NCD - a derelict Sunn project.

[Jackroadkill]

I've just come into possession of this:

 

 

I think it's from the 1970's, and it has one missing cone and one dead cone, which, given the 4ohm impedance and paltry 160w rating, I'm not surprised about.  I'd like to fit some new speakers to it and give it a bit of a spruce up.  I have heard it in action, years ago, and from what I could tell it sounded pretty reasonable, so if I can get it up and running again it might be fun.  I have the mesh grille and all the fixings, but the one 15" speaker I have won't fit in the hole in the baffle, annoyingly.  I'm not sure at present whether this is because the speaker's chassis is too big or the hole is undersized; I suspect some research may well be due.

 

If anyone has any info or insight into these cabs then I'm all ears.

 

Cheers,

 

JRK

[andytoad]

That's gonna look F.A.B... followed 🙂

[Bill Fitzmaurice]

They were pretty good bass reflex cabs. Not folded horns as they claimed, but bass reflex with tapered ports, a seat of the pants design, as there was no folded horn or bass reflex design software then and the designers, Norm (of The Kingsmen) and Conrad Sundholm weren't trained in speaker design. The drivers were Eminence rather than the JBL they used in the earlier 200S and 2000S. Driver sizes are approximate, so it's not unusual to need to do some work on the baffle to get replacements to fit.

[Jackroadkill]

26 minutes ago, Bill Fitzmaurice said:

The drivers were Eminence

 

That's great to know - if the speaker currently in it is original there's nothing to tell me that it's an Eminence.  The only distinguishing feature is the square magnet!

 

I think I'll fit it with more modern speakers that can handle a bit more oomph, as dragging a(nother!) 2x15 around isn't going to be worth it unless it'll pump out a decent volume without dying again.

[Bill Fitzmaurice]

Square magnets and small domes were characteristic of early Eminence drivers.

[Steve Browning]

As used by John Deacon and John Entwistle, among others. 

[stevie]

13 hours ago, Jackroadkill said:

 I have the mesh grille and all the fixings, but the one 15" speaker I have won't fit in the hole in the baffle, annoyingly.  I'm not sure at present whether this is because the speaker's chassis is too big or the hole is undersized; I suspect some research may well be due.

 

 

Does your driver have a cast aluminium chassis? Drivers with a cast chassis tend to be larger in diameter than those with a pressed steel chassis. So, a replacement driver with a pressed steel chassis might fit. Check out the specs provided by the driver manufacturers, where the precise diameter is usually stated.

[Jackroadkill]

12 minutes ago, stevie said:

 

Does your driver have a cast aluminium chassis? Drivers with a cast chassis tend to be larger in diameter than those with a pressed steel chassis. So, a replacement driver with a pressed steel chassis might fit. Check out the specs provided by the driver manufacturers, where the precise diameter is usually stated.

 

Ah, I hadn't thought about that; I think the originals are pressed and the other driver has a cast chassis.  I'll check when I get home.  Thanks for the tip!

[Jackroadkill]

2 hours ago, Steve Browning said:

As used by John Deacon and John Entwistle, among others. 

 

Well, that would explain the blown speakers!

[Bill Fitzmaurice]

5 hours ago, Steve Browning said:

As used by John Deacon and John Entwistle, among others. 

Not necessarily. If you see aluminum domes they were probably JBL. When Sunn first came out with the 200S one thing that made them better than the rest was JBL drivers as standard, rather than as optional. But that also made them expensive, as JBL cost two to three times what others, like Eminence, did. I still remember buying JBL E-140 for $75 USD in 1970. That would be $700 today. In the early 70s Sunn went to the far less expensive Eminence in most of their cabs, but still offered JBL as upgrades.

[Pea Turgh]

Impressive looking cab!  Would be ace to get the box measurements to see what driver would suit the box/port size.

[Jackroadkill]

31 minutes ago, Pea Turgh said:

Impressive looking cab!  Would be ace to get the box measurements to see what driver would suit the box/port size.

 

I don't know how to work all that out, which is a shame.  Is it simply a case of measuring the internal size of the cab (presumably not the ports) and going from there?

[Bill Fitzmaurice]

In this case it's not so simple, as the ports are tapered. Basic ported box speaker modeling software can't account for that. You can do it with a more sophisticated tool, like HornResp or Akabak, but they require a high degree of expertise. However I do happen to have that high degree of expertise, and my rate is reasonable. Free.  ☺️ 

[Downunderwonder]

10 hours ago, Bill Fitzmaurice said:

JBL E-140 for $75 USD in 1970. That would be $700

X2 and you are looking at the Barefaced of the day but half as loud, except with your amp it would have been twice as loud.