ROBERTLATHAM1

30watts is plenty for most small bars. 100watts will put you in any venue you want to play most peeps really only need a 50watt tube head most of them hit thier sweet spots at a tolerable level. i use several heads one as a pre amp mainly for tone and two others for power one is about (harmony) 45 watts the other is a (bogen) 100watt monster. yhe pre amp head is a marshall vs100. i use a 4x12 with g12m70's and the 100db mark aint sh--!

hey guys just got one of these bogen 100w pa's off of ebay. whats the posabilty of one of you guys having a scheamatic? its pretty straight forward though prob not need other than prescribed voltages ad so forth. havent received it yet so dont know if i will do the 6l6 coversion or not. any suggestions as i like the marshall brown sound but cant get enough of the fender pristeen cleans. p.s. mine was $130 and that was after going through several actions! thanx robert latham

from the b+ supply. i failed to draw it in. but i am very aware of where it is fed from. as for the fuzz stomp box this is a pre amp section from a marshall vs100, which does not sound like a fuzz tone, fuzz face, ect... in fact it is very versatile amp. it can go from a clean unsaturated sound to a blues top of the wave clipped signal or switch to the od 2 channel and get the "brown sound" run a ts-9 in front and go further or switch back to the original harmony stock undisturbed pre-amp for a really close fender twin tone. as for the errors on the drawing i admit it was thrown togather, but i know clearly what should be where lol. this is my absent mind at work again!

lmao! i liked those little amps back in the day LOL! well i do like tube tone, but i guess i am not what you would consider a purist. i like the tone that i am getting by using both a ss/hybred amp and a pure tube amp togather and would like to have the common features between the 2. so i guess the mod is possible, but not a recomendation for the tube purist ? has anyone here had the chance to use a marshall vs100(8100)? if you have ? you have to admit the amp does have good tonal quality and does have more warmth than a ss amp. grant it, it is no jcm! but does have a certain degree of warmth, not found in ss amplification.

well i agree that it is getting more along the lines of the jcm 900 with the jfets, but this circuit is what is used in my marshall 8100 hybred for the boost channel. i do like the way it can go from clean to blues crunch and then with the click of a switch you can go from classic rock to insane distortion. the tone stack has far more control than just the bass and treble(bass being master control) cuts of the harmony. however i do like the pristeen clean and warmth of the 5881's in the harmony so when i went to ad this circuit i wanted to be able to switch between an undisturbed harmony pre-amp and the hybred pre-amp for flexability as the harmony made a very good blues tone but volume had to be around 5 and as it is rated at 30watts this is way too loud for some places that i play. hence the need for the o.d. section as run my rig in stereo. i can also a/b switch between the two amps. this gives me the ability to get that clean jazz tube tone and still be able to come back to a big high gain sound. on the marshall i have added foot control to select between od 1 and od 2 as this was not a stock option. hence the same set up on the harmony. why settle for a vw when you can have a bugati! harmony-------\ guitar----ibenez ts 9-----alesis quadraverb+--< --- 4x12 cab with center bridge for stereo. marshall vs100/ p.s. i thought almost all the new tube amp lines use op amps now. is this not true? thanx

ok guys tell me if im right or wrong here, but i think this will work. here are the mods(od and tone stack) http://i49.photobucket.com/albums/f279/rob...harmonymods.jpg here is the original amp http://i49.photobucket.com/albums/f279/rob...am1/harmony.jpg i would really like the real amp techs here to tell me what they think. is this a posable mod or will this never fly? thanx robert latham

ok i have a harmony 535 tube amp with the same situation. no preamp gain control. i have been studing a circuit (a marshall design) and believe it will work if put in the right place. which i would break in the signal chain just behind the first gain stage on either chanlle of your amp. this is an untested design and really needs one of the guru's here to look over it and give me thier thoughts. if you pm me i will send a copy of the circuit to you.

really good artical makes you really think about more power. but! i have a 2x 6L6GC amp that i assume was rated at 35 watts but i think its closer 45 to 50 watts that is just a touch lower in perceivable volume than my 100watt marshall valvestate (solid amp with one tube in preamp) and niether seperate or togather can keep up with a heavy hitting drummer. i use a 4x12 cab with celesion G12m70's. so i.m.o.p. i think that 1 i need more efficiant speakers or 2 the need of 100watts tube power is needed to keep up with a double bass drummer bang the crap out of a set of drums. sorry! citadelmusic i just realized that was off topic

so the signal is merley pased and conditioned not boosted and the impedence is low so the tone stack is better able to filter the signal. this is the way the tube in the marshall valvestate 8100 is configured so im assuming here that it was used just for the tube conditioning and not for high gain(saturation)? and this is the cathode follower in a pure tube amp.

hey guys here goes another stupid question. i was looking at the marshall dsl 401 scheamatic and the signal on valve 3(last tube of pre amp before inverter) appears to be comming from the cathode of valve 3 to feed the phase inverter tube 4. the plates are still feed from b+ voltage(450vdc or there about) the first plate (pin 1) looks to directly feed the second grid of valve 3. the second plate of valve 3 goes straight toB+ with no junctions. the first plate of valve 3 has 1 junction to b+ and to the second grid of valve 3. the first grid pin2 is fed from earlier gain stages. woo! ok now my question is how does the signal feed through the cathode and not the plates for the signal gain? (signal is only tapped off the second cathode of valve 3). i have seen this on other marshall amps. the 8100 valvestate uses the same tube configuration on the boost channel. my question still stands "how and why does this benefit the signal. thanx robert latham

thanks pual very good reading there much better understanding of the design now.

hey guys can anyone shed some light on how LEDs are used for distortion in a cicuit. i understand the clipping part but where in the circuit and how to contol them with a pot. or even how to get a gain control circuit on 12ax7 for tube overdrive.

this looks like a very good read i will down load it and do some reading thanx lovekraft i think i have been bitten with tube amp addiction lol!

lmao! well you know i have read for months now on these things and i just about get the guts up to do a mod and then i talk to the guys on here and they prove that most of the stuff im reading is misconstrued in form or fashion to make it seem an easy thing but everything you do in one of these monsters is going to cause a chain reaction so everthing else has to be ajusted to compensate. so the mods are a reality but you have to ask yourself if you are willing to do all that has to be done. peace bro best of luck robert latham p.s. my best guess on the 5150 is a higher voltage on the plates and posablely smaller resistance on the grid resistors ala more gain and headroom at less distortion

thanx for your help paul as always you guys have managed to keep me from mutilating my gear lol