Alembic F2-B - Page 2

Nordskov · 19th April 2008, 01:06 PM

Thanks scottnixon.

I think you just saved a good part of my hair from turning gray!

Another thing: Do you know if the hi-cut switch will act like the deep switch on a Bassman 135?

scottnixon · 20th April 2008, 04:25 AM

The 'hi cut' on the referenced schematic is more of a treble shift than a cut. Deep switch on a Bassman 135 can be found here: http://www.schematicx.com/schematic/...ier-schematic/

Nordskov · 20th April 2008, 12:06 PM

I am sorry for hi-jacking your thread, Phil.
But since we are rocking the same boat and both using the same schematics, this might be of mutual benefit ;-)
I'll stop if you think I'm taking it too far.

I see the similarities of the tonestack of the Bassman 135, the Dual Showman and the Alembic (moosapotamus).
Only two things differs. The hi-cut capacitor and the size of the mid pot.
The hi-cut obviously didn't have the effect I thought it would. I was looking for a deep boost like the one on the Bassman.
The guy at moosapotamus had changed the mid pot value from 10k to 250k.
If it is not a mistake, what difference does it make?

ken.berg · 20th April 2008, 08:53 PM

The larger mid pot makes the midreange response more flat when the control is centered (the Fender 400 Hz 'suck-out' is minimized, and the response is nearly flat when all the way up)

You can see this effect with Duncan's Tone Stack Calculator.

Nordskov · 20th April 2008, 10:15 PM

Thanks ken.berg.

I've just being fooling around with Tone Stack Calculator.
It looks like the higher mid pot value kills the bass and treble control (less than 5 dB).
Stick to 10k linear!

I think that the James stack and especially the Bench stack looks very smooth and versatile compared to the ordinairy Fender stack.

phil mailloux · 14th June 2008, 04:49 AM

Wow, I'm surprised there was all this activity on the thread and I totally missed it!

I had to take a break from the project because of other projects in progress.

Nordskov, I'd love to make this thread a decent F2-B build thread! If you want to post what you've got so far would be great for the both of us to help us through this build. My build will probably go a little slower than yours though. I plan on posting pics when I start building it, I'd love to see pics of yours too.

What voltage are you using in your country? I'm on 240v @ 50hz, I stil need to have the power supply designed for me, a friend would do it but unfortunately isn't going that fast on it and I don't want to bother him too much.

Brett · 16th June 2008, 03:04 AM

Quote:

Originally posted by phil mailloux
I stil need to have the power supply designed for me, a friend would do it but unfortunately isn't going that fast on it and I don't want to bother him too much.

Download PSUD2 from Duncan Amps and have a go yourself. It's not that hard and it has enough standard parts in it's list to do the job. It's always worked out within a couple of percent in reality from the sim if I use the correct specs for the parts.

Jarno · 29th July 2008, 06:13 PM

Great, more people building the F2B, it's a great preamp!

Here's a picture of mine:

Jarno · 29th July 2008, 06:21 PM

This is just the preamp without power-supply of course. I have taken out the ECC83 because I'm going to clean it up. It's a bit of a rats nest, too small a housing I suppose. The extra two pots on the left were for a switchable tube overdrive, but I couldn''t get it to work so I took it out.
This F2B bit has got a bit of a twist, it's got a switchable "high" capacitor a-la Mesa Bass 400 and also the "Bass-shift" function, as well as the bright switch.

The powersupply is still a bunch of components on a plank, quite scary, considering the fact I had some 330uF/ 450volts capacitors lying around and used three of them...
I used two 12volts transformers back to back, and I think my anode voltage ended up being a bit higher than the specced 300 for the original F2B, I think something like 325volts.

regards and good luck with your builds!,

Jarno.

phil mailloux · 29th July 2008, 10:07 PM

It looks good, I love that sort of point to point wiring

My project has stalled a bit since I don't have a power suply for it yet and have no idea how to design one. If you get yours to work would you mind showing me a schem of your power supply? It would be helpful since we're both running from 220-230v mains.

Is the preamp schematic the modified version that you used or the original?

I'd love to see the final product when you finish with it.

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19th April 2008, 01:06 PM	#11
Nordskov diyAudio Member Join Date: Jun 2007	Thanks scottnixon. I think you just saved a good part of my hair from turning gray! Another thing: Do you know if the hi-cut switch will act like the deep switch on a Bassman 135?

20th April 2008, 04:25 AM	#12
scottnixon diyAudio Member Join Date: Mar 2001 Location: High Point, NC	The 'hi cut' on the referenced schematic is more of a treble shift than a cut. Deep switch on a Bassman 135 can be found here: http://www.schematicx.com/schematic/...ier-schematic/

20th April 2008, 12:06 PM	#13
Nordskov diyAudio Member Join Date: Jun 2007	I am sorry for hi-jacking your thread, Phil. But since we are rocking the same boat and both using the same schematics, this might be of mutual benefit ;-) I'll stop if you think I'm taking it too far. I see the similarities of the tonestack of the Bassman 135, the Dual Showman and the Alembic (moosapotamus). Only two things differs. The hi-cut capacitor and the size of the mid pot. The hi-cut obviously didn't have the effect I thought it would. I was looking for a deep boost like the one on the Bassman. The guy at moosapotamus had changed the mid pot value from 10k to 250k. If it is not a mistake, what difference does it make?

20th April 2008, 08:53 PM	#14
ken.berg diyAudio Member Join Date: Nov 2003 Location: Tempe, AZ	The larger mid pot makes the midreange response more flat when the control is centered (the Fender 400 Hz 'suck-out' is minimized, and the response is nearly flat when all the way up) You can see this effect with Duncan's Tone Stack Calculator.

20th April 2008, 10:15 PM	#15
Nordskov diyAudio Member Join Date: Jun 2007	Thanks ken.berg. I've just being fooling around with Tone Stack Calculator. It looks like the higher mid pot value kills the bass and treble control (less than 5 dB). Stick to 10k linear! I think that the James stack and especially the Bench stack looks very smooth and versatile compared to the ordinairy Fender stack.

14th June 2008, 04:49 AM	#16
phil mailloux diyAudio Member Join Date: Mar 2006 Location: Canadian in Australia	Wow, I'm surprised there was all this activity on the thread and I totally missed it! I had to take a break from the project because of other projects in progress. Nordskov, I'd love to make this thread a decent F2-B build thread! If you want to post what you've got so far would be great for the both of us to help us through this build. My build will probably go a little slower than yours though. I plan on posting pics when I start building it, I'd love to see pics of yours too. What voltage are you using in your country? I'm on 240v @ 50hz, I stil need to have the power supply designed for me, a friend would do it but unfortunately isn't going that fast on it and I don't want to bother him too much.

29th July 2008, 10:07 PM	#20
phil mailloux diyAudio Member Join Date: Mar 2006 Location: Canadian in Australia	It looks good, I love that sort of point to point wiring My project has stalled a bit since I don't have a power suply for it yet and have no idea how to design one. If you get yours to work would you mind showing me a schem of your power supply? It would be helpful since we're both running from 220-230v mains. Is the preamp schematic the modified version that you used or the original? I'd love to see the final product when you finish with it.

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