Jump to content
Gibson Brands Forums
Sign in to follow this  
Riptide

Amp Tubes

Recommended Posts

So I'm trying to get some more volume out of my Epiphone Valve Junior without it starting to break up. I'm looking at either using a 12au7 or a harder El84 like 7-10 (right now I'm running a 12ax7 and an El84 rated at 5) What do you all think the best option is?

 

Thanks!

Share this post


Link to post
Share on other sites

I don't really think you can do what you want to do. If you drop the gain value of the preamp tube, you also drop the overall volume. So while it may not break up as early according to the knob with a 12AU7, it will be much quieter at a given knob setting. Thus you will have to dial it to 80% to get what would have been 50% with the 12AX7 and vice versa. You might investigate a resistor mod on that circuit board instead. It's simple and very moddable. Another thought, add another VJ and run them in stereo. I did this for a while and it sounded pretty good.

Share this post


Link to post
Share on other sites

I don't really think you can do what you want to do. If you drop the gain value of the preamp tube, you also drop the overall volume. So while it may not break up as early according to the knob with a 12AU7, it will be much quieter at a given knob setting. Thus you will have to dial it to 80% to get what would have been 50% with the 12AX7 and vice versa. You might investigate a resistor mod on that circuit board instead. It's simple and very moddable. Another thought, add another VJ and run them in stereo. I did this for a while and it sounded pretty good.

 

Okay thanks for the reply. And getting a output tube with a higher rating (or whatever you call it) won't work either?

Share this post


Link to post
Share on other sites

Okay thanks for the reply. And getting a output tube with a higher rating (or whatever you call it) won't work either?

 

I don't think so. There is a new EL84 that breaks up earlier (the EL844) but this is the opposite of what you want. While some versions of the tube may remain a bit cleaner at a given plate voltage, the differences will be minor I think. You are just not going to get clean volume out of one EL84.

Share this post


Link to post
Share on other sites

I don't think so. There is a new EL84 that breaks up earlier (the EL844) but this is the opposite of what you want. While some versions of the tube may remain a bit cleaner at a given plate voltage, the differences will be minor I think. You are just not going to get clean volume out of one EL84.

 

Okay thanks for your help!

 

Is there a certain brand you suggest?

Share this post


Link to post
Share on other sites

what Surf says is true about total volume loss, but if it's really tone you're concerned about,

12au7=ecc82, which is what i've swapped the preamp section to (from 12ax7/ecc83) in both my Blackstar HT5 & Blues Jr, to solve that exact issue.

couldn't be happier....tone is smoother, with more volume before noticible breakup.

there's also a 12at7/ecc81 that's supposed to be even lower gain yet.....I was just looking at them online when I read your post.

Share this post


Link to post
Share on other sites

there's also a 12at7/ecc81 that's supposed to be even lower gain yet.....I was just looking at them online when I read your post.

 

Actually the 12AT7/ECC81 is actually quite a bit higher than the 12AU7. Think of the 12AX7 as 100%. Then the 12AT7 in about 60% and the 12AU7 less than 20% of the 12AX7 gain. There is also a 5751 which hangs around 75% on 12AX7 gain.

Share this post


Link to post
Share on other sites

Could part of the early breakup be the speaker? Maybe try looking into a higher efficiency speaker, or some modifications to take out some of the clipping.

Share this post


Link to post
Share on other sites

Actually the 12AT7/ECC81 is actually quite a bit higher than the 12AU7. Think of the 12AX7 as 100%. Then the 12AT7 in about 60% and the 12AU7 less than 20% of the 12AX7 gain. There is also a 5751 which hangs around 75% on 12AX7 gain.

 

just last night I was looking on "Tube-Depot" pricing wavy glass Mullard ecc82s....i'm running 3 of them in a Blues Jr.(scavenged from an older amp).....when I saw them priced at $299.95 EACH I almost wet myself. [scared] time to pull those bad boys & sell them......nah, they sound too good.

Share this post


Link to post
Share on other sites

what Surf says is true about total volume loss, but if it's really tone you're concerned about,

12au7=ecc82, which is what i've swapped the preamp section to (from 12ax7/ecc83) in both my Blackstar HT5 & Blues Jr, to solve that exact issue.

couldn't be happier....tone is smoother, with more volume before noticible breakup.

there's also a 12at7/ecc81 that's supposed to be even lower gain yet.....I was just looking at them online when I read your post.

Noted. Thanks!

 

Could part of the early breakup be the speaker? Maybe try looking into a higher efficiency speaker, or some modifications to take out some of the clipping.

I don't think so, the speaker has a pretty high rating and my amp isn't turned up that loud.

Share this post


Link to post
Share on other sites

Noted. Thanks!

 

 

I don't think so, the speaker has a pretty high rating and my amp isn't turned up that loud.

 

 

The advice about the speaker is right on... He s talking about efficiency rating not wattage. If it the stock speaker it likely is not the most efficient.

Check with a speaker expert...

Share this post


Link to post
Share on other sites

dunno how you did it Reiska666, but your avitar is the tubes that I was pithing m'self over!!

 

or, is that the Mullard "Black Sable" that nets, $599.99 each?

Share this post


Link to post
Share on other sites

+1 on the speaker efficiency comment.

 

I have a Traynor 40 watt that was refitted from a 30 watt Celestion to a 100 Watt Celestion to give more clean headroom. I've also used the 8 ohm speaker output from my Epi Valve Junior to a 200 watt PA speaker and got tons of clear headroom, but it was too sterile, not being a guitar speaker.

Share this post


Link to post
Share on other sites

Well you tell me.

 

"Thank you for your inquiry. Eminence and Epiphone engineers collaborated to

develop the Lady Luck speaker specifically for the new line of Epiphone

Amplifiers. The development and testing of this speaker has been in process for

about two years. The speaker is a 16 ohm model and is rated for 70 watts RMS.

Each speaker sports a custom Epiphone/Eminence finish in Mustard Yellow along

with the Lady Luck label on the back. The speaker has a stamped steel frame, a

front rear sealing gasket, a 34 oz magnet, 1.75" voice coil, a full paper cone

with paper edge, and a cloth dust cap. This speaker has a sensitivity of 99dB

and a useable frequency range from 80Hz-5kHz. It has a very smooth response

from the low-end through the mid range. It also has a very nice top end sparkle.

The speaker was engineered to exhibit very warm, and smooth break-up modes. The

tonality of the amp is such that very little tonal coloration from the speaker

was desired. Consequently, the speaker was engineered to provide a subtle, yet

effective compliment to the amplifier."

 

Strangely the speakers sounds really close to a Greenback.

Share this post


Link to post
Share on other sites

You can try a harder output tube - with a high rating. But you're beating your head against the wall if you're trying to get much more volume out of that amp. You can try a bigger speaker, but bigger speakers usually give you a more wimpy tone. A 12 inch speaker is pretty big for a 5 w amp.

 

I'd try a hard output tube. There's no sense messing with the preamp tubes. That won't fix your problem. Sticking a 12AT7 in there is just like having a 12ax7 and turning down the volume some.

[thumbup]

Share this post


Link to post
Share on other sites

You can try a harder output tube - with a high rating. But you're beating your head against the wall if you're trying to get much more volume out of that amp. You can try a bigger speaker, but bigger speakers usually give you a more wimpy tone. A 12 inch speaker is pretty big for a 5 w amp.

 

I'd try a hard output tube. There's no sense messing with the preamp tubes. That won't fix your problem. Sticking a 12AT7 in there is just like having a 12ax7 and turning down the volume some.

[thumbup]

Thanks, that's what people have been telling me. I only turn it up to like 10 or 11 o'clock so that's why I was asking if I could get anymore clean head room. They keep on asking me for some more volume at my church... awesome right? [flapper]

 

EDIT:: I think I just need to get another amp.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...