Tube Amps / Music Electronics
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|7/26/2004 2:52 PM|
|rooster||TSL with OEI?|
Hi. I have an acquaintance with a JCM2000 TSL playing in a HEAVY metal band (euro-style) looking for more definition and thud while keeping the distortion levels of his TSL 100 watter. I was thinking that a swap with an OEI OT may help out a bit, but looking at the OT of the TSL, it doesn't seem undersized, but I do hear a bit of mush that I don't get from my 18-watters with the Heyboer OT (even though the gain levels of my 18's aren't even in that ballpark, the OT of the Heyboer really punches on the bottom end).
Does this sound like an upgrade worth the money, or would he get more out of just going to 6L6's in the power section?
Your opinions and experience would be most welcome.
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|7/26/2004 4:03 PM|
|Chris - CMW amps
Altough not undersized regarding looks the stock OT is a po*
Changing the OT to an OEI one will make you smile, tighter low end, more "midrange information" and wayyy nicer highs.
|7/26/2004 7:41 PM|
i won't speak to whether it's a worthy upgrage - I mean what would you expect me to say?
But basic things to be aware of:
1 - The TSL OT is layown (z-mount) so you would need to do sheetmetal work to create a plate to mount the new OT on.
2 - The TSL (and 900's as well) have so much low end dialed out of the circuit that when you put in an OT with better freq response the amp may come out brighter sounding. You will probably have to fiddle with coupling caps to get things to where you want them. The stock OT's roll off more highs and lows these days than they used to.
|7/26/2004 8:04 PM|
The sheetmetal work is not a problem. I kind of figured on that. The frequency response shouldn't be too much of a problem, as he runs his lows and highs above 7, and drops his mids. I figure he can roll his lows and highs back to 4 or 5 if need be.
The other part of the equation is that he also wants to switch over to 6L6's to avoid EL34 compression, so I'd have to relabel his Z switch for the cabs (I figure the output Z of 6L6's is higher than that of EL34's, I'll check on your website for your primary Z and such to verify), but I'm thinking with the new OT, the SED EL34's he has may get him where he needs to go without changing out the power tubes.
|7/27/2004 3:46 AM|
Let me know how it goes on the tranny swap. I was thinking if it would be possible to take the bell covers from the stock one and swap it too a jcm800 tranny. ? Is that what you mean by OeI, the 800?
I own a tsl100 myself and I play metal and thrash. I bought it based on scott ians endorsement.... And I am basically pretty happy with it....or something... My home made amp with jcm800 trannies definitely has the balls on that one....
I do play live with my tsl often though, it sounds heavy as hell with an eq in the effects loop. I use one that I built up based on the eq section(s) of the boss mt-2. Which is basically a resonant boost at 100hz, a sweepable mid, and a resonant peak somewhere between 2.5K and 5khZ.
Let's assume there is no eq box in the feedback loop! From now On....
All the time, I play with the "deep" switch out/off. That circuit is an op-amp based gyrator in the feedback loop of the power amp. A gyrator is a silicon simulation of an inductor. So they paired that with a cap and ... inside the feedback loop got a resonant bass boost. So the feedback loop is decoupled in the bass region. Darn! I just erased the theoretical argument for it
I have never done the math for the frequency, but I will bet $, the gyrator / cap is set for ~ 100Hz... I don't use it because I can't get over the theoretical argument that: by useing this switch the damping factor in the 100Hz region is super low, bass distortion is probably pretty high, and the effect of a change in volume will be more drastic with it in/ON than OFF. The reason that volume changes will drastically effect the bass is because Marshall 4x12's resonance is ALSO at 100Hz....The best ones are, at any rate.... Any way, so now as the speakers get moving and the cab starts to get resonant...That perfect threshhold arrives and is gone! It is so narrow because the poweramp can't keep that frequency range dampened. Usually the cabinet gets going and the damping of the power amp still can dampen those speakers for a few more decibels before it is blown out and muddy.... Not to mention that the power amp is resonant at this same frequency!
O.K. more rambling... I don't find that the tsl lacks bass. I run the bass control at 4! (mid3, treb5). The minimum bass setting before it goes away keeps the bass clear. And I actually changed my slope resistor to 47k, because otherwise you have to crank the treble in order to get the midrange dip to be in the right place (low enough on the frequency spectrum)
The eq is a way to totally blow minds... O.k. so that is one way to get there. And maybe something to try.
And I really am playing frickin metal Too! So I hope maybe some of this helps, and I am all ears on the tranny swap!!!!!
later, Eth (guitarist for SMYT)
|7/27/2004 1:34 PM|
By OEI, I am referring to Obsolete Electronics. Speedracer makes legendary replicas of the old original Marshall OT's from when those amps were kings (and, IMO, still are). I've never heard a SINGLE bad thing about his OT's other than that they do not come in blue or red. What this customer needs is the balls of the 800's and before, with the distortion of the 2000. Personally, I prefer the modded 800 tone for high-gain, but to me, the original Megadeth sound is higher gain than I'll ever use, and that's pretty tame by today's standards (although the music blows away the modern MTV "heavy bands").
I'll do the swap, and report on the tone as it goes.
|7/27/2004 4:05 AM|
an OT swap can remove a lot of the compression from the EL34's. You might be amazed at what they can do in an alternate environment.
Just fyi our 100W has been used quite successfully with 5881's in production amps and have put out well over 100W clean in that setup. (over 120W IIRC) I still prefer the EL34's for their clearer high end and better mid crunchiness. To my ears they pretty define what heavy is supposed to sound like.
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