Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

June 20, 2024, 09:11:40 PM

Login with username, password and session length

Recent Posts

 

Vox speaker out on a AC15C2 using speaker cable, to a Fender Frontman 212R Combo

Started by ctguy1955, April 05, 2013, 07:52:53 PM

Previous topic - Next topic

ctguy1955

 I was just coming here to ask about the impedance, and everyone beat me to it. I wired up the Cliff jack and
everything is working perfectly as a normal 212R without anything plugged into the new cliff jack.

  http://s968.photobucket.com/user/CTguy1955/media/212Rmod_zps1836f515.jpg.html?sort=3&o=0

I knew that the 212R was 4 ohms, and I received the new proper speaker cable today, so I was coming
here to make sure about the ohms before I tried anything out.

If that switch in the back of the Vox that has 16 and 4 ohm rating is not for what I wanted, then I just did all this for nothing ????
Using extension in jack on the vox is the only way I can have all 4 speakers turn on, which is why I did this whole mod in the first place.....

If I have to rewire the speakers in the 212R, then what about using it as a normal Frontman combo?  If I rewire it and change
the speakers from 4 to 8 ohms, wont the signal coming out of the 212R be rated at 4 ohms and mess up the amp or speakers ????

Im sorry I dont know about this stuff, its why I came here for help.

Worse case scenario is I just bought myself a really nice used amp that I like a lot, but I bought the 212R to have a extension speaker as in having 4 speakers on, not 2.


I wont do a thing, I will leave it as is, until I know that I wont hurt anything. At least right now with the Mod I did, I could plug another head into my fender and just use the speakers as is right now, as long as its 4 ohms like the micro terror orange amp for 149 bucks.

Im glad I knew enough not to plug anything in and try it out without coming here first.
***********************************************************************************************************

When you plug into the "EXTERNAL SP" jack, The internal speaker is disconnected. And you must set the impedance switch to match the external speaker cabinet. The jack it's self is switched to disconnect the internal speaker when you use it.

When you plug into the "EXTENSION SP" jack. The internal speaker is put in parallel with the external speaker cabinet.
The external cabinet must be 16 Ohms.
And the impedance switch must be set to 8 ohms.
This is because the 16 Ohms of the extension cabinet in parallel with the 16 Ohms of the internal speaker, equals 8 Ohms.

Do not plug an 8 Ohm load into the "EXTENSION SP" jack under any circumstances.

So when I read the ABOVE, it means I cant use my setup at all ???  wow, what a bummer. 

J M Fahey

Quote
When you plug into the "EXTERNAL SP" jack, The internal speaker is disconnected. And you must set the impedance switch to match the external speaker cabinet. The jack it's self is switched to disconnect the internal speaker when you use it.

When you plug into the "EXTENSION SP" jack. The internal speaker is put in parallel with the external speaker cabinet.
The external cabinet must be 16 Ohms.
And the impedance switch must be set to 8 ohms.
This is because the 16 Ohms of the extension cabinet in parallel with the 16 Ohms of the internal speaker, equals 8 Ohms.

Do not plug an 8 Ohm load into the "EXTENSION SP" jack under any circumstances.

So when I read the ABOVE, it means I cant use my setup at all ???  wow, what a bummer. 

Why do you say so? :(
If you rewire the FM212 speakers in series they now have 16 ohms total and are **perfect** as *Extension Speakers* for your Vox amp.
You will hear *both* the internal 16 ohms speaker *and* the external 16 ohms cabinet.
Isn't that what you wanted?

g1

Quote from: g1 on April 11, 2013, 11:42:03 AM
Quote from: J M Fahey on April 11, 2013, 02:40:51 AM
afaik the Vox has 16 ohms only output, or maybe 8/16 , but that pair of Frontman speakers is wired for 4 ohms.
Oops! Thanks JM, I had forgot to consider impedances.
The Fender speakers wiring will have to be changed from parallel to series (simple).  Then it will be an 8 ohm cabinet.
  The Vox has an 8/16 switch on the back which will have to be set to 8.  The Fender cab will have to be plugged into the EXTERNAL spkr. jack, not the extension jack.  This will mean the Vox's own speaker can not be used at the same time.
  When used by itself, the Fender amp will give a tiny bit less power into the 8 ohm cab than the 4 ohm stock  cab wiring.
ctguy1955, I hope this is still a workable scenario for you.
Sorry about this, it is incorrect.  To quote you from an earlier post "I should just delete that last entry as it makes me look like the jerk that I feel I am"  :)
JM is completely correct,  if you rewire the fender speakers in series, you will have a 16 ohm cab. (not 8 ohm as I incorrectly stated).
  Then you can set the Vox amp to the 8 ohm position and use the EXTENSION spkr. jack.  All 4 speakers will be working.
  As I mentioned earlier, when you use the Fender by itself, it will be putting out a little less power than with the stock wiring, but I doubt you will even notice the difference.

g1

  If you need, here is a picture of series and parallel wiring of the 2  speakers.  Pay close attention to the + and - terminals of the speakers in the series arrangement.
http://www.svvintageamps.com/images/2-speaker-wiring-diagram.gif

ctguy1955

  Well this has been a roller coaster of emotions on my part.....   I can/cant/can/cant......but now I can....   and that is WONDERFUL news !!!!  YEA  !!!!!!!

  I only paid 10 bucks for the speaker cord and 10 bucks for the 2 jacks,  so I was not all that concerned if it didnt work, as I really like the fender amp a lot !!!

   Now that I "CAN" do what I want, I also want to learn a little more about electronics and impedance and the rules where you mulitply or divide or add
and come up with the solutions.   

  I am so thankful for all of the help that Ive received on this channel.  Ive gone to fender and vox and other places and no where was as informative and
as nice as the people on here, and I thank you all so much for helping a newb out.

Im excited to rewire the fender and test it out now, I will get back and let you all know how it sounds !!!!

  Thank You  !!!!!!!!!

ctguy1955

  I have hooked up the Frontman 212R in series as instructed, and afterwards I plugged
in and tested it as a normal combo and it works great and the sound is just fine.

  I am going to wait another day before I unplug the power cord on the 212R and then
plug in the speaker 12ga cord to the Vox extension speaker out and switch the
selector switch to 8 ohms.

  I just want to give everyone a chance to say its ok now......

  I guess a solid state amp is a lot more forgiving then a tube amp.  The 212R was made to
put 4 ohms out to 4 ohm speakers and now that its 8 ohms, I just dont know how the unbalance
( or change ) does not end up hurting the speakers or the amp.   I did see where the speakers were
8 ohm right out of the factory I think on the speaker.


((( EDIT)))   after looking at the photo  I think I may have to switch the two wires on the left hand speaker in order for this to be correct.
When I look at the right side speaker, the white wire + is going to the left speaker White + and it should not be.

I also said that in series its now 8 ohms, but then I was reading things on here and it said now I have 16 ohms, but when I hook up the vox, then they will all be 8 ohms.

So even though it sounded good, Im going to go double check that its always + to a - for every jumper and wire.

Thanks everyone !!!!      I may not even be crazy about the sound of using 4 speakers, but I do like
the sound of the Fender Frontman 212R, so no matter what, Im very happy I bought this Amp  !!!

Thank you all so much for your help with this project  !!!!!!!!!!   Tomorrow is the Day to Test !!!!!!!!!!

ctguy1955

  Sure as heck I had put an extra jumper cable in.  I have now removed it and everything goes from a + to a - now.

Works great and sounds great and Im glad I caught it from the photo and not YOU guys as it means
Im actually learning something here !!!!!!!!   YEA  !!!!

Catch you all tomorrow !!!!

ctguy1955

  I just could not wait, I went and hooked it up and I am happy to say that it worked !!!!!!!!

The tube amp Vox seems to overpower the fender speakers by quite a bit, as I do have them close together and next
to one another, but if I were to separate the fender from the vox by the 10 foot speaker cable, and stand in the middle
I think the vox side would be louder.

I did unplug the 110V cord from the fender combo and was so happy that good sound does come out of those speakers.

When I stuck my head down near the right vox and left fender, they both sounded great in each ear.

  I am so happy that with all of your help, I was able to do a project that some others said could not be done.

  I may not use it this way all that much, unless I do separate the twins, but I do really like the Fender amp and I am very
very happy that everything I wanted came to fruition and worked out great !!!


Thank you all from the bottom of my heart, I appreciate so much what you did for me, and I hope others that may read this and want to try it out too !!
:tu:

ctguy1955

   OK, one last question I have..........

  The speakers in the Fender are 50 watts each. The speakers in the Vox are 35 watts.   If all speakers are now 8 ohms, why does the volume seem louder
in the vox then the fender ?????

  I will have to separate them later today to get a more accurate idea of this, but sitting near the speakers, the vox seemed to way overpower
the sound coming out of the Fender.

  I bought 12 gauge speaker wire, should I have bought 18 for less resistance ???

  Thanks !!!!

Enzo

You asked this same question in a different thread, and I responded there.  I'm not going to re-enter it here too.  Go look.


One thing to be sure of is phasing.

You have wired your fenders in series.  It is critical they also be in phase.  Hot wire from amp/jack to the + of spkr1, a jumper from - of spkt1 to + of spkr2, then from - of spkr2 a wire back to the ground of the amp/jack.

A simple test:
PLug a cord into your Fender jack, as you would to connect it to your Vox.   Now at the free end of the cord, touch the plug tip to one terminal of a 9v battery, and lower the shaft of the plug down to touch the remaining terminal momentarily.  Each touch wshould result in a thump or pop from the speaker.  By itself that is a good test to see if a speaker even works.

But in a two speaker cab, it makes both speakers move.  SO watch the cones closely as you touch the battery.  The cones will move a little ways in one direction.   It is important that both move the SAME direction.  If not, then one is wired backwards.   Out of phase speakers make the same amount of sound, but being out of phase, the sounds cancel so it is a lot less loud.l

J M Fahey

The Fender issued speakers, although not bad, are much cheaper than the Vox issued ones, hence the lower sensitivity, attack, chime, etc.
They work well in the Fender because the 100W amp "pushes" them forward, like it or not.
Sort of a brute force approach.
But in a 15W amp, every fraction of a dB counts.

Now you see the origin of one of the myths: that "tube watts" are more than "SS watts".
It's not so, I have tested that to death for the last 40 years, but the usual (very unfair) comparison is, say, an expensive 15W tube amp ... driving 2 12" Celestions/Jensen/"good" (read expensive) Eminence, in a big cabinet, vs. a cheap SS 15W practice amp, in a shoebox sized cabinet with a weak tiny magnet 8" or 10" generic speaker.

At my shop I once had for a couple months a Mesa Boogie 4x12" cabinet, with 2 Vintage 30 Celestions above, to provide attack, and 2 EVM12L below, to provide incredible low punch and "balls".
Driven by one of my standard SS 100W guitar heads it *smashed* most 100W Tube head + original speaker put beside it (think Twin Reverb, or Laney+412 same brand, etc.) and easily matched, say, a 100W JCM900 or SLX + 1960 cabinet.
Speakers matter much more than is usually acknowledged.

Just as a side note: we all remember many important bands in the early 70's used SS amps (think Creedence, Doors, Zeppelin, etc.)
Well, those old Kustom amps often had 2 (or 3  :o ) JBL15" speakers, same as a Dual Showman cabinet, the "good" Acoustics used 2 x 15" Altec Lansing, the Acoustic 360 Bass amplifier (used by *everybody*) had a Cerwin Vega "earthquake" 18" speaker in a fridge sized horn loaded box and so on.

Enzo

I see in the other thread there might be a possibility of out of phase, so I addressed that.

Juan, I don;t want to launch the inevitable endless discussion, but the claim was never that tube watts were louder than solid state watts.  The claim was that a 50 watt tube amp can be louder than a 50 watt solid state amp.  And as Loudthud demonstrated, the tube amp was able to put a larger voltage across a speaker.   But yes, if you want to generate X number of watts into the same speaker from the two types, they will have the same loudness.  But that does not address the claim.

J M Fahey

Cool. :cheesy:
Not starting anything, just "carrying an umbrella even on a sunny day", I wanted to avoid the *opposite* "automatic" assumption , that "SS watts are cr*p" and specially insisting on the importance of speaker efficiency, which seems to be the problem here.
:dbtu: :dbtu:

PS: and yes, they may even be wired out of phase as you hinted at in another post. :o

Roly

Quote from: ctguy1955I guess a solid state amp is a lot more forgiving then a tube amp.

Er ... no, 'tother way round actually, but each really dislikes opposite things.  A solid-state amp is quite content to run into an open circuit all day, but doesn't like loads that are too low in impedance, and really don't like short circuits which will destroy the output transistors.  Valve amps are also quite tolerant of a range of impedances and won't complain too much about a short, but an open speaker circuit may cause the output transformer to flash over and die.

Don't drive a transistor amp into a short; don't drive a valve amp into an open.

If you say theory and practice don't agree you haven't applied enough theory.

ctguy1955

Wow, I am learning so much, and thank
You all so much for your answers !
  I will check the phasing later today
on the Fender amp. You guys are the best !!!