Negative feedback... found a thread... reading now... :-)

Greetings!  I have an HRM 50w OTS, purchased from eBay some months back, great amp. 

I just discovered a switch on the bottom of the amp, between the preamp tubes, facing downward.  It's not on the back, but on the bottom, below where the overdrive and preamp switches are located.  Never noticed it before.  It has a label stuck on, like someone added it, and this switch is NOT on the photos on Nik's webpage, nor is it mentioned in the manual.  The label reads LNFB.

What might this be? 

-Rf

Just saw this... Still for sale?  Please let me know either way... Merry Xmas!

Still for sale, or sold yet?

So, anyone have a head cab suggestion for a clue starved newbie? 

Side note: For my DC-30, I got myself a Klein-u-lator, and what a great unit it is.  I wish all amps had so much control over their effects loop. 

I just played my first entire gig using the DC30.  True, I can't cover the wide range of tones as can be done with my MB Mk 4... but man, the sounds I was getting all night were just GOOD... got several compliments on the tone, totally different vibe from the Mk 4, different approach: quality tone over versatility.  Pros and cons, but new territory for me, and I'm likin' it.

So right now, it's a 2x12 beast in a road case : fairly large and unwieldy.  Got some gigs coming up in SF; tiny clubs, load in upstairs, etc.... I'd love to put the speakers into individual 1X12 boxes, and have a head unit, to make it easier to pack into the hatchback, and carry into small venues.  Got the cabs all ready, need a box for the head. 

Any tips appreciated... thnks!

Thanks for that, I do intend to try several things.  But if you would kindly tell me what a TF is, I will be on my way...

Thank u very much for that thorough explanation! 

I had been reading in the interim, and I had found out about the Dumbulator; but I just could not fathom why the Dumble amp would need such a thing.  Seeing this effects loop as a "hack" as you put it, it becomes clear why just running it out to my pedal board will not work, probably ever, unless I had some kind of buffer.  Now then...

The idea of a buffered pedal sounds, um, antagonistic to the concept of preserving tone, am I wrong about that?  I've spent all this time getting custom or modded "true-bypass" pedals, and now, ironically, I need something that sounds, well, opposite to that approach... is there a pedal that just acts as a buffer and nothing else?

Last subjective question, I hesitate to open this can or worms:  what would be the impact on tone to add either buffered pedals, or to add a buffered FX loop to the circuit?  I've read some people say FX loops ruin everything, but I've owned some great amps over the years which had them.  What would this addition do, in your opinion, to THIS amp?  any / all comments welcome...

thanks again!

ok, so I had figured out (all on my own self even!) that the effects loops required insert cables, one for each channel...

Now, I have a pedal board that's been evolving over the years, used it with many amps.  It has a home-made "cable snake"; that is, 3 long leads which I normally would just plug one each into an amp's input, send and return.  For my newly acquired Dizzy30, instead of an actual insert cable, I bought a stereo plug to Y-adapter with female ends, figuring that it's wired same as an insert cable, I'd just plug in my send/return cables.

Well... Doing that causes the amp to produce a sound like a siren from a toy robot or something.  EEEEuuuuEEEEuuuuEEEEuuuu 

Swapped in for out, no improvement. 

So... Would someone kindly provide me a clue here?  I often lack them...

I read elsewhere that this amp can't deal with long effects cables;  true?  what's the fix (if any)? 

To be useful in my act, I really do need certain effects to be in the loop, not ahead of the preamp.  So if this amp is really not able to play nice with my pedal board, I will be disappointed... (with myself for failing to do my homework ahead of time!)

any help / tips appreciated... :-)

Very cool, thanks for the input!

That VVR appears to be the simplest install.... maybe?   

more annoying newbie questions coming soon...

Greetings folks - new to this forum, been reading a bunch of posts.

Just got a DC-30 combo, sounds really good, I'm just starting to figure it out.  But I can tell that I could make use of some of these mods that many of you mention.

So from what I gather, there is the VVR from Hall, and there is the Power Scaling unit from London Power.

Are these essentially doing the same thing?  Which, in your opinion, is better?

This amp is a new direction for me, and I'm glad to see there's a forum of folks who seem to enjoy helping each other find new ways to get different sounds.

Be well,
-HS