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    Seeking advice for GM speaker and tube selection

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    Irocdave12

    Posts : 18
    Join date : 2016-08-27
    Location : Philadelphia, Pennsylvania

    Seeking advice for GM speaker and tube selection

    Post by Irocdave12 on Sun Aug 28, 2016 11:35 am

    New member and glad to have found the forum. About to buy the GM and plan to use mostly  for classic rock, Rush Led Zep etc and have concerns about the reports of so much gain and brightness and like other owners would like to tame it a bit. What tube selection have most users settled on at this point. I have read quite a bit of that thread as well. I'm using 2 TM 112 cabs currently with my TM 18 and want to know if I should be swapping out the speakers for a creamback or greenback. What exact model are you guys changing to. Also I've read of members just changing one speaker to greenback and keeping one of the brighter V speakers intact? What is thought of that? Thanks in advance for any advice and guidance.
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    bordonbert

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    Join date : 2015-01-28
    Age : 97
    Location : Southern England

    Re: Seeking advice for GM speaker and tube selection

    Post by bordonbert on Mon Aug 29, 2016 12:52 pm

    I play classic rock too but lighter stuff like Free, Bad Company, Humble Pie and the like. Can't get on with that higher gain sharper American sound. I now use a Marshall 4x12 with G12M Greenbacks in it. I've tried a few other combinations but this one is a keeper for me. I started with V30s in 2 1x12s and realised my mistake. I wouldn't ever touch them again in any form with my GM36. They're far too toppy with a wide range amp. That said they may work for you depending on the sound you like.

    Valvewise there is not really too much to be gained from anything other than changing them out for better quality like JJs. Too many people think they have to come up with huge differences in sound between makes. Any genuine valve differences are "subtle at best" to paraphrase one of our professional members, and most are Emperor's New Clothes Syndrome hype from people selling, guess what, valves. I certainly would never consider swapping out for the "low gain alternatives" (yuk) like 12AT7s or 12AY7s. They are nothing like real substitutes despite what "common knowledge" will tell you. If you really want to reduce gain then you should consider 5751s, they are really close to the 12AX7 in other more important parameters so the circuit conditions are upset very little by the change. The others are totally different valves in their usage and some of their important parameters and everything goes out of whack. Just because they don't go up in smoke doesn't mean the circuit is working as it should. But you're perfectly at liberty to disagree with me in that one.
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    Irocdave12

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    Location : Philadelphia, Pennsylvania

    Re: Seeking advice for GM speaker and tube selection

    Post by Irocdave12 on Mon Aug 29, 2016 11:29 pm

    bordonbert wrote:I play classic rock too but lighter stuff like Free, Bad Company, Humble Pie and the like.  Can't get on with that higher gain sharper American sound.  I now use a Marshall 4x12 with G12M Greenbacks in it.  I've tried a few other combinations but this one is a keeper for me.  I started with V30s in 2 1x12s and realised my mistake.  I wouldn't ever touch them again in any form with my GM36.  They're far too toppy with a wide range amp.  That said they may work for you depending on the sound you like.

    Valvewise there is not really too much to be gained from anything other than changing them out for better quality like JJs.  Too many people think they have to come up with huge differences in sound between makes.  Any genuine valve differences are "subtle at best" to paraphrase one of our professional members, and most are Emperor's New Clothes Syndrome hype from people selling, guess what, valves.  I certainly would never consider swapping out for the "low gain alternatives" (yuk) like 12AT7s or 12AY7s.  They are nothing like real substitutes despite what "common knowledge" will tell you.  If you really want to reduce gain then you should consider 5751s, they are really close to the 12AX7 in other more important parameters so the circuit conditions are upset very little by the change.  The others are totally different valves in their usage and some of their important parameters and everything goes out of whack.  Just because they don't go up in smoke doesn't mean the circuit is working as it should.  But you're perfectly at liberty to disagree with me in that one.
    Thanks for the info. I have been reading most of your writings on the forum and have learned a lot and was planning on using the 5751 per your advice. Any thoughts on the gold pin option offered on all these valves? I'll be dealing with eurotube and noticed they offer gold option on most the pre amp tubes and term it as srv tone option. Have you ever heard a difference A/B on a gold pin vs a regular of same specs in regards to the added warmth etc the gold is claimed to add? Also do you think it's a waste to change just one of my speakers and keep one v30? I pondered if I would get a hybrid affect by doing so. I even noticed celestion sells a speaker advertised as a hybrid between a v30 and a greenback which is what sort of gave me the idea
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    bordonbert

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    Re: Seeking advice for GM speaker and tube selection

    Post by bordonbert on Tue Aug 30, 2016 5:41 am

    Warmth?  Please, grandma pass me the spitoon before I puke on the cat!!!  You won't hear any difference at all in a genuine A/B test Dave. (Hope Dave is the right name?)  I keep using the term because it is so common in our game - Emperor's New Clothes Syndrome!  The difference the gold pins makes is only in terms of contact integrity over a long space of time.  In the aerospace industry system critical connections are made in areas which may not get broken and remade for a long time.  Sealed gold contacts are a reliability necessity there.  And in hifi, effects which are genuinely insignificant to us are perhaps audible in the most advanced and transparent top end systems.  But this isn't hifi, it's an arena where we are introducing massive distortions into even our cleanest sounds which absolutely swamp anything a little layer of gold could deal with.  And has the matching surface in the valve socket been changed for a gold plated one too?  If anyone thinks there is a sonic difference just because a few atoms of gold are added into the signal path then they are living in cloud cuckoo land!  Assuming the contacts are clean and connecting as they should, the natural differences within tolerance between valves of the same make and type will swamp any difference that the gold could ever produce.

    In the case of our valves, we have significant voltages or currents on almost all of the pins in there which tends to keep the contacts clean (whetted, and it needs the "h") by themselves.  With fairly regular use a normal current of a few milliamps will punch through natural corrosion as it forms.  And for a high impedance line like the grid which can have signal level voltages and doesn't normally have current flowing, the resistance of a bit of general corrosion is less significant in terms of the impedance it is in series with.  There are other situations with low voltage and ultra low current, like your guitar socket and leads, which are more exposed and could perhaps benefit from gold contacts but no one has ever shown me any real practical advantage in our situation re valves.  And it only takes a few insertions before the gold starts to scratch off anyway, gold isn't very tough in mechanical terms and it's only a few atoms thick.  There will be others who will recommend them I'm sure but I don't really see the point.  It's mainly another of those "selling up" ideas that suppliers like to come up with to squeeze your wallet by attacking your confidence.  This guitar music field is riddled with them!

    If you are worried about it, it's better to do a bit of maintenance in with a regular service and just rock the tops of the valves round in a circle a couple of times to scrape clean the contacts in their sockets.  The smallest movement between the pins and sockets will do the job.  Simple and enough to keep them pristine.  I don't even bother to do that, I will just wait for a reason where I need to open the amp up and do it then as an extra.  Others will have maintenance routines with contact cleaner which does no harm, but it shouldn't really be necessary.  I could be wrong but I don't think we have had anyone complain that they have suffered from the valve pins losing contact in my time here.  And I haven't come across a genuine case of the problem in any other forum to do with amps.

    As to the speaker situation, I think that the only way you can be sure is to just try it.  You could source a secondhand Greenback say and give it a spin in your own 2x12 knowing that, if you didn't pay too much for it in the first place and there is nothing wrong with it, you can sell it on without loss if it doesn't work as you want.  If it does change things for the better and you like the sound it gives then you'll know whether you would benefit by going a bit further down that route and replacing the other one.
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    namklak

    Posts : 185
    Join date : 2015-01-30
    Location : Denver, CO

    Re: Seeking advice for GM speaker and tube selection

    Post by namklak on Tue Aug 30, 2016 12:43 pm

    On the subtle end, the guy at TubeDepot will sell you 12ax7s with gain at 90 or 110 or ??? So if you are struggling with the channel gain on your Lead and Ultra channels always being at 1, you can get a little relief by installing a gain of 90 12ax7 in V2.
    IMHO, in a guitar amp, the difference between a gold pin and an inexpensive JJ/EH/Sovtek is the hole in your wallet.
    If weight is an issue, I've been happy with the Eminence Lil Texas (with neo magnet) in a 1x12. Also a little cheaper than paying for the C name.
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    bordonbert

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    Join date : 2015-01-28
    Age : 97
    Location : Southern England

    Re: Seeking advice for GM speaker and tube selection

    Post by bordonbert on Tue Aug 30, 2016 6:47 pm

    I've heard Eminence Lil' Texas mentioned in other places Namklak, always good, particularly regarding the GM. Not something I've ever had the chance to try. They are more expensive than the C-G12Ms over here.

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