After 22 years it was time to get my Boogie MK IV re-tubed. My local Mesa/Boogie dealer informed me that I had to use Mesa tubes in it, contrary to what some of my tone freak guitarist friends had said. After the dealer installed the Mesa tubes the amp has considerably less volume on the clean channel, which also now sounds horribly thin.
I assume that I was lied to by my local dealer, or they are just simply not informed, which I doubt is the case. I took the amp to a local repair shop and he informed me that Mesa tubes are basically garbage and made in China. The Boogie would not even work properly with the tubes that the dealer installed, even though they are the tubes that the Mesa website recommended on their chart.
Help!! I am a classical guitarist for the most part and I'm now actually performing in a rock band, I need this amp to function properly. Any advice would be appreciated. Thanks.
Boogie MK IV Retube
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Littlemountainguitar
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Reeltarded
- Posts: 10189
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Re: Boogie MK IV Retube
Weaker clean channel? You have a lesser 12ax7 in there. You should use your old preamp tubes, I doubt they needed changing.
Is your local MB guy at Guitar Center? Either lying, or dumber than wood.
Banjo Mart... run away.
Is your local MB guy at Guitar Center? Either lying, or dumber than wood.
Banjo Mart... run away.
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Re: Boogie MK IV Retube
It is really very, very naughty to even think of not using Mesa branded tubes 
very quickly:
- there is a tie-you-in to Mesa brand tubes "thing" these days, but I don't recall that being mentioned when those amps came out. The new story is something about bias settings... I forget, surely a good tech can get you any tube of your choice in there?
- did the MB dealer let you keep your original tubes?
- are you talking about both the output and preamp tubes?
- It sounds like you are in a hurry, so why not have your local repair shop set it up to a high standard with respect to the quality of this amp?
best, tony
very quickly:
- there is a tie-you-in to Mesa brand tubes "thing" these days, but I don't recall that being mentioned when those amps came out. The new story is something about bias settings... I forget, surely a good tech can get you any tube of your choice in there?
- did the MB dealer let you keep your original tubes?
- are you talking about both the output and preamp tubes?
- It sounds like you are in a hurry, so why not have your local repair shop set it up to a high standard with respect to the quality of this amp?
best, tony
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vibratoking
- Posts: 2640
- Joined: Tue Nov 10, 2009 9:55 pm
- Location: Colorado Springs, CO
Re: Boogie MK IV Retube
I would go back to the original preamp tubes if you still have them. At least as a sanity check on the new preamp tubes.
MB always recommends their tubes. It's good business for them. The output section all MB amps, that I know of, has non-adjustable bias current. This is one reason why many suggest using MB tubes. You can buy matched output tubes from quite few other dealers, other than MB, that will bias properly with the fixed bias current in the MB amp. Also, the replacement tubes may be biased too low causing low output. MB designed the non-adjustable bias to save time and hassle for their users. Sometimes this backfires.
MB always recommends their tubes. It's good business for them. The output section all MB amps, that I know of, has non-adjustable bias current. This is one reason why many suggest using MB tubes. You can buy matched output tubes from quite few other dealers, other than MB, that will bias properly with the fixed bias current in the MB amp. Also, the replacement tubes may be biased too low causing low output. MB designed the non-adjustable bias to save time and hassle for their users. Sometimes this backfires.
Re: Boogie MK IV Retube
You were not lied to... Mesa Boogie designs thier amps to run fixed bias (a resistor that is not adjustable). To keep a certain standard in tone Mesa sells pre tested tubes for each amplifier, making it a pull out and drop installation.
With this said... Mesa Boogie charges a whole heep load of $$$ for the same tubes everyone else sells. Most rebranded tubes, Groove tubes (marked "C"), ruby tubes, Valve Art, etc are all chinese tubes.
Your volume drop is most likely related to a lower gain preamp tube. try swapping them out for the originals it should fix the issue.
You can use aftermarket over the counter power tubes of your choice but the amplifier will need to be modified to an adjustable fixed bias or the 33K resistor will need to be metered and swapped out for the correct bias of the new tubes.
RECAP -
You were not lied to, The dealer wasn't fluffing you, Mesa boogie wants you to believe your only choice is to buy from them.
If you use a different tube. You have to modify the bias circuit.
Your volume drop is most likely Preamp tube related. i.e. a 12aT7 in place of a 12ax7 or a faulty / dead tube. All Mesa Boogie tubes have a warranty take it back and ask for a replacement. It shouldn't be an issue.
With this said... Mesa Boogie charges a whole heep load of $$$ for the same tubes everyone else sells. Most rebranded tubes, Groove tubes (marked "C"), ruby tubes, Valve Art, etc are all chinese tubes.
Your volume drop is most likely related to a lower gain preamp tube. try swapping them out for the originals it should fix the issue.
You can use aftermarket over the counter power tubes of your choice but the amplifier will need to be modified to an adjustable fixed bias or the 33K resistor will need to be metered and swapped out for the correct bias of the new tubes.
RECAP -
You were not lied to, The dealer wasn't fluffing you, Mesa boogie wants you to believe your only choice is to buy from them.
If you use a different tube. You have to modify the bias circuit.
Your volume drop is most likely Preamp tube related. i.e. a 12aT7 in place of a 12ax7 or a faulty / dead tube. All Mesa Boogie tubes have a warranty take it back and ask for a replacement. It shouldn't be an issue.
My Daughter Build Stone Henge
Re: Boogie MK IV Retube
Egad...
Any experienced seller of tubes can give you a set of power tubes that will function properly in a MB. Preamp tubes are plug n play. Get some decent tubes. +1 on what Selloutr says. Take it back and tell them it was better before you brought it in. Before it just sounded tired. Now it sounds thin and lifeless.
Any experienced seller of tubes can give you a set of power tubes that will function properly in a MB. Preamp tubes are plug n play. Get some decent tubes. +1 on what Selloutr says. Take it back and tell them it was better before you brought it in. Before it just sounded tired. Now it sounds thin and lifeless.
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David Root
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- Location: Chilliwack BC
MESA STR 12AX7s
Where this all devolves to is the MESA STR 12AX7 of the '90s that is probably what your amp was originally equipped with. These are Chinese , so-called Beijing silvertops, that are higher gain 12AX7s that worked VERY well in Mesa Boogie circuits of the time, and earlier, too.
Check them out, if you have these, they have MESA -12AX7- STR sandblasted into the glass lengthwise, you can't miss it, do not let anyone part you from them unless they can prove to you that they are clapped out. Telling you they are clapped out does not cut it!
Oh, I forgot you are not really an electric guy, the above are the preamp tubes, Phil S is right about the power tubes. Svetlana Winged=C EL34s work well with the MESA STRs in old Marshalls so I would think they would be good in a 90s Boogie too.
Check them out, if you have these, they have MESA -12AX7- STR sandblasted into the glass lengthwise, you can't miss it, do not let anyone part you from them unless they can prove to you that they are clapped out. Telling you they are clapped out does not cut it!
Oh, I forgot you are not really an electric guy, the above are the preamp tubes, Phil S is right about the power tubes. Svetlana Winged=C EL34s work well with the MESA STRs in old Marshalls so I would think they would be good in a 90s Boogie too.