4-4-0 [2 NEW BUILDS WITH PICS; THE 2 WATT WRECK]

[cliffchappell]

Test point voltages are also now available too on the new schematic. I wish i had them when i built mine to save a lot of tinkering and time.

I have to take the blame for that. The voltages were turned off when I made the pdf and I didn't realize it for a long time.

[ER]

I'm going to build one of these for recording and just wanted to let everyone know that if you are looking for a good parts donor for one of these amps be on the lookout for a webster wire recorder; 340 volt power tranny and 6sn7 PP OPT.

I dumpstered two of these babies a few years ago...

All the iron needed and probably some decent old tubes to boot (including a 6v6 for the mic input and 6x5 rectifier).
Cool looking knobs and handle too.

Adios,

ER

[GainMaster]

I've been wondering why you were having problems with it cleaning up and I suppose that was it. I've had the current stack in mine so long, not to mention being without power for 3 weeks, that I had forgotten what it sounded like with the LIN pots in there.

Yes, its all my fault. When I first looked at the schematic I thought, that log treble pot can't be right. After all, the Marshall stack uses a 250k linear. So, I blindly put a 1m linear pot there thinking it would work better. Big big difference in tone between the two pots.

Brian

[JoeyE]

Test point voltages are also now available too on the new schematic. I wish i had them when i built mine to save a lot of tinkering and time.

I have to take the blame for that. The voltages were turned off when I made the pdf and I didn't realize it for a long time.

Im not really complaining and you have done a lot with R&D for the amp and thank you for that.

[JoeyE]

Mississippi. Our McDonalds have possum burgers

Brian

Possum meat, mmmnn tasty!
If you were here in CA i would probably disturb you too much. lol.

[Ron Worley]

Dumb question perhaps, but where is the updated schematic located???

Thanks,

Ron

[Colossal]

where is the updated schematic located???

Hi Ron,

You can find it here:

http://ax84.com/static/4-4-0/AX84_4-4-0 ... 080927.pdf

Regards,
Dave

[GainMaster]

Dumb question perhaps, but where is the updated schematic located???

Thanks,

Ron

The only other change that might soon come is changing the tube in the PI to a 12ay7 or 12av7. Both work equally well and allow you to drop R20 and R21 and reduce R14 and R15 to 5.6k. Cliff is going to try this soon and update the schematic if he likes it too.

Brian

[cliffchappell]

Dumb question perhaps, but where is the updated schematic located???

Thanks,

Ron

The only other change that might soon come is changing the tube in the PI to a 12ay7 or 12av7. Both work equally well and allow you to drop R20 and R21 and reduce R14 and R15 to 5.6k. Cliff is going to try this soon and update the schematic if he likes it too.

Brian

Well, I did, and I do!

I made the changes an installed a 12AY7 in for the PI on Friday and played it some. Sounds pretty dang good Brian! Your'e right that the AV7 has a little less gain, but I'm going to put the AY7 on the schematic since it's a current production tube. I'll cover the AV7 in a note.

I had a guest over on Sat., whom I believe posts here and had some questions about whether or not these 6SN7 based amps sound like the "real thing". I believe he found out that indeed, they do.

I'll update the 4-4-0 Studio, and the October Studio today and post them on AX84.

[GainMaster]

Dumb question perhaps, but where is the updated schematic located???

Thanks,

Ron

The only other change that might soon come is changing the tube in the PI to a 12ay7 or 12av7. Both work equally well and allow you to drop R20 and R21 and reduce R14 and R15 to 5.6k. Cliff is going to try this soon and update the schematic if he likes it too.

Brian

Well, I did, and I do!

I made the changes an installed a 12AY7 in for the PI on Friday and played it some. Sounds pretty dang good Brian! Your'e right that the AV7 has a little less gain, but I'm going to put the AY7 on the schematic since it's a current production tube. I'll cover the AV7 in a note.

I had a guest over on Sat., whom I believe posts here and had some questions about whether or not these 6SN7 based amps sound like the "real thing". I believe he found out that indeed, they do.

I'll update the 4-4-0 Studio, and the October Studio today and post them on AX84.

Great Cliff. I was hoping my ears were still propery calibrated Personally, I like the 12ay7 better than the 12av7 now but the 12av7 is a good low cost choice. The only other change you might want to make is to change the NFB resistor to around 10k. Since I built the only one with a NFB pot, I have found that the NFB on 0 seems to muffle the highs a bit. I tend to keep it on 5 but anything from about 1/4 up seems to open up the highs some.

Brian

[JoeyE]

My cab is taking me longer than i expected without any powertool, my arm muscles hurt with non-stop manual sanding.

I guess its time for a rest, order some parts and sniff some more molten lead fumes . Thanks.

[mss1]

[/quote]

Great Cliff. I was hoping my ears were still propery calibrated Personally, I like the 12ay7 better than the 12av7 now but the 12av7 is a good low cost choice. The only other change you might want to make is to change the NFB resistor to around 10k. Since I built the only one with a NFB pot, I have found that the NFB on 0 seems to muffle the highs a bit. I tend to keep it on 5 but anything from about 1/4 up seems to open up the highs some.

Brian[/quote]

Brian, with the NFB 10k resistor, did you use a 50k pot? Linear or Log?

MSS

[GainMaster]

Brian, with the NFB 10k resistor, did you use a 50k pot? Linear or Log?

MSS

I used the stock NFB resistor and a 50k linear pot, so anything from 10k to 25k or so should be fine. I just don't like it much on 0. Was the same way with the October~Studio too.

Brian

[cliffchappell]

Here is a link to the AX84 4-4-0 page where you can find the latest schematic(08.10.02):

http://www.ax84.com/4-4-0.html

[Colossal]

I had a guest over on Sat., whom I believe posts here and had some questions about whether or not these 6SN7 based amps sound like the "real thing". I believe he found out that indeed, they do.

I was that guest! and I want to say what a very kind and generous guy Cliff is! A true gentlemen. After following Brian and Joey E's work on their 4-4-0s, I emailed Cliff with some questions and it turned out we live very close to one another. Cliff and I met up and he let me noodle around with his beautiful 4-4-0 that is pictured earlier in this thread. Not only does it look great but it sounds amazing! The cleans are very clear and bell-like with a warm, delicate sustain. Cranking up the guitar volume past 5 morphs the tone into pure ringing distortion and the blooming quality is right there at your fingertips. There is quite a range on the guitar volume knob so the change from clean to distortion is not abrupt. I've never seen/heard/played a real Express, but this amp really captures the tone you can hear in a lot of the Express demos posted here. Cliff has his hooked up to a 50w Celestion Gold. Very articulate sound. Also of note is the incredible difference in brightness/mids when you switch from 100 to 500pf. Pretty cool.

The version of the amp I played had Brian's most recent updates to the power section (eliminating the 330k/330k pair and changing grid resistors to 5k6) but with Cliff's original specifications for the pot values and a 12AY7 in the PI (IIRC). The low end was great on the 4-4-0 and the October Studio I also played. Both amps were incredibly <i>quiet</i> which I attribute to Cliff's spartan and efficient layouts, impeccable wiring and ground scheme. 2W gets loud! But it is not so loud as to be uncomfortable and you can still talk over it. The low end was bold and throaty, not thin and boomy. I kept Cliff busy with an endless stream of questions and he is a wealth of information (I learned a lot - thanks man!).

I've ordered a set of transformers from Cliff and will start my build shortly. I picked up some NOS RCA 6SN7s and I'm on the look out for some Tung-Sol Tall Bottles...

Should be a fun project!

Dave