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Post by bullibeer on Oct 10, 2012 0:00:28 GMT -7
Hi again big thanks for all the help on the speaker question... i went with a Blue for now.. incoming DrZ 1 x 12 cab with blue. But there is one other point ... or actually 2 on the Carmen Ghia. 1. On the back of the Ghia there is a extra tone knob. I have the feeling it changes the mid's. 12.00 feels neutral... towards zero less and towards 18.00 more. Does anybody of you know such extra knob on Ghia's. Is that a factory option? Or someone modded it... and do more people have this mod then? And what would be an extra advantage / settings then?  Thanks again! 2. Mine is a 1999 serial and has the green light. What is the main difference in tone. I understand some components are different... but what does it mean in tone? ANd which one most of you prefer? Thanks for the info. Saturday i am planning to have a jam.... with friends. And put the Ghia through the Blue 1 x 12 and play it loud ;-) Can't wait! |
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Post by mfirst on Oct 10, 2012 3:58:31 GMT -7
Never seen that before. Almost definitely been modded. If you like it, I guess its ok. Have you heard one that is stock? You may want to check into the differences. If it were mine I'd send it to the factory to have it unmodded. The Ghia really only needs two knobs. Did the person you got it from ever tell you about any mods to the amp?
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Post by BW on Oct 10, 2012 9:10:41 GMT -7
Some skullduggery afoot there.
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Post by deaconblues on Oct 11, 2012 19:27:01 GMT -7
I suspect some kind of "duggery", as well, but at the other end of the torso.
I would like to know more about it, though.
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Post by smolder on Oct 11, 2012 20:09:39 GMT -7
Without seeing the chassis inside, the circuit, it's hard to tell. What's interesting is that there does not seem to be the typical 4 or 8 ohm option for the impedance of the speaker out. Makes me wonder if they are using the pot to vary that... but that's just a a guess.
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Post by Albert on Oct 12, 2012 4:09:06 GMT -7
How about some gut shots ...
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Post by fevzay on Oct 12, 2012 21:50:31 GMT -7
Without seeing the chassis inside, the circuit, it's hard to tell. What's interesting is that there does not seem to be the typical 4 or 8 ohm option for the impedance of the speaker out. Makes me wonder if they are using the pot to vary that... but that's just a a guess. The older Ghia's only used a single output transformer (that could be used with 4-8-16 ohm cabs). Later on down the road, that transformer company went out of business (I believe) and Doc started using a different kind (with the 4 and 8 ohm taps). Having said all of that...I have no idea what that mod could be. Gut shots are in order. Certainly not stock though. Bottom line: If you like how it sounds, then don't mess with it. |
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Post by Lefty on Oct 12, 2012 23:39:40 GMT -7
Neg feedback loop?
Back in the day there was a mod for bf fender heads (Bassman/Bandmaster) that would turn the extra speaker output into something like a presence control. Now don't quote me, it's been a lot of years and very different amps. Either way like its been said, that's not stock.
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Post by johncashdollar123 on Oct 16, 2012 6:44:19 GMT -7
that's right in the hole that one of the speaker jacks is. so my first question would be did they tell you what impedance the one speaker jack is matched to?
then i'm inclined to agree with lefty that this might be a negative feedback control. the ghia has a negative feedback loop, so maybe someone made that feedback value controllable instead of constant.
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Post by bullibeer on Oct 16, 2012 9:29:22 GMT -7
Thanks for the comments... well as the Ghia is a 1999 model (serial range) i thought it is only a 1 x 8 ohm output as also mentioned here....
But does the 1999 green jewel back panel look different then this one? As you can see .. the panel has more outputs but one has like a plastic cap on it.
What does a negative feedback control mean or do? Is it like a presence ?
At 12.00 it is quite neutral... rest changes it... will check again and try to descripe what it does ...
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Post by simpleton on Oct 16, 2012 12:44:17 GMT -7
this is interesting....It's like discovering a new species. What do the changes sound like to you bullibeer?
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Post by randalp3000 on Oct 16, 2012 12:52:40 GMT -7
Thanks for the comments... well as the Ghia is a 1999 model (serial range) i thought it is only a 1 x 8 ohm output as also mentioned here.... But does the 1999 green jewel back panel look different then this one? As you can see .. the panel has more outputs but one has like a plastic cap on it. What does a negative feedback control mean or do? Is it like a presence ? At 12.00 it is quite neutral... rest changes it... will check again and try to descripe what it does ... How about a couple pictures of the insides, it would be easy to confirm if its negative feedback or a cut control. |
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Post by smolder on Oct 16, 2012 13:07:36 GMT -7
randalp is right, the only way we or you will know is by looking inside.
from the aiken amps site (a really great source of technical information:
"The use of global negative feedback does several things: it flattens and extends the frequency response, it reduces distortion generated in the stages encompassed by the feedback loop, and it reduces the effective output impedance of the amplifier, which increases the damping factor. All of these things affect the tone in some manner"
Most NFL's are regulated by a single resistor. Sometimes a switch with two or three resistors is used, other time a potentiometer (variable resistor) is used so that you can vary the NFL... turning the NFL off in a fender silverface typically renders a more tweed like tone for instance.
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Post by jesslm02 on Nov 1, 2012 8:14:35 GMT -7
Interesting. I think we would all like to see the inside of this thing.
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Post by bullibeer on Nov 1, 2012 10:41:17 GMT -7
Yes i can imagine.... i only have 2nd thoughts about opening it. As i am not very technical. I am designer.. creative. But always was left with parts when working on bikes etc in the past.... so i don't want to damage it. I will try... maybe.
Was jaming last monday with it again.
And a friend .. 40 years musician listened to it.. and i also asked him... also about what it could be.
He listened to the settings and commented it sounds like a CUT.
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Post by Maddog on Nov 1, 2012 11:05:37 GMT -7
Honestly, you don't have to be very technically minded to open the amp. Just don't stick yer fingers into the guts......(seriously)....
Remove the chassis bolts and slip the chassis outta the cabinet.....
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Post by jesslm02 on Nov 1, 2012 11:35:08 GMT -7
Yea man, there's really nothing technical about it. Just make sure everything is unplugged, unscrew and remove the bolts on top, and slide'r out. Just try not to touch anything on the inside as Lee mentioned.
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Post by bullibeer on Nov 3, 2012 4:41:44 GMT -7
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Deleted
Deleted Member
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Post by Deleted on Nov 6, 2012 8:22:07 GMT -7
Whatever "IT" is the work was done well.
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Post by Sean on Nov 7, 2012 7:39:00 GMT -7
My curiosity has me following this thread
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Post by jesslm02 on Nov 7, 2012 8:58:14 GMT -7
It does look like a CUT knob to me.
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Post by jesslm02 on Nov 7, 2012 9:03:10 GMT -7
Definitely a CUT knob.
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Post by lowbudget on Nov 7, 2012 9:51:05 GMT -7
Kinda surprised the Doc hasn't chimed in on this.
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Post by randalp3000 on Nov 7, 2012 9:56:38 GMT -7
I was trying to figure out the 5w resistor and the cap, duh. I forgot about the cunjunctive filter on the Ghia. Looks like it's been replaced along with a tube socket.
I would also concur about the cut control..
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Post by bullibeer on Nov 7, 2012 11:27:06 GMT -7
Ehhhh filter... Etc.... Could you fill me in on what it all means.. As i am not atechnical guy....
Thanks.
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Post by mackaygtrs on Oct 14, 2013 18:25:02 GMT -7
Interesting, and on the open it up part.. I take everything apart as soon as I buy it... lol, amps, guitars, pedals, even my car... I have to know what's inside of everything and how well it's made.... :-)
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Post by erk187 on Oct 26, 2013 7:20:43 GMT -7
Yeah, post-phase inverter tone cut. But why bother with that? I'd remove it. That big messy solder glob on pin 8 looks like its going to short out on pin 9 if you move tubes around at all. Why add it to such a good sounding amp? IMHO there are so many variables in regards to pedals, pickups, guitar choice, guitar volume, guitar tone controls.. The whole idea of a two-knob ghia is to keep it simple... Isn't it?
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