Help me choose a speaker

[Hallingamp]

Hi everyone. Very long time since I was last here, but suddenly got the itch to build an amp again.

I just finished a Master Volume amp, and it sounds just like I want it plugged into my old 2x12" cab with Jensen "special design" speakers (whatever that means). Medium gain big, bold, like AC/DC in 1981.

Problem is that this was meant to be a 1x12" combo. I chose a Celestion G12H, thinking it would do the job, but it sounds like a thin, flabby, lifeless 10" in comparison.

I haven't really that much experience with different speakers, so I hope someone here can help. Is there a 12" speaker that can do the job in an open back combo? Opening up the 2x12" cab to try one of those is a terrible job, and I don't really want to butcher it.

Regards
Jan

[Helmholtz]

Could you post a schematic of your amp?

The old 12" Jensen Special Design speakers were excellent, having a nice treble response.
The Celestion G12H is a high sensitivity but darker sounding speaker.
Of course the 2x12 arrangement as well as the cabinets make a difference.
For a better comparison I would try one of the Jensens in your combo.
If your amp has a presence control, the G12H would benefit from a higher setting.

[Hallingamp]

Hi Helmholtz, and thanks for the reply. The description "dark sounding" was actually why I chose the G12H. The one Hendrix liked, right? But it sounds the exaxt opposite, thin, high-middy, no balls, and no punch at all. I guess I'll have to open up the 2x12" cab and try one of the Jensens.

The schematic is this Marshall model 2000 preamp including the fx-loop: https://images.app.goo.gl/8L7wtA1Hf6iKiZnx7

I have done just a few minor tweaks to it and coupled it with a very standard cathode biased 4xEL84 power amp. (I don't really need the 250W power amp of the model 2000! )

[Helmholtz]

Bass response definitely depends on the cabinet (and where you place it). What G12H do you have (resonant frequency)? Are you sure it's good?
Not directly related to sound, but the 30W power rating of the G12H may not be sufficient for a 4xEL84 amp.

For a while I used 2xG12H in an AC30 cabinet. While loud, the sound was too dark and boomy for me.

[Hallingamp]

It's this one:

https://www.gear4music.com/Guitar-an...m-Speaker/2JOT

Resonant freq 85Hz, but "dark and boomy" it's definitely not.

The amp should in theory be 36W, and I never play that loud anymore anyway, so it should be fine in that regard. I'll try another speaker tonight, I found the original speakers from my 2x12" in the garage. I was sure I had thrown them away, cheapo Bugeras. If they sound better than the G12H, there must surely be something wrong with it.

[Helmholtz]

Resonant freq 85Hz, but "dark and boomy" it's definitely not.

Should be either 55Hz or 75Hz. But doesn't matter as these were the ones I tried.

[Hallingamp]

I tested the Bugera (12G70J8) and the Celestion against each other now - mounted in the amp, and I auctually prefer the Bugera. It also sounds as if the amp is distorting more with the Celestion, regardless of volume, and not in a good way. With the Celestion I constantly reach out to turn the gain, treble and high mids down. (Amp has got mid-sweep) It's like the bugera and the 2x12" cab "holds the horses" while the Celestion "runs away"... Terrible description, but it's like there's less resistance in the Celestion. God, I struggle to explain this! Do you think this indicate a faulty speaker?

[g1]

If anything is interfering with the cone movement, you will lose bass first. I would guess the coil is rubbing or the coil former is swollen and not moving freely in the gap.
Or, if it was recently shipped (and mishandled), the magnet can shift and pinch the coil in the gap.
Can you move the cone freely (carefully) by hand?

[Hallingamp]

Hi G1.

Yes, cone moves more freely on the Celestion than on the Bugera.

[The Dude]

I'll add: Brand new speakers can be a bit stiff and harsh sounding at first. Breaking it in for a while might change its response.

[g1]

Perhaps the spider has come loose, or the surround? Everything looks good?
What is the history of this Celestion, is it a new purchase?

[mozz]

I was always under the impression that a Celestion is not meant for a open back combo cabinet. I do know people who run vintage 30's in Fender combo's though.

[Chuck H]

JM2C,...

Most Jensen "special design" speakers have a nice top end for clean and crunchy tones. Sometimes the mids can be lacking for leads. Your 2X12 cab is moving enough air to get a decent bass response, but a single one of those speakers in a 1x12 combo configuration isn't going to sound the same at all. I'm so sure of this I wouldn't even bother trying it, personally.

The Celestion line sounds so NOT Jensen that I wouldn't expect any analogs comparing the G12H (anni or heritage) loaded into a 1x12 combo cab either. You've heard something you like. Whether it's closed back or open the 2x12 cab just has more oomph and interior volume. And you like the top end of those speakers with the amp you built. It's also unlikely you're pushing any wattage limits on the 2x12 cab because the speakers rating is combined. So...

I don't think you're going to get a 2x12 cab sound out of a 1x12 combo cab (which has even less interior volume for the single 12 than is afforded to each in the 2x12). But I might try an EV speaker like the EVM12L. It's been THE go to speaker for players and designers trying to get a bigger sound from smaller cabs for time immemorial. I'd probably shop for a used one for two reasons. They're expensive and if you buy used you can always sell it used having lost no value (other than maybe shipping).

[pdf64]

I find that most Celestion guitar speakers with a ‘H’ weight magnet have an excessively ‘brash’ / strident character for use with overdriven guitar. Especially so with the G12H30, it’s that classic Celestion ‘kerrang’ tone but exaggerated too far. Whereas those with an M weight magnet tend to have a tonal balance I find much more pleasing.
Whether in a open or closed back cab, for me it’s hard to beat a G12M25, other than by running them in multiples, or in combination with alnico types.
The much derided G12T75 is a fine alternative if a higher power rating is needed, with the benefit that they’re readily available second hand from people ‘upgrading’ their cabs.

[Hallingamp]

Thanks for the replies.

It's funny to see how different experiences you have with the G12H.

The Celestion is brand new and shipped from England to Norway, so something may have happened. Everything looks ok tho, and the cone moves freely with no scratching. The Bugera speaker is really stiff in comparison, but sounds much better. It does not sound like the 2x12" cab, but it's surprisingly OK. I was just expecting the Celestion to be far better, and I now honestly think there's something wrong with it. I have found a Jensen C12K for sale nearby cheap enough to just buy and try, so I think I'll do that.

I'm not expecting a 1x12" open back to sound just like a 2x12" closed back, but I would like it to sound like the same amp is being used. Like a JCM800 1x12" combo still sounds like a Marshall even if it's not a 2203 with a 4x12". I'll report back on the C12K.

Thanks for helping.
Jan