Practice amp.. Marshall Valvestate 8020 vs 8040
adam79
at a local store and fell in love with it. however it was defective.. it
would sound fine, then it would stop working, and you would have to turn it
on and off a couple times to make it work again. anyway, here's my
questions..
has anyone compared the 20watt and 40watt valvestate models? do they sound
the same, except that one is louder? i know they have different celestions
in them. if the only difference is the wattage, i'd rather go for a 8020,
but sound comes first.
thanks,
-adam
Jim
Adam,
They are NOT the same. The 8040 has a preamp tube in it for distortion.
The 8020 doesn't. The 8020 is a 10" speaker, 8040 is a 12".
I bought an 8020 for my nephew as a first amp. He still has it, he
doesn't play that much. Like virtually all SS amps, it sounds buzzy to
my ears. You can play with gains and EQ to tame the SS buzz, but it's
there. If you don't care about that, because it's only for practice, it
might work fine for you. Be advised that both options come with really
cheap circuit board mounted pots. Be willing to clean the pots from
time to time. They tend to get scratchy more often than they should,
and cleaning is a bit of a hassle.
jh
Hi adam,
if you fell i love with the 8040 (*), check it out again and patch the
FX loop with a short cable. If the symptoms are gone then, it´s a
corroded or dirty switch contact of the return jack..
You could either use it till the end of our days with the patched loop,
or have it fixed for about 40-50 $.
regards
Jochen
(*) although I can´t understand why
adam79
opened it up and clean the posts out with some electronics cleaner it would
fix the problem? Any chance it could be a bad pre amp? The amp works, but
when you play longer than 5-10 minutes all the volume cuts out.. when you
turn it on an off it make a crackling sound; turning it on and off doesn't
fix the problem.. if you turn it off, and leave it be for 10 minutes it
works fine when turned on, but the volume eventually burns out the same way
it did the first time.. i just bought it today, so i still have a chance to
return it, but if it's an easy fix.. than i'd keep the amp.
thanks,
-adam
"jh" <jh-audio...@t-online.de> wrote in message
news:fj2s9m$oj5$01$1...@news.t-online.com...
> Hi adam,
>
> if you fell i love with the 8040 (*), check it out again and patch the FX
> loop with a short cable. If the symptoms are gone then, it愀 a corroded or
> dirty switch contact of the return jack..
>
> You could either use it till the end of our days with the patched loop, or
> have it fixed for about 40-50 $.
>
>
> regards
>
> Jochen
>
>
> (*) although I can愒 understand why
Jim
> how would i go about doing that, the fx loop suggestion? you think if i
> opened it up and clean the posts out with some electronics cleaner it would
> fix the problem? Any chance it could be a bad pre amp? The amp works, but
> when you play longer than 5-10 minutes all the volume cuts out.. when you
> turn it on an off it make a crackling sound; turning it on and off doesn't
> fix the problem.. if you turn it off, and leave it be for 10 minutes it
> works fine when turned on, but the volume eventually burns out the same way
> it did the first time.. i just bought it today, so i still have a chance to
> return it, but if it's an easy fix.. than i'd keep the amp.
>
> thanks,
> -adam
I'm a hobbyist that has built, modified and repaired tube and SS amps
and effects. I am not a pro and don't claim to be an expert. Other
than that...
My crystal ball tells me that it's probably a broken solder joint. When
there's enough heat from the power transformer and output devices, the
board expands and you get an open circuit. Either that, or there could
be some sort of overheat protection tied to the heat sink for the output
devices (probably a chip in that amp, but I don't know). If that's the
case, something is wrong, causing it to overheat. I'll assume that you
meant cleaning the POTS, not the posts. That ain't gonna fix it.
My crystal ball is not always right. But why did you buy a broken amp?
What did you pay? For perspective, I think I paid $20 for a 8020
with scratchy pots. Gave it to my nephew. Kind of a mistake, because
now I get to clean the pots on a regular basis. ...and direct
replacement pots are oddballs that aren't that cheap!
If you have electronics skills, or at least a good soldering iron and
the ability to solder, you might try resoldering all of the pots and
jacks to start with. But this design is NOT a good one. Look forward
to more problems like this, and dirty pot hassles. IIRC, you gotta pull
all the knobs, take off all the hex nuts, pull the board... HASSLE!
My advice: BRING IT BACK.
jh
> how would i go about doing that, the fx loop suggestion?
Just try it, costs you nothing, but dirty switch contacts at the jacks
cause about two thirds of the problems with these amps. Especially with
the symptoms you described. If it does not cure the problem, ok but you
tried it.
you think if i
> opened it up and clean the posts out with some electronics cleaner it would
> fix the problem?
No I don´t think so. IME the pots (at least in a valvestate) are seldom
so dirty that the amp cuts out and comes back after restart.
Any chance it could be a bad pre amp? The amp works, but
> when you play longer than 5-10 minutes all the volume cuts out.. when you
> turn it on an off it make a crackling sound;
many Valvestates have that, might be normal
regards
Jochen
turning it on and off doesn't
> fix the problem.. if you turn it off, and leave it be for 10 minutes it
> works fine when turned on, but the volume eventually burns out the same way
> it did the first time.. i just bought it today, so i still have a chance to
> return it, but if it's an easy fix.. than i'd keep the amp.
>
> thanks,
> -adam
>
> "jh" <jh-audio...@t-online.de> wrote in message
> news:fj2s9m$oj5$01$1...@news.t-online.com...
>> Hi adam,
>>
>> if you fell i love with the 8040 (*), check it out again and patch the FX
>> loop with a short cable. If the symptoms are gone then, itŽs a corroded or
>> dirty switch contact of the return jack..
>>
>> You could either use it till the end of our days with the patched loop, or
>> have it fixed for about 40-50 $.
>>
>>
>> regards
>>
>> Jochen
>>
>>
>> (*) although I canŽt understand why
>
>