Well I don't see a treble pot on the schematic or the layout you posted so I'm assuming you are altering from the design quite a bit (at least adding a tonestack) and I probably shouldn't be using your photos/design to figure stuff out...
Well actually, if you're putting the treble pot/tonestack between the preamp tube and power tube, I think I have that right anyway, the orange would go to the pin5. yes?
Something I just observed is the master volume is between the two 12ax7 triodes. I've never seen that before. Why wouldn't it be between the preamp and power tubes?
I see the tone stack is located before the MV between the triodes as well. What is the reasoning for this location rather than between the Preamp and Power tubes?
I see the tone stack is located before the MV between the triodes as well. What is the reasoning for this location rather than between the Preamp and Power tubes?
That is the typical blackface V1-tonestack set up that is basically the same in all the BF amps. The BF type of tone stack is quite lossy, and the tweed style tone stack found in the 5F2A/6G10 is better in this regard for such a simple amp - it offers a higher input impedance to the following stage's grid, so you don't lose as much bandwidth and gain (as you do with a BF tone stack)
The other triode of V1 goes after the tone stack to boost the signal to a level sufficient to drive the next stage adequately.
I see the tone stack seems to come off pin 6, the second triode. This seems better. I also see a second 12ax7 in there. It looks to me like this is driving the tremolo only. Is this assumption correct?
Also, if I had this amp, what is the tremolo "jack" for? I have the two pots for speed and intensity. Wouldn't that be all I would need? I am having a hard time understanding what the jack is for unless it switches the tremolo ON/OFF? Thanks.
Well I am considering the "upgraded" kit from RJ or sourcing and building on my own. If I do my own I think I will do the ceriatone circuit though the layout shows V1 pin7 connected to nothing...
I haven't gotten to the heaters yet. I did look at the pics on the ceriatone website though for guidance. I am currently trying to figure out how to select a proper PT and OT.
Zippy wrote:What happened to the minimalist-tweed-Champ-with-fewest-parts-and-easy-to-build-for-the-noob concept?
Only option to the 5F1 IMO should be the 25mf cap on the cathode of V1a, and that cap should definitely be included in the kit. .68/1/2.2 are all good too. I like a pull vol pot switching btwn 1 & 25 myself. I could see a toggle with 1-none-25 as pretty useful. These options can be mentioned in the instructions.
BTW today I ran my 5F1 thru a pair of UK Celestion V10-60s, Allen OT, open back cab, sounded really fine. Loud, nicely bright, and rocked hard. Great stuff.
rp wrote:Only option to the 5F1 IMO should be the 25mf cap on the cathode of V1a, and that cap should definitely be included in the kit.
I agree that the cathode bypass is a simple and worthwhile switchable option, as is the NFB connected/not connected switch. These two options really increase the range of this very simple amp.
i think you are all getting way ahead of this builds intension.
It's a champ not a vibro champ, it's simple easy to build and unlike most small cheap amps they sound respectable stock. If you need an EQ use a pedal.
it's great you want to modify the amp but it's supposed to be for the person that has little to know experience with amplifier building and wants to get started. It would be fun to have another thread after the amps start shipping for builders with technical know how for modification ideas and tips, but it has to crawl before it can run.
xtian wrote:I agree that the cathode bypass is a simple and worthwhile switchable option, as is the NFB connected/not connected switch. These two options really increase the range of this very simple amp.
That's what the soldering iron is for - it's a tweaker's kit.
Mine is going to have a volume option realized by switching tubes.
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