amps and solutions

[Andy Le Blanc]

busy monday ........ all fenders.......

bandmaster blackface...... nice, almost all original it had some work a long
time back to the trem.... blown opt..... filter caps blown..... it looks like it was
stored in a very damp place ..... and it will still need a 50k pot and opto for
the trem...... nice amp.... sounds really good with the power side restored
original signal chain.... gonna have to clean the inputs.... again

red knob twin....... this one has been in a couple three shops since may
with a weird distortion....... no one could figure it out....great....wheres the
holy water..... turns out to be a fried 1 ohm resistor on a test point.....
these have the power tube cathodes connected to ground thru a really small
1ohm res. paired with a diode......so when the res. fries youll hear the
nonlinear distortion thru the diode..... sounds like an issue with the pre
but heres the rub.... the instructions to bias the thing are on the back
and theyer for ma. (.04 v)...... when this happens youll get readings in
volts from 25 to 35 v........ de da deee...

hot rod deluxe...... crackle pop..... screen grids and plate resistors....
thats the issue with these ..... if anybody tries to sell you any fender with
a noise issue like this talk the price down and turn it around for a profit
fender had vender bender.....

[Andy Le Blanc]

heres a good one
I got this fender blues deville..... another one thats been thru a couple techs

this is an amp with nothing wrong

the amp is returned again and again with non functioning tone controls
this baffles everyone..... and after quite a while its my turn

after looking at it I find theres nothing wrong with the thing

so I start digging for a reason why the guy would think the tones dont work
peculiar to this model and many "new" fender designs is the tone control
placement and configuration...... its more like an early bassman than the
black or silver face amps..... like a marshall.... so the responce is not
what most would call "fender"

ok..... so what....... theres nothing wrong with the amp......

now heres the thing that a couple other techs missed.....(or maybe not...
the last tech sold the guy some speakers) ..... the owner had tacked
this tye-dyed fabic over the grill..... its a heavy fabric that is in no-way
acoustically transparent....... what a trip..... pull off the tye dye
the tones work great

[Structo]

That's funny isn't it.
The fabric was dampening all the tone!
Geez, people.

[Stanz]

That's funny isn't it.
The fabric was dampening all the tone!
Geez, people.

Yeah, but I bet he looked really cool on stage.

Reason #101 why most musicians should not be audio engineers or amp techs.

[rfgordon]

Forgive my anal retentiveness (and I'll prolly get mercilessly flamed for this), but, for the record, the word is damp not dampen.

To dampen: verb: to make wet

To damp: verb: to reduce the magnitude of (as in damping an oscillation)

I know it's really neither here nor there, but what kills me is that even amp makers who should know better (like Mojave amps) put "Speaker Dampening" controls and such on amps. So.....does it really squirt water onto the speakers?

Sorry, I'm a geek. Can't help myself. Carry on.

[Buschman]

I will never forget this 50 watt marshall combo I once bought. It looked like a cat toy with frayed cloth and vinyl everywhere. Got it cheap cause it sounded like ass. Went through everything I could think of until I realized the speakers were out of phase. I fixed that and then it was too loud for me to use.

[Stanz]

I know it's really neither here nor there, but what kills me is that even amp makers who should know better (like Mojave amps) put "Speaker Dampening" controls and such on amps. So.....does it really squirt water onto the speakers?

No, he is right. Dampen is used as it should be, the sound has been dampened, or squashed, muted.


Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This
damp·en Audio Help /ˈdæmpən/ Pronunciation Key - Show Spelled Pronunciation[dam-puhn] Pronunciation Key - Show IPA Pronunciation
–verb (used with object)
1. to make damp; moisten: to dampen a sponge.
2. to dull or deaden; depress: to dampen one's spirits.

...and having a dull sounding amp will definitely dampen my spirits.

[morcey2]

I picked up a Harmony H-306 that wasn't working from a pawn shop for $50. I knew that the speaker wasn't a guitar amp speaker because of the massive chrome-covered hole-in-the-middle magnet in it.

I got it home, pulled the speaker out to see what it was. Someone had put in a 1000-Watt automotive sub-woofer with a blown voice coil. (I pulled the speaker apart and the coil was burnt/melted together. ) The grill cloth was replaced with this ugly brown polyester knit. I bought some salt-n-pepper grill cloth for it an when I pulled off the polyester, the original grill cloth was underneath in perfect condition!

I threw a $15 ebay magnavox alnico speaker in it, converted the preamp to a 6G3 pre, and put in a new 6SH7 for the trem. It now sounds awesome.

http://mcorey.dsl.xmission.com/H306/index.html

I also picked up a Gretsch 6150-T from a different pawn shop for $40 that had the hi-voltage center tap wrapped around a ground, but not soldered. I fixed that, replaced the microphonic 6V6 with a GE that I had kicking around, and sold it for $200 to a friend a few weeks ago. Cool little amp, but I never really played it that much. Turn it up all the way with a Les Paul plugged in and you have instant "Kinks". The 6V6 that I took out of it is a black-plate RCA. It works great in heads (hi-octane and P1-extreme) but is totally unusable in a combo. It resonates at about 110Hz.

http://mcorey.dsl.xmission.com/gretsch/index.html

I've done lots of SS amp repairs and almost all of them involved taking the PCB out, turning it over to find the bad solder joints, reflowing them, and putting the PCB back. I've only had one or two that actually required new components.

Slightly off topic: Something that I found with both of these amps is that they LOVE the new Tung-Sol 6V6s. They're both tweed-ish circuits, one 5E3-ish and the other 5F1-ish. The JJs are too compressed in them and don't break up the right way. They don't sound bad, they just don't have the tweed growl that the tung-sols have.

Matt.

[Andy Le Blanc]

I got this SWR 500w head in to look over..... the guy had had the problem
of the amp suddenly crackling and then not working at all after about fifteen
minutes..... he thought it was a bad speaker jack..... so.... when I pick up the
amp its in a nice shiney new slim road case....I get it to the bench.... get it
out of the road case and fire it up...... and for two days I cant for the life of
me get it to exhibit the fault....

theres nothing wrong with the amp.... great.... another one......

the unit is fan cooled I notice..... the fan is right in the middle of the
chassis and moves air through a heat sink channel and then out the side
the look on the guys face will be priceless...... hes gonna have to cut some holes
in that brand new... nice and shiney ...slim road case

[strato17]

Please, keep these coming. These are very educational and entertaining!

[km6xz]

Please, keep these coming. These are very educational and entertaining!

Actually it is depressing.
The number of "techs" who should have no ethical right to charge for their general incompetence is no where as high as in the pro audio market. Basic diagnostic skills seem to be a lost art, replaced primarily by myth and belief in magic.
There might be a number of causes of this, lack of education is a major one but it is also a matter of thinking style that never relied on critical thinking skill development. But whatever the causes, there are very few people working in pro audio repair that are not likely to cause more damage than they can resolve.
I used to live in California(still have a house there) but live in St Petersburg Russia now. Here it is just the opposite in education which is very high but little practical experience in pro audio which results in similar results.
The same with musicians: in the US, there is limited music eduction and music theory but lots of seat of the pants experience. Here, high level conservatory graduation is common, guitarists can play the notes but have no concept of tone or presentation. I don't know how many times I have walked to an amp in a club where a band is playing with horrible sound and tweaked the eq or gain(something that would get you shot in the US) and have both the musician and audience applaud at the improvement. Interesting to say the least.
Although one of the largest tube manufacturers is right here in St Petersburg very few tube amps are used. Fans are very knowledgeable about music but neither the musicians or fans care what things sound like or why it sounds the way it does, and few adjust or tweak by ear.
What it really comes down to is optimum balance between knowledge and feel, whether is it diagnostics or playing music, a deficit in either causes the results to be the same; less than desirable.
I've met techs all over the world and have come way with the impression that the level of training in MUCH higher in Europe and Asia than in the US. A college or university level technical education is good for Engineers but there is no quality education available for techs in the US, as if there are only two types of people, professional degree holders and laborers and nothing in between.
Being a pro-audio tech in the US means being condemned to a much lower income level than an engineer regardless of the skill of either. As a result, it is not a career for someone raising a family or becoming established in a traditional sense, more hobby than profession with the resulting low standards. If competence and knowledge it to be injected into pro audio services higher standards and higher incomes will be required to turn it into a profession. It may seem strange that a pro audio tech here is paid more than a doctor or engineer but there are more of doctors and engineers and virtually no unemployed techs, who usually have BSEE or MSEE degrees.

[Tubetwang]

Gordie Johnson live's in Austin, TX. Great tech. Great guitar player.

He recorded a local band and they raved about his skills...

Got this Daniel Lanois Gold top Edition "Here is what is" DVD...huh...er... here...Daniel has soul...great tech.

None of these guys have any University degrees that i know of...

Not knocking schools but...

Twang

[drz400]

heres a good one
I got this fender blues deville..... another one thats been thru a couple techs

this is an amp with nothing wrong

the amp is returned again and again with non functioning tone controls
this baffles everyone..... and after quite a while its my turn

after looking at it I find there's nothing wrong with the thing

so I start digging for a reason why the guy would think the tones dont work
peculiar to this model and many "new" fender designs is the tone control
placement and configuration...... its more like an early bassman than the
black or silver face amps..... like a marshall.... so the response is not
what most would call "fender"

ok..... so what....... theres nothing wrong with the amp......

now heres the thing that a couple other techs missed.....(or maybe not...
the last tech sold the guy some speakers) ..... the owner had tacked
this tye-dyed fabic over the grill..... its a heavy fabric that is in no-way
acoustically transparent....... what a trip..... pull off the tye dye
the tones work great

It is hard to find a good tech since the pay is for shit, same as a guitar guitar tech.
Musicians expect to pay $45 to get their amp fixed and $150 for a fret job.

What bugs me more are the manufacturing problems that send the owner to the tech which should never happen especially with companies who know better and have re$ources.

A stupid problem I have seen in Blues Deville / Deluxe series
The switching supply is taken from high voltage and a zener, Resistor is mounted badly on the board, gets hot enough to unsolder the tiny traces on the PC Board and the switching becomes intermittent. Quick fix is get the heat sink type resistor and mount to the chassis, I must have fixed 5 of those. Bad bad design, is an extra tap on the transformer too costly Fender?

Fender Tone Master, early amps popped badly when switching.
The designer (Zinky) forgot to put diodes across the relays and they were not drawn in on the schematic or shown on the relay (as in built in) Dooohhh!

I used to do amp tech work, worked alongside with a guy who had a degree who used to spend hours looking for a leaky cap, not realizing a ground wire broke, he was always looking for something deep when it was in his face There is no replacement for experience.

[Andy Le Blanc]

I got in to this field to learn how to build amps..... for the ussual reasons
I did not want to be a repair tech....... but the word of mouth thing comes
back to haunt you..... and then theres offers of payment etc.....
there is a clear need in my area for the repair and upkeep of gear
but the economy can not sustain it..... I cant charge a bench fee....
its by the hour..... if I did impose a bench fee Id have no repairs....
which is the trickle that keeps what I really want to be doing... a seemingly
worthwhile endevour...... its light manufacture...... one hell of a thing to
build a business..... where the economy has been slowly collapsing since
Carter lost to reagan....

I had another one in this week..... a small peavey keyboard amp
no output and no one could figure it out..... for a few months.... jeez
I looked it over for loose bits before opening it.....one of the jacks in the back
looked funny..... it had one of those small 1/4" to 1/8" adaptors in the
headphone jack.......imagine that.....

[CaseyJones]

I got in to this field to learn how to build amps..... for the ussual reasons
I did not want to be a repair tech....... but the word of mouth thing comes
back to haunt you..... and then theres offers of payment etc.....
there is a clear need in my area for the repair and upkeep of gear
but the economy can not sustain it..... I cant charge a bench fee....
its by the hour..... if I did impose a bench fee Id have no repairs....
which is the trickle that keeps what I really want to be doing... a seemingly
worthwhile endevour...... its light manufacture...... one hell of a thing to
build a business..... where the economy has been slowly collapsing since
Carter lost to reagan....

It's the same everywhere. Musicians always have dough for beer and a baggie but when it comes to changin' their barf caked strings fer instance they'll let it go until they're too rusty to make it through the set.

If you want a steady stream of repair work plug into the Portland area.

There are towns where the locals bitch about the poor economy, they ain't seen a poor economy! Detroit for example. Boo hoo, boo hoo. Plenty o' dough there, don't let 'em fool ya. A poor economy is when a small town relies on one industry to survive and that industry crawls up its own ass. My latest kick is microbusiness takin' over to fill the void Big Business leaves when it goes belly-up. The good ideas start small and take on a life of their own if they're really good.