GSS Sumo Monster - That Watts Vs Volume thing?

[Jaybeevee]

Anyone fancy educating me..?

I bought A Sumo monster on a whim  really. I'm going through a rationalisation of my gear, basically selling stuff etc, and then pops up a Sumo monster for reasonable money. I've been hanging on to Dave Hall VT1 pro and i thought, hang on.. Power amp.. pre amp.. i'll have a dabble.

 

The VT1 is a killer pre-amp, but not what this is about. I run a couple of TKS 1126s which are really great, but have a rather low sensitivity. My gear selling left me with my ThunderFunk 550 to run these sweethearts, which it does magnificently well. The TKSs are rated at 250 - 600w at 8 ohms

 

So i assumed the Sumo's 1200 class D watts would be mega, and i'd need to be careful with the master volume etc..

 

What i actually found is that the Sumo caused me to overdrive the speakers (farts and crackles... not good) long before I reached rehearsal volumes? The Thunderfunk is much 'louder' in perceived volume and doesn't kill the speakers. 

 

So whats going on? Why is the Sumo not delivering volume?

 

.....Sounds mega though , that VT1 really is a colourful little fellow

 

[warwickhunt]

Interested to know the answer as I have backline gear (inc T'funk 550 and a TKS115) but I generally run a preamp pedal into PA.  I'd like to have a little Sumo sized power amp for the occasion when cabs are supplied/available.

[Downunderwonder]

Probably the Sumo has insufficient HPF, or none at all. 

[Bolo]

Are you running the vt1 through the Thunder's pre or plugged in to the fx-return, bypassing its preamp?

 

Does the vt1 have a line out or di out instead of the speaker out?

 

Or could the Sumo be faulty.

Edited Monday at 23:28 by Bolo

[Jaybeevee]

I'm running theVT1 into the Sumo, then into both cabs daisy chained. 
Had another rehearsal last night. I drove the VT1 quite hot (output) and the Sumo just about managed rehearsal volume beforte it distorted the cabs. I reckon i'm at about 7 on the volume dial of the Sumo. 

 

I have tried the pre amp out from the thunderfunk where I usually run the gain at around 6 or 7. Tnat really gave the Sumo some umph, but again, it was killing the cabs. Had to turn down to just below rehearsal levels..

[aniki]

I'll no doubt need my flameproof suit once anyone's read this but here goes!

This sounds EXACTLY like my experience of class D amps. I know; people say "ah you didn't EQ it right" or "not all class D amps are the same" but my experience is the same regardless and that's why I still use a pair of tube amps. 20 odd years ago I bought one of the first QSC class D rack amps. Exact same problem and declared never to touch class D again. Tried several 'game changing' amps since but none were good.

More recently, I took a 750w TC head to band practice with a modified cab containing a 250 watt Celestion Neo driver.

The amp could drive the speaker to full excursion with ease. But did it sound or feel loud? No, it sounded either quiet and 'OK for home volume levels' but anything louder and everything turned to crap.

I played through the PA (which used old tranny amps) to get through the session.

Returned the amp to the shop as not fit for purpose.

For reference, I play in a fairly loud band. I've got two ancient tube amps, one 150w and one 200w. I usually use both amps running a dual-mono rig but even on their own, either amp will easily drown out a loud drummer or shake the floor of the rehearsal room using the exact same speaker cab with absolutely no distortion.

-

I've tried various modern mini amps over the years but never found anything even close to being a suitable substitute...

[JPJ]

Are you driving the Sumo hard enough? Given that the output of any amplifier is governed by the ‘strength’ of the input signal, it sounds like you might need to turn the VT1 up a bit to give the Sumo something more to amplify?

[jrixn1]

Does this help, from https://www.basschat.co.uk/topic/402727-class-d-power-amps/?do=findComment&comment=4005551 ?

 

On 11/02/2020 at 20:43, CamdenRob said:

I recently got a Baby Sumo to pair with my One10s. It’s awesome and fits in my gigbag. I received the following advice regarding preamp pairings when I emailed GSS.

”The Baby Sumo requires a preamp with at least +15dB of gain and an output impedance smaller than 10 K Ohm.

Its input is unbalanced.

There are a number of suitable preamp options. Here is a quick test video we did with some of the most popular pedal format preamps on the market:

https://www.youtube.com/watch?v=x6AFO-h1xC4&list=PLDrCd9bBoihp3FaPl9igKbYMGOvPwCVam&index=3

Anything from a $50 Mooer Graphic B eq pedal with gain or a One control Sonic Silver Peg, or Sadowsky SPB 2, or a more feature-rich Fishman Platinum Pro... will work fine.

If you want to get the very best out of the Baby Sumo, you can also use a high end studio grade preamp such as the Avalon U5.”

I bought a Fishman platinum pro which whilst it sounded awesome, with only +12db of output boost wasn’t loud enough. I needed the Baby Sumo on almost full volume to keep up with the band. I’ve since bought an MXR clean boost with +20db of boost and it’s fine now. Easily loud enough to keep up with a full band, with bags of power to spare. I just go from the bass, straight into the boost pedal, into the baby sumo  

My entire set up is now in a gigbag on my back and with a One10 in each hand. I can now get my rig to the gig on public transport 👍 

 

[Chienmortbb]

Sounds to me like the Sumo is very insensitive requiring you to drive the Preamp into distortion. The GSS website is appalling. No mention of input sensitivity, no online user manual, no real spec at all. Also don't believe the Class D denyers. They have probably worked out so much to carry their SVTs that their thought processes have been distorted🤣

 

[JPJ]

3 hours ago, Chienmortbb said:

Sounds to me like the Sumo is very insensitive requiring you to drive the Preamp into distortion. The GSS website is appalling. No mention of input sensitivity, no online user manual, no real spec at all. Also don't believe the Class D denyers. They have probably worked out so much to carry their SVTs that their thought processes have been distorted🤣

 

Found this on the GSS site - input sensitivity 10kohm? 

[Downunderwonder]

On 19/11/2024 at 20:35, Jaybeevee said:

I'm running theVT1 into the Sumo, then into both cabs daisy chained. 
Had another rehearsal last night. I drove the VT1 quite hot (output) and the Sumo just about managed rehearsal volume beforte it distorted the cabs. I reckon i'm at about 7 on the volume dial of the Sumo. 

 

I have tried the pre amp out from the thunderfunk where I usually run the gain at around 6 or 7. Tnat really gave the Sumo some umph, but again, it was killing the cabs. Had to turn down to just below rehearsal levels..

So, the cabs ran out of headroom; or the amp ran out of headroom? Either way rehearsal is way louder than needs be.

[Chienmortbb]

14 hours ago, JPJ said:

Found this on the GSS site - input sensitivity 10kohm? 

That is the input impedance, the sensitivity would either be quoted in mV, V or or possibly dB. 

[bertbass]

I don't care what anyone says and they'll aways say a watt is a watt but, valve amps are loud!  Transistor amps are only half as loud as valve amps and class D amps are only half as loud as transistor amps.  I do use a class D amp myself but only because I'm getting old and valve and transistor amps are getting heavier.  But I accept the limitations and 600w class D is loud enough for me.  Back in the day though, a 100w valve head and a pair of 4 x 12s would have been more than enough for any venue without P.A. support.  In fact, there was no P.A. support!

Edited Wednesday at 12:44 by bertbass

[Jakester]

23 hours ago, JPJ said:

Are you driving the Sumo hard enough? Given that the output of any amplifier is governed by the ‘strength’ of the input signal, it sounds like you might need to turn the VT1 up a bit to give the Sumo something more to amplify?

 

I had a Baby Sumo; I had exactly the same issue; I think that although the preamp I was using was supposedly a line level output, it wasn't enough to properly drive the amp, meaning for a given value compared to an 'all in one' amp it was quieter. 

 

You could try another preamp before/after your main output, or try a buffer pedal that could up the output. 

[bertbass]

Don't forget that to the ear, a 1000w amp is only twice as loud as a 100w amp.

[Jaybeevee]

On 19/11/2024 at 14:26, JPJ said:

Are you driving the Sumo hard enough? Given that the output of any amplifier is governed by the ‘strength’ of the input signal, it sounds like you might need to turn the VT1 up a bit to give the Sumo something more to amplify?

THe VT1 has input level, gain and output level. The input (i read) is to compensate for output level of the Bass, active/passive etc. I have that pushed past noon, the gain similar (just a touch of break up) and the output cranked), but to answer your questions, the Sumo could be pushed a lot harder. The pre amp out from my Thunderfunk drives the Sumo much harder, but I still see the same issue where Cabs are overloaded before I reach volume I need to cover the Band. The thunderfunk, needless to say is ample. It drives the same speakers to easily loud enough without any complaints from the cabs

[Jaybeevee]

On 20/11/2024 at 10:50, Downunderwonder said:

So, the cabs ran out of headroom; or the amp ran out of headroom? Either way rehearsal is way louder than needs be.

Drums is drums

[Jaybeevee]

22 hours ago, Jakester said:

 

I had a Baby Sumo; I had exactly the same issue; I think that although the preamp I was using was supposedly a line level output, it wasn't enough to properly drive the amp, meaning for a given value compared to an 'all in one' amp it was quieter. 

 

You could try another preamp before/after your main output, or try a buffer pedal that could up the output. 

Yes, the pre amp from the Thunderfunk drives the Sumo much better, but same issue exists, the cabs become overloaded before they get loud enough. This is the original enquiry I had.. Wondering technically why, as my Thunderfunk drives the same cabs way louder without any complaint

[Chienmortbb]

I think it’s time to get GSS involved. The problem is clearly with their amp as the Thunderfunk declares the cabinets not guilty. 

Edited Thursday at 11:27 by Chienmortbb
Broken glasses.

[Bolo]

On 20/11/2024 at 13:41, bertbass said:

I don't care what anyone says

That's a good thing too. Because your amp class comparison is, eh, less than accurate.

 

[Bill Fitzmaurice]

On 20/11/2024 at 07:41, bertbass said:

I don't care what anyone says and they'll aways say a watt is a watt but, valve amps are loud!  Transistor amps are only half as loud as valve amps and class D amps are only half as loud as transistor amps.

Myth. A decibel is a decibel, no matter what the source. The primary reason why valves sound louder is the compression inherent with valves. Duplicate that compression, and all the rest that results in the amp transfer function, and SS amps of any class will sound the same as valves. Said compression and the rest takes place in both the pre-amp and power amp stages, so using the same pre-amp into different power amps will give different results. Valve compression results in easing into clipping, SS without an external compressor doesn't. That can result in very different results even when the power output and decibel levels are identical.

 

[warwickhunt]

2 hours ago, Bill Fitzmaurice said:

Myth. A decibel is a decibel, no matter what the source. The primary reason why valves sound louder is the compression inherent with valves. Duplicate that compression, and all the rest that results in the amp transfer function, and SS amps of any class will sound the same as valves. Said compression and the rest takes place in both the pre-amp and power amp stages, so using the same pre-amp into different power amps will give different results. Valve compression results in easing into clipping, SS without an external compressor doesn't. That can result in very different results even when the power output and decibel levels are identical.

 

 

That inherent 'compression' which can be replicated; is that why (old) GK RB amps sounded louder than the rated (solid state) watts @Bill Fitzmaurice?  Did they use compression?  I seem to recall harmonics/boost etc being bandied about.

[Bill Fitzmaurice]

I don't know about GK but TC uses compression and other DSP tweaks to approximate valve transfer function with their RH amps, with power ratings of what they claim they sound like, as opposed to what they measure, leading to the 'TC Watts' scandal. The RH 750 is actually only 236 watts 'but it sounds like 750'. 🤔

[warwickhunt]

5 minutes ago, Bill Fitzmaurice said:

I don't know about GK but TC uses compression and other DSP tweaks to approximate valve transfer function with their RH amps, with power ratings of what they claim they sound like, as opposed to what they measure, leading to the 'TC Watts' scandal. The RH 750 is actually only 236 watts 'but it sounds like 750'. 🤔

 

Yes I'm aware of the general over exaggeration of some of the new amps but I seem to recall the old RB400 (200w) being very loud (for solid state), the 800RB seemed way louder than the 300+100w.

 

[Chienmortbb]

You can compress the 5h1t out of a signal but it will not increase the power significantly. At most 40%.
 

Edited 20 hours ago by Chienmortbb