Sounds pretty decent (and a tidy build, btw), but sure is a tough call whether it sounds "tubey", what with running it through a couple of other boxes and a pignose. What's it sound like as a standalone thru a clean amp? Which of the several schematics on that linked page did you build? And where'd the cool hinged box come from?

Were you looking for a particular sonic character of tubes (like compression or frequency response)? Guess I just tend to go for what sounds good to my ears these days and "tubey" is a pretty subjective (and oft debated) label.

rob

Check the other thread you have going on this.

http://www.ssguitar.com/index.php?topic=550.msg3811#msg3811

Rob


Use the Force -- Open Source!

QuoteHow do I know what pins go to what wire?  I'm working from this schematic: http://www.sophtamps.ca/schematics/sopht_12al8-v2.jpg
It says about how to wire the heaters, but that's it.

Major downloadable tube database with specs (including pinouts) plus links to several tech sites for additional info (application notes, etc.) for just about any tube you're likely to run across.

http://duncanamps.com/tdslpe/index.html

Have you been doing your homework, Beaver?
Oh, Ward ... leave the poor kid alone!


Rob

Use the Force -- Open Source!

This a good "sticky".

I've referenced those linked articles for quite a while and appreciate the additional comments here, particularly those regarding mains wiring. It's been a while since I've wired "safety updates" on old 5-tube radios and guitar amps.

I think some of the pcb layout techniques used in RF/HF could prove useful in audio. F'rinstance, I recall some method of isolating an input by utilizing circuit traces around it; forget details or what it's called but should look into this stuff again.

Although it won't correct faulty design or faulty mains wiring, I use a surge and noise suppression unit to plug my gear into. It really works great to suppress EMI/RFI line noise plus it warns you of line faults. Comes in handy when playing in seedy bars with an ancient freezer out in the kitchen. Talk about serious power conditioning -- you should see the filter banks in this thing! Mine was a gift from brother-in-law but looks like $50 on the net. If interested, here's spec's:

http://www.tripplite.com/products/product.cfm?productID=99#applications

Obviously, don't use one with a two-prong adapter. :duh


Rob

I took your advice, Teemu, and have been playing around with LTspice for a couple of hours. Looks like the opamp library features their proprietary chips but gives you the ability to "roll your own" and, as you say, unlimited model imports and component counts. Lots of neat features to check out. They even have a user group with additional tutorials and libraries. I downloaded the quickstart and help pdf's, too.

Thanks -- this a heck of an improvement over the old Orcad Pspice I have. Check this one out, Gary.

Rob

Thanks, Gary! Dunno how I missed that.

Never did get that head opened up; it's in a snowbound storage trailer (record 100+ inches up here in NH). Soon though --- gives me time to beef up my rusty and lacking skills. Like SPICE. Just checked and I downloaded it exactly eight years ago yesterday. Got lazy and started using those little freeware calculators instead. Having been away from this hobby for several years, I'm finding more fun in "learning how to fish" anyway. Such as modeling an active eq for those cap changes you suggested.

BTW -- have you lit up that Road yet?

best,
Rob

Thanks for the tip, Gary.

That board is likely the same 17-11 rev. I have. Problem is, I'm temporarily in an assisted living home and the amp is at home. I'll bring it up here next week and check it out.

Interesting thread you have going with Teemu about your Road head.

rob

  No real help here, but did you check schems for Rickenbaker Road series amps? -- unsure how much of the original circuitry they retained after buying out Road amps, tho. Location and damage sounds like diodes. What did third leg tie to?
  BTW, I'd be glad to take that old hunk of iron off your hands to save you further grief. (wink, wink)

rob
 

Warning, learning curve ahead!

"Biasing in electronics is the method of establishing predetermined voltages and/or currents at various points of a circuit to set an appropriate operating point."

http://en.wikipedia.org/wiki/Voltage_bias

Google: biasing transistors or biasing tubes or read Teemu's book for more in depth info

The 'Biasing' of tube amps commonly refers to "... setting the idling current in the Power Tubes in PushPull output stages" *

*Long definition:
http://www.lynx.bc.ca/~jc/bias.html

As per Teemu's advice:

http://ax84.com/

Take 1 faq, articles as tolerated, digest well and post results in SS,Tube/Hybrid and Hampster Wheel Guitar Amp sub-forum in the morning.

Caution: May be habit forming! Support groups (tube forums) work best for most.

Dive in, dude, the water's fine!

  I own a generation 2 ('72-'76) Acoustic Control 150 head -- love their amps. I want to give it a general housecleaning (recap, check voltages, clean pots, etc.) but, (re inspired by Teemu's book!) I'm also considering some minor mods like inserting an fx loop, tweaks to the tone stack and small improvements to the power amp. Thanks to the folks at the Unofficial Acoustic Control site I have access to the owners and service manuals, with schematics and signal+dc parameters, for the pre-'72 150 head. Problem is, the newer ones (at least the 17-11 preamp board) were revised. The only info I've been able to scrounge off the 'net about the revision is: the rated power output went from 110rms to 125rms and the tremolo circuit dropped the optocoupler for a FET component. Suppose I could trace the pcb's and hack a schematic, but my eyes and head for the maths to calculate voltages and freq's are kinda shaky lately.

I feel pretty cheesy asking, but I really can't afford $20 just now to buy a scan of the service manual/schematic and wonder if anyone here could email (or provide a link to) a copy relating to this revision for me? (Hangs head, shuffles feet)

Thanks!
Rob

The lm386 played a big part in my (ongoing) electronics learning curve - low financial and safety risk for early wacko designs ("So what if I did reverse the battery in my DuoRotoPhase S***Fire?") I avoided playing with mains powered stuff until I learned WTH I was doing, but there is much to be learned from low voltage circuits. For me, component datasheets and application notes have been a great place to start: Google the component part # of your choice plus the keyword data and get something like this:

http://www.national.com/ds/LM/LM386.pdf

See the typical applications and application hints? Look familiar? Also interesting is the Equivalent Schematic and Connections Diagrams for the chip -- if I'm not mistaken, one could build a discrete amp using this as a basic blueprint. (Not practical for a BBB delay, unfortunately. :-))

A quick search of the DIY forums will show this little amp chip has been tweaked to death for use in tone and gain controls, preamp stages, distortion/compression/octave effects, etc.. BTW, these come in 3 different power ratings.