Recto 2x12, speakers replaced with EV-EVM-12L's. Problems?

[mightywarlock]

so i am not sure if any of you have been following the trials and tribulations in the Classifieds section, but someone in CA tossed on ebay some brand new circa 1983 Electro-Voice EVM 12L's. I went and picked them up last night, and took my Recto 2x12 apart tonight, and tried to pop the new speakers in there.
First problem I had was that the screws that secure the speakers in place were too short and i had to go get different screws to mount the new speakers, due to them being much thicker at the base than the Celestion-v30's.
so i get them mounted, and decide to run them in Serial, (each speaker is considered 8ohms (even though it read as 5.3ohms on the meter). I run the wire from the jack tip to left speaker's red post. then black to the other speakers red post. then black to the jack's ground (as someone told me to do in the classifieds section posting).
I test it with the voltmeter and it reads 10.something ohms. ok...so i plug the stiletto's 8ohm output to the speaker input, and turn it on...and it works!
but...
when i start cranking the amp, once i start getting pretty loud, it sounds like the speakers start...making the farting noise, and get kinda crackly.

so...what could this be?

did i buy bad speakers? they looked brand new, in the box...looked untouched.

or do i have a problem with my wiring perhaps?

as i turn it up, could i have a loose wire that is vibrating loose, causing that noise to happen?
when i turn it back down again (less than 10:30) the speakers sound fine. they seem to have less treble and a bit more bass than the v30's in the 2x12.
But i cant use it if they are no good, and will have to replace the celestions if i cant figure this one out.

any suggestions?

 

[vic]

do you have any cold solder joints?.try resoldering that might work

 

[Newysurfer]

I'd keep the V30's in there - best rock and blues speakers you can buy

 

[Anonymous]

check first if the speaker are ok:

get your 5 fingers equally touching the space between cone (middle) and ring (outer side) like a circle.

then carefully push the membrane (you could also use a 9v block battery, switching from plus to minus)

there should be no scratching or any sandy noise coming up.

open the back of the magnets and detach the screws to loosen the magnet from the socket. if you get this done you should see the speaker coil. take a close look for any distorted area, black wire etc.

ev's are quite reliable, though i owned a few ev 15"b (fantastic speaker)some years ago which needed all reconing

good luck!

 

[mightywarlock]

now here's a quick question...
can the sound i am hearing be "MOTORBOATING"?

can something to do with these speakers and their load cause this in the amp?

here's a few things i have noticed since last night.

i am getting more feedback. albeit, i have been close to the amp and cab with my guitar in hand, but it seems as though i am getting more howling feedback.
i noticed this last night, and tonight, i only tested the amp out for a minute with the cab, and i noticed a big flash from behind the amp (i am assuming one of the tubes) when i had cranked it up, and was doing some palm muting to get it to make that sound again...i thought i blew a tube, and quickly got the amp in standby, and shut it off.
i checked the tubes and at first glance they seem fine.

now...

before i turned the amp on tonight, i took the voltmeter to the cable out of the cab again tonight, and it read 12 something ohms. when i checked the jack positive and negative it read as last night, 10.3 ohms.

previously with my vintage 30's in the cab it always read something like 7.2
i checked the wires and they seemed ok at first glance as well.

now i was able to get the amp pretty loud before it made this sound and i saw the flash, which is making me now wonder if it's the amp not liking this cab with these speakers, the way it is set up.




could this be??


if so, i might just put the v30's back in and forget about it.

 

[NoGlassNoClass]

...ok...so i plug the stiletto's 8ohm output to the speaker input, and turn it on...

Two 8-ohm speakers in series = 16 Ohms. Use the 16-Ohm out from your amp. 8 Ohms is the *nominal* impedance of the speaker. At rest it will read 5 or 6, at full excursion it can be upwards of 30. Also, your treble response should improve with the cab plugged in to the proper jack on the amp.

You could also wire the cab in parallel, for a 4-ohm load. In the unlikely event one of the speakers fails, your amp will see an 8-ohm load and be protected. If a speaker fails in a series connection, your amp sees no load...bye bye output transformer.

Crackling noise could be a loose wire in the cab, a bad speaker cable, dirty connection, preamp tube, any number of things....look around carefully and you will find it.

 

[NoGlassNoClass]

now here's a quick question...
can the sound i am hearing be "MOTORBOATING"?...

...i am getting more feedback. albeit, i have been close to the amp and cab with my guitar in hand, but it seems as though i am getting more howling feedback...

i noticed this last night, and tonight, i only tested the amp out for a minute with the cab, and i noticed a big flash from behind the amp (i am assuming one of the tubes)...

"Motorboating" is a symptom of a bad preamp tube (sounds more like a helicopter than a boat to me...)

Bright flash...power tube or rectifier tube. play loud and watch the tubes...if one of them sparks or the plates glow red, replace them. If a rectifier tube fails it will prob blow the fuse.

Excessive feedback...yeah you're probably just too close, but could also be a preamp tube.

 

[mightywarlock]

now here's a quick question...
can the sound i am hearing be "MOTORBOATING"?...

...i am getting more feedback. albeit, i have been close to the amp and cab with my guitar in hand, but it seems as though i am getting more howling feedback...

i noticed this last night, and tonight, i only tested the amp out for a minute with the cab, and i noticed a big flash from behind the amp (i am assuming one of the tubes)...

"Motorboating" is a symptom of a bad preamp tube (sounds more like a helicopter than a boat to me...)

Bright flash...power tube or rectifier tube. play loud and watch the tubes...if one of them sparks or the plates glow red, replace them. If a rectifier tube fails it will prob blow the fuse.

Excessive feedback...yeah you're probably just too close, but could also be a preamp tube.

but could the new speakers, or the new load on the amp from the new speakers, have caused one of my tubes to blow like that? i have had no issues with the Deuce at all until i plugged this cab with these new speakers into it. and it's not until i push the amp that i seem to have a problem. the speakers sound ok until i get to about 10:30, 11:00 on the dial, which is fairly loud.

and by the way to someone else, the stiletto only has 8 and 4 ohm outputs, no 16.

 

[Boogafunk]

if it has no 16 ohm tap then why in the world would you wire the speakers in series for a 16 ohm load. btw don't pay attention to what the multimeter tells you, they're 8 ohm speakers. wire them up parallel and use the 4 ohm tap on your amp. depending on your amp design, running loads that are not reccommended can be harmful to your amp. i'm not a tech, but i imagine there is no 16ohm output on your amp for a reason.

 

[siggy14]

Running 8 Ohm into a 16 Ohm load is perfectly safe and actually softer on your amp then running 8 ohms into 8 ohms. However you will not get full output and it will be more relaxed.

I would honestly rewire it in parallel, why you ask, because in serieds if one of the speakers blows in a 2x12 cabinet, then you have no load at all on your amp and you just fried it. With parallel if one speaker blows the second one is still ok and putting a load on the amp.

As to the rattling, make sure all your screws are tight on both speakers and the back part of the cab.

if it has no 16 ohm tap then why in the world would you wire the speakers in series for a 16 ohm load. btw don't pay attention to what the multimeter tells you, they're 8 ohm speakers. wire them up parallel and use the 4 ohm tap on your amp. depending on your amp design, running loads that are not reccommended can be harmful to your amp. i'm not a tech, but i imagine there is no 16ohm output on your amp for a reason.

 

[boogietone]

I did the exact same thing replacing V30's with EV12L's in a Mesa 2X12 cab. I wired them exactly as the V30's were. So, parallel @ 4ohms. They sound awesome. I had to get some new fasteners as well due to the originals being too short. While I was at I installed beam blockers. MKIV and MKIII sound killer! So, to echo everyone else, wire it in parallel.

 

[Boogafunk]

again i am no tech, but i believe with tube amps the impedance rules are backwards from solid state. with a solid state amp it is safe to go above the rated impedance, but it will cost you power. your amp will have less of a strain pushing power at a higher impedance.

with a tube amp i believe it is not always the case and depending on the amp design it might be harmful, but it is definately not optimal. maby one of you ee types can enlighten us. not saying you're wrong, siggy, but i have heard that quite a few times over the years. (it might be complete bs however)

 

[sbalderrama]

In nearly every Mesa manual I've seen they mention that mismatches are not that big of a deal, so I think Mesa has overbuilt their amps enough so that 16 into 8 or 4 into 8, that kindof thing, are probably not going to damage things, at least immediately. I just had my old Mark 1 at Mesa for clean up and recap. It only has 2 unmarked speaker jacks on it and I asked Mike what they are rated. He said that basically I only have 4 ohm taps on that amp, even though the speaker in the combo ( which looks to have been original to the amp) is 8ohm. Using a higher rated speaker will mellow the highs a bit and knock down the output volume.

As for the EV... they should have alot less farting sounds than V30's when cranked. Somehow you probably need to figure out if its coming from the speakers or some other mechanical vibration in the cab.

 

[t0aj15]

so i get them mounted, and decide to run them in Serial, (each speaker is considered 8ohms (even though it read as 5.3ohms on the meter). I run the wire from the jack tip to left speaker's red post. then black to the other speakers red post. then black to the jack's ground (as someone told me to do in the classifieds section posting). any suggestions?

That wiring does not sound right to me, maybe you explained it wrong but that is not serial wiring. Serial wiring is simple, take the red wire from the jack and connect it to the red terminal on speaker A, then connect the black wire on the jack to the black terminal on speaker B, then you simply connect the black terminal of speaker A to the red terminal of speaker B. Using a meter you should get a reading of approximately 12 ohms. This would be considered a 16 ohm cab. If however your using the cab with a Boogie amp the cab should be wired in parallel for 4 ohms, and plugged into the 4 ohm out of the amp. For a very handy impedence calculator with wiring diagrams down load the spreadsheet on this website:
http://www.duncanamps.com/technical/impedance.html
Make sure to look at the bottom of the spreadsheet where you select 2, 3, or 4 speakers and how you want to wire them.
PS.The reason the readings on the meter don't match the actual rating of the speakers is that the rating of the speaker is an impedence measurement while the meter reading is a resistance measurement.

 

[mightywarlock]

so the latest developments...

so last night i decide to wire the cab up Parallel...4-ohms.
right away i noticed it sounded different, not as smooth as the 16 ohms...
and i thought all was well...

but...once i put the back on...

when i cranked it in ch. 2, i heard that same sound.

so now i have to wonder if it is my speakers.

so i pulled the speakers out of the box, and tossed the vintage 30's back in there for now until i can check things out further.

oh. and remember that flash i posted about earlier that i saw in the tubes?

so when switched to Fat Clean, i noticed a occilating low sound, and thought i saw a tube out (preamp). shut off the lights and sure enough, one of my 12ax7's was out. swapped it out and all was well.

but why would pushing my amp, with the EV speakers, when they were wired 16ohms, into the 8ohm jack, have blown one of my clean preamp tubes when i was probably in ch.2 not ch. 1??

eh.

maybe i'll just sell the speakers. i'm starting to lose interest.

 

[siggy14]

It wouldnt have blown your preamp tube, just might have been one of those fluke things where something goes bad while changing something else.

Did you change the tube before going back to the V30's? Might have been the tube causing that noise.

so the latest developments...

so last night i decide to wire the cab up Parallel...4-ohms.
right away i noticed it sounded different, not as smooth as the 16 ohms...
and i thought all was well...

but...once i put the back on...

when i cranked it in ch. 2, i heard that same sound.

so now i have to wonder if it is my speakers.

so i pulled the speakers out of the box, and tossed the vintage 30's back in there for now until i can check things out further.

oh. and remember that flash i posted about earlier that i saw in the tubes?

so when switched to Fat Clean, i noticed a occilating low sound, and thought i saw a tube out (preamp). shut off the lights and sure enough, one of my 12ax7's was out. swapped it out and all was well.

but why would pushing my amp, with the EV speakers, when they were wired 16ohms, into the 8ohm jack, have blown one of my clean preamp tubes when i was probably in ch.2 not ch. 1??

eh.

maybe i'll just sell the speakers. i'm starting to lose interest.

 

[mightywarlock]

It wouldnt have blown your preamp tube, just might have been one of those fluke things where something goes bad while changing something else.

Did you change the tube before going back to the V30's? Might have been the tube causing that noise.




yes....i did change the tube while i had the EV's in there.

hell of a time for a fluke then!

heh