Ampeg SVP-CL Tube Recommendation?

[Juicyanalog]

Hello TBers,..
I'm finally getting my hands on the OOP Ampeg SVP-CL. (yea) The Previous owner said that the preamp tubes might be shot from laying around...... {i know..that sounds quite odd to me too} regardless,... wanted to hot-swap em anyway...any suggestions for what the sweetest preamp tubes would be for this Pre?

Tanx... Juicy

[JimmyM]

i love nos stuff. maybe some rca's, maybe some mullards if money is no object. jj makes a good new production tube as well.

[Juicyanalog]

Thanks Jimmy.....i was thinking Mullards, for the 12AU7's,...price is no object...only tone...and i hear that Mullard is back in production again...do they stand up to the NOS's?

[JimmyM]

no clue about the new mullards. or the old ones, for that matter. too rich for my blood. i rock the rca's or sylvanias.

[smo]

The SVPCL seemed to sound pretty good with the stock tubes.

I tried a whole weekend of swapping when I had mine, and came to the conclusion that JJ's were pretty good all round.
The stock EH-12AX7WA and WC was decent for the 12AX7 positions. The EH-12AX7LPS was pretty good too.

Weirdly; the 12AU7 positions didn't really seem to really have much difference in tone regardless of what tube I used, unless I slammed the input with a huge input volume, then the difference was more obvious.
I ended up with Phillips 12AU7's there.

[12bass]

Was meaning to try some different tubes in my SVP-PRO when I had it open the other day but didn't have a chance. Quite like how the Tung-Sol 12AX7 sounds in my Eden.

[Juicyanalog]

Originally Posted by smo

The SVPCL seemed to sound pretty good with the stock tubes.

I tried a whole weekend of swapping when I had mine, and came to the conclusion that JJ's were pretty good all round.
The stock EH-12AX7 WA and WC was decent for the 12AX7 positions. The EH-12AX7LPS was pretty good too.

Weirdly; the 12AU7 positions didn't really seem to really have much difference in tone regardless of what tube I used, unless I slammed the input with a huge input volume, then the difference was more obvious.
I ended up with Phillips 12AU7's there.

very useful info, thank you...

i don't know much about this pre (or 12xa7's compared to 12au7's for that matter) so excuse my ignorance....as i said, the dude who i'm buying it from, said the tubes are "no good" {for watever reason}..otherwise, i would leave it...but imo, the EH's generally, are mediocre compared to the better NOS's of yesteryear.. it seems to me by what you and others are telling me, is that the first tube in line (12ax? 12au?) is the tube that is going to impart the most character on the tone.

btw..you refer to "WA's" & "WC"s...what are those?...

[JimmyM]

W. i believe, means military grade. i'm sure the A and C mean something too, but no clue what it is.

[Juicyanalog]

Jimmy,.. you're officially the Ampeg Guru on this forum. (Along with Bongo's comp world..)
I'm learning some new technical stuff on every post
i couldnt agree more that the military grade mull's & nos rca's, are the way to go.. (right after i take out a second mortgage, that is...)

last completed album

http://www.adastraband.com/

setup: moded 1974 acoustic 301 cab / 1974 ampeg B40 head/ Neve {1073?}pre / shure beta 56...
..and a P.O.S. squire 5 bass

god bless this forum....
Juicy

[JimmyM]

thanks juicy, but i am so not the ampeg guru on this forum. i know about 5-6 people who know way more than me, including the chief engineer for ampeg when slm owned it. you'd be surprised how many pm's i get about ampegs that i have to answer with "duh, i dunno"

but i do love them and i've played every model of svt there is except the new heritage.

[smo]

Originally Posted by Juicyanalog

very useful info, thank you...

i don't know much about this pre (or 12xa7's compared to 12au7's for that matter) so excuse my ignorance....as i said, the dude who i'm buying it from, said the tubes are "no good" {for watever reason}..otherwise, i would leave it...but imo, the EH's generally, are mediocre compared to the better NOS's of yesteryear.. it seems to me by what you and others are telling me, is that the first tube in line (12ax? 12au?) is the tube that is going to impart the most character on the tone.

btw..you refer to "WA's" & "WC"s...what are those?...

Originally Posted by JimmyM

W. i believe, means military grade. i'm sure the A and C mean something too, but no clue what it is.

Neither - just the label on them, and a different coloured print.

RE: EH tubes quality:
The 12AX7-LPS was the pick of the EH tubes for me.
I try not to avoid any manufacturer's tubes I can easily get my hands on locally, as NOS is non-existent locally, being some 2716 km (1,688 mi) to the next city.
Through a lot of experimenting I've learnt that some tubes just sound magic in some equipment, but average or worse in others, so don't read too much into internet opinion... ....including mine!
Just depends on what equipment you have, how deep your pockets are, and what sound you're trying to achieve!

EDIT:
The 12AX7's have a higher gain than the 12AU7's.
If you put a 12AU7 in the position for a 12AX7, you'll get a lower volume & cleaner output.
But;
If you put a 12AX7, in a position for a 12AU7, you may have more tonal options OR problems.
This will increase the signal going through the circuit, potentially giving you more gain and dirt in your tone. I love doing this in old 70's amps!
BUT THE CIRCUIT may not be designed for the extra signal strength, and may damage something in the SVPCL.
I never attempted this when I had one.
I'd email Ampeg before attempting it, unless someone else can chime in?

[Juicyanalog]

Thank you smo....extremely informative.

Well... got the svp-cl a couple of days ago (slm 2004)....fired it up, to my modded ampeg V4 Guitar 4x12 cab (now 1kw@4ohm) {& yeah..i know it 'can' be a mudbox with the mod, if not properly eq'd or driven..but that's another story...}
....& of course, via my BGW 750-F Power Amp...

.....and....ok...

....let's just say i can get more 'output', from my retarded deaf-mute grandma with tape over her mouth....
{note: no grandmothers were actually harmed or defamed during this post....}

seriously....jeez....i had to dime the master and (just about) dime the 'input gain' all to just to drive my bgw.
..and i had to goose the vol on the power amp way more than i'm used to...
{...i dunno my 1979 solid state ashly sc40..KILLS with the bgw}

{but before you think i'm gonna bash the svp-cl,..chill }

I immediately popped the hood on the svp, and found these tubes; {from lft to rt}




Mojo Tone {"electronic tube"} 12AX7A-MC [2x];
GT 12AT7 {ECC81/6021} [2x]

first of all...12AT7's????...i thought they were supposed to be "12AU7's" on the right.
and "Mojo Tone"???....who the hell are they?....
....sounds like Kellogg's Cereal went into the electron tube business while i was away.....

Now... i can still hear the 'character' of this pre, even through these sh%^&ty tubes....
....it's a 'clean' ampeg svt voice , (the 'tubes' issue is an easy fix...we all went into that already...thank you)
....& it's a keeper, if i can fix the overall "output"... (or is the "crappy tubes THE" output issue?...anyone?)

Was the seller's, "Tubes are prob shot from laying around..." jazz, just an act?...
...for the fact that he really raped it of the stock tubes?....or am i off base with things?...

I'm ignorant & confused...(but still fly.... )

[JimmyM]

i know you asked me to help you in a pm, but i have no clue other than changing the tubes out to the right ones, which might just work.

[coreyfyfe]

I think these originally came with ampeg "Hot Rods" (rebranded chinese manufacture) and sovtek tubes, so I would definitely say whatever is in there isn't stock.

Mojo Tone tubes were, as with the Groove Tubes, just rebranded tubes made by other manufacturers, either russian or chinese in origin.

I'd say start with getting the correct tubes in place, that could be your issue, although not necessarily. There could be some other circuit issues. If the tubes don't fix it (or while you have the top down) take a look around and see if there are any visibly damaged components - burnt/lifted traces on the PCR, blown out caps/resistors/etc.

Here is handy chart comparing the 12A*7 family gain characteristics:

http://cydathria.com/fdm/12AX7_sub.html

[Juicyanalog]

all good Jimmy..its cool..gonna do
thank you coreyfyfe....i thought so....& i'll use that guide.

[yamaha]

Quite a while back, I tried quite a few in mine, and the original EH models was what I finally opted for. Did not like the LPS. But I do love a super clean, and warm tone.

[coreyfyfe]

Originally Posted by yamaha

Quite a while back, I tried quite a few in mine, and the original EH models was what I finally opted for. Did not like the LPS. But I do love a super clean, and warm tone.

The LPS is supposed to be a pretty good tube. It was designed to have the tonal characteristics of a long plate 12ax7 while maintaining the quiet operation of a short plate. If I'm remembering the tube correctly it was originally in my V4 and I later moved it into my SVT when I was trying out different tubes, but it didn't fit inside the tube sleeves of the SVT pre-amp (or maybe that was the one that did and other didn't? not sure). Either way, it was ok, but not my favorite in that spot.

[bluesrx]

I had one of these a few years back. It also had low output... if I remember correctly there was a modification available through Ampeg. Involved some resistors and a pot.

[bluesrx]

Some info...

http://www.talkbass.com/forum/archiv.../t-237898.html

[Juicyanalog]

Originally Posted by bluesrx

Some info...

http://www.talkbass.com/forum/archiv.../t-237898.html

Thanks bluesrx...& i'm gonna def look into that mod...