Peavey Classic 30 - extension speaker?

flatout

I've recently acquired a Classic 30 combo, and I already have a 1x12 extension cabinet with a Vintage 30 8 ohms that I'd like to use with it.

But I'm nervous and thoroughly ignorant of the whole impedance thing.

The Peavey has a 16 ohm speaker, and an extension speaker socket that says "This is provided for connection of an external speaker cabinet. Minimum total impedance is 16 ohms."

Does that mean I can use the extension speaker? or that I shouldn't? Help?!

 

djspecialist

I believe the wiring is similar to the C50:

• Internal cab is 16R
• Optional external cab
• When an external cab is connected, the output transformer is tapped to expect 8R overall impedance
• Extension cab is connected in parallel with onboard - 2 x 16R in parallel = 8R overall

16R + 8R in parallel = 5.3R, which is lower than the amp expects to "see".  I'll let someone better qualified than me (paging @ICBM) comment on whether or not that's a good idea...

ICBM

It will be safe if the amp isn't really cranked, but I might be a bit more wary if you're going to drive it hard.

Although running a one-step downward mismatch is not normally a risk with most valve amps, and actually reduces the output power in most cases, C30s are notorious for weak power transformers so I would be inclined to avoid anything which could increase the current draw.

If you're only going to run it at lower volume - if you can still get a completely clean sound on the clean channel and the dirty channel isn't any louder - then it should be OK, but if you're planning to drive it harder than that in a band situation then I would swap the V30 for a 16-ohm one.

flatout

That's really helpful - thanks! I'm finding it difficult to imagine what running a C30 cranked must be like - as clean volume on 3 is utterly deafening! But I'll heed your words with a low volume test and swap out for a 16 ohm V30 if I like what it does. Cheers all!

ecc83

So IC, is that a £700 combo with no 8 Ohm jack?

Dave.

ICBM

ecc83 said:

So IC, is that a £700 combo with no 8 Ohm jack?

It does have an 8-ohm jack, but it's slightly more restricted - the internal speaker is 16-ohm and hardwired, and there's one extension speaker jack which is in parallel and automatically switches the amp to 8 ohms.

I would usually not worry about running a 5.3-ohm load from an 8-ohm tap at all, but these amps have a known history of PT failures so I'm just a bit more cautious about anything other than a proper match...

crunchman

flatout said:

That's really helpful - thanks! I'm finding it difficult to imagine what running a C30 cranked must be like - as clean volume on 3 is utterly deafening! But I'll heed your words with a low volume test and swap out for a 16 ohm V30 if I like what it does. Cheers all!

You might be better off with something other than a V30.  I had one in a Classic 30 years ago it I didn't like it - it sounded harsh.

I'm not a fan of the C30.  It sounds good which is why I bought one as my first valve amp but it is horribly constructed and will be a nightmare to fix if it goes wrong.  Personally I'd sell the C30 before it breaks and get a Hot Rod Deluxe.

Even if it doesn't go wrong it will cost you a lot more to run long term.  It's chews up EL84s at a phenomenal rate.  I used to have to replace them at least once a year - and you have to buy 4 of them so while they are cheaper valves it costs as much to revalve as something with 2 6L6s.  A set of 6L6s used to last me years in my HRD.

ecc83

ICBM said:

ecc83 said:

So IC, is that a £700 combo with no 8 Ohm jack?

It does have an 8-ohm jack, but it's slightly more restricted - the internal speaker is 16-ohm and hardwired, and there's one extension speaker jack which is in parallel and automatically switches the amp to 8 ohms.

I would usually not worry about running a 5.3-ohm load from an 8-ohm tap at all, but these amps have a known history of PT failures so I'm just a bit more cautious about anything other than a proper match...

So, it switches the transformer to an 8R tap but leaves the internal speaker connected? If so, weird!

BTW, whilst talking of things weird? AFAICT the new Blackstar ID Core 100 and 150W combos do NOT have the facility to connect external speakers.

I had assumed they used the same class D "block" as the ID TVPs which seem to have proved pretty bombproof?

I still think the new combos will prove to be good value, light and versatile amps, if only as a backup/spare but the inability to connect to your 4 Ohm 4 by 12 will surely put some players off?

Dave.

ICBM

ecc83 said:

So, it switches the transformer to an 8R tap but leaves the internal speaker connected? If so, weird!

No, logical - the idea is to use the matching 16R extension cab so that and the internal 16R speaker need the amp switched to 8 ohms. Just a bit restrictive.

ecc83 said:

BTW, whilst talking of things weird? AFAICT the new Blackstar ID Core 100 and 150W combos do NOT have the facility to connect external speakers.

I had assumed they used the same class D "block" as the ID TVPs which seem to have proved pretty bombproof?

My guess would be that the ID blocks were too expensive for the Core series. Let's hope they're as good...