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Firefly Speaker choice
Hi, I'm Pierre from Belgium and this is my first post !
Last week I finished my first tube amp, I builded the Firefly amp with rev.8 PCB, to my sourprise it worked right away !
I have a little Marshall amp (a 15 watts MG something) and I borrowed its speaker (a 8" 8 ohm no-name speaker) just to test the amp, the sound didn't please me a lot, I guess the speaker is not the right one, once you pass a certain volume, the amp sounds like an angry sreeming baby, distortion is far from smooth, maybe a little to harsh...again, the speaker is not the adequate for this amp...
I'm about to order a speker more suitable, my budget choices are the G12H and G12M Celestions made in China...Wich one should I get? or Wich one is more suitable? and Are these Celestions made in China speakers good for this project?
I'm sorry if this subject has been discussed before, It seems that I don't really get a direct answer from the serch fuction...
Please excuse my poor English...
Thanks a lot,
Hi Pierre and welcome to the forum.

The FireFly has low headroom (it's only 1W or so) and is mostly popular for its distortion. Having said that, a speaker can make considerable difference, but suitability depends on where you want to use it.

I own a FireFly and an open-back cab with a 12" 98.86dB WGS 'Retro 30' driver. So let's test on the fly, in an average-sized bedroom, with the guitar plugged directly to the amp (no effects). My results:
-The overdrive for a chord starts at about 2/10 gain (boost off), with a single-coiled bridge pickup, without stroking very hard.
-About 4/10 for a single note, ceteris paribus.
-When playing clean, no matter where I stand in relation to the speaker, the sound is adequate for the room, but not anywhere near loud.
-When playing dirty, let's say gain at 5-10/10, the sound is more than adequate, but not too loud. I have been told that it's audible in other apartments in the building.
-With the boost on and at about 5/10 and the gain at 5/10, it is almost painfully loud in the room and I have been told that it's perceived as noisy in a small distance around the building.

This setup is nowhere near adequate for a studio. If you want to play at home, I think it depends on your definition of 'adequate', but judging from my results I'd probably go for the 100dB G12H, or something even more efficient (there was a good article somewhere about speaker efficiency and how much difference it makes, but I can't find it right now).

You could also consider a cab with more than one drivers and/or replacing the 12AU7 tube with an ECC99 which, reportedly, has a little more headroom and nicer distortion (careful, you'll need to adjust the bias too).

Someone more knowledgeable will hopefully chime in.

- CT
Congradulations on your amp! I've also built a tube amp by stripping out the guts of an MG cabinet/chassis and replacing things with a proper tube amp. I can confirm that those speakers are total garbage. Pretty much *any* quality speaker will make a huge change for the better with your amp.

The advise to bring your amp somewhere (anywhere) where you can try it out with different speakers is good. Different speakers do sound noticably unique. Hearing for yourself what you like has no real substitute.

I'd look for a music store that may have cabinets you can audition. Perhaps you have friends with cabinets? Is there a place where local musicians hang out?


P.S. I myself am a fan of weber speakers. But there are many other varieties/brands that sound good. You just need to hear them with your amp.
I tuned the original Firefly to a G12H30 70th Anniversary Celestion in a sealed 1x12 cabinet. You may want to adjust C8 for different speakers or to suit your personal taste. Higher values of C8 will roll off more highs and vice versa.

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