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Topics - Hackinblack

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Schematics and Layouts / Blackstar HT-1 schematic
« on: November 10, 2015, 11:40:42 AM »
for the good people of the forum;at long last i found a proper schematic for the little blackstar HT-1
on the same day i snapped up one used 'locally' only 150Km round trip! :duh it's christmas already <3)
 courtesy of the wierd wired interweb,via Korea.. 8) (an official factory PDF no less!) :tu:

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Tubes and Hybrids / Kustom tube 12A
« on: October 23, 2015, 04:09:37 PM »
picked up one of these used,based on the 'tube amplifier' label...very misleading! 1 x RC4558P and 1 x 12AX7 feel the power :lmao:
i read this forum's post
http://www.ssguitar.com/index.php?topic=1356.0
and noted the errors on the 1 schematic wafting about the web (the one on the forum is corrupt too)
but the photos of the errors posted seem to be corrupted;anyone have copies of these?
this little amp has the makings of a nice one, 'Champ-meets-Valvestate' the thing a has a remarkable bass response,considering the 8" speaker and an open-backed cab
but boy is it StRanGe:-no gain adjustment on the clean channel,but with the gain switch on HORRIBLE RAT-type raspy distortion;like a cross between a small PA amp and the worst distortion pedal ever made :duh
i can't wait to scope,prod,and tweak mercilessly...

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Amplifier Discussion / Marshall MG30DFX op-amps
« on: March 08, 2014, 06:07:42 PM »
a new addition to the Obidia Trumpworthy home for badly behaved amplifiers >:(

a slightly ill MG30DFX which wouldn't switch from clean to grubby
fixed that, but i am slightly puzzled,as the amp is full of TL072 op-amps;whereas the schematic i have (dated 2002) is full of 4558 DD's
(the high gain version of the 4558)

is this a factory revision, or has someone 'upgraded' it? anyone have a more up-to-date schematic to compare?

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Amplifier Discussion / fender amp schematic
« on: December 25, 2012, 11:24:40 AM »
i've just got hold of a 'Fender H.O.T.'solid state amp made in the good ole' US of A ;along with a battered 10yr old squier strat 'crafted in china' yeah right...

i have never heard of this model before,and can't find any references on the web apart from people slagging them off,or selling them(encouraging,no?) anyone have a schematic for this or similar?

basic spec:- 2 input channels,high and low, 1 'contour' control (no other tone controls)volume and reverb,'CD input' RCA jacks(80's vintage?)headphone output, line out,and unusually, effects send and return jacks

it has 3 TL072 op-amps feeding a UPC1188H NEC power amp IC which is rated at 20W

as a supreme example of BS from fender the only thing on the chassis label says 'input power 75W' to fool people into thinking it's a 75W amp.

the clean channel sounds REALLY nice,but switching onto the 'crunch' or 'lead' channel and it all goes HORRIBLY wrong;the crunch channel is quieter than any of the other channels,and the 'lead' channel makes the  £15 fuzz pedal i bought as a kid sound like velvet...IT SUCKS
though bizzarely;if you turn the volume on the guitar right down it gets a 'just on the edge of overdrive' sound which is fantastic! it sounds like someone stuffed the wrong parts on the board :loco the gain on crunch is way too low and on lead WAAAY too high ???
i can see a couple of diodes on the board but without a schematic/prodding it with a meter i dont know whether they are input limiting or op-amp clipping.once i've found the gain setting resistors for the crunch and lead op-amps i can tame its unruliness :trouble ;and maybe Marshall-ize its crunch  8|

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