DRBILL Posted June 14, 2005 Share Posted June 14, 2005 I just "changed the oil" (tube check and control cleaning) on a very nice British-made Marshall amplifier/speaker unit. Can anyone tell me why so many of this type of unit have the tubes located so as to bake the circuit board and other heat sensitive components? I have seen this same thing on units by Fender and Ampeg. DR BILL Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 14, 2005 Share Posted June 14, 2005 well ... if the tubes were Mounted to the p.c. board ... that Marshall's an embarrasement to the Name new, throw-away Crap the Quality Marshall's, like the SuperLead, esp, pre say, 1969.. have chassis mounted ceramic sockets, tubes mounted vertical, and plenty of ventilation in the cabinet ... i have a couple, the '73 i bought new ... Quote Link to comment Share on other sites More sharing options...
j-malotky Posted June 14, 2005 Share Posted June 14, 2005 I have never liked Marshall guitar amps. Although the old ones were built better, the bios sucked. You never knew what your amp was going to sound like when you turned it on...... So Frustrating. I would say the mid 70's was the best for Marshall, not that I would ever buy one again. My all time fav guitar amp was Music Man amps. Leo Fender fixed all the crap CBS did to his equipment.... JM Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 14, 2005 Share Posted June 14, 2005 i don't know, Leo ... mine been kickin'A$$ for 32 years now ... always sounds the same ..LOUD .. unless the EL 34's are goin' .. what problems did you have ..?? mines only smoked twice in all that time .. a broken lead from transport, and a runaway power tube Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 14, 2005 Share Posted June 14, 2005 i've watched Music Man amps climbing in value .. a very under appreciated amp .. Quote Link to comment Share on other sites More sharing options...
Heideana Posted June 14, 2005 Share Posted June 14, 2005 Word on the grapevine is that for as crappy as the new Marshall's are, they are way better then the new Fender stuff. Best bet is to replace the pc board with P-T-P. Also, KT-66's and KT-88's tend to sound better in Marshall's, or at least to my humble ears... Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 15, 2005 Share Posted June 15, 2005 ........+1 ... on the new Made in China, of course FENDER crap i bought a Vibro-King, and a Prosonic at a Mars Music Closeout ... probably the Last American made stuff we'll see outta the Scottsdale Custom Shop .. what, i still think the custom shop makes the, oh, hell what is .. the 100 watter ...??? Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted June 15, 2005 Share Posted June 15, 2005 the Quality Marshall's, like the SuperLead, esp, pre say, 1969.. have chassis mounted ceramic sockets, tubes mounted vertical, and plenty of ventilation in the cabinet ... i have a couple, the '73 i bought new ... ++++++++++++++++++ BSA; You da Man! Quote Link to comment Share on other sites More sharing options...
DRBILL Posted June 15, 2005 Author Share Posted June 15, 2005 Come on guys. Don't forget about me. I'm just the kindly old tech that keeps them smoking. I'm still not sure why they put the tubes UNDER the chassis. Nor can I understand why the controls are on the FRONT of the unit. On stage, isn't the player BEHIND it? Does he lean over it and read up-side-down? I wouldn't bother asking if I didn't need to know! DR BILL Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 15, 2005 Share Posted June 15, 2005 Nooo, Bill the amps behind you , you turn around, the amps on toppa yer 4/12, knobs are right at hand... sayin' the tube's hang down, sounds like somma the newer Crapola Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 15, 2005 Share Posted June 15, 2005 OOOOH, Bill ... maybe it's aCombo ... you really didn't mention what you were workin on ... Bias is important on Marshalls, as well as a good connection on the Output Impedance selector ... if not BOOOM ...output xfmr time .. they , and the power tube s arc over with little provocation ... Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 15, 2005 Share Posted June 15, 2005 Man, i Am gettin' old ... it's the "71 i bought new ... not the '73 didn't have the money for a PLEXI >> Quote Link to comment Share on other sites More sharing options...
blindman Posted June 15, 2005 Share Posted June 15, 2005 DRBILL, BSA is right on...the "main amplifiers" that the instruments are connected to are b-e-h-i-n-d the players on stage. Therefore the amplifier controls are on the front side (the side that faces the audience and the musicians). Having the controls on the front also allows the audience to enjoy seeing the glow from the "jewel pilot lights" ...just part of the "visual" show. The main speaker cabinets for the instruments are also behind the musicians. This is especially important when you need to create "feedback tones" between the instrument and the speakers. The strings of a guitar pick up the vibrations from the sound waves coming from the speakers and feed them back to the amplifier, which the speakers then use to send more sound waves back out to the strings, which then send that signal back to the amplifier, and on, and on, and on. That is why a musician will turn his instrument toward the speaker cabinet (and away from the audience) to enhance the ability of the instrument to pick up the vibrations of the sound waves coming from the speakers. This also explains why the PA speaker cabinets are in front of the musicians...to reduce unwanted feedback from occurring. What you may be thinking about when you see other speakers in front of the musicians are the "monitor speaker cabinets" that are spread out all over the floor in front of the players. Those are positioned in front of the players so that they can "hear each other better". Those speakers are actually aimed back toward the stage, not toward the audience. Before someone came up with the idea of those monitors, each player had to put a separate speaker cabinet connected to their own amplifier on the other side of the stage. Otherwise the players could only hear themselves...not very conducive to keeping everyone on the same beat, and it was way too easy for one player to drown out the other players since they had no idea what volume the other players were playing. The lead guitar shouldn't always be the loudest instrument. I apologise if this explanation seems too elementary, but I recognize that unless you've actually played in a band (or worked as a roadie), it may not be that obvious what all the on-stage equipment is actually for. Some bands even stack loads and loads of speaker cabinets on stage for "show only". They may be playing though one small cabinet, and mixing everything through a sound board and public address system (actually this is quite common). The "wall of speaker" cabinets are not even connected to anything...it's all an illusion to give the audience the impression of a "wall of sound" and for "showmanship". Again, part of the "visual" show. Quote Link to comment Share on other sites More sharing options...
DRBILL Posted June 16, 2005 Author Share Posted June 16, 2005 Thanks, Blindman, That's just the kind of information I needed to do a better job. Most of my work is in high end vacuum tube audio, so I am just guessing how the band equipment is used. I DID used to play in a band in the '50's. Nothing plugged in! I've never been to a modern rock performance. They don't let me out that often, and certainly not that late! I have spent most of my life teasing out the last traces of harmonic distortion from tube amplifiers. Then this Marshall hits my bench with a knob that ADDS some really harsh odd-order harmonics! I'm expecting the Mad Hatter at any minute. DR BILL Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 16, 2005 Share Posted June 16, 2005 ODD ??? ... NOOOO.. ! somethings wrong, or it's got the Dreaded DIODE CLIPPING CIRCUT ....in a Tube Amp, no less .. as in JCM 900 ....BLEECH ..! we Want Even Order Harmonics, no Sawtooth, either ... i think you were working on a JCM 900 Combo ... not a Great Example of a Good Marshall ... Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 16, 2005 Share Posted June 16, 2005 By the way... what make sthe Characteristic Marshall "chrunch" ... is Power Tube Distortion .... Yum .... Quote Link to comment Share on other sites More sharing options...
wheelman Posted June 16, 2005 Share Posted June 16, 2005 bsa you got a good taste for tone. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 17, 2005 Share Posted June 17, 2005 ....You obviously know the Score, Wheelman ...( pun ... ..) us Guitar guy's are the original "Tubes for Tone" advocates.... nothin' can compare to a SL 100/ 4/12 Greenies .. ............................................flappin yer pant's leg on stage the Amp is alive ! no wonder Hendrix OD'd .. he probably was tryin' to get back to the Sonic Nirvana he had left hours before ..... ................................................................................ Side Note .. i don't get to play out much anymore but i did jam at a graduation party with a bunch'o "dudes" used a Marshall 20/20 ..... absolutely SMMMMoked all the Randal Warheads, etc.... with my lousy 20 watt's .... ...Dude .. that's HUGE Tone ...what is it ..?? they were convinced that crappy, totally compressed, odd harmonic . transistor sound ...was it ... untill they heard the REAL thing .... Quote Link to comment Share on other sites More sharing options...
DRBILL Posted June 17, 2005 Author Share Posted June 17, 2005 ---------------- On 6/16/2005 7:11:30 PM bsafirebird1969 wrote: ODD ??? ... NOOOO.. ! somethings wrong, or it's got the Dreaded DIODE CLIPPING CIRCUT ....in a Tube Amp, no less .. as in JCM 900 ....BLEECH ..! ----------- It is a JTM60. With pure sine-wave in, the scope shows a distinct "tooth" a little over half the way up. It can be made to grow or disappear by manipulating the gain and volume controls in the so-called "boost" section. The amplifier, in general, exceeded the rated power output before clipping. DB Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted June 17, 2005 Share Posted June 17, 2005 JTM 60 ...not a Great amp ... they burn up alot, too yea, All Marshalls greatly exceed "rated watts" my '71 Super Lead 100 watter, actually puts out about 173 continious watts, clipping Quote Link to comment Share on other sites More sharing options...
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