Closed vs open back cabs

[sclitheroe]

Been playing the Greta more these days, just to change it up. It has a closed back cab with a 12" Celestion Seventy Eighty (bear in mind, the Greta is 2 watts), and it's quite a change coming from open cabs. To my ears, it's a much darker, boxier sound, and I keep wanting to open up the highs on the EQ, but wondering if that's counterproductive and I should learn to appreciate the difference in tone, and work within its boundaries. It almost sounds like it sits further back in the room than it is, but that could also be because the Greta is a pretty quiet amp, it only just keeps up with my monitors when I'm playing along with songs or backing tracks.

How many of you run closed cabs, what do you like about it, and what are your tips for getting the most out of them? Particularly with dirt..go brighter? More mid-hump to work that punchiness harder?

Gratuitous Greta shot for attention

Hope you're all doing well and keeping safe!

-Scott

Webp.net-resizeimage (2).jpg (213.74 KiB) Viewed 24184 times

[fuzzbuzzfuzz]

That looks particularly tasty set-up wise, including the Tele!
I have a similar issue with my Orange 2 x 12 cab  (with OR15 head). It's very directional, blasting the audience directly ahead with treble, whilst I hear muffled bass and keep turning it up! Of course it is also "tight" where-as I think I'm a "loose" kind of guy  

[bigtone23]

I prefer closed back cabs for the focus and low to low-mid punch.
Open back is nice for unmic'ed gigs where the extra spread around the stage is useful.

[laurie]

"boxy" ... I hate that tone/feeling. I've been using open-back for years because of it.

[tunghaichuan]

Another choice is ported cabinets.

I have two RSA-branded Thiele speaker cabinets based on this design:

https://robrobinette.com/images/Guitar/ ... _plans.pdf

I have them loaded with EVM12L Classic reissues.

They seem to work better with high gain preamp distortion, vs. pushed power amp distortion. They have a huge amount of low end for such a small box. The EV speakers are very efficient at 100db/watt/meter so they can get stupid loud in a hurry. The EVs don't seem color the sound like a Celestion does. The cabs can be kind of beamy, but I wouldn't use "boxy" to describe them.

[sclitheroe]

Would pulling the entire back off the cab be the answer? Or should a cab have some portion of the back covered?

[tunghaichuan]

Would pulling the entire back off the cab be the answer? Or should a cab have some portion of the back covered?

Can you do that without damaging the cabinet?

[sclitheroe]

Would pulling the entire back off the cab be the answer? Or should a cab have some portion of the back covered?

Can you do that without damaging the cabinet?

Good question because the answer is...no. Just took a look. For some reason I thought there was an easy way to do it, but there certainly isn't. And I'd be reluctant to permanently modify the Greta cab, it's quite rare (not that I'm a collector really, I just don't see the sense in hacking it up)

I could always line out the Greta into the JC-120 or the Bassman for open back cab if I wanted, just need to look at what the output specs are before I do it

[laurie]

Would pulling the entire back off the cab be the answer? Or should a cab have some portion of the back covered?

Acknowledging the Greta cab can't be converted...

Can I convert it to open back? Should some of the back be covered? There is a very long and detailed engineering answer to this that depends on the Thiele and Small parameters of the driver: https://en.wikipedia.org/wiki/Thiele/Small_parameters

The risk of getting it wrong is that the driver has excessive excursion and is damaged, or other electromechanical faults due to the impedance curve occur (e.g. burning out the driver). Or it simply sounds like crap. And unless you know the exact model number of the driver and the manufacturer has provided the Thiele and Small parameters, there is actually no way to use the math to figure things out.

However... With only 2W of power from the amp the risk of any speaker damage is pretty much zero. So I'd say just try various configurations until you find something that sounds good-to-your-ear.

Plugging the Greta into the speakers for the JC-120 might not sound as nice - the JC-120 has very "clinical" speakers to my ear. The Bassman speakers would be a better bet?

Or something like a V30 in an open-back

[laurie]

Some interesting speaker stuff:

Ported (closed back) enclosures for JBL drivers - not for guitar, but an interesting read
https://jblpro.com/en-US/site_elements/ ... sure-guide

Someone's open back design:
https://www.instructables.com/An-Open-B ... -and-Bass/

Open back cab design (PDFs near the bottom):
https://guitargeary.com/how-to-build-a- ... p-cabinet/