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Tube power sections, what am I missing?

#161
Chucky Stiletti said:
As will the rest of the tube stages. How do you differentiate?
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I modded many guitar amps over the decades. Many had pre-PI masters, which didn't have enough gain stages before the master to develop decent distortion...like silverface Fenders. Changing the pre PI master to a post PI master (I usually used a stacked dual pot, but sometimes used a cross-line master) improved the quality of the distortion greatly.

In the early 80's, the Sholtz Power soak and to a lesser extent, the Altair power soak were popular especially with non-master Marshall players in our area. I put quite a few post PI masters in non-master and pre PI master Marshalls belonging to players who were using power soaks, and got to compare the tones of all three...pre and post masters, and power soaks.

The PI is part of the power amp. The tube stages preceding are part of the pre amp. True that all overdriven stages add to the distortion picture in an amp, as well as transformers, power supplies, speakers, etc. My original point was that players usually refer to "power tube" distortion as being "superior" to preamp distortion, but do not realize the breakup of the PI, then amplified by the power tubes, IS the sound they are hearing.
 
#162
jazzbass_5 said:
Was looking at the Traynor YBA300 as an alternative to getting a SVT any feelings or opinions about these two in comparison?
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I'm going to suggest that you take the plunge and get a full SVT rig, but be sure you obtain US made version and matching 810 cab. Two if you have the room and physical ability to handle and haul it all. After you set up to jam, turn the master all the way up, dial up the gain to obtain your desired playing volume and rock out. Just make sure you bring a change of clothes. The blissful sensation will have you using all sorts of senseless descriptors and you will finally know what the hype is all about. It's like having sex for the first time with a really hot chick
 
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#163
lynnchpin said:
I'm going to suggest that you take the plunge and get a full SVT rig, but be sure you obtain US made version and matching 810 cab. Two if you have the room and physical ability to handle and haul it all. After you set up to jam, turn the master all the way up, dial up the gain to obtain your desired playing volume and rock out. Just make sure you bring a change of clothes. The blissful sensation will have you using all sorts of senseless descriptors and you will finally know what the hype is all about. It's like having sex for the first time with a really hot chick
Click to expand...

Great explanation!
I have an 8x10 heritage cab among a few other miscellaneous two tens, four tens, and two twelves. And I do plan on eventually getting and SVT head. Which one do you recommend? Besides being American made, The VR? CL? The Heritage?
I mostly play Modern and classic rock. I use a Fender American Deluxe precision V string.
 
#164
Steve Dallman said:
I modded many guitar amps over the decades. Many had pre-PI masters, which didn't have enough gain stages before the master to develop decent distortion...like silverface Fenders. Changing the pre PI master to a post PI master (I usually used a stacked dual pot, but sometimes used a cross-line master) improved the quality of the distortion greatly.

In the early 80's, the Sholtz Power soak and to a lesser extent, the Altair power soak were popular especially with non-master Marshall players in our area. I put quite a few post PI masters in non-master and pre PI master Marshalls belonging to players who were using power soaks, and got to compare the tones of all three...pre and post masters, and power soaks.

The PI is part of the power amp. The tube stages preceding are part of the pre amp. True that all overdriven stages add to the distortion picture in an amp, as well as transformers, power supplies, speakers, etc. My original point was that players usually refer to "power tube" distortion as being "superior" to preamp distortion, but do not realize the breakup of the PI, then amplified by the power tubes, IS the sound they are hearing.
Click to expand...

Guess we have to agree to disagree. PIs (regardless of the topology) are designed for maximum linearity and unity gain. For this reason you will typically see low to medium mu (voltage gain; dVp/dVg) triodes such as the 12AU7 or 12BH7 (instead of X7s or T7s) in these stages.

Higher gain would lead to balance impurity driving the push pull stage that could lead to damage to the output tubes and/or transformer.
 
#165
jazzbass_5 said:
Great explanation!
I have an 8x10 heritage cab among a few other miscellaneous two tens, four tens, and two twelves. And I do plan on eventually getting and SVT head. Which one do you recommend? Besides being American made, The VR? CL? The Heritage?
I mostly play Modern and classic rock. I use a Fender American Deluxe precision V string.
Click to expand...
My experience is with the CL. I've heard a VR in live performance and knew the person playing it, who just happens to be the one who turned me on to the SVT. I believe very little separates CL from VR besides aethetics and some features which I can't recall from memory. I can't comment on Heritage as I have only recently learned of their existence, but I can say what I have heard about them is limited to cabs, they have been regarded highly by some. If there's any chance that you can get your hands on any of the early model SVT units I would go with that before anything produced recently. All I can suggest is if none are available, the safest choice at maintaining what I have synthesized in my explanation is to go with the CL. Not to confuse you, but I'm willing to bet that you could pick any of them, so long as they are American made, that you will have an incredibly satisfactory experience in the realm of tube amplification that is cherished.
If I ever get an a financial position to where I can squander to my heart's content, I will certainly have another full SVT rig as well as many others
 
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#166
lynnchpin said:
My experience is with the CL. I've heard a VR in live performance and knew the person playing it, who just happens to be the one who turned me on to the SVT. I believe very little separates CL from VR besides aethetics and some features which I can't recall from memory. I can't comment on Heritage as I have only recently learned of their existence, but I can say what I have heard about them is limited to cabs, they have been regarded highly by some. If there's any chance that you can get your hands on any of the early model SVT units I would go with that before anything produced recently. All I can suggest is if none are available, the safest choice at maintaining what I have synthesized in my explanation is to go with the CL. Not to confuse you, but I'm willing to bet that you could pick any of them, so long as they are American made, that you will have an incredibly satisfactory experience in the realm of tube amplification that is cherished.
If I ever get an a financial position to where I can squander to my heart's content, I will certainly have another full SVT rig as well as many others
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Well, with that being said, I love my SVP-CL and my SVP-PRO is 3rd to my Sansamp RBI.
So, yeah.. thank you for your input! I'll some test drives.
BTW, my 8x10 cab is a modified classic cab, nor a heritage.
(Modified in that I ported the lower 4x10s for lower frequency response)
 
#169
baxter_x said:
How do you compare those three? How the SVP-Pro produces nice distortion or the Sansamp is better for this?
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Well, let me tell you @baxter_x.. I love my Ampeg preamps.
My SVP-CL when driven properly has a great Ampeg clean sound and if pushed at the input it can even have the Ampeg growl. It's a great 4 tube preamp (2 ax7s, 2au7s) and I would not hesitate recommending this preamp to anyone looking for that sound.
My Ampeg SVP-PRO on the other hand does not have the buzz problems inherent to many svp-pros (including my first svp-pro) but EASILY gets that Ampeg growl and distortion if I want it. It's not as easy when I want the clean sound but I use both in my rack.
As for the Tech 21 Sansamp RBI. This company has their s*** together.
I love my RBI and use it a lot when I don't feel like carrying all the extra b*******. It's mounted in a 2U rack with a DPC1400X and I use it in any combination of the cabinets I have. Quite honestly as much as I love my Ampeg tube preamps the RBI holds its own.
So, in conclusion.
I'll use my Ampeg rigs with my Ampeg Classic 4x10 mostly for show. But when it comes to ease of use and PA friendly set up I'll use my RBI and use the DI.
When I have the funds for a great all tube amp (probably the SVT-CL Heritage) I buy it and use it as my primary amp/rig with the 8x10.
 
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#172
jazzbass_5 said:
@JimmyM
I respect all these opinions but I'd like your 2 cents on an Ampeg SVT head.
If you were to buy a head what one would you buy keeping in mind that you were doing classic and modern rock.
I've had my eye on the brand soaking new SVT (CL) heritage.
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That's what I ended up getting. But I have a 69 as well, and I love it, too. I'm basically of the opinion that there is no such thing as a bad SVT. Slight differences here and there over the years, some prefer single volume versions like the VR, some prefer being able to get preamp overdrive at lower volumes, but to me it's all good because they all sound like SVT's. I got the Heritage because of looks mostly :D
 
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#174
Chucky Stiletti said:
Guess we have to agree to disagree. PIs (regardless of the topology) are designed for maximum linearity and unity gain. For this reason you will typically see low to medium mu (voltage gain; dVp/dVg) triodes such as the 12AU7 or 12BH7 (instead of X7s or T7s) in these stages.

Higher gain would lead to balance impurity driving the push pull stage that could lead to damage to the output tubes and/or transformer.
Click to expand...
With the master after the PI, you aren't driving the power tubes harder, just including the breakup of the PI in addition to preamp stages breaking up when the amp is pushed. It works and it just sounds good...similar to using an attenuator between the amp and speaker but more coherent sounding, and better than preamp distortion alone, especially in Fender amps that don't have enough gain stages to produce decent distortion with a pre PI master.
 
#175
Steve Dallman said:
With the master after the PI, you aren't driving the power tubes harder, just including the breakup of the PI in addition to preamp stages breaking up when the amp is pushed. It works and it just sounds good...similar to using an attenuator between the amp and speaker but more coherent sounding, and better than preamp distortion alone, especially in Fender amps that don't have enough gain stages to produce decent distortion with a pre PI master.
Click to expand...
How do you do a master after the PI? You use a stacked pot? Two differential signals...
 
#177
baxter_x said:
Very interesting. Would you say that if you need clean and quick tone, go SS amp, and if you need some overdrive or bloomy tone go for an all tube amp?
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SVT's are quick and clean until they are VERY loud, they were first made because SS amps were blowing up back then and they needed something loud and clean for bass that worked, The SVT was the first really loud clean bass amp that wouldn't blow up, to overdrive an SVT it needs to be extremely loud to the point I wouldn't want to be standing in front of it, I think that a small minority of players overdrive SVT's. As far as blooming they just sound bigger even when soft.
 
#178
bobyoung53 said:
SVT's are quick and clean until they are VERY loud, they were first made because SS amps were blowing up back then and they needed something loud and clean for bass that worked, The SVT was the first really loud clean bass amp that wouldn't blow up, to overdrive an SVT it needs to be extremely loud to the point I wouldn't want to be standing in front of it, I think that a small minority of players overdrive SVT's. As far as blooming they just sound bigger even when soft.
Click to expand...
But they did blow up. Ampeg had to change the phase splitter and output tubes from 6146 to 6550.
 
#179
Chucky Stiletti said:
But they did blow up. Ampeg had to change the phase splitter and output tubes from 6146 to 6550.
Click to expand...

Only when guitar players used them to create sustained distortion. 6146's don't like to have the hammer down for extended periods of time. They were changed to 6550's in about 1 year's time when there still weren't any really reliable SS amps. The only one that worked that comes to mind were the Acoustic 360's and I think those also used to blow up but not as often as the rest.
 

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