I put a 8F125 from Ted Weber on the bottom of the DT and a Weber Sig Ceramic on the top. A couple of years ago, I ordered a Ceramic Sig S, and just last night I realized that the speaker is not the S! My receipt says I ordered the S, but the speaker is not the S. Oh well, I love it! However, I ordered the 8F125 as a beefier Ceramic S. Thankfully, the 8F125 is darker than I would have thought. Works for me…but I could have ended up with two feedback prone speakers.
With only 2x8 and 18w, I like the ceramic mix. The 8F125 has more bottom, but seems to be the same volume as the Sig. I couldn't get a 8F125 or the like to fit in the top speaker slot…one 8A125 and one 8F125 might have been sweet!
I tried 2 AlNiCo, 1 AlNiCo with the Sig and then the 8F125 and then the current combo. The amp seemed to feedback at the same point regardless of combination. For each combo I placed the amp in the exact same spot. I then stood in the same spot with the mic a foot off the grill on one speaker. I then turned the volume up until the first squeal (tone on 10). I then did that for the second speaker. There was the same feedback volume (4) on the dial within a 1-2mm twist of the volume knob for each speaker. Next I set the volume on 7 and tone on 6. I then stood about 6 feet away from the amp and played to check tone and feedback. I switched speakers out and then repeated. Eventually I added a BBE Two Time in line. The delay seems to be warmer/darker with this amp than the Fenders I've tried it with. That is a good thing. It really sounded excellent…but bare in mind this is all being done in the family room. I think the room tends to create feedback more than most stages, but the amp will surely sound different at a gig.
I decided against the stock AlNiCo for the simple fact I decided a while back I don't like buzzy speaker distortion (couldn't replicate it with an AlNiCo in a Vibro Champ). I am not saying that speakers or bad of the DT should come with different ones. It might seem strange, but for harp, I am not a fan of lots of speaker distortion. I like compression, but not the sound of an 8” distorting. I don't think the DT is any louder now, but it does have a bigger bottom end. Neither ceramic speaker seemed to fart out even with a Low F harp and tone all the way down.
Also, this amp is going to be used at a range of volume levels. I think the “cleaner” ceramic speakers make the amp more consistent sounding from low to high volume. Some players are going to prefer the smoother sound of the stock speakers at low volumes and the all out nasty flavor of the speakers when cranked.
I still have JJ 6V6 tubes in there with a GE 12ay7. I was too lazy to monkey with rolling tubes as I have a limited number of 6v6 and 12ay7 tubes and time on my hands. This week I'd like to try a Mullard 12at7 and JAN 5751, but I have a strong feeling I'll keep a 12ay7 in there. The stock tubes may sound the exact same, I don’t know, but I have really liked the JJ’s in my other 6V6 amps. I use a SM57 and can sometimes use hotter tubes and still be ok.