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Rob's Amp tests

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On 4/23/2020 at 10:37 PM, SME said:

Good points about live kick drums used in rock and metal.  When you talk about the 100-1000 Hz decade being attenuated are you talking about live music shows too?  Or just content mixed for release? 


If you look at the native frequency response of two extremely popular bass drum mics (mostly used for live events) that question will likely be answered:

Audix D6:
0567.png


Shure Beta52A:
0219.png


I like to have two high shelves on my mixing desk for the kick drum, one centered at 1-2khz and one around 4-6khz, which I can individually boost to colour the sound to my liking.
Sometimes a broad boost around 1.5-2khz can be very pleasant with extremely muffled kick drums aka Evans emad style. The Shure Beta91 has a dip switch, which basically is a cut around 400Hz (~two octaves effective range).

Studio mics generally tend to be more flat, to leave it neutral for the engineer to work with, but most of the midrange will be scooped to make room for other stuff in the mix. That'll be extremely busy if you add an orchestra to a band, or generally have a lot going on (Fallujah - Starlit Path as extreme example).

Neuman U47:
0710.png

Keep in mind that mics used for live settings are usually cardioid mics. These don't care much about room resonances. Most 'mud' you'll be fighting will be instruments competing for the same frequency range. Or for example sustained instruments leaving no room for transients in a certain frequency area. If the room is small enough to cause resonance problems in the low mid range, you'll be fighting much much bigger problems anyways (stage bleed).

 

@kipman725Are you sure about the Q of 4? I'd go as far as saying that a change like that will be inaudible to most. Maybe the guy in the PDF mixed up bandwidth with Q there.

  

On 4/23/2020 at 10:37 PM, SME said:

I don't put much stock in generic EQ recommendations.  Every situation is different, and it's good to be able to identify and fix the major problems at whatever frequency region they occur in.  That takes a lot of skill and experience though.

Agreed, it's most important to learn to interpret what you're hearing. Some people reading such a guide might not even be able to identify a certain problem as "muddy" and try to fix it by breaking something else. I know that from experience, done that long ago when I 'followed' a Yamaha sheet on how to mix. I'd boost all guitars at 2khz no matter what. Today I basically cut all guitars at 2khz because the presence region delivered by amps sounds good with a guitar cab, but not good when you mic said cab and amplify it through the PA. If you cut the presence region you can make the guitars louder without them being ear-piercing, which helps a lot in busy rock/metal mixes.

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Small update from my side: I was very eager on posting results here but the blown amp has demotivated me to the part that I went on to finish other projects first. So now I have a vacuum hold down on my CNC. And about the broken amp, the replacement power input board arrived and it blew up as well. Means the PSU is broken, which will run me about 300$ probably.

Good thing is that I've watched a movie with one of the spare amps I had in the store and the clip lights didn't even light up once. I didn't change the settings and volume matched everything properly. Means I can now run the quieter amp (fan noise) with much lower idle power draw without any performance penalties. The spare amp does like 2000W total, which is fine with the SKHorn as efficient bass maker and the BOSS platform as efficient TR maker.
Now that I think back about the times that I had the bridged clone amp on the SKHorn and this bridged amp on the TR I realize how overkill it was. I watch my movies at -10MV with the EQ at +15db at 20Hz. No dynamic EQ.

Will post the first test results some time next week I guess, I will add different frequency tests when I have the time to do those.

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Sanway FP-13000 (MKI)

X6KDTVO.jpg

Vmax(RMS): 134,9V

No frequency response since it blew up. It's +-1db from 3,5Hz to 44khz.

Idle power draw: 115W

Efficiency at 4KW output: 78%

Highest observed amperage readout: 48A (@231V)

Blew up after 90 seconds of 4KW output. PSU broken, power input board damaged, internal fuses on the amp stage damaged.
Soft limiter was non-functional. It just clips the waveform.
VPL kicks in at 188V, hence the lower ratings into 8 and 4 Ohm. I'll check if I can adjust that internally when I manage to bring the amp back to life.

 

Single Channel

1x8Ω - 2075W @1khz
1x4Ω - 3964W @1khz
1x2Ω - 7197W @1khz

iB9LhPR.jpg

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Will post the results of the other amps I have soon and add other frequency tests when I have the time to do those. All test durations will now be ~12s so I have enough material for my 10 second window. The Sanway delivers solid power and I think it blowing up and tripping my 230/16 breaker constantly wouldn't have happened with actual music content. The 10KW spikes will thou. I'm not a generator expert, but I've been told it's not good for them.

Anyways, next amp on the list is super famous in Germany and that for a reason as I found out.

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these are very solid numbers, if it could avoid blowing up it would probably be OK with 2ohm load.  What kind of instrumentation are you using on the supply side?

 

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9 minutes ago, kipman725 said:

these are very solid numbers, if it could avoid blowing up it would probably be OK with 2ohm load.  What kind of instrumentation are you using on the supply side?

 

I'm using a Stairville PD-332 Power Distributor, which provides me with basic voltage and current readouts. It's probably not the most accurate but it works well enough to approximate the data I'm after (idle power draw and efficiency under heavy load). Being able to check on the voltage sag is also useful. And the fact that I have the breaker right where I can reset it quickly is nice with bigger amps.

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t.amp TSA-1400

zLWKu37.jpg

Frequency response:

lStCCzv.jpg

Vmax(RMS): 68,9V

Idle power draw: 25W

Efficiency into 8R and 4R: 80-85%

Efficiency into 2R: 70-75%

Highest observed amperage readout: 14,8A (@232V)
Mains connection is a C14, which is rated at 10A. There should be an S10 fuse inside.

Started smoking 20 seconds into the 2x2 test. Test aborted, no damage. Amp is fan modded, but the part where the smoke came from is isolated from the air flow.
Fans are temperature controlled and have 3 speeds. Fan speed lowers when amp is under heavy load (Voltage sag from PSU).
Soft limiter is quick and reliable. Can't be bypassed. I couldn't get the amp to hard-clip, except for a few ms at the beginning of a test.

C47Usqw.jpg

 

Single Channel

1x8Ω - 502W @1khz
1x4Ω - 904W @1khz
1x2Ω - 1460W @1khz

5vJ5Wor.jpg

 

Dual Channel

2x8Ω - 2x463W @1khz
2x4Ω - 2x799W @1khz
2x2Ω - 2x1231W @1khz

weXy8my.jpg

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t.amp TSA4-300

6SOd9AP.jpg

Frequency response:

e96lBba.jpg

Vmax(RMS): 66,9V

Idle power draw: 95W

Efficiency: 80% at around 500W output, gradually drops to 60% at 4KW output.

Highest observed amperage readout: 17A (@230V)
Mains connection is a C14, which is rated at 10A. Resettable fuse triggered during 4x8 and 4x4 tests.

Long term power output tapers down to about half the numbers seen here. Amp goes into protect after about 90s during any 4 Ohm test. 4x4 triggers the fuse after 15 seconds.
Fans are temperature controlled and have 2 speeds.
Soft limiter is quick and reliable. Can't be bypassed. I couldn't get the amp to hard-clip, except for a few ms at the beginning of a test.

 

Single Channel

1x8Ω - 475W @1khz
1x4Ω - 682W @1khz
1x2Ω - 278W @1khz

 

Dual Channel

2x8Ω - 2x450W @1khz
2x4Ω - 2x698W @1khz
2x2Ω - 2x237W @1khz

 

Quad Channel

4x8Ω - 4x392W @1khz
4x4Ω - 4x594W @1khz

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Gotta say I'm impressed that these amps sustain more power than what they're rated for. Especially the naming scheme threw me off.
Being used to other manufacturer namings I'd expect the 4-300 to burst 4x300W into 4R, but instead it does 4x400W into 8 and 4x600W into 4.
The soft limiter is a nice feature for a non-dsp amp, as I think it's better than hard clipping. Gonna sell it for 250 bucks, as I have no use for it anymore. Very nice amp for the money.

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KMT LC1300

QgAxewU.jpg

Frequency response:

PYUmoMe.jpg

Vmax(RMS): 70,4V

Idle power draw: 0W (current readout was 0,0A)

Efficiency into 8R: 83%

Efficiency into 4R: 78%

Efficiency into 2R: 69%

Highest observed amperage readout: 13,5A (@232V)

DC protection relais kicks in below 20Hz (only above a certain volume threshold about 10db near max output). It mutes the output for half a second.
Fans only spin up when both channels are under load, amp started smelling 2 minutes into the 2R test.

 

Single Channel

1x8Ω - 507W @1khz
1x4Ω - 842W @1khz
1x2Ω - 1304W @1khz

 

Dual Channel

2x8Ω - 2x451W @1khz
2x4Ω - 2x723W @1khz
2x2Ω - 2x1069W @1khz

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