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 Post subject: Preamp Tubes for Ampeg SVT?
PostPosted: April 28th, 2014, 1:00 pm 
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Joined: April 6th, 2010, 12:24 pm
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Location: Portland, Oregon
Hi Folks,

Time for a quick question on tubes.... having spent far too much time reading the Talkbass version of the world, I thought I'd ask the fine folks here who have tube amps what they prefer in the way of preamp tubes. I currently have 3x JJ 12AX7's (ECC83 S) in my SVT-IIP preamp. They sound way better than the knackered tubes it came with (and it seems that Ampeg are now shipping units with JJ's in as stock), but I'm interested in your practical experience with preamp tube rolling. There does seem to be many distinct camps - some say that as long as they are "decent", it doesn't matter, while others point to the first tube being the most critical, and the one to experiment with the most. I see lots of folks with full-blown SVT's on this site, so I'd love to hear what you folks are rocking inside :D

Cheers!

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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: April 28th, 2014, 1:44 pm 
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Joined: March 14th, 2008, 10:57 am
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i cannot speak to that particular amp, but I will say this:
tube preamp design has come along way in the last 4 or 5 years, to the point where using NOS tubes doesn't always yield huge changes. Now, there's a big caveat there IMHO.
I still think it's worth investing in NOS tubes, but I also think it's worth doing as much research as you can before you drop 50 to 150 smackers hoping to find "the one".
I'll also say that NOS tubes have produced huge improvents in tone in my guitar amps. In my lone (SB300) tube bass amp? Not so much at all.
I'll agree with what you mention below, in that changing V1 ususally will yield the biggest change, assuming V1 is what's driving the tone stack.

Tube power sections are another story altogether. IMO, really good iron (transformers) and power tubes make a HUGE difference in the tone of the amp (assuming your preamp tubes are in good shape).


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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: April 28th, 2014, 6:14 pm 
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Joined: August 1st, 2009, 6:19 pm
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AzWhoFan wrote:
i cannot speak to that particular amp, but I will say this:
tube preamp design has come along way in the last 4 or 5 years, to the point where using NOS tubes doesn't always yield huge changes. Now, there's a big caveat there IMHO.
I still think it's worth investing in NOS tubes, but I also think it's worth doing as much research as you can before you drop 50 to 150 smackers hoping to find "the one".
I'll also say that NOS tubes have produced huge improvents in tone in my guitar amps. In my lone (SB300) tube bass amp? Not so much at all.
I'll agree with what you mention below, in that changing V1 ususally will yield the biggest change, assuming V1 is what's driving the tone stack.

Tube power sections are another story altogether. IMO, really good iron (transformers) and power tubes make a HUGE difference in the tone of the amp (assuming your preamp tubes are in good shape).


+1
I used Groove Tubes Gold in my SVP II - It worked but I don't think you'd hear much difference over the JJ's.


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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: April 29th, 2014, 7:55 pm 
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I don't have any specific answers to offer up but would simply say you should survey the current landscape of tube offerings, consult with 2 or 3 informed tube users (players & tech types), look at your budget (everyone has a max $ they're comfy stayin' under whether it's $20 or $200/per tube), then just buy.

My experience has been pretty good following this course and I think it's about as good as can be taken considering the moving target that tubes seem to be. Fortunately I haven't needed tubes in a while but my experience has been that quality can "float" around among and between mfgs. like smoke at a campground.

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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: April 29th, 2014, 8:18 pm 
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Joined: April 6th, 2010, 12:24 pm
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Thanks everyone ! Much obliged

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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: May 28th, 2014, 4:11 pm 
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Joined: May 27th, 2008, 6:15 pm
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I used Sovtek 12AX7 tubes (Russian Made) in my Ampeg SVT-4's. They get dirty if needed if you crank up the gain. Sovtek is a good cheaper dirty tube. If you want clean, go with JJ's or GT's


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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: May 30th, 2014, 3:49 pm 
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gravesbass wrote:
I used Sovtek 12AX7 tubes (Russian Made) in my Ampeg SVT-4's. They get dirty if needed if you crank up the gain. Sovtek is a good cheaper dirty tube. If you want clean, go with JJ's or GT's


Awesome! thanks a lot. I will dabble sometime :).

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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: March 11th, 2016, 3:47 pm 
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Joined: January 25th, 2011, 4:40 pm
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I also have J/Js in my svt-ll (non-pro) seems there are a few of us with this amp on leftybassist. I think Ampeg puts them in their Heritage line as they are the best current production tube today, i won't buy NOS tubes to try them out, but if you do i suggest a telefunken tube or a ruby high gain. Without a master and a gain on our amp trying different tube types (i.e. 12ax7, 12at7) will result in dirtier or cleaner tone than different brands will. Cheers.


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 Post subject: Re: Preamp Tubes for Ampeg SVT?
PostPosted: April 5th, 2016, 7:57 am 
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JJ (Tesla previously) is the stock tube for most tube amp builders these days, save for Mesa.

In my experience, the pre-amp section isn't going to benefit a whole bunch from switching tube brands around.
However putting different tube types of the same socket will yield some minor changes to tone.
So replacing a 12AX7 with anything from a 5281 (or ECC84), 12AU7, 12AY7, or 12AT7 will provide a different rate of gain in the preamp based on where you place them in the chain.


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