Essential changes for using 6L6's

[tom_kinki3]

Hi,

I'm building my own 5E3 from scratch, i want to put 6L6 valves in for that Neil Young tone.

What essential changes will i need to make and what changes COULD i make in order to achieve Young's distinctive sound?

I've heard something about screen grit resistors? What are they?

Regards,

Tom

[tom_kinki3]

1 input on 5E3

Hi,

I'm building a 5E3 and making a few changes.

I want to just have 1 jack input and then a switch between the bright channel and normal.

How do i achieve this? Where do i out the switch? I'm partially confused because i can't actually see a difference in the bright and normal channel...

Any help would be much appreciated!

Tom

[MWJB]

Why not just have one channel and switch out the 500pf cap between wiper of the volume pot and RH tab of the tone pot (this cap is the difference between the bright & normal channels as it doesn't affect the normal channel on a stock 5E3)?

[tom_kinki3]

2 Different speakers...

Hi all,

I am going to have two 12" speakers in my homebuild 5E3. I was wondering whether it would be possible to use two different types of speaker (some ohmage and wattage), for example one Jensen P12Q and one C12Q. Would it work? And secondly, would it sound at all good, or would they just end up sounding pretty muddy?

Also, does anyone know what speaker Neil Young has is in 5E3, i've heard various different rumours - C12N maybe?

Thanks alot for all your help guys!

Tom

[MWJB]

Same ohmage is a very good idea, as is similar efficiency (SPL, though less critical), so that both speakers share the load reasonably evenly. If you had mismatched impedances the lower impedance speaker would do more work than the higher impedance speaker . Similarly, if you had a 95dB SPL speaker and a 102dB SPL speaker the 102dB would be doing most of the work.

Wattage is less relevant as long as the speaker with the least wattage is up to the job, e.g. if you put a 30W and a 100W speaker in the amp, you're overall wattage rating would really be 60W as the 30W speaker is still expected to do half the work.

It could sound good...depends on the speakers you choose. The 2 you mention would be fine. Be aware you will be greatly increasing the weight of your amp and reducing portability...2 of the great features of a 5E3.

[tom_kinki3]

Hi, thanks alot for your help!

The C12Q has got 93.9dB SPL and the P12Q has got 96.1. Will this be a problem? Or would it be better to use te C12N which has got 98.4dB which the P12Q? The C12N is 50W as opposed to the 35W of the others though...

Thanks again for your help!

Tom

[MWJB]

C12Q & P12Q (2db), won't be a problem...not one that you will hear anyway (which is the acid test). Theoretically, the P12Q will do a little more work but the mismatch is certainly not enough to make the idea unworkable.

Forget wattage in this instance. As long as the lower wattage speaker is enough to handle the power you are OK (all the speakers you mention do). Wattage is just an indication of how much heat the speaker can take before it blows, in the same way that resistors have a wattage rating.

[tom_kinki3]

Right, so now i know it will work, what do you think it will sound like? Personal opinion, is it worth doing?

I can see that it'll either be amazing, and i'll get a great overall sound, or they will just end up being muddy? What do you think?

[MWJB]

I think it is entirely up to you.

Your overall speaker load (ohms) should be matched to the OT, so you will probably want 2x16ohm speakers in parallel for 8ohms.

Don't see why it would necessarily be muddy. It's probably just overkill. There are plenty of good sounding efficient speakers that you could use just one of. Experiment by all means but what is it that you want to achieve?

[Bruce / Mission Amps]

Here's a thought... would the speaker rated at 100dB per watt will do less work then one rated at 94dB per watt?
The 100dB is more effeicent so wouldn't it have less work to do to reproduce the same volume level as the 94dB speaker?

[RickyD]

The SPL is a measure of speaker efficiency. The two speakers would each dissipate the same amount of power if their impedances are identical. The 100dB speaker would be a lot louder than the 94 dB speaker (6dB louder, right?) at any power level. So the 100 dB speaker would be doing a lot more work, moving a lot more air.

Isn't the difference in gain between the #1 and #2 inputs on a 5E3 6 dB? That could give you a feeling for the difference. Connected to the same output in parallel, I don't think you'd hear much of the 94dB speaker.

Tom, I suggest that your plan will probably work out best if the SPL ratings of the two speakers are within 1 dB. That way, you will be able to hear both speakers, which is the point. If it were my project, I would use 2 speakers from the same manufacturer with identical SPL's.

[Bruce / Mission Amps]

The SPL is a measure of speaker efficiency. The two speakers would each dissipate the same amount of power if their impedances are identical. The 100dB speaker would be a lot louder than the 94 dB speaker (6dB louder, right?) at any power level. So the 100 dB speaker would be doing a lot more work, moving a lot more air. ...

I'm not so sure about this and the reason why I suggested it as a question.
Why?
Well, the difinition of power, work, SPL and all that are not totaly linear here and possibly comparing apples to oranges....

**WORK:
Physics, The transfer of energy from one physical system to another, especially the transfer of energy to a body by the application of a force that moves the body in the direction of the force. It is calculated as the product of the force and the distance through which the body moves and is expressed in joules, ergs, and foot-pounds.***

My confusion lies in that we are talking about loudness vs energy used and the 100dB speaker uses less power to sound louder.
How can it be working harder (transfering more energy) while using less current at the same SPL.
I guess it does do more work with less energy... and the real problem is that the 94dB speaker is wasting energy/power, generating less SPL.

[Jag]

I guess it does do more work with less energy... and the real problem is that the 94dB speaker is wasting energy/power, generating less SPL.

This is one of those topics that I get a headache trying to figure out. That definition works for me though.

[tom_kinki3]

Tom, I suggest that your plan will probably work out best if the SPL ratings of the two speakers are within 1 dB. That way, you will be able to hear both speakers, which is the point. If it were my project, I would use 2 speakers from the same manufacturer with identical SPL's.

Ye, but Jensen don't do two different TYPES of speaker with identical SPL, well at least i don't think they do. Do you really think 3dB will mean that you won't actually be able to hear one of them?

Tom

[RickyD]

Tom - Decibels are a logarithmic scale. I was taught that a 3dB increase in volume requires a 10x increase in power. So, IMO, 3dB is too much difference. Try Eminence or Weber. I would use Weber Signature speakers, a 12 and a 12S. Email Weber, they seem to give good advice.

Bruce - Let me recognize your excellent works. The Mission 5E3 is a great amp. I don't want to change anything, mod anything, or upgrade anything. I want it to stay the same. Thanks for your advice while I was building it.

Working harder is not really a technically defined term, so I'm going to stick to speakers doing more (or less) work. People accomplish more with less effort by working smarter, not harder, but that doesn't work for speakers.

The more efficient speaker has more turns on the voice coil and/or a more powerful magnet. Probably both. Hit both speakers with identical signals for just a half wave. Both speakers start and stop moving at the same time. The more efficient speaker has greater force applied to the cone by the voice coil and moves faster, therefore moves farther, therefore does more work (defined as force X distance), thereby transfers more energy to the air, and sounds louder. It generates more acoustic power output per watt of electrical power input.