Limited Edition Ampeg SVT

[Pow_22]

https://www.ebay.co.uk/itm/325672466216?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=5FL9HKvQQzW&sssrc=2349624&ssuid=oN5XbKSRQjS&var=&widget_ver=artemis&media=COPY
 

being sold with non compatible 8ohm cab so may well have been used and abused with it. Never see anything cool like this in my local CC 😫

Edited May 31, 2023 by Pow_22

[Reggaebass]

What would one normally go for 

[Beedster]

1 minute ago, Reggaebass said:

What would one normally go for 

These days less than they’re asking 😕

[Pow_22]

10 hours ago, Reggaebass said:

What would one normally go for 

 

With it being a CC there probably wont be any service history or knowledge of valve age.  Plus as mentioned, it comes with an 8ohm cab which isnt compatible - it may suggest the head has been used long term with the cab which itself could've caused issues.  Assuming everything was a-ok i would probably offer £1k, flip the cab and spend the cab money of a service with a competent tech.  As @Beedster mentions also though, heavy iron just doesnt seem to shift nowadays

[Reggaebass]

Thanks for that, it’s probably difficult to know how much if any damage has been done, it’s about an hour away from me, I don’t think I’ll bother, they do look pretty cool though 

[Max Normal]

10 hours ago, Reggaebass said:

What would one normally go for 

Don't know about this "limited edition" but you can pick one up for £600-£700. They sound sublime with an SVT810E cab, which always makes your local venue landlord's face light up with joy when you wheel it in.

 

With a smaller vented cab like a 410HLF, they lose their punch and sound a bit slack, so I sold mine. Also, they weigh as much as a neutron star.

 

Only good for bigger gigs IMO.

[Snook]

They also had for sale an Ampeg SVT18E cab, which I assume was paired with this one. Therefore they might have actually run both at 4 ohms.

[Beedster]

4 hours ago, Max Normal said:

Don't know about this "limited edition" but you can pick one up for £600-£700. They sound sublime with an SVT810E cab, which always makes your local venue landlord's face light up with joy when you wheel it in.

 

With a smaller vented cab like a 410HLF, they lose their punch and sound a bit slack, so I sold mine. Also, they weigh as much as a neutron star.

 

Only good for bigger gigs IMO.

More than a neutron star 👍

[NikNik]

These were usually sold with the accompanying 8 x 10" cab. I played through one a few times and they're freaking loud but really prone to interference due to the gain stages, I'd guess.

[Reggaebass]

1 hour ago, NikNik said:

These were usually sold with the accompanying 8 x 10" cab. I played through one a few times and they're freaking loud but really prone to interference due to the gain stages, I'd guess.

I read somewhere that the fan is also loud, did you notice that at all 

[Hellzero]

Running an 8 Ohms cabinet on a 4 or 2 Ohms output won't damage anything, it's the opposite that will blow out the output transformer...

 

So it's absolutely not a non compatible cabinet, but a totally compatible one. 😉

[JottoSW1]

I was under the impression that running a 4ohm Valve Amp into 8ohms wasn't good for them at all

Calling @agedhorse

[bagsieblue]

7 hours ago, JottoSW1 said:

I was under the impression that running a 4ohm Valve Amp into 8ohms wasn't good for them at all

Calling @agedhorse

Nope, its a minimum load not a maximum load.

[BigRedX]

2 hours ago, bagsieblue said:

Nope, its a minimum load not a maximum load.

 

IIRC that's just for solid state amps. Valve amps need to matched exactly to the correct impedance. The valve guitar amps I've owned have all had multiple speaker outputs marked for different speaker impedances.

[tauzero]

15 hours ago, JottoSW1 said:

I was under the impression that running a 4ohm Valve Amp into 8ohms wasn't good for them at all

Calling @agedhorse

 

I think that's right - running a valve amp with no load is very bad for it. ISTR (but I could well be wrong so check with an expert) that you ideally should match impedance but that it's possible to run into a lower impedance than marked, so you could run a 4 ohm load from the 8 ohm output.

[Hellzero]

Definitely right @dmccombe7 ! 🤦🏻‍♂️

[dmccombe7]

2 hours ago, Hellzero said:

Definitely right @dmccombe7 ! 🤦🏻‍♂️

Don't really know enough about it TBH but i have noted that some Ampegs only have 2 or 4 ohm on the back but the manual does state its not a problem running into an 8 ohm cab as you say @Hellzero

I'll be guided by others that know better.

Dave

[paul_5]

SVTs will play with 8Ω cabs all day long, they just won't be able to deliver their maximum power. 

 

Speaker impedances on amps are MINIMUM ratings.

 

Bigger number good, smaller number bad. Very bad.

[agedhorse]

On 02/06/2023 at 01:45, bagsieblue said:

Nope, its a minimum load not a maximum load.

Actually, it depends very much on the amp. 
 

Tube amps reflect the speaker’s impedance back through the output transformer to the plate circuit. This output matching transformer maintains the voltage (and current) ratio so that the high impedance plates transfer the energy effectively to the low impedance load. 
 

When the load is mis-matched to the plates, the voltages can increase to unsafe levels, especially when the output stage is overdriven. This effect is generally worse when the load is higher than the impedance tap is set for.

 

some amps are more forgiving of mismatches than others, though the cost of being wrong can become awfully expensive. 

[dmccombe7]

Are the big Ampeg 810 cabs 4ohm ?

Dave

[Hellzero]

2 hours ago, agedhorse said:

Actually, it depends very much on the amp. 
 

Tube amps reflect the speaker’s impedance back through the output transformer to the plate circuit. This output matching transformer maintains the voltage (and current) ratio so that the high impedance plates transfer the energy effectively to the low impedance load. 
 

When the load is mis-matched to the plates, the voltages can increase to unsafe levels, especially when the output stage is overdriven. This effect is generally worse when the load is higher than the impedance tap is set for.

 

some amps are more forgiving of mismatches than others, though the cost of being wrong can become awfully expensive. 

 

And to add even more confusion to this, while speaker impedances are most often rated at 2, 4, 8, 16, 32 or higher Ohms loads (or even lower than 1 Ohm, and even with decimals), their real impedance will vary between 6Ω and 32Ω for an individual speaker, whatever impedance is labelled on the speaker or the cabinet.

 

A lower impedance cabinet or speaker than the tap output labelled impedance will, in the end, see the wire itself burn because of the heat generated or break because of the higher extension of the cone(s) blowing the output transformer (see @agedhorse explanation above).

 

On the other hand, if speaker impedance is really too high, say 32 Ohms on a 2 Ohms tap, the amplifier's power may not drive the speaker at all, but who would do that...

 

Maybe we can also talk about of the form of wave generated by the output stage when driven too hard to add even more complexity to what originally was a simple question...

[dmccombe7]

Its all getting very techy now and even tho i have an electrical / electronics background its way over my head.

Obviously there's far more going on than i ever gave any thoughts to.

When i bought my Handbox WB-100 it was made clear on the instructions not to mis-match the speaker impedance to the amp so i'm a lot more careful to make sure no damage is caused by mis-matching.

With SS amps i just plug and play as my cabs are nearly always 8 ohm. If i have a choice i always go for 8ohm cab versions. Its just easier for me to calculate things.

1 cab = 8 ohm

2 cabs = 4 ohm

3 cabs = my brain hurts

4 cabs = i give up and go home.

 

For bass players ........... just keep it simple is always best IMHO.

 

Dave  

Edited June 4, 2023 by dmccombe7

[Reggaebass]

Getting a bit confusing now, my Ampeg has 2,4 and 8 ohm outlets which covers most cabs I would think, including my BB2 which is 8 ohm, but if I got another Ampeg with only 2 or 4 options I’m not sure I would trust them matching now 

Edited June 4, 2023 by Reggaebass

[Hellzero]

21 minutes ago, Reggaebass said:

Getting a bit confusing now, my Ampeg has 2,4 and 8 ohm outlets which covers most cabs I would think, including my BB2 which is 8 ohm, but if I got another Ampeg with only 2 or 4 options I’m not sure I would trust them matching now 

You still can rewire the cabinet itself to change the overall impedance.

[Hellzero]

46 minutes ago, dmccombe7 said:

For bass players ........... just keep it simple is always best IMHO

And you are right.

 

To keep it simple with (valve) amplifiers always use the amplifier's output (tap) matching the cabinet impedance, never use a lower impedance cabinet than the output impedance (tap) chosen on the amp, but you can use higher impedance cabinet than the impedance of the amplifier's output (tap), even if it can create some slight distorsion or slight out of phase sound, which you won't really notice and certainly not the audience.

 

Clearer?