Franken-Champ

[galaxiex]

..................

Anyone know any decent free schematic programs for windows?

Express PCB is free, comes with a schematic drawing program.

I like it, works good for me.

Example....



This has been converted to jpg

Also consider DIYLC

Do it yourself layout creator.

Also free.

[J M Fahey]

I also u8se Express PCB Schematic

[glebert]

I liked EasyEDA.com, layout editor was very similar to expensive tools, and liked that you could save your Gerber files to import them into another tool. PCBs that I had fabbed were very cheap and well done.

[mattm]

Thanks guys.

I'm up in Canada in Ottawa. Bloody snow just won't leave so cabin fever is sinking in. This is a perfect project to get to summer. I won't do any of the work but drawing it out I can definitely do, even if it takes me a while.

[Tony Bones]

I'll add another vote for ExpressSCH (which is bundled with ExpressPCB.) I tried every free schematic capture and PCB layout package I could find and ExpressSch is definitely the easiest to learn and use. I ended up deciding to go with Kicad myself, but that's only because the PCB layout software has fewer limitations than ExpressPCB. If you just want to draw up schematics to save and share, then ExpressSCH is the way to go.

[Chuck H]

Thanks guys.

I'm up in Canada in Ottawa. Bloody snow just won't leave so cabin fever is sinking in. This is a perfect project to get to summer. I won't do any of the work but drawing it out I can definitely do, even if it takes me a while.

Spoken like someone that's familiar with a case of "shack nasties" Not near as bad in my area, but it does happen. And you need projects that seem valid to occupy your time. If only to avoid asking yourself "WTF am I doing!?!?" at the end of a day.

[mattm]

Upon a bit further inspection the two big transformers are both fender parts, from '67 and '68 and both come from a Fender Bassman amp. Speaker output one is 50w.

Would bass amp transformers be/sound different than ones used in a guitar amp? I can't see it having been modified into a bass amp unless they wanted a really quiet one. 50w isn't much bass. My wife just had to go up to 500w from 300 to match her new band (plays bass in a heavy band, practice is very loud). On the other hand a little 50w would be perfect for apartment practice with the bass but why not just use headphones on a louder amp?

[Chuck H]

Well the Fender "Bassman" was very popular with guitar players. It wasn't just a bass amp. So it's entirely possible this was still intended as a guitar amp. The speaker is the tell. It's a guitar voiced speaker.

[Justin Thomas]

In 1967, there were no such things as "bass transformers." Or "bass speakers." Everything related to bass was about EFFICIENCY, not power. If bass sound would go back to that, you'd be surprised at how LITTLE power you need to be heard.

Take that measly 50W "Bassman" of yours, and go plug it into an old pair of speaker cabs from way back (a couple Dual Showman JBL-equipped 2x15 s would be nice) and I guarantee you'll be surprised by how loud 50W can be. "I simply MUST have more than 300W!" said no bass player ever after plugging into a real 300W 6550-equipped SVT.

The problem with "bass" amps is one of speaker efficiency, not power.

Justin

[Leo_Gnardo]

Upon a bit further inspection the two big transformers are both fender parts, from '67 and '68 and both come from a Fender Bassman amp. Speaker output one is 50w.

Would bass amp transformers be/sound different than ones used in a guitar amp? I can't see it having been modified into a bass amp unless they wanted a really quiet one. 50w isn't much bass. My wife just had to go up to 500w from 300 to match her new band (plays bass in a heavy band, practice is very loud). On the other hand a little 50w would be perfect for apartment practice with the bass but why not just use headphones on a louder amp?

Worthy of mention: the impedance mismatch between your 4 ohm transformer and (presumably) 8 ohm speaker. If your amp was to be used with external speakers that added up to a 4 ohm load, OK then that's fair. You'll get about 25 watts to 8 ohms as-is.

You & the missus should start learning sign language, or prepare to communicate by sending notes back 'n forth. The second solution is common these days, people text each other even if they're sitting across the table, don't they... Say what? . . . . . WHAT??? Everybody's doing it now!

[Helmholtz]

the impedance mismatch between your 2 ohm transformer

The 022871 BM OT is 4 Ohm (with 4.3k primary impedance).

It's basically a 4 Ohm version of the (2 Ohm) Super Reverb OT.

[Justin Thomas]

Yup. Bassman heads are 4R not 2.

Justin

[Leo_Gnardo]

Yup. Bassman heads are 4R not 2.

Justin

Whups.. I stand corrected. And edited my post accordingly. Sorry, a bit of early AM confusement, as I was also scanning another thread on the tweed 4x10 Bassman. Thanx Justin & Helmholtz!

[mattm]

"You & the missus should start learning sign language, or prepare to communicate by sending notes back 'n forth. The second solution is common these days, people text each other even if they're sitting across the table, don't they... Say what? . . . . . WHAT??? Everybody's doing it now!"

Yeah, she's already going deaf. I got her some ear plugs but she needs properly fitted ones. She used to play mostly jazz/funk type stuff and the old mb300 was fine for that. She had to have it cranked at almost full for practice, though, hence grabbing an mb500. Also of note is that she's got a 500w cab but it's a GK Neo, super light, so she can actually carry it around. It's LOUD. She does loud shows un-mic'ed with the 500. Band is just bar level for now.

I noticed the impedance mismatch and figure it was meant or designed to be used with an external 4 ohm cab. I might replace it with an 8 ohm speaker, we'll see. Likely depends on how much it costs to get it working/fixed.

Right now it powers on, tubes light up but there's no sound so something is wrong with it. Since I don't know what it's staying unplugged for now.