5F1 build with a 12" speaker?

nick79

For a long time now i've been hankering after a Champ or similar, and being as i like to get stuck in and build stuff i thought i would buy a kit and put one together myself. At the same time i've got a Blackstar HT5 combo (with the 12" speaker) that has been a pain in the arse repeatedly and i never really like the sound of it anyway. Ive had to replace 3 pots on it, something else that i cant remember and last time i used it wasn't working again... 

So my cunning plan is to put together a 5f1 circuit and transplant it into the Blackstar. 
How does the 5F1 circuit sound with a 12" speaker? I'm thinking maybe use a Greenback. 

As far as the build goes, i can solder and i've spent a fair bit of time lately reading how amps work, and i've got a good basic understanding now of what the various components do in that circuit. For a chassis i think i'm going to have make one up as copy of the Blackstar one, cant really think of a way to repurpose it, unless anyone knows different? 

So yeah, thats it really. Thought i would make a thread just sounding out my idea, and if it gets that far, (and people are interested) i'll do a build log - God knows i'll need all the advice i can get! lol 

ICBM

A 5F1 sounds fantastic into a 12" - that's what quite a few small makes do nowadays, with a 5E3 Deluxe-size cabinet. I think it's a vast improvement over the original 8", although some people have differing opinions...

It may not be quite as straightforward as you think if you were planning to re-use the transformers though - the HT5 is actually a push-pull, whereas the 5F1 is single-ended - so you'll need a new output transformer.

nick79

Cheers ICBM
That's what i was hoping to hear

No plans to use the HT5 transformers, or any other electrical components - Current thinking is get a kit from somewhere like Modulus, that way i'll have everything i need in one fell swoop. 

ICBM

nick79 said:

No plans to use the HT5 transformers, or any other electrical components - Current thinking is get a kit from somewhere like Modulus, that way i'll have everything i need in one fell swoop. 

There's also a valve rectifier in the 5F1, which will need an extra hole in the chassis - but to be honest, I would probably not bother. If you use a couple of resistors (probably 100 ohm) in the HT feeds to a solid-state rectifier you'll get close enough given that the current draw of a single-ended amp doesn't vary that much so there isn't much 'sag' as such.

PeteC

Go for it.  If you can get hold of a copy of aspen pittmans tube amp book it will give you more than enough build and layout info to make an excellent 5F1 and lots of other amps besides  - the prints of the fender amp layouts are superb.  I built my first few valve amps using info from that book.   The champ into a low efficiency 12” speaker , cranked, is an experienced al, guitarists should have....
take care and good luck with it.  

ICBM

A Champ into a high efficiency 12” - or better still an old Marshall 4x12” wired for 4 ohms - and cranked is even more an experience all guitarists should have! Absolutely epic, and hard to believe it’s only 5W...

Lebarque

Celestion Blue. Done

Winny_Pooh

Lebarque said:

Celestion Blue. Done

I'd do this (plus add a negative feedback switch) however you'd need the beefier classictone champ OT as you cant find a blue in 4ohms. 

I recently put my silverface champ into a 12" and ended up with a decent old 4 ohm Fane "blue". But If I had to do over from scratch I'd get the biggest classictone OT to be able to use a wider range of speakers.

You can repurpose the current chassis with some work. Add a new alu sheet across the old faceplate to cover the holes etc. 

Winny_Pooh

springhead

Winny_Pooh said:

Lebarque said:

Celestion Blue. Done

I'd do this (plus add a negative feedback switch) however you'd need the beefier classictone champ OT as you cant find a blue in 4ohms. 

I recently put my silverface champ into a 12" and ended up with a decent old 4 ohm Fane "blue". But If I had to do over from scratch I'd get the biggest classictone OT to be able to use a wider range of speakers.

You can repurpose the current chassis with some work. Add a new alu sheet across the old faceplate to cover the holes etc. 

Are Classictone transformers available in the UK or are you paying shipping and import tax from the US?

NPP

I find my Champ clone has quite a lot of bass and would use an EQ in front of the amp, or perhaps even include a bass cut pot in your build, if going with a 12" speaker. That said, I usually dial down bass on almost every amp or hifi I touch. 

Winny_Pooh

springhead said:

Winny_Pooh said:

Lebarque said:

Celestion Blue. Done

I'd do this (plus add a negative feedback switch) however you'd need the beefier classictone champ OT as you cant find a blue in 4ohms. 

I recently put my silverface champ into a 12" and ended up with a decent old 4 ohm Fane "blue". But If I had to do over from scratch I'd get the biggest classictone OT to be able to use a wider range of speakers.

You can repurpose the current chassis with some work. Add a new alu sheet across the old faceplate to cover the holes etc. 

Are Classictone transformers available in the UK or are you paying shipping and import tax from the US?

You'd need to pay duties etc or have a look at this:

https://modulusamplification.com/Champ-5F1-Style-Output-Transformer-8ohm-Output-P5282193.aspx

PeteC

The small hammonds also work pretty well in champ circuits 

nick79

Excellent, cheers guys. I think im going to use the original chassis, making a new one would be a bit beyond me. I'll just modify it to suit. 
Next step is get in touch with Modulus and get some parts ordered!