Ohm Confusion

[XsSpeed]

I am confused about the whole ohm thing. FOr the last year and a half I have been using a Sunn Coliseum 300 head which says 2 ohms on the back, with a Ampeg SVT 8x10 which says 4ohms on the back.

Everythign has been fine up until last friday when my amp "timed out". I had it bench tested yesterday and the tech told me a capacitor so he told me to get both replaced.

I am in the market for a more reliable head but still want to use the cab. Should I try to match the ohms? Aren't some new heads 2,4, and 8 ohms all in one with different wattages for each?

SOrry for the dumb question.

[Hopkins]

Your cab wasn't your problem. Your amp is a 2 ohm minimum load, It makes 300w @ 2 ohms, 200w @4 ohms. It would actually run another 810 if you wanted it to.

I would guess It just died of old age.

[nashvillebill]

Originally Posted by XsSpeed

....Everythign has been fine up until last friday when my amp "timed out". I had it bench tested yesterday and the tech told me a capacitor so he told me to get both replaced...

If it's "just a capacitor" time to get the TECH replaced, not the head. (and why did he say to replace the cab too???)

Now, in all likelihood the amp does need a cap job (35 year old electrolytic caps are well past their expected life span). But that does not necessarily warrant a new amp. A cap job on that amp should cost somewhere in the $100 to $150 range, tops.

Find another tech! Even though IMO the old Sunns have been surpassed by newer designs, there's still no reason to chuck your amp based on what sounds like poor advice.

[Oren Hudson]

Total agreement with the others. That is a real good head even now, but things do wear out on any quality gear at some point. That Sunn is one of just a handfull of heads from any time period that will safely do 2 ohms. And if you do a search on here, you'll find info on the super EQ on these along with other compelling reasons for using this head. Dump the "tech" and find one that will replace what you need done - and be happy. Ditto on using 2 8-10 cabs (if your ears can stand it.)

[BassMonstrum]

Two 8x10's??? You won't even need to be miked or DI'ed! (Well, maybe not literally, but y'all get the point... it's loud!)

[Von Felgenhauer]

Originally Posted by BassMonstrum

Two 8x10's??? You won't even need to be miked or DI'ed! (Well, maybe not literally, but y'all get the point... it's loud!)

If its too loud you are too old?

[XsSpeed]

I'm sorry I meant the Tech told me to replace BOTH capacitors not the head and cab. He said he'd do it for 140. He comes well reccomended. I think I'll go that route.

[billfitzmaurice]

Originally Posted by nashvillebill

35 year old electrolytic caps are well past their expected life span.

By about 15 years, to be exact. And capacitor storage values per cubic inch of size have increased substantially in the last three decades, so there's literally a lot of 'room' for improving the amp by replacing the caps with better than the original spec. While he's in there I'd replace all the electrolytic caps, not just those of the power supply.

Find another tech!

Why? As I read it he said one of the PS caps was toast, and that he should replace both of them. That's exactly what he should have recommended.

[XsSpeed]

So after having that done Bill, do you think I could feel confident in the reliability of my Sunn? I love the Sunn/Ampeg sound I get when I play and I'm only playing in Small punk venues (although we play loud) but my volume knob stays at noon or less.

Thanks

[Down & Outman]

So jealous. I had one of those Sunn heads back in the 70's. Get er fixed and rock on with it. I abused my head and it just kept on trucking.

[JimmyM]

Originally Posted by nashvillebill

If it's "just a capacitor" time to get the TECH replaced, not the head. (and why did he say to replace the cab too???)

Now, in all likelihood the amp does need a cap job (35 year old electrolytic caps are well past their expected life span). But that does not necessarily warrant a new amp. A cap job on that amp should cost somewhere in the $100 to $150 range, tops.

Find another tech! Even though IMO the old Sunns have been surpassed by newer designs, there's still no reason to chuck your amp based on what sounds like poor advice.

I think you misread the post

[nashvillebill]

Sorry, maybe I wan't fully awake! I read the post to mean that the tech said to replace the head and cab, since the OP was inquiring about another head.

So...nevermind!

[JTE]

Originally Posted by XsSpeed

I am in the market for a more reliable head but still want to use the cab. Should I try to match the ohms? Aren't some new heads 2,4, and 8 ohms all in one with different wattages for each?

Most tube amps (tube power sections) have multiple impedance taps on the output transformer and deliver the same power as long as your cabinet impedance matches the transformer tap they're plugged in to.

Most solid state amps have a minimum impedance rating, and the power available varies with the load. It's roughly halved each time the impedance goes up, so a head rated at 400 WRMS @ 4Ω will put out around 230 or so into an 8Ω load. Given that in most cases the increase in power with different impedance results in a negligible increase in volume, a good rule is to get a head that'll handle whatever load of cabinets you can imagine needing.

Now in your case, you've got a cabinet that seems to be just fine for all your needs, so getting a head that would go down to 2Ω wouldn't be critical. If you ever envision hooking TWO of those cabinets up, you'd need a 2Ω capable amp. But if you never see yourself needing that much speaker, then any 4Ω minimum amp would be fine.

If I were in your position, I wouldn't worry about it though. Every SS amp I know of will work fine at 4Ω, and if you find one you like that'll go down to 2Ω it won't hurt it at all to run it at 4Ω. Just concentrate on the power rating at 4Ω and sound you want to get from it, not whether it'll go to 2Ω.

John

[Tractorr]

Originally Posted by nashvillebill

Even though IMO the old Sunns have been surpassed by newer designs, there's still no reason to chuck your amp based on what sounds like poor advice.

Sorry Bill, I don't mean to pick on you and you are hardly the first person on this forum to say something to this effect, but I think this notion of amp designs being surpassed is kind of nonsense. Sure new amps can certainly do things that older amps cannot do, but all amps have their own sound. If the amp is giving you the sound you want that is all that matters.

[nashvillebill]

Originally Posted by Tractorr

Sorry Bill, I don't mean to pick on you and you are hardly the first person on this forum to say something to this effect, but I think this notion of amp designs being surpassed is kind of nonsense. Sure new amps can certainly do things that older amps cannot do, but all amps have their own sound. If the amp is giving you the sound you want that is all that matters.

Well, my old Sunn was noisy (background hiss) and not made very well.

As far as the design itself, mine was semi-complementary and transformer-coupled. Hi-tech in 1972 but most folks considered that design obsolete by the mid-70's. Remember, when that amp was designed, solid-state power amp design was less than 15 years old.

Solid-state amp designs have evolved quite a bit since the early 70's. MOSFET's and Class D architecture, for example. Even traditional designs using BJT's have been significantly refined, circuits have been worked out to make the amps more stable and less prone to HF oscillation for example.

So I hardly think that it's "nonsense" to say that new solid-state designs surpass the older stuff.

edit: Note though, that if the OP likes the sound of his amp, I still believe he'd be better off paying $140 for his cap job than to buy a whole new head.

[Tractorr]

Obviously the designs are more efficient (for lack of a better word), but if your amp is giving you exactly what you want then it has not been surpassed. You and I and probably a lot of people do not want a really 60/70s solid state amp but if someone wants the sound that that amp makes it has been surpassed by nothing.

[fingerbun]

Originally Posted by Tractorr

Obviously the designs are more efficient (for lack of a better word), but if your amp is giving you exactly what you want then it has not been surpassed. You and I and probably a lot of people do not want a really 60/70s solid state amp but if someone wants the sound that that amp makes it has been surpassed by nothing.

I have a Peavey Mk III twin channel head that I think is a late 70's design (I got it in 1981 I think). It does what it does well, and also has sentimental value so I actually use it reasonably often.

I think there's a certain amount of personal taste here. From time to time I try out new amps but I don't like how they sound. I do like the smaller size though :-)

[Tractorr]

Originally Posted by fingerbun

I have a Peavey Mk III twin channel head that I think is a late 70's design (I got it in 1981 I think). It does what it does well, and also has sentimental value so I actually use it reasonably often.

I think there's a certain amount of personal taste here. From time to time I try out new amps but I don't like how they sound. I do like the smaller size though :-)

Exactly my point that amp works for you. I just got a new amp after using the same Hartke for the last 15 years. The Hartke was fine but I wanted a thick full tube amp. The Hartke just could not cop that sounds no matter what. Even though I don't really play slap very often, I tried out some slap on the new amp and I didn't care for it. The Hartke is a better amp for slap style. I know this comparison is apples to oranges but this is my point, these amps are completely different beasts.

[fingerbun]

Originally Posted by Tractorr

Exactly my point that amp works for you. I just got a new amp after using the same Hartke for the last 15 years. The Hartke was fine but I wanted a thick full tube amp. The Hartke just could not cop that sounds no matter what. Even though I don't really play slap very often, I tried out some slap on the new amp and I didn't care for it. The Hartke is a better amp for slap style. I know this comparison is apples to oranges but this is my point, these amps are completely different beasts.

What tube amp did you get? If I buy another amp it will be a tube beast. But Ampeg and Mesa Boogie are not cheap, and I struggle with justifying the price to myself.

[JimmyM]

Originally Posted by fingerbun

What tube amp did you get? If I buy another amp it will be a tube beast. But Ampeg and Mesa Boogie are not cheap, and I struggle with justifying the price to myself.

Just do it quickly and forget about what it costs immediately afterward.