Tube Amps / Music Electronics
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|3/18/2004 9:17 PM|
|Le Basseur||Re: Wow!I'm excited as for the first date!|
Also,there is a similar topology of the Acoustic 165 amp (this one has a hardwood enclosure):
The second link is a German one,but somewhere there's a promise that the entire site will be translated in English by April this year
|3/19/2004 1:35 PM|
|3/19/2004 8:51 PM|
But...isn't this a general issue regarding an entire generation of loudspeakers having a certain quality of paper membran?Did you have some special experiences with the EV12L's ? I'd say your observation applies to all drivers whose membranes are not impregnated or coated with some sort of hygro-protection.If I'm wrong,please correct me...if I'm right,then we'll have to agree that the mentioned "touchiness" had another cause(s)!
Thanks for everybody's inputs on this theme.
I understand that the amp in question is a rather unknown product for the most of you or,maybe,a too common thing (according to the Mesa Boogie resemblances) for being discussed extendedly,and I accept any of the two reasons,or both
I actually "married with my first date" (I bought the amp 2 hrs ago for a fair price of around 350 bucks).Now it comes the harder part (minor repairs and cosmetics).
...and geeee,I just hope I didn't "marry" with Quasimodo!!!
|3/20/2004 3:15 PM|
i didn't mean to imply that only the EVM speakers are effected by ambient humidity, just that the speaker in the amp looked like it could be an EVM and that maybe this could be a factor to consider if you're looking for possible sources of tonal inconsistency .
i haven't personally experienced the problem in a long time, because i now live in a climate controlled home with modern HVAC (tightly regulated temperature and humidity), and i don't play out. my speakers don't experience enough climatic change to cause noticable problems now.
quite some time ago i lived in a highrise apartment with no AC and I had to leave the windows open in the summertime and cool the place with fans. the EVM speakers were horribly inconsistent from one day to the next -- it was so frustrating that there were some days that I'd just shut off the amp and quit playing. years later, i still have the speakers but don't have the problem because of the better climate control.
way back when i didn't have other brands of speaker to compare, so i can't speak from experience about other paper coned drivers. i do share your opinion, though, that this kind of artifact should effect all paper coned speakers.
so if we factor speakers out of the equation, maybe you should stay focused on electronic components. i know, i just restated the obvious.
best of luck.
|3/20/2004 4:16 PM|
The deal you did on this amp seems a good one.
I have the successor of your amp , a G100T ; its appearance is exacly the same including the EVM 12 L speaker. Thanks for the url of the German site, lots of great info.
What I never liked about my amp is that the distortion channel lacked a tonecontrol so I built one inside the amp on a separate pcb, also took out a few caps which bled the treble to ground.
And the vactrols ( I think theye are ? )don't react fast enough, sure would like to fix that !
It's a pity that the 164 schem on that site was hardly legible, I would like to have one with a higher resolution for comparison.
I also tried the amp with 5881s when I didn't have any spare 6L6s this made it sound a bit darker with less treble. Oh and I nearly forgot the printtraces which carry the 6,3 filament current dropped some voltage so I rewired it for the outputtubes.
Hope this information is of some use to you
|3/20/2004 10:08 PM|
You're welcome for the German link.
I just noticed that on the Acoustic mother site:
,your amp is listed as a "known to exist,but no pics",so maybe you'll want to sent them some pictures of your G100T.And no,you don't have to dissasemble it,the Acousticians are not THAT picky,they'd need only some good-quality photos from the outside of the amp.
I understand your complains about that distorsion thing,but my amp will be a bass one (I sense a perfect match between this amp and my fretless),so this isn't an issue for me.The driver gets also replaced (the EV cannot hold with a bass instrument) with a Eminence Kappa Pro 12'' I have on spare.
Please enlighten me about a term you used:"vactrols".I surely missed on that lesson and I vaguely recall the name without identifying it with a component...since you mentioned "speed",a "vactrol" is a relay,or what?
About the schematics,what's to say?The quality is poor indeed,but they're the only free-downloadable references about these amps.True,there are some guys who sell a blueprint for 20 bucks and up,but I'm not willing at all to pay anything to someone who just had the occasion to get some originals about he has no intellectual contribution and/or copyright,but intrinsically abuses by declaring himself as a certain brand's expert (sorry to everyone for this digression).
Currently I use a quartet of those trusty military Russian 5881's (they're not dark at all!),but that's only temporary,'till I repair and eventually tweak the amp.Later,I'll put some black metal-jacketed RCA 6L6's that I got a long time ago,or maybe some GE's I kept for years in the same "value box"...we'll see.
Also,thanks about the filament traces' hint,but it seems I'm not gonna rewire this section.Actually,I always had some problems with Fenders because their original PT's are winded a little strange; on the 228-231 VAC on the outlet I couldn't use the 230VAC position on that primary selector (as found on export models) because the filament's voltage measured at the farthest tube's socket was over 7 VAC,so I always prefer to put the selector at the 240VAC position,wich gives a fair 6,5 VAC.
On the Acoustic amp,however,this is not happening at all.The PT primary has only two windings corresponding to 120V and 240V respectively,and on the socket's contacts I have 6,2 VAC.
|3/21/2004 1:24 AM|
Well, since you asked, I had two of the 50-watt versions that I gutted and rebuilt as Plexi copies. About a year ago or so, somebody brought me yet another one to work on. I found it so difficult to service that I declined the work.
To be fair, though, I had a 100-watt head from that series that was my main amp from 1980 to 1986. Mostly, I really liked it back then. But, I always struggled with how midrange-y it got switching into the distortion channel from a nicely-set clean channel.
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