Nace Pro 18

patb

Blues Junior
Nace Pro 18 head about 4 to 5 years old. Suddenly the sound cut drastically , sounds tinny with little volume.
The Small tubes EL 81 and 83 are unlit and barely warm to the touch. I don't see any evidence of burning. No obvious burned filaments or black on the glass. I replaced these a couple of years ago. The EL84 tubes glow and are HOT. ( don't ask).
If the 81 and 83 are replaced should I go ahead and replace the 84's?
Suggestions and experience appreciated.
Thanks, Pat


 

Silicon Valley Tom

It makes me happpy to play The Blues!
Well, replacing the tubes with new units could be the solution. I would suggest if you replace the tubes you do so one at a time. Find out which one is defective. If you have the equipment and knowledge to troubleshoot, that may be the possible next step or bring the unit to a qualified repair person.

Tom
 

CapnDenny1

Student Of The Blues
Some tube amps use DC for the preamp tube heaters, or filaments. My Rebel 20 does, but they are in parallel. So if one were to burn out, the others would stay lit. The Peavey Classic 30 however uses a DC filament circuit with them wired in series. So if one were to open, they other's would also be unpowered.

Some preamp tubes glow more than others, and they take a lot longer to get hot. Try to replace with a know good tube one at a time.
 

mountain man

Still got the Blues!
I've got the Pro-18 combo and I also have the Pro-18 head. Just before the last BGU Live at Lake Arrowhead my combo was acting up and I called Art and described the problem. He recommended that I replace the tubes. All the tubes. The Nace has no way to adjust the power tube bias by design. I got the "matched" power tubes and the amp has never sounded better! I recommend getting a complete set of tubes and replace them all at once (how are you going to know which one or two is bad to replace one at a time?). You can keep the old set as spares if you like and test them one at a time and discard any bad ones. :Beer:
 

MarkDyson

Blues Hound Wannabe
So far as I know Art still responds to questions about issues with his amps. Sounds like @mountain man already has some inside scoop but, if you're unsure, you might try reaching out to him.
 

mountain man

Still got the Blues!
So far as I know Art still responds to questions about issues with his amps. Sounds like @mountain man already has some inside scoop but, if you're unsure, you might try reaching out to him.
Art does not think that matched power tubes are necessary. I found a difference in the tone of the amp so I'm sticking with them. It's worth the extra $5 to me. As far as testing each tube prior to replace one. I for one am not going to test one at a time as I drive too and from Guitar Center or wait for UPS to deliver the next tube. I'm getting them all and changing them all and then the amp works again. $70 is not going to break me. At that point I've got the old spare set to test in the amp and keep the old tubes as spares. I don't have a shop nor do I have the appropriate testing meters so this works for me... :Beer:
 

CapnDenny1

Student Of The Blues
Matched tubes, and adjusting the bias are not the same thing. Except for amps that can adjust the bias of each tube independently.

But by all means listen to what the designer says. Nobody knows better than the designer. There are boutique Amp sellers who peddle snake oil, but Art is 100% the real deal!
 

Bernie Fitz

Blues Junior
I reached out to Art about 2 1/2 years ago because my M1-18 was sounding kind of dull. He directed me to Antiques Electronic Supply for a new set of tubes. The person who responded to my inquiry said he owned the same amp and suggested a matched set. I also opted for the "burned in" and was happy with the result.
On a side note I've been meaning to contact Art again because I'm getting a very sporadic problem with the reverb. Every now and then I'll turn the amp on and there is no reverb at all. It can sometimes take a few times before it works. Hasn't happened in a couple of weeks.
 

patb

Blues Junior
I followed Mountain Man and replaced all 4 tubes with the EL84 matched set. It works so I don't know which one or ones failed. It sounds a little more crisp with more tenor but i assume that will settle down with some hours. I wasn't aware of the "burned in" option.
Thanks to all who responded.
Pat
 
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