Crate Power Block question

[hector]

Thinking about a Crate Power Block as a backup to my gigging amp. I called Crate tech support and honestly don't think the guy I talked to knows what he's talking about. This is a (now discontinued) solid state 75 watt stereo amp, 150 bridged (so I guess it's two independent 75 watts amps?). Anyhow, 8 ohms at 150W OR two 4 ohm connects at 75W each. My cab is 4 ohms, 275W (2x12 with Swamp Thang and Lil Texas). The tech tells me it's o.k. to connect to one 4ohm out and leave the other speaker out unused. However, he then tells me that my 275W cab is too much for the 75W amp and the speakers will fry. I told him that I connect my 20-50W tube heads to this same cab all the time with no issue. Am I missing something here with the Solid State amp? Does the wattage with SS have to match that closely? Is he confusing wattage with impedence?

[fyler]

he's wrong. you have PLENTY of wattage with those speakers.

[Buckeyedog]

Usually a cab is "not enough" .....not "too much" for an amp. Flyer is right, no harm at all even running the 150 watt amp into your 275 watt cab. Heck I ran my power block into my 100 watt cab all the time. Of course my volume and gain wasn't dimed!! Just running one side? No sweat.

[hector]

That's what I thought (regarding the wattage).
But, it is safe to run just one 4 ohm side of the powerblock?

Plugging my 4 ohm cab into the 8 ohm mono bridged out probably isn't wise, correct?

Finally, can I go with no load (no speakers connected) when using the headphone out? (I know that no load with a tube amp is bad news.)

[Norjef]

Methinks YOU mebbe wrong about a "275 watt cab" (which WOULD work fine with PowerBlock, I use 2- 200w EVMs with mine).

2 times the lesser wattage speaker's rating - if you have a 50 watt and a 225 watt speaker, your cab can still only take ~100 watts.

[hector]

Methinks YOU mebbe wrong about a "275 watt cab" (which WOULD work fine with PowerBlock, I use 2- 200w EVMs with mine).

2 times the lesser wattage speaker's rating - if you have a 50 watt and a 225 watt speaker, your cab can still only take ~100 watts.


Yes, you are right. Still wondering about my Ohms and headphone out questions though.

[danel59]

I use the EVM-12L with mine as well but only in the Bridged mode. The only thing I can think of that you may want to check is that a solid state amp clips differently when driven into clipping (more square wave) and it could make the speakers overheat and blow prematurely as opposed to a tube amp that clips more symetrically. Depending on the levels you are playing at it, there could be some truth to what the person said. My .02 worth


Re Headphones out you can run the PowerBlock without a load

Dan

[rockindillo]

I think I'm right in saying you are quite safe to run only one side of the Power Block without too many problems. I have also, in extremis, run a single 4 ohm bass cab from the mono out on mine when I needed to use the PB as an emergency bass amp and it coped just fine - got a bit hot, but kept on running.

Great little amps. I wouldn't leave home without one.

[hector]

I use the EVM-12L with mine as well but only in the Bridged mode. The only thing I can think of that you may want to check is that a solid state amp clips differently when driven into clipping (more square wave) and it could make the speakers overheat and blow prematurely as opposed to a tube amp that clips more symetrically. Depending on the levels you are playing at it, there could be some truth to what the person said. My .02 worth


Re Headphones out you can run the PowerBlock without a load

Dan

The tech was using the term "square wave" while we talked. Telling me that SS amps react differently to speakers than Tube amps. Now I'm confused again. He suggested actual speaker rating +/- 25%. However, some guys here are telling me that they run high watt cabs with this amp all the time.

[ReginaldBisquet]

Thinking about a Crate Power Block as a backup to my gigging amp. I called Crate tech support and honestly don't think the guy I talked to knows what he's talking about. This is a (now discontinued) solid state 75 watt stereo amp, 150 bridged (so I guess it's two independent 75 watts amps?). Anyhow, 8 ohms at 150W OR two 4 ohm connects at 75W each. My cab is 4 ohms, 275W (2x12 with Swamp Thang and Lil Texas). The tech tells me it's o.k. to connect to one 4ohm out and leave the other speaker out unused. However, he then tells me that my 275W cab is too much for the 75W amp and the speakers will fry. I told him that I connect my 20-50W tube heads to this same cab all the time with no issue. Am I missing something here with the Solid State amp? Does the wattage with SS have to match that closely? Is he confusing wattage with impedence?


I have one and this is how I've been using it:

2x12 cab with two Eminence Tonkerlites.
http://lh3.ggpht.com/_WxLfCCnkMtg/Suu1PsNNeTI/AAAAAAAABLA/b6UEgjL-9u0/s640/DSCF1576.JPG

Mine are 8 ohms with each rated for 125 watts power handling. The speakers are wired in series - so it's a 16 ohms. I've run the Powerblock at very loud volumes for stoner blues and doom as well as rock & blues. No issues after many hours of shenanigans.


4x12 cab made by Ampeg in 1973.
http://lh3.ggpht.com/_WxLfCCnkMtg/Suu1OpB5GbI/AAAAAAAABK4/GMKyrC2P1NA/s512/DSCF1541.JPG

Crappy CTS 8 ohm speakers wired series/parallel for 8 ohms. Been using this with the Power Block at stupid volumes for stoner blues & doom. I use the main output jack (bridged button pushed in) for all applications. No problems.

The Powerblock is mighty and it's awesome. You are fine to run your cabinets via the main output. Don't forget to use a speaker cable!

[eyeball987]

I use mine all the time with headphones, a modeler, and MP3 player with no load. I know that they had some QC issues but if you get a good one, they are really hard to break.

There is one on my local CL right for $199. A little greedy. I highly doubt they will get that. I can't wait for the self designated CL police to comment on that.

[RGB]

This thread may help. Great little amp for the dough!

http://www.thegearpage.net/board/showthread.php?t=479322&highlight=block

[hector]

Wow, lots of talk created here. I guess this amp is worthwhile. Let me rephrase my setup in simple terms, to try to get a straightforward answer. I have a single 2x12 cabinet, speakers are 125W at 8ohms and 150W at 8ohms, running in parallel for a 4ohm total cabinet. For me, gig level is a 40-50 Watt tube amp at the max clean level (maybe 60% vol), then slightly pushed up with an OCD or Rat type pedal for driven tunes. How do I safely connect this cab to the Power Block to play at my gig level?

[RGB]

You probably won't get the same levels from a solid state 75w as you're getting from a 50w tube amp, but it should be loud enough to gig.

Just make sure the PB is NOT set to bridge and take your output from one of the 75w, 4 ohm outs to your cab. That's it. You have plenty of power handling with that cab and using your guitar into the PB's pre section won't clip the amp so your speakers are safe.

[hector]

Thanks RGB.
But, won't I be clipping the amp if I'm using my overdrive pedals before the PB? Will this potentially hurt my speakers?

[RGB]

I can't believe using an OD before the PB's preamp will cause it to clip, but your ears will tell you right away if there's a problem. If you hear any cracking from the speakers, then the amp is clipping and I'd stop right away. Not likely to happen, though...maybe if you're running it wide open, but that would be pretty loud.

[hector]

Maybe I'm missing something here. The purpose of an OD pedal "is" to cause preamp clipping, correct? You're talking about speaker clipping?

[RGB]

Nope, amp clipping...and an OD does not cause amp clipping, (necessarily). An OD distorts the input signal and outputs it as a distorted signal. The distortion is coming from the OD, NOT the amp's power section. If you're hitting the amp's front end hard with the OD, it may cause the amp's preamp to drive the power section harder, but shouldn't cause clipping.

If this still doesn't make sense to you, maybe I'm just not able to explain it clearly enough. Sorry, if that's the case! :)

There are much more qualified people here and maybe one of them will chime in.

[Buckeyedog]

Bottom line is that you really should be fine. I hit mine hard with an O/D pedal and it was never a problem.

[GT100]

Thinking about a Crate Power Block as a backup to my gigging amp. I called Crate tech support and honestly don't think the guy I talked to knows what he's talking about. This is a (now discontinued) solid state 75 watt stereo amp, 150 bridged (so I guess it's two independent 75 watts amps?). Anyhow, 8 ohms at 150W OR two 4 ohm connects at 75W each. My cab is 4 ohms, 275W (2x12 with Swamp Thang and Lil Texas). The tech tells me it's o.k. to connect to one 4ohm out and leave the other speaker out unused. However, he then tells me that my 275W cab is too much for the 75W amp and the speakers will fry. I told him that I connect my 20-50W tube heads to this same cab all the time with no issue. Am I missing something here with the Solid State amp? Does the wattage with SS have to match that closely? Is he confusing wattage with impedence?

First, go and get a new tech -apparently this guy dosen't even know all the BASICS!

He right about not having to have a SOLID STATE AMP plugged into a load. Just for the record you do need to have a tube amp plugged into a speaker while playing or you can smoke your amp.

But the idea that its a bad to use this combination because the amp is rated less than the speaker cabnet is totally wrong.

If the opposite was the case then he would be correct.
The fact that your speaker cabnet can take 200 more watts than your amp is rated for is means that you will have a hard time blowing the speakers with this amp...

[hasserl]

Nope, amp clipping...and an OD does not cause amp clipping, (necessarily). An OD distorts the input signal and outputs it as a distorted signal. The distortion is coming from the OD, NOT the amp's power section. If you're hitting the amp's front end hard with the OD, it may cause the amp's preamp to drive the power section harder, but shouldn't cause clipping.

If this still doesn't make sense to you, maybe I'm just not able to explain it clearly enough. Sorry, if that's the case! :)

There are much more qualified people here and maybe one of them will chime in.

There is a difference between the distortion of the signal created by a distortion pedal, or even the preamp, and the distortion of a solid state power amp that is pushed into clipping. In the case of the pedal or preamp that is voltage amplification, where the signal is amplified from a very small signal supplied by the guitar into a larger signal; the power amp section of an amp is a current amplifier. When the a pedal or preamp clips the signal it is not typically hard on a speaker, but when a power amp (SS) clips it is. The large square wave of a clipped solid state amp will damage a speaker no matter how high the wattage rating.

That is what the tech was trying to convey in the OP. What happens very often is people match up very high power speakers with relatively low powered amps, then they push the amp hard because they think it can't possibly hurt the speakers, because they are so over rated for the application. But when they push the amp hard enough to cause it to clip the outputs it will damage the speakers. The tech has probably had to deal with this many times, so he is only giving you his professional advice from the perspective of someone who has had to deal with it many times.

If you develop the sound you want with pedals, and/or the preamp of the PB, but keep the volume level down low enough so that the power amp section runs nice and clean, there will be no harm done to the speakers. They will be fine with the distortion of the predal/preamp. And you can use just one side of the PB set to stereo mode, leaving nothing plugged into the other side (no dummy load needed) and it will be fine as well.

Hope that helps.

[hector]

Yes, I understand. Much thanks to everyone here who responded to my questions. Once again, proves it's great to be part of this TGP community.

[pipedwho]

When people talk about 'underpowering' speakers and damaging them by clipping the amp, there are a couple of things to consider.

1. The huge power boost in upper harmonics during excessive hard clipping can damage an underrated tweeter. This is the case for multi-driver full-range (ie. PA / hi-fi) speakers that are designed for full range typical musical program material. Hi-fi speaker power ratings also tend to be underrated when compared to an equivalent guitar speaker.

2. Guitar speakers don't have this problem as they have a fairly high impedance at high frequencies (they are huge 12" drivers after all). Also, guitar speakers tend to be quite conservatively rated as they are designed to reproduce a heavily distorted signal without sounding overly harsh.