Mark V Combo conversion to Head + 2x12 Cab Questions.

I have a few speaker cabinet related questions I could use some input on.

I currently have the Mark V Combo with the Black Shadow C-90 in it. Now that I am playing with a band at higher volumes I was kind of thinking it would be better for the tubes and my amp all the way around if I went with a head/cab setup instead.

I'd like to do some of the work myself, but I'm not sure if my idea is functional or not. I'm thinking of buying an empty 2x12 cabinet shell (I would gladly take suggestions on cabinet shells), and one other Celestion speaker. Then I would pull the speaker out of my combo, and place it in the other speaker slot of the cab. My confusion is really about which of the other Celestion speakers would mesh well with the Mark V while being paired with the C-90? And would it be best to wire the two speakers in-series so I can have the maximum wattage handling from the cabinet, allowing me to run the Mark V at Full Wattage with Distortion?

I often play in Eb to C tunings, so I am also aiming to get a tight bass response from the cabinet once it's complete, so any tips towards this goal would also be very welcome as well.

That's a lot of questions. I'll handle the last ones.

In my experience, all the Boogie speakers work well together. You could run two C90, a C90 and a V30 (my favorite), a C90 and an EV. Whatever.

For power handling, it makes no difference if the speakers are series or parallel. Make sure they are the same impedance (both 8 Ohms or both 16 Ohms). Whether in parallel or series, each will take half the power from the amp. Both the C90 and V30 are rated for enough power to take half of what the V produces.

HOWEVER, you need the right impedance also. If you wire in series, you will have too high an impedance for the amp. Two 8-Ohm speakers in series is 16 Ohms, which is at best a safe mismatch. Better in parallel at 4 Ohms, which is a correct match.

Two 16-Ohm speakers in series is 32 Ohms, not a safe mismatch. In parallel they are 8 Ohms, a correct match.

For tight bass, roll off 60-100Hz with a narrowband EQ in the loop.

elvis said:

That's a lot of questions. I'll handle the last ones.

In my experience, all the Boogie speakers work well together. You could run two C90, a C90 and a V30 (my favorite), a C90 and an EV. Whatever.

For power handling, it makes no difference if the speakers are series or parallel. Make sure they are the same impedance (both 8 Ohms or both 16 Ohms). Whether in parallel or series, each will take half the power from the amp. Both the C90 and V30 are rated for enough power to take half of what the V produces.

HOWEVER, you need the right impedance also. If you wire in series, you will have too high an impedance for the amp. Two 8-Ohm speakers in series is 16 Ohms, which is at best a safe mismatch. Better in parallel at 4 Ohms, which is a correct match.

Two 16-Ohm speakers in series is 32 Ohms, not a safe mismatch. In parallel they are 8 Ohms, a correct match.

Click to expand...

Thank you very much for your response. Hopefully you don't mind traversing through some more of my rambling questions. I don't want to risk damaging a speaker at any point doing this.

Just so that I know I am understanding this correctly, the C-90 in the Combo is 8 ohms, so which ever speaker I select should also be 8 ohms. Then I should wire them in parallel, resulting in a 4 ohm impedance for the cabinet, of course going to the 4 ohm jack on the Head? Is that most likely the optimal configuration for what I am aiming for? Looking at your signature and from what you said above, it sounds like you did exactly what I initially had in mind, a 2x12 with a C-90 and V-30.

I just wasn't sure how safe the wattage handling difference between the two speakers would be when running the amp at 90w with heavy distortion. Feel free to correct me if I'm wrong, if I want to run the amp at 90w with heavy distortion I would want roughly 130+ watts of handling from the cabinet to be safe? With the C-90 (90w) and a V-30 (60w) for example, the maximum ~130 watts of output from the V would be distributed evenly between the two speakers? So I would only risk damaging the V-30 if I was stupid enough to actually push the amp to outrageous volumes.

Yes, you should select an 8-Ohm speaker and wire it in parallel.

Given that your Mark V combo shipped with a single 90W speaker, I think it is fair to say that the C90 is capable of handling whatever the amp can throw at it. Adding an additional speaker just makes it that much more unlikely that you will damage the speaker.

I don't know where you come up with the 130W number. The speakers are derated quite a bit, and the amps put out high peak power, but not so high continuous power. And again, Mesa ships the combo with a 90W speaker, so that must be sufficient in their opinion.

Back in the day, Drop-A guitars were pretty much unheard-of, so I could see potential concern with whether a Mark II could handle it, but the Extreme mode makes it clear that Mesa knew at the time of design that people would essentially be playing bass guitar through the amp with massive overdrive.

Either way, the two speakers will handle a combined power of 90+60=150W. Plenty. When the power is split, the V30 is capable of 60W, but will only see 45W. If you have any concerns, cut the 80Hz slider. Upwards of 80% of the power dissipated is at less than 200Hz. You'll get tighter low-end as well. For sure cut anything below 60Hz.

You can buy very nice cabinets (with or without speakers) fro Avatar. I run my Mark V through either a Marshall 1936 with Celestion 12T-75s or a 2x12 with Celestion 12K-100s, and they both sound great. But, I've heard a lot of people say the Celestion Vintage 30s are a great match for the Mark V.

My ~130 watt estimation was based on a rule of thumb that an old English amp tech had explained to me. Just to play it safe he usually tried to have the wattage handling on cabinets be at least 1.4x the max wattage from the Amp when pairing it with a cabinet. Going off that estimation a 100 watt clean amp would actually put out in the neighborhood of 140+ watts if heavy distortion was added. As he explained it to me, it was more or less the threshold for speaker damage, so I guess I was under the impression that I would want a minimum wattage handling from the speaker combo I choose.

I know how loud the Mark V can be, it's rare that I even push the Output past 11 o'clock. I was thinking the low wattage Celestion Speakers like the Blue Alnico's or the 25 watt Greenbacks, wouldn't be enough, so I was leaning towards the V-30 or the 65 watt Creamback for a 2x12. But you raise a good point, Mesa did ship the Combo with the C-90 and no warnings about damaging or burning out the speaker, so you are probably right, nothing to worry over.

John BNY said:

You can buy very nice cabinets (with or without speakers) fro Avatar. I run my Mark V through either a Marshall 1936 with Celestion 12T-75s or a 2x12 with Celestion 12K-100s, and they both sound great. But, I've heard a lot of people say the Celestion Vintage 30s are a great match for the Mark V.

Click to expand...

Thanks for the reply on those higher wattage Celestions, I was curious about those, but thought they might be a little harsh in conjunction with the C-90. I'm hoping to find a speaker that will kind of fill out any deficits in the C-90.


Does anyone have any direct feedback on the difference in sound between the various Celestion speakers when used with the Mark V? Greenbacks, Blue Alinico's, Creambacks (65w, 75w), V-30's (What about them works well with the Marks?), etc?

The Mark V is fantastic with the V30. I bought a combo that had a V30 pre-installed and love it. A few weeks ago I saw the John Petrucci play through of the Mark 5:25 and he said he records with a single V30 for a more focused sound.

I have read most reputable speakers can handle double the wattage they are rated for. After 3 years with the V30, it still sounds great and has no issues. A caveat, I have not turned up the volume past 12 (I want to but have not used it in a big enough setting yet).

The Mark V is fantastic with the V30. I bought a combo that had a V30 pre-installed and love it. A few weeks ago I saw the John Petrucci play through of the Mark 5:25 and he said he records with a single V30 for a more focused sound.

I have read most reputable speakers can handle double the wattage they are rated for. After 3 years with the V30, it still sounds great and has no issues. A caveat, I have not turned up the volume past 12 (I want to but have not used it in a big enough setting yet).

MarkV said:

The Mark V is fantastic with the V30. I bought a combo that had a V30 pre-installed and love it. A few weeks ago I saw the John Petrucci play through of the Mark 5:25 and he said he records with a single V30 for a more focused sound.

I have read most reputable speakers can handle double the wattage they are rated for. After 3 years with the V30, it still sounds great and has no issues. A caveat, I have not turned up the volume past 12 (I want to but have not used it in a big enough setting yet).

Click to expand...

So wait...

You've been running the Mark V with just a V30 the whole time? No other cab or speakers with it?
I'm curious because there's nights where I'd like to leave my ext. cab home but would like to take
the V30 that's in it instead of the C90 that's in the combo.