Why arent all amps 2 ohm stable?

[grendle]

What year did Ampeg start doing that? My current cab is a 2001 810e, and although lots of people say that 01 wasn't a great year for Ampeg, I love this cab. I suppose I don't need two 810's, but I'm young, don't mind the weight, and see a lot of big cabs going for cheap now. I also love the look on stage, and would imagine that my bass would sound so clear with two of these cabs.

Works for me I guess. That's a LOT of volume though.

 

[Lazarus.Bird]

Another concern some (I) have is that for any design the lower the output impedance you run the higher the distortion level (SS amps). If clean sound is your bag you DON'T want to run 2 ohms.

Also due to the aforementioned heat concerns I don't like to run any amp at 2 ohms whether it is designed for it or not. Just my .02

In addition the whole "I want to maximize my amps output by running at the lowest impedance it will run" idea is not really sensible as a doubling of output (seldom achieved through halving the load) only provides a 3 db increase in sound pressure. And this is only if compression or heat limitations don't soak up part of that 3 db. Overall not a very realistic way to increase volume, most people in this situation really need a bigger amp AND more speakers. Further the best way to get more volume out of your rig is to replace your speaker system(s) with models with higher sensitivity. THIS will give you more volume with out another amp.

Sorry snake oil man, I'm not buying what you're selling

 

[R Baer]

not true. if an amp is proprely designed to run at 2 ohms then it will have no more distortion than when it's running at 4 or 8 ohms. an ampeg SVT for example has a specific transformer tap for 2 ohms and runs just as well (and just as clean) as it does when it's running at 4 ohms.

i've run my SS crown power amps at 2 ohms all night long (5 hours continuous), as well as my little Yamaha BBT500H, my Eden WT550-B, my acoustic 370 and my acoustic 320. i've never had a problem running at 2 ohms with any of them.

+1 No manufacturer is going to tell you the amp is rated for 2 ohms, if the amp can't safety run at that load. Stretching the truth here will only result in a lot of warranty work, at great expense to the company and their reputation.

 

[walterw]

the bit about 2Ω operation creating more distortion with solid state amps is true (check any straight-up power amp spec sheet).

if the amp is designed to be pushed to the wall like that then great, but it doesn't mean you're not still pushing it to the wall.

 

[dukeisdog]

Works for me I guess. That's a LOT of volume though.

It's gonna be tons of volume. Maybe I don't need the 1KW of the SVT 7 pro, but I wanna get that SVT tone. I think I need to get a VT pedal or just suck it up and save for the real deal.

 

[Korladis]

You could opt for a used Ampeg preamp and an inexpensive power amp.

Or just look for a long time for a used SVT. They pop up for good prices sometimes.

 

[dukeisdog]

You could opt for a used Ampeg preamp and an inexpensive power amp.

Or just look for a long time for a used SVT. They pop up for good prices sometimes.

Such as the SVP CL? Or maybe I could just go rackmountable Sansamp like the RPM or RBI.

I found a used Ampeg V4 head with the master volume for $900. Is that a good price? I'm not sure of the year, but it's in good condition. I'd really like to get a V4B as I'm quite confident that 100 tube watts through even just 8X10's would be enough, but they're not rackable.

 

[seamonkey]

How are micro amps such as the Carvin BX500 able to run at 2 ohms then?

Carvin has a switch you have toggle to make it 2 ohm stable. It lowers the rail voltage. You don't get more "watts" but you get load stability.

If you forget to toggle the switch, the amp will likely shutdown at higher volume levels. It won't permanently damage it. It just shutsdown to protect itself, as it should.

I don't think most people get "stable" meaning not more power into lower impedance loads, instead, no protection shutdowns into lower loads. Seems most want/expect more power.

 

[dukeisdog]

Carvin has a switch you have toggle to make it 2 ohm stable. It lowers the rail voltage. You don't get more "watts" but you get load stability.

If you forget to toggle the switch, the amp will likely shutdown at higher volume levels. It won't permanently damage it. It just shutsdown to protect itself, as it should.

I don't think most people get "stable" meaning not more power into lower impedance loads, instead, no protection shutdowns into lower loads. Seems most want/expect more power.

That's not what I'm looking for at all. I really don't need more power, I just need something that can safely drive both cabs.

 

[Korladis]

Such as the SVP CL? Or maybe I could just go rackmountable Sansamp like the RPM or RBI.

I found a used Ampeg V4 head with the master volume for $900. Is that a good price? I'm not sure of the year, but it's in good condition. I'd really like to get a V4B as I'm quite confident that 100 tube watts through even just 8X10's would be enough, but they're not rackable.

I actually prefer non-rack gear. I made my amp a head box because it was rackmount and I didn't have any other rackmount gear and generally stay away from such.

The V4 is said to be really loud through eight 10"s. But you won't have much clean headroom. If you're like me and you don't care about headroom, then that's fine. However, if you do, then it might not be enough.

Also... I'm not sure what the going rate is, but $900 seems slightly high, to me. Can you talk the seller down at all? I also don't know if the V4 does 2 ohms or not.

 

[Korladis]

Carvin has a switch you have toggle to make it 2 ohm stable. It lowers the rail voltage. You don't get more "watts" but you get load stability.

If you forget to toggle the switch, the amp will likely shutdown at higher volume levels. It won't permanently damage it. It just shutsdown to protect itself, as it should.

I don't think most people get "stable" meaning not more power into lower impedance loads, instead, no protection shutdowns into lower loads. Seems most want/expect more power.

Ah, yeah. Like I said earlier, it's a totally different design.

 

[dukeisdog]

I actually prefer non-rack gear. I made my amp a head box because it was rackmount and I didn't have any other rackmount gear and generally stay away from such.

The V4 is said to be really loud through eight 10"s. But you won't have much clean headroom. If you're like me and you don't care about headroom, then that's fine. However, if you do, then it might not be enough.

Also... I'm not sure what the going rate is, but $900 seems slightly high, to me. Can you talk the seller down at all? I also don't know if the V4 does 2 ohms or not.

What kind of amp do you have? Do you have a picture of the box you Amadeus for it? And no, the headroom isn't a big issue. I'll most likely be playing with a nice overdriven tone anyway, that would be great if I didn't need a pedal for it. But yeah, I figured $900 seemed high. I don't think the seller is willing to go down on price as he said 900 was the highest offer. I'll just have to wait for a good deal to come by.

 

[seamonkey]

That's not what I'm looking for at all. I really don't need more power, I just need something that can safely drive both cabs.

Your only choice is to look for a class-d that is advertised for 2 ohms. Which as you've found there aren't many because there is not much demand. It mainly means it is not likely to shutdown/go into protect mode, at 2 ohms. If you used a class-d rated for 4 ohms, and plugged it into 2 ohms, but never drove it to thermal limits - it probably would not shutdown either. And not very likely to cause any harm to the amp, since the amp has built in protection.

If it did cause a problem, It would only void the warranty if you were an honest person. i.e. if you claimed ignorance no one would know. This would be fraud of course, but gee if a speaker or cable shorted out your amp shouldn't die, it should just protect itself.

One way to test and amp is to check that it does protect itself from short circuit, or thermal problems while it is under warranty. If they advertise "protection" then it better work.

I wouldn't try this with class-ab, but I wouldn't buy class-ab anymore.

 

[Lowbrow]

You might look for a used Carvin B800 SS head.

Here's an accidental monster rig: the Carvin powering 2x 8-ohm Bag Ends 15s, and 1x 4-ohm Schroeder 15. Just luck - there is amazingly even sound level across the 3 cabs as well as complementary sound characters. Also looks like a cool war robot!

Carvin gets hot, yet doesn't break a sweat. Like it was built that way.

 

[Korladis]

What kind of amp do you have? Do you have a picture of the box you Amadeus for it? And no, the headroom isn't a big issue. I'll most likely be playing with a nice overdriven tone anyway, that would be great if I didn't need a pedal for it. But yeah, I figured $900 seemed high. I don't think the seller is willing to go down on price as he said 900 was the highest offer. I'll just have to wait for a good deal to come by.

I have a Mesa/Boogie D-180.

I do have a couple pictures, but they're not very good. Just grainy cell phone shots.

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The antlers are not attached, they just sit on top.

I got it for $800 from another TBer. It is really good, however, it only goes down to 4 ohms.

 

[One Drop]

What kind of amp do you have? Do you have a picture of the box you Amadeus for it? And no, the headroom isn't a big issue. I'll most likely be playing with a nice overdriven tone anyway, that would be great if I didn't need a pedal for it. But yeah, I figured $900 seemed high. I don't think the seller is willing to go down on price as he said 900 was the highest offer. I'll just have to wait for a good deal to come by.

Those modern Ampeg 810s really sound good with more power pumping into them- I'd really try a cranked V4b or an SVT with one before buying a second one and humping it around for the looks and bragging rights.

I've had great results getting more OD with a VT pedal in front of mine when I can't crank the SVT to get enough breakup because it will be too loud (which is most of the time). The tones available are truly identical when you use one in front of an SVT, just at lower SPL.

But as you've said, to each his own.

 

[MAMMOTHvolume]

the bit about 2Ω operation creating more distortion with solid state amps is true (check any straight-up power amp spec sheet).

if the amp is designed to be pushed to the wall like that then great, but it doesn't mean you're not still pushing it to the wall.

It does, but you'll be lucky to hear it

 

[bassmeknik]

the bit about 2Ω operation creating more distortion with solid state amps is true (check any straight-up power amp spec sheet).

if the amp is designed to be pushed to the wall like that then great, but it doesn't mean you're not still pushing it to the wall.

Thank you, Many amp manufacturers don't list the distortion specs at different load impedances because they don't want you to know how dirty they get at 2 ohms. Granted that the amount of distortion coming from most modern SS amps is below the threshold of hearing but not all, there is a lot of misinformation and old school attitutes born out of ignorance. Read Read Read

 

[anderbass]

That's not what I'm looking for at all. I really don't need more power, I just need something that can safely drive both cabs.

Then you could power both 4-ohm cabs with your old amp by plugging them in through a series Y-cord adaptor to end up with a combined 8-ohm load. (although solid state poweramps would achieve a lower max output level compared to running a 4-ohm cab load)

I made my own series-speaker adaptor but you could buy one here: Pro Cables N Sound Power Y cables, high quality Y cables for speaker cabs and combo amps

 

[Bob Lee (QSC)]

I have read a lot of spec sheets in my day and I have never seen any solid state amp with the same or less distortion at the lowest impedance. They are all slightly dirtier at lower impedance.

It's pretty rare for spec sheets to give distortion specs for various load impedances. Many people confuse power specs (which are given at various load Z's) with distortion specs, though. In a good amp design, the THD into 2Ω might be a small tick higher than into 4Ω but still should be negligibly low.