Metropoulos Forum

ok i put one of metros boards in a 73 superlead.....i luv it but id like to try and gain it up like a jcm 800..i also put the rich mod mv in and that helped a lil ...any help would be kool....oh yeah....i dont like pedals it dont sound right....thanks

That should be easy, use a 100K Feedback resistor (connected to purple wire from the presence pot) put the purple feedback wire on the 4 ohm tap. This should be a start. You can change the .68 Cap in the pic to 330uf.
Also, i think lowering the value of the very first 250uf cap will add more dirt, like to 200uf or 220uf, the experts around here are more knowledgeable than me. Have you bridged the channels witha patch cord? Put a chord from the Channel I low to the Channel II High input, then use both volume controls together.

When you've already got a capacitor on the tube cathode like those above, changing the value is really adjusting the frequency range that the cap will give you a gain boost in. The 250-330uF cap on the far left is so big that you probably won't notice much difference until you get less than a 5uF cap in that spot. But you won't notice a gain boost as much as a little LESS gain in your low end when you start lowering the value of that cap.
The .68uF (the one on the right that Dax has pointed out in his diagram) is boosting highs and upper mids. You can get some more gain in your lower mids by going with something in the 2 - 3uF range in that spot; your top end won't change much. A 330uF there is the supposed-EVH value but I can't recommend that much cap in that spot. It's going to aggravate your low end (maybe making it quite mushy I'd think) and it may start to tax your power supply into ghosting by trying to boost those low frequencies.

Dax-The-Ax wrote:That should be easy, use a 100K Feedback resistor (connected to purple wire from the presence pot) put the purple feedback wire on the 4 ohm tap. This should be a start. You can change the .68 Cap in the pic to 330uf.
Also, i think lowering the value of the very first 250uf cap will add more dirt, like to 200uf or 220uf, the experts around here are more knowledgeable than me. Have you bridged the channels witha patch cord? Put a chord from the Channel I low to the Channel II High input, then use both volume controls together.

A 100k on the 4 ohm tap will definitley increase gain to a degree. You probably should use 100k and its easy enough to try out each tap but the gain from less NFB is very hairy. Changing the .68 bypass on stage 2 to 330 may increase a small amount of gain but what its doing more of is shifting the frequency of the gain boost thats already there with the .68. You can try it. Some people feel its too much. I changed my 330 out to 5u for a full range guitar boost without boosting the really low end that only rumbles things up. Other people prefer the mid-emphasis the .68 gives for 'cut' and 'sing' qualities. The same is with the first 250 on the board. Going to 200 wont change the gain much at all. It will just up the shelf of bass your boosting. 250 and 200 are both so below gthe guitars range the effect is more of an influence then a direct EQ shift. The lower the value the higher the shelf on the bass. If you want to cut some of the rumbly or muddy low end from the Normal channel you can lower that cap but it wont really change the gain much in usable frequencies until you get down to much lower values.

Lowering the voltage can help you with gain. Make sure you have 20k of resistance next to the bias pot on those big 2W resistors. Thats either one 20k resistor or 2 10k's. Increasing that value will help and trannys that put out less voltage helps as well. Your amp is a 73. Im not sure how high the voltage is on 73s. Theres probably not much else you can do without altering the tone more.

I was close. I did try raising the two 10k's to the left of the bias pot and it definitely raised the gain, i went back to just one 10K. I think the feedback resistor/wire and upping the 10K's should do it for ya. Could you just change one 10K to a 20K?

Dax

Flames1950 wrote:When you've already got a capacitor on the tube cathode like those above, changing the value is really adjusting the frequency range that the cap will give you a gain boost in. The 250-330uF cap on the far left is so big that you probably won't notice much difference until you get less than a 5uF cap in that spot. But you won't notice a gain boost as much as a little LESS gain in your low end when you start lowering the value of that cap.
The .68uF (the one on the right that Dax has pointed out in his diagram) is boosting highs and upper mids. You can get some more gain in your lower mids by going with something in the 2 - 3uF range in that spot; your top end won't change much. A 330uF there is the supposed-EVH value but I can't recommend that much cap in that spot. It's going to aggravate your low end (maybe making it quite mushy I'd think) and it may start to tax your power supply into ghosting by trying to boost those low frequencies.

Yep I agree with Flames and Dan, I tried most of the combinations (330ufs....) and its an overkill situation. Try a high quality bosst pedal in front like a AC Booster or a Time machine boost.....

well i think im gonna sit on it for a while cause everything seems to be very subtle....i got a sovtek mig 60 and a soldano avenger so i got gain...i think im gonna leave things alone.....but u guys rule coulnta put the board in with out ya....thanks johnny eggz......oh and i recorded with the amp saturday it sounded great..i used it for chord stuff....sounded great...later

I know you said no pedals but I agree a good boost or treble boost can work great. Sometimes the treble boost actually lets you get more bass in the end since you can pump the bass control all the way up without being muddy or farty when your running a T-booster and the bass at that point is punch city with all the added gain and clarity.

I've been after this on my SL for quite some time. I finally gave up and ran a Boss SD-1 in front of the amp. Seemed to get what I was after as far as "hair" was concerned. Used a 6 band MXR eq after the od pedal to give myself a more "metal" tone shift running into the amp.

You might want to check out the settings Jon posted in this thread.

http://www.metroamp.com/forum/viewtopic.php?t=1943

I tried these on my amp with no pedal and what I ahve been after was practically there. Again use of the Boss MXR combination though both to a much lesser degree than before and I'm grinding out some nice 80's metal tone. I am thinking that it is somewhere in between British Steel era JP and Haunting the Chapel Slayer but with that characteristic SL sing to the overall sound.
I do have to say though that my amp is on its way out right now as I am getting some serious PO (methinks its in serious need of new Filter caps and a new set of tubes as she is starting to sound a bit bassy).

i was thinkin about changing the filter caps since there the old dalys...how can ya tell if ya need new ones?.....oh and i jumped the channels internally

johnnyeggz wrote:i was thinkin about changing the filter caps since there the old dalys...how can ya tell if ya need new ones?.....oh and i jumped the channels internally

From what I've read on this and other boards is its a good idea to change them if they are leaking, bulge-ing(mis-shapen), or over 15 or so years. There are probably quie a few other reasons as well. Im sure others can chime in with more reasons.

You'll get two very distinct opinions on filter caps.
There's the guys that say they have to be changed every ten to fifteen years -- NO MATTER WHAT. Doesn't matter if the amp sounds fine and works properly.
Then there's the approach that if it ain't broke, don't fix it. Tim Swartz has sixties Marshalls that he says the original filters are just fine on.