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Old 06-21-2011, 01:29 PM
SwimTrunks SwimTrunks is offline
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Default Frusterated with my tube amp sound - Peavey Bravo 112

Hey guys, have a bravo 112, 25 watt tube amp, and switched the tubes because they were well over 10 years old. Ive been told that this amp is self biasing, and I could just plug and play.

I felt like I heard a big difference at first, but now playing, it sounds farty again, seems to breakup early, and I'm also getting quite a vibration sound that I cant seem to pinpoint.

I think its time to take it into a tech.

Approx what would a tech charge to look at it? And to put a new speaker in it?

Other than a new speaker, what else might they do to make this thing sound better?

Maybe I am expecting too much from this thing? Ideally, I would like to be able to gig bars and such with it for a little while, being mic'ed, untill I can buy something better.
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Old 06-21-2011, 01:56 PM
terrapin terrapin is offline
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The "farty" thing you describe. Is it mainly in the low notes? These little amps are known for saving cost by using an "economy" output transformer. many people don't notice the results of it, but it can sure cause "farty" lows and an otherwise lacking tone. I recently replaced the Output Transformer in my Princeton Reverb Reissue and the change was immediate. You could look into that. Mercury Magnetics and Heyboer make OT replacements for most popular amps. Heyboers are great and much cheaper then Mercury. They are easy to install if you feel comfortable inside of a tube amp.

The rattle could be anything that is loose in the amp from tube sockets, to input jacks to speaker to baffle... I would check and make sure the speaker baffle has not somehow come loose. It may have been glued in originally and glue dies!

None of the symptoms you mention necessarily point to a bad speaker. Did the speaker sound bad prior to the tube change. What brand tubes did you use? Perhaps the rattle is a microphonic tube...Even new ones can be microphonic. Did you retube the preamp and the output tubes?

A good tech is most likely to have a bench rate of about $75.00 an hour!!!
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Old 06-21-2011, 01:57 PM
Dru Edwards Dru Edwards is offline
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Hey SwimTrunks.

Regarding the vibration sound, it could be a lose screw anywhere in the cab or possibly even a tube not quite situated correctly (i.e. loose). Take a screwdriver to those screws.

What kind of tubes does the amp recommend? i.e. (power tubes) EL-34's, EL-84's, 6L6s, 6V6s, etc; (preamp tubes): 12AX7, 12AT7, etc. If you went from an EL-34 to a 6L6 that would most likely cause issues.

Even though the amp is self-biasing, is there a trim knob to bias anyway?
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Old 06-21-2011, 02:10 PM
terrapin terrapin is offline
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Quote:
Originally Posted by Dru Edwards View Post
Hey SwimTrunks.

Regarding the vibration sound, it could be a lose screw anywhere in the cab or possibly even a tube not quite situated correctly (i.e. loose). Take a screwdriver to those screws.

What kind of tubes does the amp recommend? i.e. (power tubes) EL-34's, EL-84's, 6L6s, 6V6s, etc; (preamp tubes): 12AX7, 12AT7, etc. If you went from an EL-34 to a 6L6 that would most likely cause issues.

Even though the amp is self-biasing, is there a trim knob to bias anyway?
The Bravo is an EL84 based amp with 12AX7's in V1 and V2 as well as the Phase Inverter. These are actually cool little Peavey clones of a Marshall Bluesbreaker. There are a TON of simple modifications folks are doing on these to tighten them up. To the OP.....don't give up on this amp. Try the simple stuff like tightening everything and making sure all the tubes are good. Simple things tend to be the problems a great deal of the time.
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Old 06-21-2011, 02:14 PM
Dru Edwards Dru Edwards is offline
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Quote:
Originally Posted by terrapin View Post
The Bravo is an EL84 based amp with 12AX7's in V1 and V2 as well as the Phase Inverter. These are actually cool little Peavey clones of a Marshall Bluesbreaker. There are a TON of simple modifications folks are doing on these to tighten them up. To the OP.....don't give up on this amp. Try the simple stuff like tightening everything and making sure all the tubes are good. Simple things tend to be the problems a great deal of the time.
Thanks for the info Terrapin. I always enjoying discussing tube amps.
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Old 06-21-2011, 02:22 PM
SwimTrunks SwimTrunks is offline
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Appreciate the comments guys.

I used 12ax7 and EL84 tubes.
I couldnt see any type of trim knob for them.

I pushed them in well and they seemed to be snug.
I will look around for a loose screw or something, I will also inspect the speaker.
The vibration is new since I put the new tubes in, so maybe I left something in the bottom of the amp I cant see, or something. It seems to be coming from the speaker more than anything.

As for the farty sound, I guess maybe its less farty, and just breaks up more.
I think the sound was quite farty before the new tubes, and less farty now, but it just doesnt seem to be clean, crisp, and punchy like I want it to be.
Like I said before, maybe I'm asking too much of it.

I will inspect all of these things, and then repost, and maybe take it to a tech. Either way, I should probably start with a new speaker maybe, because I would think that would be an immediate upgrade.
Can I get a good speaker for it for under $150? The cheaper the better, since I want to buy a fender amp for gigging when I get the money.
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Old 06-21-2011, 02:41 PM
terrapin terrapin is offline
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Quote:
Originally Posted by SwimTrunks View Post
Appreciate the comments guys.

I used 12ax7 and EL84 tubes.
I couldnt see any type of trim knob for them.

I pushed them in well and they seemed to be snug.
I will look around for a loose screw or something, I will also inspect the speaker.
The vibration is new since I put the new tubes in, so maybe I left something in the bottom of the amp I cant see, or something. It seems to be coming from the speaker more than anything.

As for the farty sound, I guess maybe its less farty, and just breaks up more.
I think the sound was quite farty before the new tubes, and less farty now, but it just doesnt seem to be clean, crisp, and punchy like I want it to be.
Like I said before, maybe I'm asking too much of it.


I will inspect all of these things, and then repost, and maybe take it to a tech. Either way, I should probably start with a new speaker maybe, because I would think that would be an immediate upgrade.
Can I get a good speaker for it for under $150? The cheaper the better, since I want to buy a fender amp for gigging when I get the money.
It is a 12" speaker, right? you can get a very good used one over on The Gear Page (http://www.thegearpage.net/board/) for $50-75. It would most likely be money well spent. If you want the amp to have more clean head room try replacing the 12AX7's in V1 and V2 (furthest from output tubes) with 12AY7's of 12AT7's. These are lower gain versions of the 12AX7 and can make quite a difference. V1 is most important as that is your primary gain stage. The third 12AX7 is your Phase Inverter and has minimal impact on the gain/tone. You can even try just removing the 12AX7 from V2. The amp will still work fine, but may have a bit more clean headroom.

Good Luck.............
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Old 06-21-2011, 02:45 PM
SwimTrunks SwimTrunks is offline
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Quote:
Originally Posted by terrapin View Post
It is a 12" speaker, right? you can get a very good used one over on The Gear Page (http://www.thegearpage.net/board/) for $50-75. It would most likely be money well spent. If you want the amp to have more clean head room try replacing the 12AX7's in V1 and V2 (furthest from output tubes) with 12AY7's of 12AT7's. These are lower gain versions of the 12AX7 and can make quite a difference. V1 is most important as that is your primary gain stage. The third 12AX7 is your Phase Inverter and has minimal impact on the gain/tone. You can even try just removing the 12AX7 from V2. The amp will still work fine, but may have a bit more clean headroom.

Good Luck.............
Nice info, thanks Russ.

Ok just took a better look at the amp. So I found a pencil in it, oops!! This seemed to be the major vibration happening.

It's still quite farty when turned up, to my ear, it seems to be coming from the speaker. I can't see any visible problems with the speaker itself, but I dont really know what I'm looking for.

I'll try the tube thing, and look around for a new speaker and then repost again. Thanks!!
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Old 06-21-2011, 03:10 PM
Dru Edwards Dru Edwards is offline
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Quote:
Originally Posted by SwimTrunks View Post
Nice info, thanks Russ.

Ok just took a better look at the amp. So I found a pencil in it, oops!! This seemed to be the major vibration happening.
It's still quite farty when turned up, to my ear, it seems to be coming from the speaker. I can't see any visible problems with the speaker itself, but I dont really know what I'm looking for.

I'll try the tube thing, and look around for a new speaker and then repost again. Thanks!!
That makes me laugh ... and here I thought it might have been a loose screw. Glad you found it. If you took it into a tech with a pencil in it he would have thought you were prime for overcharging!
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Old 06-21-2011, 03:10 PM
terrapin terrapin is offline
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Quote:
Originally Posted by SwimTrunks View Post
Nice info, thanks Russ.

Ok just took a better look at the amp. So I found a pencil in it, oops!! This seemed to be the major vibration happening.

It's still quite farty when turned up, to my ear, it seems to be coming from the speaker. I can't see any visible problems with the speaker itself, but I dont really know what I'm looking for.

I'll try the tube thing, and look around for a new speaker and then repost again. Thanks!!
The "fartiness" would always SEEM to come from the speaker because it is the ultimate source of the sound signal. But, it does not mean the sound originates at the speaker. It could, but it could also be the Output Transformer. The louder you turn an amp up the harder the transformer has to work. I agree with trying a new speaker.
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Old 06-21-2011, 03:12 PM
JCW308 JCW308 is offline
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Try 5751 preamp tubes for less break-up and a different speaker.

Quote:
Originally Posted by SwimTrunks View Post
Appreciate the comments guys.

I used 12ax7 and EL84 tubes.
I couldnt see any type of trim knob for them.

I pushed them in well and they seemed to be snug.
I will look around for a loose screw or something, I will also inspect the speaker.
The vibration is new since I put the new tubes in, so maybe I left something in the bottom of the amp I cant see, or something. It seems to be coming from the speaker more than anything.

As for the farty sound, I guess maybe its less farty, and just breaks up more.
I think the sound was quite farty before the new tubes, and less farty now, but it just doesnt seem to be clean, crisp, and punchy like I want it to be.
Like I said before, maybe I'm asking too much of it.

I will inspect all of these things, and then repost, and maybe take it to a tech. Either way, I should probably start with a new speaker maybe, because I would think that would be an immediate upgrade.
Can I get a good speaker for it for under $150? The cheaper the better, since I want to buy a fender amp for gigging when I get the money.
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Old 06-21-2011, 04:15 PM
lmacmil lmacmil is offline
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Quote:
Originally Posted by SwimTrunks View Post
Can I get a good speaker for it for under $150? The cheaper the better, since I want to buy a fender amp for gigging when I get the money.
Weber Signature series, C12 or C12S, $35.

https://taweber.powweb.com/weber/
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Old 06-21-2011, 04:54 PM
mrmatt1972 mrmatt1972 is offline
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You should inspect the speaker for tears or cone rub to find out if it is the source of the problem... An easy thing to try,if the amp has a speaker out, is to disconnect the speaker in the cab and run the amp through another cabinet (like a friend's 4x12 or something). If the fartiness is gone, it's the speaker. Proximity to a wall or furniture can often mess with the tone of a little combo too. Also, turn the bass knob down.
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Old 06-21-2011, 06:22 PM
SwimTrunks SwimTrunks is offline
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Quote:
Originally Posted by mrmatt1972 View Post
You should inspect the speaker for tears or cone rub to find out if it is the source of the problem... An easy thing to try,if the amp has a speaker out, is to disconnect the speaker in the cab and run the amp through another cabinet (like a friend's 4x12 or something). If the fartiness is gone, it's the speaker. Proximity to a wall or furniture can often mess with the tone of a little combo too. Also, turn the bass knob down.
thanks,

when I turn the base down to 0, the fartyness is gone,
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Old 06-21-2011, 06:42 PM
terrapin terrapin is offline
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Quote:
Originally Posted by SwimTrunks View Post
thanks,

when I turn the base down to 0, the fartyness is gone,
Of course, the "fartyness" would be in the low end. At this point I say it is probably the speaker and if not it is the Output Transformer.
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