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View Full Version : Frusterated with my tube amp sound - Peavey Bravo 112


SwimTrunks
06-21-2011, 01:29 PM
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.

terrapin
06-21-2011, 01:56 PM
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!!!

Dru Edwards
06-21-2011, 01:57 PM
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?

terrapin
06-21-2011, 02:10 PM
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.

Dru Edwards
06-21-2011, 02:14 PM
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.

SwimTrunks
06-21-2011, 02:22 PM
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.

terrapin
06-21-2011, 02:41 PM
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.............

SwimTrunks
06-21-2011, 02:45 PM
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!!

Dru Edwards
06-21-2011, 03:10 PM
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!

terrapin
06-21-2011, 03:10 PM
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.

jwoertz
06-21-2011, 03:12 PM
Try 5751 preamp tubes for less break-up and a different speaker.

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.

lmacmil
06-21-2011, 04:15 PM
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/

mrmatt1972
06-21-2011, 04:54 PM
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.

SwimTrunks
06-21-2011, 06:22 PM
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,

terrapin
06-21-2011, 06:42 PM
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.

Landru
06-21-2011, 06:45 PM
Here's an interesting point:

What brand of tubes did you have, and what brand do you have now?

SwimTrunks
06-21-2011, 07:13 PM
Here's an interesting point:

What brand of tubes did you have, and what brand do you have now?

the two el84's are groove tubes i believe, they were about 35$ for two, and I forget what the 12ax7's are.

I have no idea waht they were before, they were stock peavey tubes.

SwimTrunks
06-21-2011, 07:18 PM
So, I unplugged the Peavey speaker, and plugged in the stock 12" speaker out of my friends Traynor YCV 40, and it was so much louder.

It still seemed to be fizzy and buzzy, but much less farty. But, the traynor sounded a bit fizzy itself. I have no idea if I'm making any sense, its hard to explain sounds.

I plugged the peavey speaker back in, and it was still quite fizzy, and distorting early.

I cant tell if the fizzy sound is the amp vibrating or something else.

Landru
06-21-2011, 07:34 PM
Well - find out what the 12ax7's are.

If there is nothing wrong with your amp and the tubes are the only things that changed before you noticed the bad bass, I'd venture it's the tubes. If you've got groove tubes, you've got Russian or Bulgarian or Chinese - I kind of trust groove tubes, just don't trust the tubes they use.

Try this: Change out the ax's - they are responsible for tone and maybe one is not doing the job. It's a little tough if you don't have a tube tester or tube knowledge, but try it. What would I recommend?

Well - to do this right you'd ebay some vintage Mullard or Amperex ECC83 (12AX7 euro equivalent). Do a bit of snooping and find out what is a strong rating (tubes tested on different machines have different strength scales, making it tough to keep things straight). If the seller is using a TV-7-type tester, 25=65% and 40=100%. If the seller does not list the strength, pass on to the next set - and, they don't have to be matched in strength. Try to find them at a not too expensive price. If done right, these are the best tubes in the world - manufactured in England and Holland in the '50's - '60's. Sound incredible and last forever.

What I've recommended is muy exotica, that's for sure. Tubes are important.

mrmatt1972
06-21-2011, 07:46 PM
It sounds like the speaker is part of the problem, but also the power tubes are more likely the culprits if ugly bass and fizziness are heard. It is also VERY likely that your amp needs a "cap job" - most if not all of the symptoms you describe can be attributed to this problem.

I'd try popping in the old preamp tubes to see if it makes a difference - decent ones almost never wear out anyway.

Anyway, good luck. Here's one of the best links on the web for amp trouble shooting

http://www.geofex.com/ampdbug/ampdebug.htm

terrapin
06-21-2011, 08:55 PM
Well - find out what the 12ax7's are.

If there is nothing wrong with your amp and the tubes are the only things that changed before you noticed the bad bass, I'd venture it's the tubes. If you've got groove tubes, you've got Russian or Bulgarian or Chinese - I kind of trust groove tubes, just don't trust the tubes they use.

Try this: Change out the ax's - they are responsible for tone and maybe one is not doing the job. It's a little tough if you don't have a tube tester or tube knowledge, but try it. What would I recommend?

Well - to do this right you'd ebay some vintage Mullard or Amperex ECC83 (12AX7 euro equivalent). Do a bit of snooping and find out what is a strong rating (tubes tested on different machines have different strength scales, making it tough to keep things straight). If the seller is using a TV-7-type tester, 25=65% and 40=100%. If the seller does not list the strength, pass on to the next set - and, they don't have to be matched in strength. Try to find them at a not too expensive price. If done right, these are the best tubes in the world - manufactured in England and Holland in the '50's - '60's. Sound incredible and last forever.

What I've recommended is muy exotica, that's for sure. Tubes are important.

So true about Groove Tubes suppliers...The Mullard/Bugle Boy preamp tubes are certainly a wonderful idea EXCEPT the OP's amp is not worth the cost of a Preamp retube with those tubes at NOS tested prices from a reputable dealer and I would have a tough time trusting E-Bay for $100 tubes.

And someone mentioned a Cap job.......that could easily be involved with this and expensive tubes can't function as possible with bad, leaky caps....

Landru
06-21-2011, 09:52 PM
Yeah Russ - you did find the holes in my tube seminar. Unless experienced, things might so south.

soma5
06-22-2011, 08:53 AM
It may just be that you aren't really a fan of the low-power EL84 sound. I have never bonded with that sound. For low power, I really like the sound of 6V6 tubes (think small Fender amps from the '60s). I've got two old Deluxe Reverbs and one old Princeton Reverb and they all sound great to me. I have owned a couple of low-power EL84 designs (Fender Pro Junior and Peavey Classic 30) and never really got them to sound the way I liked or to repond to my picking the way I wanted. There is usually a limit to how much energy one is willing to put into an amp before one says "Enough!" and moves on. Maybe you're getting there.

terrapin
06-22-2011, 09:00 AM
It may just be that you aren't really a fan of the low-power EL84 sound. I have never bonded with that sound. For low power, I really like the sound of 6V6 tubes (think small Fender amps from the '60s). I've got two old Deluxe Reverbs and one old Princeton Reverb and they all sound great to me. I have owned a couple of low-power EL84 designs (Fender Pro Junior and Peavey Classic 30) and never really got them to sound the way I liked or to repond to my picking the way I wanted. There is usually a limit to how much energy one is willing to put into an amp before one says "Enough!" and moves on. Maybe you're getting there.

EL84's are not necessarily "low-power". Just look at the volume and projection that Vox gets from 2 EL84's in an AC15. The power thing basically depends on how much rectified voltage you are giving the power tubes in the bias configuration. EL84's are the most readily available power tube on the market these days. The OP's Peavey has often been copmpared to "a poor man's Deluxe Reverb". My point is that with a bit of knowledge and work hiis little amp could be quite nice. He said he wants to get a Fender, so the Peavey would make a great back-up amp. The Telecaster Forum is loaded with ideas for simple mods for this amp to improve the basic design and circuit.

soma5
06-22-2011, 09:09 AM
EL84's are not necessarily "low-power". Just look at the volume and projection that Vox gets from an AC15. The power thing basically depends on how much wattage you are giving the power tubes in the bias configuration. EL84's are the most readily available power tube on the market these days. The OP's Peavey has often been copmpared to "a poor man's Deluxe Reverb". My point is that with a bit of knowledge and work hiis little amp could be quite nice. He said he wants to get a Fender, so the Peavey would make a great back-up amp. The Telecaster Forum is loaded with ideas for simple mods for this amp to improve the basic design and circuit.

No tube produces only inherently low-power designs, clearly. What I said was that the sound of low-power EL84 designs has not appealed to me. The model we are discussing is a low-power EL84 design.

Perhaps with enough time, energy and monetary input he will wind up with something he likes. Personally, and understand that I speak only for myself here, I have not been able to succeed before my patience wore out. If your experience is different, that would be no surprise to me. I am not contradicting you at all. I'm just mentioning my own experience and wondering if it might apply to the OP, who is already frustrated.

terrapin
06-22-2011, 09:33 AM
No tube produces only inherently low-power designs, clearly. What I said was that the sound of low-power EL84 designs has not appealed to me. The model we are discussing is a low-power EL84 design.

Perhaps with enough time, energy and monetary input he will wind up with something he likes. Personally, and understand that I speak only for myself here, I have not been able to succeed before my patience wore out. If your experience is different, that would be no surprise to me. I am not contradicting you at all. I'm just mentioning my own experience and wondering if it might apply to the OP, who is already frustrated.

Yes, your points are well taken. I just think so many people abandon tube amps when a few simple, inexpensive tweaks could have gotten the amp close to where they want it. I have friends who have decided to abandon an amp as a lost cause when the only problem was a few capacitors that had aged and drifted off spec or the output tranny was dying or the factory installed negative feedback loop was making the amp sound constipated...

soma5
06-22-2011, 09:49 AM
Yes, your points are well taken. I just think so many people abandon tube amps when a few simple, inexpensive tweaks could have gotten the amp close to where they want it. I have friends who have decided to abandon an amp as a lost cause when the only problem was a few capacitors that had aged and drifted off spec or the output tranny was dying or the factory installed negative feedback loop was making the amp sound constipated...

I completely agree. I have in fact been the happy beneficiary of such frustration...

At this point, I would only buy an amp if I had already played one that I liked a lot and never based on reviews. I'd do exactly the same mods as the one I'd played and start my own tweaking from there. I've found that the seemingly short journey from an amp that sounds decent to one that I'd call a keeper can be frustratingly long.