Feel free to ask Myles

[BD7]

Ok, is it ok to tap on the tubes to see if there is any sound?Someone suggested that, but I thought I would ask you. Reason I ask is the amp works fine in my studio at home, but playing last week in church it acted up twice on 2 different nights. At home I can't get it to recreate the sound.

[myles_rose]

It is fine to tap on tubes to check for physical microphonics. You will always hear something. It is the degree, level and tone that you think about or any continued ringing.

[Junior 1]

Hi Myles,

It's been a long time since I've asked a dumb question so...

I know if you have an 8 ohm tube amp, you must use a cabinet that is a least 8 ohms or better. I have a Vox DA10 with 2 6.5 inch 8 ohm vox speakers in it. The amp is solid state and 8 ohms. Players on the vox forum are connecting 2 6.5 inch Jensen Mod 4 ohm speakers to the amp. Is this OK? Is it different with a solid state amp? Thanks.

Anthony

[myles_rose]

Anthony - Solid state amplifiers do not have an output transformer and generally can run from about 2 - 16 ohms. As the ohm loading goes up the wattage generally goes down and visa versa.

 

You are probably safe at 4 ohms but the increased current could possibly cause an issue down the road if the etch work is thin or components have no margin in design.

 

If you look at a speaker impedance curve you will see that a 4 ohm rated speaker only hits 4 ohms at specific frequencies and generally runs higher so this is one more reason you should be safe.

 

http://www.jensentone.com/images/mod6-15_speakerg.jpg

 

[Junior 1]

Hi Myles,

As usual, thanks for an expert answer. I'm going to leave those Vox speakers in there.

[myles_rose]

You are quite welcome

[Zephyr]

Just have a quick question: Would you happen to know if the power rating of a Celestion G12H30 (30 watts) is peak or RMS? I was considering hooking up a 45 watt power amp to it as a sound system (keeping things conservative volume-wise), but I just want to be sure; it's a nice speaker.

[myles_rose]

H30 is a 30 watt peak speaker. V30 is a 60 watt peak speaker.

 

The H30 is a great speaker, one of my favorite and what I use in my 1x12 cab that I use most often.

[Zephyr]

Cool, thanks.

 

It really is a great speaker, especially for giving open back cabs some oomph.

[Caevan O’Shite]

Hmmmnnn... Say, Myles, would it be unwise to put a G12H 30 or similar 30-watt speaker like the Weber AlNiCo 1230 in my 1x12 Carvin 'Vintage 33', which is apparently rated at a nominal 33 watts?

 

I do tend to push the amp hard, using my guitar's volume-control to vary cleaner and dirtier tones, and sometimes punish it with pedals like a Foxrox Octron...

[myles_rose]

If you push the amp hard I would use a higher rated speaker.

[LeftyBlues]

Hey Myles how's life on the left coast brother? I'm thinking about building a tube amp, 5W or even less and found AX84.com website that seems decent. I have a degree in electronics tech. by the way. Are you familiar with this site or should I steer towards a different port? Greatly appreciate your time and input as does everybody here.

L.B.

[myles_rose]

Lefty,

 

That AX84 amp .... tons have been built and amps have been born due to that amp giving folks enough faith to build their own who later went into the amp business.

 

Lots of online help from folks that built them.

 

They are a lot of fun and sound great.

 

 

[LeftyBlues]

Your knowledge is priceless Sir Myles, I love to make stuff so I am going to do it. I don't have a drill press so I'll pay the upcharge for a pre-drilled chassis. Something fun to do during winter, I'll remember to practice too.

L.B.

[myles_rose]

You will have a blast and realize that the less "stuff" in a signal path the bigger an amp will sound. Take your time building, don't rush, have fun with the building experience.

 

Keep in mind the amp will NEVER have problems once running other than tube replacement now and then. The reason it will never have a problem is because since you built it you can easily fix it ... so based on cosmic forces, the amp will never break

[Caevan O’Shite]

Keep in mind the amp will NEVER have problems once running other than tube replacement now and then. The reason it will never have a problem is because since you built it you can easily fix it ... so based on cosmic forces, the amp will never break

 

True; now, anything that's NOT easy to fix, WILL REPEATEDLY break down on you!

[TuskBuffer]

Hey Myles--long time no see! I used to post here years ago--didn't realize how long it had been until I saw that this topic goes back to 2002, and I remember when you first put this up as a sticky. I hope all it well with you, and that your holidays are great!

[adam79]

Hi. Looking for your opinion on the best current production 6L6, EL34 and 12AX7 tubes on the market.

 

Thanks,

-Adam

[myles_rose]

Hey Myles--long time no see! I used to post here years ago--didn't realize how long it had been until I saw that this topic goes back to 2002, and I remember when you first put this up as a sticky. I hope all it well with you, and that your holidays are great!

 

All is fine for me. If you are on facebook find me, I am at www.facebook.com/mylesr

 

[myles_rose]

Hi. Looking for your opinion on the best current production 6L6, EL34 and 12AX7 tubes on the market.

 

Thanks,

-Adam

 

Adam,

 

Tubes are personal taste and preference. They all sound differently. Reliability is not consistent.

 

This is a very complex question sort of like me asking you ... what is the best burger on the market.

 

There are over 500 pages on my GAB website that go into a lot of this info and that is the best place to start to gather info.

[Junior 1]

Hi Myles.Happy Holidays and thanks for all your help.

Anthony

[myles_rose]

Anthony,

 

You are more than welcome and have a great holiday season and great 2011.

[d halfnote]

Is there any formula for computing ohms/resistance for non-matching speakers in a single cab ?

[myles_rose]

Do not use non-matching speakers as in 4,8,16 ohm speakers they will not match a common output transformer impedance.

 

Formulas to do all these issue - look on a search engine under ohms law.

[d halfnote]

Perhaps I mis-phrased my question.

What abt using speakers from different manufacturers in a single cab ?

I recently read of a project along those lines intended to shortcut the use of several cabinets, but I lost the original source.

 

Workable ? Good or bad idea ? Thoughts ?

Would the actual effect be too different from the use of independent units ?

[myles_rose]

That is fine of they are very close to the same efficiency otherwise one will overpower the other and not be heard very well.

 

Different cabs vs different speakers in the same cab will sound different due to cab volume and construction plus other factors

[Caevan O’Shite]

Hey, Myles-

 

Just how safe is it for me to run my Fuchs Lucky 7 with an 8 ohm speaker-out into my old GT Electronics Speaker Emulator (the original model) set to 16 ohms? Is this alright, or should I set the Sp Emu to 8 ohms?

 

Particularly considering that I tend to push the amp hard, very often running the Lucky 7's volume full-up, "playing the amp" with my dynamics and the guitar's volume-knob... and I also sometimes hit the amp's input pretty hard with the boosted output from various pedals, including octave-up AND octave-down fuzz from an Octron (and even two octaves down from a Blue Box). I figure, this must be a torture-test at the very least, and wonder about this impedance mismatch...

 

I like the way the Lucky 7 sounds and feels when the Speaker Emulator is set to 16 ohms, as actually recommended in the GTE Sp Emu owners-manual. It's subtly, but noticeably, different from being set to 8 ohs.

 

Thanks in advance for your time and effort!

[myles_rose]

You can always safely run the amp set to puch a higher impedance speaker, not the other way around. If your amp is set to see an 8 ohm load and the load is 16 ohms this is safe. There will be a little power loss but no problems. Speakers impedance is always changing depending on frequency and even an 8 ohm speaker is only 8 ohms at certain frequencies and generally much higher.

 

http://www.jensentone.com/images/c12n_speakerg.jpg

 

[Caevan O’Shite]

Cool, thought so, but was leery, especially considering how hard I push the amp, and tube-amps in general. Thanks!

[bassin bill]

out of warranty, no power.

i checked it w/ a spkr hooked up. before the fuse went the sound coming out of the spkr sounded like sap burning in a fire, the room lights flickered and the fuse blew w/ a slight burning smell. visual inspection showed no melting or burning in the head. sounds like some kind of power issue. does this sound like an easy fix i could take on? or should i just send to authorized repair?