Groove Tubes SUBSTI-TUBE 928-PR

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GONZO-X

GONZO-X

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bought a pair of these off of Ebay, just installed them last night.


PR928-solo.jpg



Groove Tubes SUBSTI-TUBE 928-PR

Duet Power Reducer Class A converter
Octal to 9-pin adapter for the use of EL-84 tubes in an octal socket.

This converts class A/B amplifiers to class A for lower power.

'These will reduce the load on your power transformer, and allow your amp to reach distortion, with a nice AC-30 or EL-84 sound and feel at levels that are lower and more friendly to recording and venues where your amp will not feel, play, or distort at the amplifier's normal higher sound levels.'

:D

i've only played them for one night, so i'll save a full report for later....

but at first blush, i was amazed at how it changed (for the better) the voicing of my mesa boogie mark2b head.

the boogie is a 60 watt head, so it has (2) 6L6's.....
so both of the power tubes are replaced by this adapter with a little EL84, cuts the power about in half.

These are groove tube EL84s, for those of you that are into tubes... they're rated at 4, out of a scale of 1-10 (1-3 is rated for quick breakup, 4-7 is rated for normal breakup, 8-10 for almost no breakup)


the sound:

well, i'm having to tame a 60 watt beast, to be able to record at lower volumes with it.
i've found that the amp really only does it's magic, when the master volume is at least halfway.

which is grounds for divorce, eviction, incarceration.
;)

i know the boogie amp well.... i've had it since 1981, and gigged full time with it for the first 5 years of it's life...

the 6L6 sound, is a classic american tube sound....
but can be harsh with certain settings at high gain, and with presence dialed in.

the first thing i noticed about the new 'substitubes', was that the high end sounded smoother.....
sweeter....chimey...
more dialed in, and in a word, lush.

these tubes are also more 'responsive' than the 6l6's on idle were...
this could be because my 6l6's are simply getting old, but i don't think so.

this is a tone that's specific to the EL84, i believe. it doesn't have quite the frequency range of the 6l6, especially in the low end, but to my ears, sounds better, in a more 'guitar-friendly' frequency range.

the only other amp that i've played in recent years, that struck me as to having that greasy, smoother, darker, creamier sound, was a Vox AC-30.
very similar to that....

but, with the circuitry of the mesa being more high gain than the vox, the mesa has more of the tone i'm looking for.

if you could morph an older boogie tone, to a vox ac-30 tone, that's what i have now.

there's more presence at low volume, but without sounding 'trebly'.
on the lead channel, set at low gain, it almost sounds like a DR. Z MAZ 18.

it's hard to explain.

it's like, more saturation, but at the same time, more clarity.

i think that with the wide range of groove tube distortion/character ratings, you could dial in exactly the amount of power breakup, to match the gain settings and tone you like on the amp.
i dig the #4 rated tubes that are in it now, but of course, i haven't a/b'd that to anything yet.

on both humbuckers, and single coil sounds, the amp has more clarity than i've ever heard out of it before.
i'll follow up on this 'experiment' with some sound bites, and some more info on how the amp responds to different guitars, the effects loop (the sound of it changed too) and pedals in front of the amp.....

i'm extremely happy with the sound, i've just got to really push em hard for a while, and see if there are any weaknesses.

my next step in the tone search for low volume recording:
a Weber Mass.


~~~~~~




here's a link, to a comparison between the GT 928-PR's, and the THD yellowjackets, which were the other power tube adapter i was looking at...
http://www.groovetubes.com/assets/1778_GT928-PR_vs_THDYJSD_Test.pdf
 
?
no interest?

anybody used the yellow jackets?

anybody experimenting with taming high wattage amps for recording purposes?
 
These look pretty interesting, but I prefer my amp cranked. :D
 
GONZO-X said:
?
no interest?

anybody used the yellow jackets?

anybody experimenting with taming high wattage amps for recording purposes?
Well, I'm trying to tame a low wattage amp (Epi Valve Jr.) for recording :o :rolleyes:
I just got a MicroMASS (you mentioned the Mass) which is great for amps <15 watts. I think it has the advantage of separate attenuator controls for treble and bass over the Mass, but it doesn't suck the tone out of the amp. Definitely a cool little unit!
 
Nice. I use a THD Hot Plate attenuator myself. And my amp (Matchless SC-30) has a switch that cuts out two of the four EL84 power tubes so it operates at 15 watts instead of 30. Makes it tolerable to play and record at home or in small venues. Maintains marital harmony :D
 
I've got several yellow jackets and I've used the EL84's I rather like their sound but they are a little on the thin side to my ears. After realizing that half power is barely a perceptable change, I went to the THD hotplates. A way more effective way at reducing volumes without having to sacrafice tone.
 
great replies all...

yeah, every rig is going to sound different with these..

my rig, which is thick in the mids, really sounds better with a 'thinning' of the full spectrum that the 6l6's normally give..
it makes close micing the rig, sound even bigger, if that makes any sense...

i'm still experimenting a lot, having decided the best settings/recording setup/etc yet, but i'll land on something soon....
doing a lot of tracking these days....

it'll be interesting to slap an attenuator on it, and see how far i can go before the 'tone suck' occurs.....

i'll run it into a demeter iso cab, loaded with a low watt speaker (eminence legend 122) and see how much low end i can tweak out of it..
the idea is, to really make the speaker thump, but at manageable volumes.

the franken-amp experiment continues...................
 
GONZO-X said:
?
no interest?

anybody used the yellow jackets?

anybody experimenting with taming high wattage amps for recording purposes?

I've got a 50 watt Marshall with a pair of Yellow Jackets in it, and they reduced the cranked volume significantly without adversely affecting the tone. Happy camper here.
 
hey Ggunn, I have been wanting to try the yellow jackets (the tube things), glad to hear a positive. ( here in MS "yellow jackets" are the slang for Miller High Life! LOL) :D
 
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