Daryl

I just need you guys to put my thinking straight on a few things, please take these as theoretical questions not that I would ever do some of these things or want to in real life.

1) Am I correct in thinking that if you have a 100w head you need a higher than 100w rated cab? Would running a lower rated cab damage the amp, speakers or both?

2) Am I correct that if you had a 150w cab and tried to power it with a 20w amp it would damage the speakers being under driven?

3) Am I correct that if I had a 100w solid state amp but kept the volume on 1 it is actually only putting out a fraction of that 100 watts?

4) If I AM correct about question 3 does that mean than running a 100w amp with the volume at 1 (thus lowering the wattage it is putting out) into a 150w is a bad idea as the speakers would be underdriven, effectively like using a smaller wattage amp.


I hope that those questions explain what i'm trying to understand.

Hope you guys can clarify it all a bit more for me.

Marshall Amps

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CaptainZero

To keep it simple since I'm on a phone:
Yes the speakers not the amp as long as the ohms are correct,no,yes,no

Marshall Mann

Hey Daryl,


Welcome to the forum.

1) Yes. Your speakers should have at least the same if not greater wattage ratting as your head. Remember that wattage rating is usually RMS not peak. You can cause damage to your speakers over time if they are rated too low.

2) No. In this case you will not under power the speakers. Just be sure to match the impedance (ohms) to your heads output.

3) See #1

4) See #2

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Marshalls a Mesa and mostly Les Pauls

Micky

Yes
No
Yes
No

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I can understand stupidity, but there is no excuse for ignorance...
Marshall MHZ15, DSL40c, M4, 4X12 full stack, Gibson LP, VOX, Eminence, Celestion, Ovation, Fender & more...

Daryl

Thanks guys that clears things up.

I guess all that stuff I read about it being bad to put a low watt amp into a high watt cab was just rubbish.

Tomorrow i'm going to try my VT20+ into my new 4x10 cab

CaptainZero

Yep. That doesn't matter at all.

mickeydg5

Hi Daryl

What matters is not to connect expensive quality speakers to a cheap amplifier. I would imagine that VOX has this covered.

The main question should be "What is the impedance of your 4x10 and how do you plan on connecting it to the VT20+?".

Daryl

The cab is 8 ohms.

I was going to undo the wires going to the internal speaker and connect them to a 1/4 jack plug so I can plug in using my normal speaker cable.

I believe the VT20+ speaker is 4ohms.

mickeydg5

Cool. As long as the 4 ohm internal speaker is disconnected the 8 ohm 4x10 should not be a problem.

Daryl

Is there a type of jack plug I can buy that will disconnect the internal speaker when I plug in the speaker cable going to the cab?

If thats correct, what are they called?

mickeydg5

Do not know what your speaker connection looks like. Pictures?

Daryl

Hi its just two spade connections going to the speaker.

I think all I need is a switched jack socket?

This is what I was thinking: http://joewebbguitars.com/images/Ext...ctions.pdf.zip

Ken

When I run my full stack I have a 50 watt amp into 640 watts of speakers. I like it that way! Keeps the speakers out of the mix when it comes to overdrive. Note the "typical" Marshall stack with G12T-75's is 600 watts; people run 100 watt amps through them as a matter of course.

One other point: do NOT use under rated speakers and think you're okay if you keep the volume down. I blew 3 of 4 speakers in a cabinet once that way and I swear I wasn't playing very loud. Apparently it was loud enough though.

Ken

__________________
1999 Marshall DSL 50
Music Man 65 Reverb late 1970's (?)
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1980 Model 1982A 4x12 cabinet G12H-80's 444 cones
1983 Model 1982B 4x12 cabinet G12-80's 444 cones
PRO 4x12 from the 1970's
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1976 Les Paul Standard
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mickeydg5

I could not get joes site to work right. ???
How much is his kit?

All you really need is a good NC (normally closed) jack and a mounting plate. No one I know off hand has fuses on their outputs to speakers.

The NC connection breaks when a plug is inserted and the signal is redirected to the plug.

Daryl

The kit is $15

But I was just going to copy his components.

microhead

Rean NYS2122 1/4" Mono Jack Switched 092-120

just find the right amount of real estate on your combo's rear panel, hook up this baby and you're good. and btw prepare to rediscover your combo once you triple the surface area you're moving with it.

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If Zakk has a "Wall of Doom", I guess my rig is a "Partition of Impending Inconvenience"

mickeydg5

Warning! I would not buy REAN until you check the specifications.

The NYS2122 can only handle 1A. Your VT20+ puts out 30W @ 4 ohms and you need a jack that can handle 3A or more.

I suggest a real Neutrik or Cliff jack.

Daryl

Will this one do what I want?

eBay - The UK's Online Marketplace


Also for the extra wires I need to knock up, can I use crimp on spade connectors or should I use solder on spade connectors?

eBay - The UK's Online Marketplace
Or
eBay - The UK's Online Marketplace

And what wire is best to use? guage etc

Maklaca

Hi all,

Can I add another question?

I have heard that sometimes sometimes amps actually put out more wattage than the amp's rating.
That being said, if I run a plexi 50W into a cabinet with two 25W greenbacks for a total of 50W rating, will that be OK, or would there be amp peaks that could blow the speakers?

Thanks

Georgiatec

If you crank it there's a good chance they'll blow. At modest volume you will probably be ok, but then why have a plexi?. Myself I'd have a 4 x 12 with greenies in for a 50 watter (two for a 100w). That amp will be putting out way more than 50 watts cranked.

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JCM1H
1960B CAB
MARSHALL 412, 1922 & 1912 CABS
1978 PEAVEY CLASSIC 212 COMBO
'04 GIBSON LES PAUL CLASSIC
'12 GIBSON LES PAUL TRADITIONAL STD PREMIUM
'00 USA STANDARD TELECASTER
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EPIPHONE LP std+ (498T & 490R), VINTAGE VS6 (SG) & SA535 (335) COPIES.

IF YOU CHANGE SHIT, THEN SHIT WILL CHANGE. IF YOU DO NOTHING YOU WILL GET THE SAME OLD SHIT.

mickeydg5

Yes that jack is good for 3A. The model number indicates no nut, but I see the seller states washer and nut included. Make sure you get them.

Quick connect or solder, I use both. Whichever is best or easiest for you. I crimp my quick connects, the female end, a little to make them tight.

18-22 gauge is fine for 30 watt amplifier and a 150 watt cabinet.

Maklaca

Thanks Georg.

I thought that might be the case. I actually am running 2 x 12 with a V30 (60W rating, so I am sure that one is OK) and a G12M (25W. That's the one I am worried about).
With no room or need for a 4x12 right now, I guess I have to watch the levels, or find something else in place of that G12M.

Georgiatec

Your cab is only going to rate at 50watts because of the G12M ( 2 x the lowest rated speaker). I would go for something like a creamback or a Heritage G12 65 in with the V30 for a good mix. A boring old G12T 75 sounds great with a V30. I have a 1922 2 x 12 with this combo and it sounds great. Sound clip with my Haze 40.

HAZEDEMO by Georgiatec on SoundCloud - Create, record and share your sounds for free

__________________
JCM2000 DSL100 & 401 COMBO
VINTAGE MODERN 2466 & 425A CAB
2061x
JCM1H
1960B CAB
MARSHALL 412, 1922 & 1912 CABS
1978 PEAVEY CLASSIC 212 COMBO
'04 GIBSON LES PAUL CLASSIC
'12 GIBSON LES PAUL TRADITIONAL STD PREMIUM
'00 USA STANDARD TELECASTER
FENDER MODERN PLAYER TELE+
'94 FENDER MIJ '62 RI FOTOFLAME STRATOCASTER
EPIPHONE LP std+ (498T & 490R), VINTAGE VS6 (SG) & SA535 (335) COPIES.

IF YOU CHANGE SHIT, THEN SHIT WILL CHANGE. IF YOU DO NOTHING YOU WILL GET THE SAME OLD SHIT.

Daryl

Just had a look on ebay and i'm a bit confused.

Is 18 guage thicker than 22 guage?

Also being in the UK they don't seem to use the same sizing. They give you the number of strands?

e.g

24 : SPEAKER CABLE 2M RED/BLACK 6A AUTO CAR HI-FI SPEAKER WIRE 2 X 24 STRAND 2 METRES | eBay

105 : Prowpower HQ Speaker Cable OFC 105 Strand Speaker wire | eBay

or this one thats cheap but doesn't say any size???
5m Loud Speaker Cable Wire OFC Car Audio Hi-fi Home | eBay

zenfly

I've been playing for 49yrs... just joined here and love all the tech talk and great advice I get with my Marshall questions.. Kind of off subject for this thread but I haven't listened to much rock from Kiss etc. up to date..More than the choice of guitar,cords,pedals,amps,tubes >(my favorite subject)and speakers too.. connect your heart to your fingertips more that your over complicated brain.. Hendrix,SRV,Clapton,and by far my favorite Eric Johnson..

If you get a chance to try some WGS American Made British style , they're my favorite and I have Celestions,Jensen,Weber,JBL,and Tone Tubby in other amps.. I bought a 2x12 cab from Sourmash cabs for my JTM45 loaded with WGS that I never heard of before and every amp I own sounds better to me through them..

Maklaca

I guess I will be taking a look at some new speakers.

Zen, you mentioned Souarmash cabinets. I just ordered a new custom sized head box from them. Nice quality at a good price. Bob at Sourmash is a great guy too, and will answer any questions you have.

Anyone who needs a head box or cabinet done, these guys really do great work, with lots of tolex, piping, etc options.

mickeydg5

Output specifications are usually given with equipment. A normal RMS wattage value is given at a specified distortion, usually a low percentage. Sometimes as a second specification a manufacturer gives a RMS wattage value at about 10% distortion, being maximum or maxed out for musical amplifiers. That wattage is usually between 1.5 and 1.8 times the normal wattage.

Now we have to keep in mind that RMS power is continuous. With musical amplifiers we are dealing with musical power, non-continuous.

Speakers too are rated RMS. Some manufacturers also specify a speakers musical power handling. That number is basically 2.0 times the RMS handling value.

Therefore a 100W amp may be able to put out up to 180W when maxed.
And a 100W RMS cabinet can handle 200W musical power.

Still for tolerances, safety and longevity it is best to go with speakers that are rated higher than your amplifers normal output.

Case in point; the old Bassman amps were capable of 40-50 watts with a 15 inch speaker that was rated about 40 watts or so. Bass frequencies are power hogs. Needless to say people were blowing the 15 inch speaker left and right. That is why the 4x10 came about.

mickeydg5

The smaller the gauge, the larger the diameter of the wire.

22ga = .34mm
18ga = .75mm

If the seller will not specify the gauge then do not buy. You can ask him to update his lsiting.

mickeydg5

I like Sourmash too.

zenfly

Yea.. I wasn't trying to push Sourmash or WGS speakers .. Just saying I'm impressed with both and very pleased with the price, quality, and sound...