5f1 questions

[benjamminn]

Hey all, due to a move, I've had to downsize my amp of choice from a beloved JTM 45 () I built to something more manageable in an apartment. Not looking for a gigging amp or anything overly loud, just something to play with that sounds as good as possible. Right now I'm just playing into an old Ruby solid state I built into headphones I'm interested in building a 5f1, but I have a few questions about the amp.

1) I'm curious about the Tweedle Dee Champ layout ( https://tubeamparchive.com/viewtopic.ph ... 0deb6516ac )--how would you characterize the changes from the standard 5f1 layout? I've seen the 5f1 described as everything from glossy/bright to dark sounding, so any descriptions on what that might get me would help.

2) I've also read that the small tweed amps start getting dirty around 4 on the volume knob--is it useful at all to try to get some increased headroom, or am I changing too much of the character of the amp? (I was thinking about trying the 40-18031 OT but leaving the 6v6 tube.) I do noodle around with some clean/ambient stuff, so I wouldn't mind a little more headroom.

3) I run almost no OD/dist pedals usually (usually just a klone as a clean boost), more of an amp overdrive kind of guy. That said, I've built lots of fuzzes over the years, and I'm worried about what I've read about the 5f1 not dealing well with any kind of higher gain input. Anyone have any experience? I can't find a fuzz + 5f1 clip for the life of me.

4) (Sorry this is getting really long!) Will there be any earth-shattering differences from running this amp into a 12" speaker vs. the standard 8"? I can't do any woodworking here obviously, and a custom 12" cabinet cut for a 5f1 chassis can't be cheap. Would I be better off just leaving the chassis naked (again, not gonna move this from my apartment) and try to score a cheap 1x12 cabinet?


I think that's all for now--thanks for any help and for this fantastic forum

[RWood]

I built a 5f1 using 5-15w upgrade transformers which I sometimes use 5y3/6v6 into 10" Jensen which breaks up nicely with good sag very early(around 5-7).

Other times I use a Weber copper cap rectifier/6L6 power tube into 12" Swamp Thang speaker. This way it has less sag, great clean punch, much higher headroom via a switchable bypass cap and trimpot for nfb, and stays clean til about 7-8.

I would not build one without the switchable bypass cap or variable nfb, as this gives you much more tonal range possibilities.

[rp]

[quote="benjamminn"]Hey all, due to a move, I've had to downsize my amp of choice from a beloved JTM 45 ()

Shouldn't have sold it, never know might have to move again

1) I'm curious about the Tweedle Dee Champ layout .. I've seen the 5f1 described as everything from glossy/bright to dark sounding, so any descriptions on what that might get me would help.

Dark, certainly with an 8". It's a single coil amp, I don't think Leo gave much of a hoot for HBs back then. Don't mess much with the circuit it's a dead end IME, use a Boss GE7, EP Boost, I like my modded wah (mfs, wimas, BC109b) as a boost/eq into it. Keep the plate V reasonable <370V, keep Rk very near spec. Definitely the bypass cap on V1, it was left off the schematic by mistake. Only 3 tubes, use NOS. Try some old molded caps, you only need two, can add a 3D quality, more swirl. No idea what HAD did, didn't look close at the pict.

2) I've also read that the small tweed amps start getting dirty around 4 on the volume knob--is it useful at all to try to get some increased headroom, or am I changing too much of the character of the amp?

IME not much you can do except waste your time, but it's good learning. the headroom issue is just a matter it being 5Ws, not the circuit. What helps is the Allen champ PT, it's great and keeps the fender sound. 8 ohm tap is a big plus here. Using different speakers, 10"s and 12"s is the best way to tweak this circuit's sound. Haven't tried the upgraded MC OT, absolutely don't use their cheap OT.

3) I run almost no OD/dist pedals usually (usually just a klone as a clean boost), more of an amp overdrive kind of guy.

at low volumes OD is only good as an MV, but cranked it's too much and unnecessary w/ a 5f1, if there's one amp that was born for straight in it's this one. BTW a cranked Champ's pretty loud, neighbors will still hate it.

4) (Sorry this is getting really long!) Will there be any earth-shattering differences from running this amp into a 12" speaker vs. the standard 8"?

Yes, IMO this is the best way to tweak the sound. I'd build for a 10" to keep the portability but can't go worng with a 12" either. Maybe a lightweight alnico or neo 12? Don't build a cab for an 8, use a 10". You can always retro-fit a baffle with an 8" if you insist, but you won't. Hard to find a good 8", and you'll be stuck a pile of festering 8"s. Never tried an old '60s 8" jensen from ebay, I got tired of wasting money.

Build it straight, mod it latter. Have fun.

[martin manning]

Haven't tried the upgraded MC OT, absolutely don't use their cheap OT.

rp, have you tried the MC "standard" Fender Champ 022905 replacement (40-18030) and found it lacking? The "upgrade" (40-18031) is a larger core 15W OT.

[rp]

Martin, I got it from Triode maybe in the late '90s? It was pretty much all there was then for Champs. I haven't got the # on it, but it was their only model then and ~$20 IIRC. I don't recall Pri and Sec options, mine was just 5K/4 IIRC. I actually A/B'd it with the Allen and an Edcor in a 5C1 & 5F1. It stank, pure mud, I was kind of shocked, I expected different not lousy. The Edcor was great but not Fendery. The Allen was great and Fendery. Looking at the current MC model, it may be improved?

I need to go into the 'cantina' and go though a box of amp stuff, if I find it I'll get the #, unless I tossed it.

[benjamminn]

Thanks so much for the feedback! I've also heard good thing about everything from Allen, and the TP25 seems like a solid choice for me (and pretty cheap, all things considered). The HAD mods seem pretty subtle, swapping out the 16/8/8 caps for 20s, but I wonder if this is a conscious mod or just "this is what I had in the shop at the time". Same goes for the few resistor value changes.

Thanks for the recommendations on the speakers too--8" speakers have always sounded kind of farty for me, but I'm coming from a few years on a 4x12, so who knows what my ears can expect

I'll make sure to add the bypass cap and variable nfb too, those are great ideas.

[Mark]

Have you had a look on the AX-84 site, I think some of the 2 watt amps might what your after. A Pignose is roughly two watts, I find the Champ still quite loud at home, I certainly can't crank it up.

http://ax84.com/media/ax84_m276.gif

If you're going to build a Champ, I like the Mercury fat stack Champ transformers, they have more bass and mids which I like in a Champ, if your a purist it has to be the vintage output transformer.

https://www.youtube.com/watch?v=0Xuh0bLE6MQ

https://www.youtube.com/watch?v=HXmreHo2LMg

https://www.youtube.com/watch?v=aur-k26c_7A

https://www.youtube.com/watch?v=4nvnHaQ ... ur-k26c_7A

I think the amp sounds a bit thin, but I'm sure it cuts through the mix nicely.