Model-t problems...:(

[thomas]

i have a 70s model-t which i mainly use as a guitar amp. there are new preamp tubes in it (2x Ruby ECC83Cz, 1x GE 5751 in PI-Slot) but old power tubes (2x sovtek 6550, 2x tung sol 6550). the tubes are glowing
kind of blue. i use it with a ´78 ampeg v-4 4x12. we play mostly doom stuff. tuning is 2 steps below the standard (C,F,Bb,Eb,G,C) and strings are 56-13.  i don´t get any decent or concrete tone from this amp. it really sucks to me. you cant play any chords and even power chords suck. i´m not sure if my guitar is shit (epiphone sg-400) or if my cab´s speakers are broken. there´s nothing clean or thick to it and it´s not even that loud as i read about it. it is really more a bass-amp cause single notes can blow your stomach? i love this amp and really want it to sound cool, so i bought new svetlana 6550 and look for somebody to get them in, cause it´s not that simple here in germany. what else can i do? the distortion is really harsh and fuzzy and not concrete. master is on 6, both channels on 5. bass is on 7, mids are 3 with switch to far right, treble on 2 and presence on 3. this really bothers me. so if somebody could help me out, would be cool. greets, thomas

[high on fire]

hey thomas, ive got a 73 model t and it came with three of the tung-sols,one was missing.anyways i bought some electro harmonix 6550 power tubes and mesa boogie preamp tubes,and its loud and heavy sounding...im just running either a sunn reissue 4x12 or two sunn 410s cabs with it...think the two 410s sound the best.thats just my opinion..im just really experimentingg with that..but as for the model t goes try getting them tubes in there and then get it biased.i would thank that would make a big difference..the model t is is a killer amp..o))

[thomas]

thanks for that. i think so, too. hope it will get a killer amp after the retube. i want to combine my 4x12 with a 1x18 to get it real thick. greets, thomas

[JoeArthur]

One thing I would do... is to swap the 5751 with the second stage ECC83.  The Model T really does much better with a 12ax7 type as the phase inverter driver - the power amp will be more sensitive and you might be able to turn down the master volume slightly.

Second... this second generation Model T (since you have the model with the mid switch), well I would agree that it is much better suited as a bass amp.  The distortion sound can be harsh and your control settings are helping to make it harsher.  I would set the middle setting... by setting it at zero.  The 3K boost, even at a control setting of 3 is happening in the second stage, which is the one being overdriven.  Recover the treble by boosting either the treble or presence setting - and personally I would use the presence for less harshness.

Third... only if extremely desparate would I use a mix of different makes of 6550's.  The position of the tubes would be such that one of each make would be distributed to both the push and pull side, to better even out the balance.  One make doing the pushing and another make doing the pulling wouldn't be in the best interest of achieving a balance in the power amp.

Since you are in Germany... is your amp stock for 240 (or whatever the supply voltage is...) or are you using a step down transformer?  If the latter, make sure that it is 120 volts (not 110) and that the wattage rating is high enough to properly supply the amp... and any extra if you are using the accessory outlet on the amp.