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  #1  
Old 01-22-2012, 08:11 AM
Lonesomedave's Avatar
KEED SPILLS..no, wait..PILL SKEEDS..SKILL PEEDS?
 
Join Date: May 2011
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AMAZING PRE/POWER AMP...THD Univalve

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howdy.

just wanted to share news about a piece of equipment i recently purchased for my son.

it is a THD Univalve pre amp/power amp.

here is a picture:



it's real function is as a 15 watt guitar amp, TUBE AMP, NOT SOLID STATE....admittedly not too exciting for a site devoted to high power bass amps, but in it's secret identity it is a monster piece of gear.

it has one 6550 power tube and two 12AX7 pre amp/driver tubes, and herein lies to secret to it's amazing potential.

the THD has what is called a dummy load. this means that, unlike most tube amps, you can use it as a pre-amp WITHOUT ANY SPEAKERS ATTACHED!

further (and i admit i don't really understand how it works, but it does), it has the ability to either be used as a pre amp for a true power amp or as a pre amp stage before a guitar or bass amp. in this case, my son uses an acoustic B450 combo bass amp.

the thing functions flawlessly, without any hiss or noise at all! it is amazing.

Now, for the truly jaw dropping aspect.... this amp/pre amp has the ability to self bias with almost any power tubes or pre amp/driver tubes! just plug and play. want to try a combination of a kt88 power tube with one 12 AX 7 and one 12AU7 pre amp tubes? just pop the tubes in and away you go.

admittedly we won't be using the power tube swap feature because we are using it just as a pre amp, but the thing can take about 20 different power tubes and the same number of pre amp/driver tubes: 2 12AX7's no problem....2 12AU7's.... 1 12AX7 and 1 12AU7, any combination at all, ... still no problem.

just plug and play.

I popped it open and found the pre amp tubes were an old RCA tube and one no-name chinese tube, both 12AX7's. who knows how old the RCA tube is! 30 years? no idea but they have not been made in decades. (we bought the unit used from GC) I swapped the no-name chinese tube for a groove tube 12AX7, and, obviously, left the RCA tube right where it was. the sound, again, is just fantastic.

we love it and it sounds great.

let me know your thoughts.

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Last edited by Lonesomedave : 01-22-2012 at 09:03 AM.
  #2  
Old 01-22-2012, 09:37 AM
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Seems like the perfect platform to make a two-tube bass version.
  #3  
Old 01-22-2012, 09:48 AM
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Cathode bias SE (Single Ended) amps are self bias. No secret magic there. Nice unit though!
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  #4  
Old 01-22-2012, 10:00 AM
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Quote:
Originally Posted by Lonesomedave View Post
let me know your thoughts.
My thoughts: $900 ("Open box" / "Warehouse resealed") is way more than I ever see myself spendind on a preamp.
  #5  
Old 01-22-2012, 10:10 AM
Lonesomedave's Avatar
KEED SPILLS..no, wait..PILL SKEEDS..SKILL PEEDS?
 
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Quote:
Originally Posted by wcriley View Post
My thoughts: $900 ("Open box" / "Warehouse resealed") is way more than I ever see myself spendind on a preamp.
don't blame you there, but we got ours used at GC for about 500.00....still a lot i grant you, but for what it can do, i could not pass it up.



ps... and on ebay they run from 6 to 800.00...still pretty expensive.
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any time, any place...any song, any bass

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"it is depressing to think that by the time he was my age, Mozart had been dead fifteen years" --Tom Lehrer

Last edited by Lonesomedave : 01-22-2012 at 10:19 AM.
  #6  
Old 01-22-2012, 10:24 AM
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Quote:
Originally Posted by someparts View Post
Seems like the perfect platform to make a two-tube bass version.
Well, it's not a dedicated bass amp, but don't let that stop you. Plenty of guys have gotten great tone out of amps that weren't labelled "bass."

THD Electronics
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Meh.
  #7  
Old 01-22-2012, 10:30 AM
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Quote:
Originally Posted by Lonesomedave View Post
don't blame you there, but we got ours used at GC for about 500.00....still a lot i grant you, but for what it can do, i could not pass it up.



ps... and on ebay they run from 6 to 800.00...still pretty expensive.
I'd love to know how this compares.

Quote:
Designed by Andy Marshall and licensed by THD Electronics
Jet City Amplification PicoValve 5W Tube Guitar Amp Head: Shop Guitars & Other Musical Instruments | Musician's Friend
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Meh.
  #8  
Old 01-22-2012, 10:49 AM
Lonesomedave's Avatar
KEED SPILLS..no, wait..PILL SKEEDS..SKILL PEEDS?
 
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Quote:
Originally Posted by NecroticImbecil View Post
looks pretty good. i do not know if it has all the features of the univalve. but definitely worth a look see.

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  #9  
Old 01-22-2012, 11:55 AM
Lonesomedave's Avatar
KEED SPILLS..no, wait..PILL SKEEDS..SKILL PEEDS?
 
Join Date: May 2011
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looking at it more closely, i can see the jet city amp does not have all the features of the univalve.

the univalve has the famous THD "HOT PLATE" which has the effect of turning up the gain (or anyway, raising distortion) without raising the volume. THD sells these separately.

the jet city amp also does not have the "attitude" which, while i don't know exactly what it does, according to THD it determines how the driver tube responds to the signal and alters how distorted or clean the sound is.

also, the univalve has two inputs, one of which has an extra gain stage. if you use the other, you bypass one gain stage and the sound is cleaner. the jet city amp pictured just has one input.

all of these features are engaged before the line out signal, so are available to you when you use the univalve as a pre amp, as we are doing.

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any time, any place...any song, any bass

Quote:
"it is depressing to think that by the time he was my age, Mozart had been dead fifteen years" --Tom Lehrer

Last edited by Lonesomedave : 01-22-2012 at 11:58 AM.
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