Need help! (Can I use a combo amp as a cabinet?)

[leo_nejrl]

Hi!

I have just bought my first tube amp head (a Marshall jvm410hjs) and I need a little help regarding ohms.

Up to now, I have used a Blackstar Silverline Combo amp and i wonder if it’s possible to use it as a cabinet. On the Blackstar, it is possible to detatch the cable to the speaker itself (see picture) and my idea is to plug that cable into the marshall head. However, the marshall has a lot of different outputs with different impedance and i don’t want to damage my marshall. I am unsure how many ohms the ”cabinet part” of the Blackstar has, but the blackstar has the same amount of output wattage as the marshall. (100 watts rms)

My question is; is this even possible to do and in what output jack should the cable go into? 1x16ohms maybe?

Im very thankful for any answers!


This is the back of the Blackstar combo amp



This is the back of the jvm

 

[Leonard Neemoil]

Welcome to the forum.

Congratulations on the JVM, people rave about them.

The answer to your question is yes. You'll have to measure the impedance of the speaker(s) in the Blackstar combo or see if the speaker(s) tell you how many ohms they are.

Then we can tell you what jack to use on the JVM.

 

[fitz]

Hi!

I have just bought my first tube amp head (a Marshall jvm410hjs) and I need a little help regarding ohms.

Up to now, I have used a Blackstar Silverline Combo amp and i wonder if it’s possible to use it as a cabinet. On the Blackstar, it is possible to detatch the cable to the speaker itself (see picture) and my idea is to plug that cable into the marshall head. However, the marshall has a lot of different outputs with different impedance and i don’t want to damage my marshall. I am unsure how many ohms the ”cabinet part” of the Blackstar has, but the blackstar has the same amount of output wattage as the marshall. (100 watts rms)

My question is; is this even possible to do and in what output jack should the cable go into? 1x16ohms maybe?

Im very thankful for any answers!


This is the back of the Blackstar combo amp
View attachment 124945


This is the back of the jvm
View attachment 124946

to the forum.
Put a meter on that speaker cable, or check the ohms on the speaker labels and determine how they are wired together (series or parallel).
You probably either have 2 x 8 ohm speakers wired in series to a 16 ohm load, or 2 x 16 ohm speakers wired parallel to 8 ohms.
That will determine the appropriate jack to use on the JVM.

 

[leo_nejrl]

I

Welcome to the forum.

Congratulations on the JVM, people rave about them.

The answer to your question is yes. You'll have to measure the impedance of the speaker(s) in the Blackstar combo or see if the speaker(s) tell you how many ohms they are.

Then we can tell you what jack to use on the JVM.

I had to unscrew the back to see. It’s only one speaker, a celestion v type. I found a label on the side telling me it’s 4 ohms.

 

[Mike_LA]

The manual says it has a 4 ohm speaker

 

[leo_nejrl]

Update: the speaker in the Blackstar is 4 ohms!

 

[fitz]

The manual says it has a 4 ohm speaker
View attachment 124948

That's the little 20w combo.
OP has the 100w.

Blackstar Silverline Stereo Deluxe 2x12" 2 x 100-watt Combo Amp

100-watt Digital Combo Guitar Amplifier with 2 x 12" Stereo Speakers, 6 Amp Voicings, 6 Virtual Output Tube Types, 12 Onboard FX, Speaker-emulated Output, and USB Connection

www.sweetwater.com

2 x 70w 12" V-Types, but doesn't specify ohms rating in the SW listing.

 

[Mike_LA]

Ok the 100 watt is still 4 ohms

 

[leo_nejrl]

Ok the 100 watt is still 4 ohms
View attachment 124949

So what output jack of the jvm should I use then?

 

[fitz]

Ok the 100 watt is still 4 ohms
View attachment 124949

Cool. Probably two 8 ohm speakers parallel.
So you'd want to use either of the 1x4 / 2x8 jacks.
I'd still recommend checking the speaker cable with a meter to verify.

 

[Leonard Neemoil]

I had to unscrew the back to see. It’s only one speaker, a celestion v type. I found a label on the side telling me it’s 4 ohms.

Update: the speaker in the Blackstar is 4 ohms!

Cool. Probably two 8 ohm speakers parallel.
So you'd want to use either of the 1x4 / 2x8 jacks.
I'd still recommend checking the speaker cable with a meter to verify.

Seems like only 1 speaker at 4 ohms so the 4 ohm JVM jack right fitz? That's my understanding anyway.

 

[Leonard Neemoil]

I had to unscrew the back to see. It’s only one speaker, a celestion v type. I found a label on the side telling me it’s 4 ohms.

What's the wattage rating on that speaker?

 

[fitz]

Seems like only 1 speaker at 4 ohms so the 4 ohm JVM jack right fitz? That's my understanding anyway.

I missed that 1 speaker post.
Seems odd to have a 100w amp with one 70w rated speaker.
Yes to 4 ohm jack.
No to would I plug a 100w JMV into one 70w speaker

 

[leo_nejrl]

I missed that 1 speaker post.
Seems odd to have a 100w amp with one 70w rated speaker.
Yes to 4 ohm jack.
No to would I plug a 100w JMV into one 70w speaker

.. to be clear, the jvm wouldn’t be harmed if you did though, right?

 

[Jethro Rocker]

.. to be clear, the jvm wouldn’t be harmed if you did though, right?

No it would not. Plug into one of the 1x4 jacks and don't turn amp up too high as it is 100 watts into 70 watt speaker.
It will work fine.

 

[leo_nejrl]

No it would not. Plug into one of the 1x4 jacks and don't turn amp up too high as it is 100 watts into 70 watt speaker.
It will work fine.

Thank you! Thank you all for all the help!!

 

[fitz]

.. to be clear, the jvm wouldn’t be harmed if you did though, right?

Like @Jethro Rocker said, no harm to the amp at low volume.
If you turn the amp up enough, it will eventually blow the speaker.
Once the speaker blows, the amp will follow in short order.

 

[Leonard Neemoil]

So the v type is only available in 70 watts?

That's some crazy stuff that they'd use a 70 watter for a 100 watt amp.

 

[Jethro Rocker]

So the v type is only available in 70 watts?

That's some crazy stuff that they'd use a 70 watter for a 100 watt amp.

Yes very strange. So amp is not a 2x12 and is 100 watts for sure?
EVH makes a 1x12 cab for the 5150 50 watt that has a 25 watt Greenie....

 

[Rokinroller]

Just because an amp is rated 100w does not mean it will be driven constantly at its maximun output . That would be extremely rare . Even when you think you are cranking an amp usually its not even putting out half of the 100w .
Same as : a car that can do 250mph . You dont do top speed with it every time you drive it .

That 70W V-Type can handle that 100w amp spec no problem for normal use .