Early Breakup on '95 Blues Deville

[Flatted Fifth]

Hi there, I'm here by the recommendation of my guitar teacher, an apparent frequent member here. Not sure what his username is, but his name is Griff. Anyway, I'm looking for advice on how to go about swapping the tubes in my '95 Blues Deville in the most knowledge soaking way. I'm relatively inept when it comes to technical whatever in amps, so I'm looking to learn as much as possible while changing out the tubes in my amp.

[phsyconoodler]

Well the tubes are a major source of tone from your amp and if they are tired they will need to be changed.Especially if they have been in there since'95.
The power tubes are the ones you need to concentrate on.Get a new set of 6L6GC power tubes from a reputable dealer.KCA comes to mind.
Then install them and set the bias.If you are not comfortable with electronic devices that have LETHAL voltages inside,take it to a tech and get it done.
Preamp tubes can make your amp sound more pleasant too.
KCA are you here? He can answer any tube questions you might have.

[Flatted Fifth]

I don't mind it being lethal, as long as I have an idea what I'm doing. I have no idea what a bias is though. But according to Griff, I need tubes with a ton of clean head room since I'm running overdrive and distortion pedals in front of it.

[brad347]

Make sure you're treating the right problem, as well.

If by "early breakup" you mean that it starts to distort at relatively low numbers on the volume control dial, then the issue is not actually one of headroom.

See, the Deville has a linear-taper volume pot as opposed to the 'correct' audio or logarithmic taper (probably to simplify production and reduce cost). As a result, about 70% of the volume control's range is between about 1 and 4. Turning it up to "3" would be about the same as turning it up to "6" if it had the correct volume pot.

So pay no attention to what you see on the dial. If it's loud enough and clean enough, you're good. If you feel like it should stay clean past "3," then you're right, it should... and probably would if it had the right volume pot. But it wouldn't be any louder/cleaner. :)

It may be possible to eke out slight amounts more headroom with tube swaps, but if you're really feeling like it's breaking up at too low a volume (hearing volume, not numbers on the dial), then it might be that the amp just isn't right for you. A good place to start as far as trying to maximize headroom is speaker efficiency... look for one with a high sensitivity, like 102dB at 1w. You might also check on the filter caps and even consider beefing up the first stage with a slightly higher value. Good luck.

[Flatted Fifth]

Oh no, it was clean at acceptable levels a couple months ago when I first bought it. I hadn't been used regularly in awhile. I just have a feeling that the tubes are going out and that's what causing an early breakup, but if I can get tubes that have more headroom than the ones I currently have, I'd rather have those.

You're saying that the linear-taper volume pot essentially makes the volume pot extremely touching, right?

Edit: Mmmm I lied, it's been at least a good year since I bought it...my how times flies.

[Blue Strat]

Could be tubes or could be an internal problem. A friend with one of these amps had VERY low headroom....it started breaking up at 2. One of the plate load resistors on the PI was open.

SED 6L6GCs should do the trick. Those are loud amps and any decent 6L6GCs should have sufficient headroom.

If you're looking for preamp tubes, the Tung Sol Reissues are a good, economical, solution.

[Flatted Fifth]

I don't know which tubes would be causing the early break up, so should I just replace both? And how do I go about changing the bias (whatever that is)?

[Blue Strat]

A new pair of 6L6GCs is highly recommended. SED's would be fine.

Biasing info here http://studentweb.eku.edu/justin_holton/bias.html

You could have one or more problem 12AX7 tubes as well.

[Flatted Fifth]

SED's being Svetlanas, right?

[Blue Strat]

SED's being Svetlanas, right?

Svetlana Electron Devices = SED but doesn't not equal Svetlana since New Sensor hijacked the US trademark in the early 2000s.

For the sake of clarity http://www.kcanostubes.com/products/110/Winged-C-SED-6L6GC.htm

[Flatted Fifth]

Very cool...and then what would you recommend as far as pre amp tubes? Tung Sol Reissues? Another set of 12AX7s?

[Blue Strat]

Tung Sol Reissue 12AX7s would be fine.

[Flatted Fifth]

Thanks...but it doesn't appear as though I'll be able to do this myself.

Can I bias my Fender Blues Deluxe/Deville?
The Blues Deluxe/Deville were made prior to the Hot Rod Deluxe/Deville. They were discontinued in 1996 after the release of the Hot Rods. To answer the original question: Sorry, you can not. These amps do not have an adjustable bias control, they have a fixed resistor that sets the bias range. You'd need to have a tech install a bias pot, and use a bias probe like a Weber Bias Rite or Bias King.

[Blue Strat]

Thanks...but it doesn't appear as though I'll be able to do this myself.

You're probably correct. If you order "low current draw" 6L6s I can supply ones that will run safely without rebiasing.

[Flatted Fifth]

Is it more worth it just to take my money and amp to a tech to have him install and bias the new power tubes? In the ideal situation I'd ask to be there when he does it so I can watch what he's doing...

[Blue Strat]

Is it more worth it just to take my money and amp to a tech to have him install and bias the new power tubes? In the ideal situation I'd ask to be there when he does it so I can watch what he's doing...


Not a bad idea. The MOST ideal situation would be to have him install a bias pot and test points and show you how to bias the amp using them.

[Flatted Fifth]

Oh right...the Blues Deville's can't be biased without installing those. Or can they? If I didn't want him to install a bias pot and test points how would he do it besides using low current draw 6L6's?

[GearHeadFred]

The HRDs have a bias pot and a test point on the PCB. With info from the Holton site and others (there are videos on the web you can find) and a low-cost multimeter, you can easily bias one. The voltage at the test point is non-lethal (under 1 volt), BUT THERE ARE POINTS IN THE AMP WITH 500 volts nearby that CAN kill you, so you need to be aware of this and make your own personal decision about it.

[Flatted Fifth]

I've got a Blues Deville, not a Hotrod. But what's a PCB?

[brad347]

PCB= "printed circuit board."

I recommend going the route of having the tech install a bias pot and test points, and showing you how to bias it yourself, if you can afford it.

This will save you money in the long run, if you plan on playing guitar for awhile. ;)

This probably won't be your last set of tubes (or last amp, for that matter!)

Knowing how to bias accurately is also a good stepping stone toward performing other simple repairs, maintenance.

[GearHeadFred]

I've got a Blues Deville, not a Hotrod. But what's a PCB?

PCB = printed circuit board.. It's the green board that holds all the parts.

I had a Blues Deville as well... It uses the same PCB as the deluxe, and the HRD, and the HRDx.. They just stuff a few different components to make the different models.

Now I remember why I sold it!!

[Flatted Fifth]

Oh I'll be playing guitar for quite awhile! I'm 17 and have been playing for 4 years, it's definitely part of my life. How much would it cost in general to get a bias pot, test points, and new tubes installed?

Haha this is my first tube amp, so it certainly won't be my last, but until that Dumble comes... : P

[brad347]

It's hard to give an estimate on that. It will vary depending on your location and the individual tech. If you are in Orange County California, it will probably be more expensive than if you were in, say, Mississippi somewhere.

[Flatted Fifth]

Haha alright good point. I guess we'll find out...