OT - Tubes for Hot Rod Deluxe?

[solarplexus]

Hi there,

I got a Fender Hot Rod Deluxe and have some Blue Fender Tubes in there and I was wondering if any of you guys had a Hot Rod with other tubes that would give it a sweeter sound?  Kinda little harsh on dirt channel!

Thanks,

matt

[wampcat1]

get ahold of bob @ eurotubes, he'll hook you up!
bw

[solarplexus]

Thanks for the tip.  Nice site!  Now I'm wondering if I have to drain the capacitors before changing the tubes and biasing or I don't have to ?!

[kurtlives]

Wont need to drain caps...

Biasing depends if your amp is cathode or fixed biased.

[solarplexus]

I know for a fact that HRD's are not fixed bias like my previous amp Peavey Classic 50.

[The Tone God]

HRDs are fixed bias but I don't think you understand what that actually means. You probably think it means you cannot adjust the bias. Fixed bias is using negative voltage to bias the tube instead of other methods most commonly cathode bias. The bias is adjustable on the HRD but it is the fixed bias method.

In Canada check out The Tube Store. They are located in Ontario.

http://www.thetubestore.com/

Andrew

[solarplexus]

I guess I was misinformed with the fixed bias then.  Should I try to rebias my amp before ordering new tubes?  Could it improve the sound alot or the tubes are somewhat the reason for the shrill highs and farty bass on dirt channel?

Thanks!

[sweetwilly]

The Tone God delivereth the truth.

I'm in the UK and ordered new tubes for my HRD from The Tube Store.  Great tubes and great international service!  I also found the dirt channel pretty much unuseable until  I swapped ALL the tubes out.  I've got the new issue Tung Sol 12AX7s in V1 and V2, a NOS JAN Phillips 5751 as the phase inverter and 2 new issue Tung Sol 6L6GC STRs for power tubes.  Fan-freakin-tastic results!

For ALL things HRD check out - http://studentweb.eku.edu/justin_holton/

HRD's SHOULD have 6L6GC power tubes.  The stock tubes I got in my HRD are rebranded (twice - 1st by Groove Tubes and 2nd by Fender!) Sovtex 5881WXTs.  Under Fender logo printed on the tube it says they are GT6L6Bs.  NOT true 6L6GCs at all.

Install some PROPER 6L6GC tubes (biased slightly hot) and some better quality preamp tubes and you will be amazed how much better this (already good) sounding amp can actually be! 

Willy.

[GibsonGM]

the HRD has a bias pot located on the L side of the lower PCB.  Install the new tubes making sure they are going in the right way (with amp unplugged), remove back panel.  Do NOT touch anything on the board or those big ugly filter caps!!!!!  They are still charged and dangerous.
    Clip a jumper to the chassis, and to your meter's - probe.   Plug in amp, let warm up for a minute, turn on (clean channel), turn volume all the way off.   Measure the voltage at the point on the PCB near the pot that says "bias test".   Set it to about 69mV, and you are all set.    Power down, remove jumper, put back panel on.   Check the bias 1-2 times per year.   
This assumes you are still using 6L6's, there are mods you might need to do for other tubes.   Check out "Hot Rod Deluxe Forum"  (Google) for a lot of info on this stuff, the site is by Justin Holton.   The drive channel on HRD's is very harsh no matter what (IMO).   The solution might be to get Yellowjackets and run EL84's, to lower the headroom and use less gain, more "amp pushing".....40W is too much, you can never get it loud enough to really punch.

[solarplexus]

In eurotubes video, Bob tells to bias to 90mV.  Is that too hot?

[The Tone God]

And for good measure:

http://studentweb.eku.edu/justin_holton/

Andrew

[GibsonGM]

90mV seems REALLY hot to me, the highest I've seen referred to was around 72.  Bet the plates would be glowing at 90!!  I keep mine on about 69.
BTW, putting a 12AT7 in V3 (phase inverter) chills out some of the harshness of the drive channel.  Still plenty of gain left.
I did all the Holton mods except the sag one; I am happier with the amp now!

Working on a switch to go between 2 reverb knobs (for lack of a better way to say that) using a relay, to wet up the signal for solos....

[AL]

Hey guys, I don't mean to sound negative - so please don't take it that way - but 90mv and 69mv are meaningless numbers. If your amp is working OK then these numbers may be in the ball-park but if you've got a problem you may be out a set of tubes.

You need to enter your mV into a formula to make sure you have the right wattage. Those numbers may be OK depending on your amp. Then again, they may not.

Read through this article on biasing. It should help.

http://www.duncanamps.com/technical/lvbias.html

AL

[kurtlives]

Yes it all depends on dissipation and plate voltage but still in a factory produced amp 90mV is a bit high.