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    Any thoughts on what would be the schematic of the GM36 and why?

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    bordonbert

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    Any thoughts on what would be the schematic of the GM36 and why?

    Post by bordonbert on Sun Nov 01, 2015 9:25 am

    In the valve swapping thread, Namklak interestingly offered some ideas on what he thought the basic layout of the GM36 would be.  As the schematics are still "hidden from our sight", we can only speculate.  That speculation is the stuff of my own 3am ponderings, and I'm sure tugs at the more sensible curiosity of other users too!  So I decided to take Namklak's idea and open a thread to collect everyone's opinions and any real information that we can come up with.

    I'll be up front here.  While I work in design with discrete solid state, (i.e. real individual transistors along with ICs rather than just "lego block connecting" chips), and this includes the guitar and hifi audio field, I openly admit I'm not a valve expert.  However, I understand valve workings well and how they compare with solid state, and that's in real terms not just collected hearsay.  I also have done a lot of spare time work over many years into the area of what is audible and what just plain 'aint!  I need to know more, always!  And with that in mind, I for one would welcome input from others who have better experience in some areas to add than mine.  I learn, we all learn, we understand more clearly, we all sound better, things get more predictable and freer from the superstition which plagues it!

    I really can't see V3 used as a single sided splitter/inverter, with the output stage setup and bias control H&K have that just isn't, ...well..., sophisticated enough nowadays.  The long tailed pair approach taking up the whole valve is much more likely in my honest opinion.  I could be wrong but if that is how they did it I would be surprised, (not necessarily disappointed).

    My guess is there are probably two valves free for the preamp shaping stages, that's four triodes.  a) An input matching and clean amplification stage, b) a second gain stage, c) perhaps even a third as we have Ultra to consider, d) tone circuitry driver, e) tone circuit return, f) loop driver, g) loop return, h) output driver.  The reverb is digital so no reverb loop.  Any more I've missed?  d) e) f) g) and h) are impedance matching considerations and some of them could be performed by the same triode.  So what do people think of the setup of those sections as regard the allocation of valves?  And, more importantly, why?

    To extend this or for other functionality, it is very plausible to expect them to use Solid State ( Shocked affraid  pale ) in certain places.  This is NOT a problem in any way but the best soluition if applied carefully.  If any stage whose job is amplification beyond overdrive conditions is performed with a valve, you have valve tone and overdrive characteristics.  Clean amplification, impedance matching, driver tasks, can be done by solid state means without any addition to or subtraction from that sound quality.  I repeat, again, yet again, boringly to distraction, the idea that solid state inherently "sucks tone" is a myth!!!!!  If there is no distortion produced by a stage there can be no change to the signal other than its size and hence there can be no "tone suck".  If an opamp stage has say 0.05% distortion and would satisfy most hifi buffs, (not all of us  Twisted Evil ), how does that audibly affect the guitar signal which is deliberately being given up to 10% distortion by the other stages?  Even on a clean setting with less deliberate distortion it's inaudible to the Nth degree!

    So perhaps they may use opamps to drive and return the tone stack/control and loop networks.  Other highly respected pinnacle amp manufacturers do too and it works perfectly.  It's even been proposed that there may be a solid state stage at the front end, (tube screamer setup was suggested, back to back diode was meant, but it could just be a clean matching/amplification stage driving the valves harder), which is possibly selectable by the Channel and Boost functions.  That's feasible.  I predict that if that turns out to be the case, there will be a wailing and gnashing of teeth from a lot of people, who will promptly buy a "purist" valve amp with no solid state in it, then add their own Tube Screamer to the front end in an attempt to get "authentic classic sounds"!  Razz

    Plonkers?  Perhaps that's too unkind.  (Perhaps not!)  But they are missing the point.  Amp selection is about the sound it produces not just how it does it.  The only valid criteria is how your ears and brain interpret what you hear from your rig.  Personally there are days at home when I make my mind up that the GM must go!  I just cannot get it to sound as I want and remember at those family and neighbour friendly levels.  Then I go to a rehearsal and it all comes to life again and I just love it.  But it is in everybody's interests to figure out how the design choices could affect the sound in a genuine repeatable way.  Better amps come from better engineering not from increased mojo! One day maybe I'll have the time to open up the box and get out the cutters!
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    bordonbert

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by bordonbert on Sun Nov 01, 2015 1:25 pm

    Just saw Ignantios's post in the Valve Swapping thread. If you come across this here Ignantios, what is the choke mod?

    And as to your claim that capacitor changing makes it sound much better, I'd have to hear the same amp before and after capacitor changes before deciding either for or against on that of course, but in 99% of cases I can tell you the capacitor type can make no difference at all and that can be measured objectively! In this case I should not comment. Wink
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    namklak

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by namklak on Mon Nov 02, 2015 11:34 am

    Bring on the mods, but I want a little technical discussion with the mod. BTW, I'm a little more of a believer than bordonbert's 1% if that cap is in the signal path - changing a bypass cap puts me in the less than 1% range of belief.
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    namklak

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by namklak on Mon Nov 02, 2015 11:35 am

    I'd throw $10 at anyone who came up with a schematic of the analog parts of this amp.
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    ignantios

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by ignantios on Mon Nov 02, 2015 1:39 pm

    I am not an expert but as far as I am concerned it's an inductor that is used to enhance an broaden the amp's dynamic and tonal characteristics. Usually they substitute a resistor which in combine with some capacitors in the power section smooth out the power delivery and storing energy to handle transient peaks. The capacitors act as high pass filters letting more harsh highs pass when the coil(choke)does the opposite.Cuts highs that sounding harsh and let's the lows pass.Something like that don't know if it reflects the truth though.
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    ignantios

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by ignantios on Mon Nov 02, 2015 1:49 pm

    bordonbert wrote:

    And as to your claim that capacitor changing makes it sound much better, I'd have to hear the same amp before and after capacitor changes before deciding either for or against on that of course, but in 99% of cases I can tell you the capacitor type can make no difference at all and that can be measured objectively!  In this case I should not comment.  Wink
    .
    I'll put it like that.....let's just say that some guitar players hear great differences between an orange drop capacitor in their strats than other regular 0.22 μf capacitors out there.Some don't.....And we are talking about just a small capacitor which is being used on a tone control of a guitar.Imagine now how much influence "might"be with 4, 5 or 6 capacitors on an amp.I am just confessing what I have experienced from my deluxe amp.I might be wrong. Cool
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    bordonbert

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    Re: Any thoughts on what would be the schematic of the GM36 and why?

    Post by bordonbert on Mon Nov 02, 2015 4:11 pm

    No Ignantios, I have to disagree. Some guitarists "claim" to be able to hear the difference between the mystical Orange Drop capacitor and standard types. When they are presented with the two in blind listening tests they can NEVER differentiate. When they know which is which they are able to hear what they want to hear. When they don't know somehow, mysteriously, they all sound the same. The rigourous test format is the easiest one to set up correctly, and in many tests over the years I have never found anyone who can tell any difference at all. Quelle surprise!!!!!

    There are a number of well respected high profile people who are finally taking this issue on in order to put it right. You should look here towards the end, (notice the website domain!):

    http://www.seymourduncan.com/tonefiend/guitar/customize-your-caps/

    It's a myth, and that's polite for total bollocks!!! Very Happy

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