Waaagghhh! Lightbulb moment!
 
Jay Tee, you said something that sparked a synapse somewhere in my brain and set me on a route to sorting my sound out... It was your comment about DI-ing with your Marshall and Roland.
 
I checked the manual (pdf was but a pipe-dream when I bought my Twin Amp) and connected the Pre-Amp Out Jack into my desk, unplugged the mighty twin speakers from the Main Spkr jack at the back and was then able to crank the volume up without sending tremors through next door's fishtank. The recorded sound was pretty much spot on - spangly enough to slice a sequin but meaty enough to make Mr T weep. 
 
POD's still cool for some wangy overdive sounds ('specially the Fuzzbox setting) but it looks like I'll be using the DI through the Twin Head for main guitar sound from now on.
 
Thanks for your comments on this everyone - sometimes the answer is so close to your face you look right through it 'cos it's so blurred...
 
Frink.
 
 
 
 

Do not play a Fender Twin without a speaker or load dump plugged in for very long... unless you want to buy a replacement output transformer.

Mike is absolutely right.
For clarity:
DO NOT OPERATE ANY TUBE AMPLIFIER WITHOUT A PROPER LOAD ATTACHED!
 
Tom

Wonderful...I don't even own a speaker for the Marshall. Ok...whats the downside of a load dump? How hot do they get? Can I run the pre forever and write off the amp if I never use it? Guessing headphones in the headphone jack  don't count as enough of a load, right. What's the move here, cuz I have no intentions of ever driving the room beyond DI to the daw and mains. Been doing this since January 2010 w no probs I know of...yet.

Are you asking about your $50 solid state Marshall or another Marshall tube head you have?
 
If it is a Marshall tube head, which head is it? Some tube amps have a protective load resistor built in.
 
The Fender Twin does not.
 
If you want to run a Twin with out a speaker or load dump hooked up you should have a fire extinguisher handy.
 
 
 
edit spelling

The head is a Class 5 Valve Amp, and there are two ports for ext speakers, marked 8 and 16 ohm, w a painted line connecting them to the headphone out jack. Interrupting that line is a switch, marked Select.
 
I was recently looking at a Fender Twin, for similar purpose, and IIRC, it seemed appropriate solely cuz it had a line out port. Choice was tween that, a Champ, and  Princeton Reverb, one of which had a line out and the other didn't. Haven't pulled the trigger on a Fender yet. Now I'm glad. Time to RTFM. I haven't counted the 6 way outlets here in a long time, but just about every outlet has 1 or more. I do make sure I know how every circuit is loaded, and I've spent $5k on dedicated circuit additions, but...fire is NOT my friend. In fact, after reading Tesla biographies, its probably my biggest fear.

The rear panel consists of a selection switch for the headphone jack, which when activated bypasses the internal speaker.
On THIS amp (Marshall 5 watt) you'll be fine, evidently it was designed for that.
Not so much with the Twin; although if it has a "Line Out" its a "modern" Twin,
MAYBE the line out can be used without a "load" attached.
I doubt it.
A Marshall "power brake" or one of the many "power soaks" out there would be fine.
THD comes to mind as one that would work well; Andy is a bloody genius...
 
T

Marshall Class 5 appears to have a 15ohm "protection" resistor rated at 25watts to keep people from ruining their amps, output transformers, power tubes and power supply. :-)
 
http://cdn.tonegeek.com/wp-content/uploads/Marshall-Class-5-Mods1.png
 
I think built in protection has become somewhat common in small designs made after consumers got used to not having to worry about this with their solid state transformerless amps.
 
Back when home stereo and music instrument amps were all tube and transformer coupled everyone knew that running an amp without a speaker load ruined the fun. 
 
Don't be confused by my statement though, as there is no practical way to provide built in protection for large 100 watt amps. It takes too much space to soak up 100 watts and so the big Marshalls and most other new heads don't have any on board protection.
 
Have fun!!!
 
 

DeeringAmps
The rear panel consists of a selection switch for the headphone jack, which when activated bypasses the internal speaker.
On THIS amp (Marshall 5 watt) you'll be fine, evidently it was designed for that.
Not so much with the Twin; although if it has a "Line Out" its a "modern" Twin,
MAYBE the line out can be used without a "load" attached.
I doubt it.
A Marshall "power brake" or one of the many "power soaks" out there would be fine.
THD comes to mind as one that would work well; Andy is a bloody genius...
 
T

Hi Tom,
FWIW, "The Twin" and the "65 VRI" schematics don't appear to have any protection. The older Tweed, Brown, Black, and Silver versions certainly did not. :-)
 
best regards,
mike

Totally unrelated to recent comments, but maybe different amp sims (e.g., Amplitube Fender) might get you there.