that rectifier tubes can increase or decrease power. The '76 has a 5U4GB and the DRRI has a 5AR4. How much of this difference in punch and headroom is from the different rectifier tubes?

 

I've also upgraded the speaker in my DRRI to a Cannabis Rex. I know this accounts for some of the difference in punch and headroom. I'm thinking I'm going to move this speaker into the '76 and then put the Jensen in an extension cab to be added shortly. I just want to know how much of the difference in sound is from the rectifier tube before I move the speaker.

 

So I assume I can just swap the rectifier tubes, but I want to make sure because they are very different amps. Not being too into working on amps, I find it better to be overly cautious then just going for it.

 

Thanks. I'll add some pics as I'm taking her apart and getting her all set up.

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Here's the answer quoted from www.kcanostubes.com (great site and I'm not afflicted in any way):

 

"Here's the list of the most common guitar amp rectifiers in order of most to least clean headroom (highest to lowest voltage output) and least to most sag:

 

 

1) Solid State Rectifier (NOT Weber Copper caps)

2) 5AR4/GZ34

3) GZ37 (3 amp filament current)

4) 5V4G/A (Possibly lower if plate current of the power tubes is high enough)

5) 5U4/G/A/B (3 amp filament current)

6) 5R4G/A/B

7) 5Y3G/B

 

 

They're all interchangeable within limits. Every amp and each type of power tube has different limits so there are no general rules that apply universally.

 

All of these will "work" in the sockets intended for any of the other ones on this list.

 

Cautions: Most of these require 2 amps of filament current, the 2 exceptions are listed. Using a rectifier which requires higher filament current than the rectifier your amp was designed for, pose a potential risk of power transformer overheating. Often, there's no problem using them but caution should be exercised.

 

When changing from a lower output to a higher output rectifier, the new higher B+ voltage may pose a danger for the filter caps in your amp. Rebiasing of your power tubes is absolutely required. NEVER make this type of swap in an amp with 15+ year old power supply capacitors (in reality, you should never operate an amp with 15+ year old power supply caps anyway). Always check the new B+ voltage against the maximum ratings of the capacitors.

 

In addition, when changing to a higher output rectifier in a "self biasing" (aka "cathode biased" amp, eg, Champ and others) never assume that the power tube(s) is/are safe. ALWAYs check the bias and idle power of the tube with the new rectifier to be certain that it is running within spec. Increasing the cathode bias resistor is often necessary."

 

Hope that helps.

 

Hazy

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I should have read a bit more...

 

Have you checked the following:

 

     

    Also, I'm not familiar with the Emminence speaker, but a more efficient speaker will be louder and possbly seem punchier. That '67 Jensen may not be able to keep up with a new speaker. I put a V30 in my '66 DR and love it. Personal choice but the speaker difference could be huge.

     

    Don't do any of the electrical unless you can discharge the capacitors...they really hurt.

     

    Hazy

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