Choobs, choobs, choobs...

[thekiwidisciple]

Hi all,

Yesterday I picked up a second hand Fender HRDx (for $600 less than retail ). I'm of the opinion that it needs new tubes though. The previous owner only used it to play harp through, and on very low volumes. The amp itself is in very good condition, I gave it a good looking-over. The reverb however is sounding a bit odd, but I think this is from needing new tubes?

He's had it for four years and wasn't actually aware that tubes needed to be replaced every now and then.

My question to you all is what tubes should I get for a HRDx. Bearing in mind that I know literally nothing about them. It has stock tubes in there at the moment. I'd like ones that give me a good Fender clean sound, I don't use the drive channel because it sounds bad. (This reminds me, I need to give DVM some $$ in the next couple of weeks for a Rabid Rodent). The drive I'm using at the moment is an MI Audio Blues Pro (highly reccom- ...go and buy it!).

Ben.

[tunghaichuan***]

Here's the schematic if you need it:

http://www.blueguitar.org/new/schem/...rod_deluxe.pdf

The reverb however is sounding a bit odd, but I think this is from needing new tubes?

The amp uses an opamp to drive the spring reverb pan, no tubes involved. If you're having an issue with the reverb, you'll need to have a tech check out the amp.

He's had it for four years and wasn't actually aware that tubes needed to be replaced every now and then.

My question to you all is what tubes should I get for a HRDx. Bearing in mind that I know literally nothing about them. It has stock tubes in there at the moment. I'd like ones that give me a good Fender clean sound, I don't use the drive channel because it sounds bad.
Ben.

To retube the amp you need a matched pair of 6L6GC tubes and three 12AX7 tubes. The 12AX7 tubes you can replace yourself. For the input tube, I'd recommend a low noise/low microphonics tube, this stage is very sensitive to noise and vibration. Some tube sellers screen for this. The second 12AX7 is in the drive channel, so any decent 12AX7 should do. For the phase inverter tube, the last 12AX7 right before the 6L6GC tubes, you might want to go with a tube tested for good balance between the triodes.

The amp will most likely need to be re-biased after the 6L6s are replaced. You will have to take it to a tech to do this as you can't tell unless the amp is hooked up to test equipment.

What tube sellers are in your part of the world? If you provide a link, I might be able to make recommendations based on what is available to you.

HTH.

[bigG]

Congrats on a nice score there, Ben!

[markb]

Four years of low volume playing and it needs a complete revalve? OTOH you can take this opportunity to put something a bit better than those Fender GTs in it while you're spending. New valves might even improve the drive channel but I wouldn't count on it.

[thekiwidisciple]

I think it needs one but even if it didn't, I still want to do it. As you said, get rid of the GTs. It'll get a service from a tech too, and a new speaker at some point.

[hubberjub***]

I really like JJ tubes for the price. The HRDx has a good clean tone but the drive is really buzzy. It sounds like you got a good deal on it. Congrats.

[thekiwidisciple]

I have hear of JJtubes, their fairly cheap here.

[Spudman***]

If you talk to Bob at Eurotubes he can set you up with a calibrated set of JJs to really make the HRDx sing. The dirty channel is the most problematic to get sounding good. He has sets that help that channel to sound better. Also, you need to get the bias right and then it will all come together. Ask Bob his recomnedations on bias and also check Justin's site.
http://studentweb.eku.edu/justin_holton/