Ampeg SVT-3 Pro power discussion

[BassmanPaul]

9 hours ago, Undertone said:

By the way, anyone know a good bass amp tech in London who really knows what they're doing please (with an SVT-3 Pro)?  (In case the biasing needs adjustment in future)

Otherwise it's off to Milton Keynes.

Why would the bias level need to be adjusted. It's a set it once at initial power up and then leave the thing alone!.

[peteb]

4 hours ago, Undertone said:

When you say that's not how you use it, where do you have Gain and Master for live performance?

 

I'm not sure if this is addressed to me, but if so... 

 

First of all, I've used a SVT3 a few times, but never actually owned one. I've used a SVT4 more often, as that is the standard hire-in house rig for most of the bigger multi-band festival gigs that I do from time to time. I believe that they have a similar EQ section and I have owned the Mesa Boogie equivalent for many years. 

 

I always have the gain just at the point where it starts to break up, usually at about one o'clock. This thickens the sound out with it just having a slight hint of overdrive, but not distorted. If you want to put more hair on the note then turn the gain up, or turn it down if you want a sweeter, more transparent top end. Then you set the master to determine the volume. Of course, there are some (mainly guitar) players who will do it the other way round, especially guitarists who want to get a SRV type sound...! 

 

Starting with all the tone controls to the left is just drastically cutting the volume of those frequency points (by 15db on the Boogie). I would suggest everything at 12 o'clock (flat) to start, although personally I will generally slightly boost the lo-mids and slightly notch the hi-mids. Remember that you want to hear the full range of the instrument and that a little goes a long way when boosting or cutting frequencies. it is possible to very quickly go beyond the realm of a balanced musical tone and blow holes in your sound if you excessively cut or boost frequencies.  

 

Edited June 14, 2023 by peteb

[peteb]

2 hours ago, Undertone said:

When you say that's not how you use it, where do you have Gain and Master for live performance?

 

Double post

 

Edited June 14, 2023 by peteb

[peteb]

2 hours ago, Undertone said:

When you say that's not how you use it, where do you have Gain and Master for live performance?

 

 

Triple post! 

 

 

Edited June 14, 2023 by peteb

[Undertone]

Yes that was for you peteb - thanks for the response.  That would have been my approach but for some reason couldn't get it to work. Perhaps it will now that I better understand the amp.

[DGBass]

I recently serviced an Ampeg B2RE for a fellow bass player who was reporting low output and a bit of unwanted fizz. The B2RE has the same 450 watt output section as the SVT-3. The SVT has the mutli valve pre-amp as opposed to a much more basic solid state pre-amp in the B2RE. Both have a very similar boost and cut range in their EQ structure. There were two things causing the low output. First was a multi way connector linking the pre-amp board to the output board. It had worked itself up at one end ( can't recall which end) but snapping it back into place and a bit of hot glue to retain it had a huge effect on the signal level. Also the output section has a tiny little screw on the base of the amp that grounds the rectifier for the amp to a heatsink plate. It's a really odd design and the actual screw had fallen out so only the weight of the power board was making poor contact with the chassis. Replacing the screw( a tiny m2.5 self tapper) and cleaning the ground plate turned it into a super quiet almost studio quality amp and a total gig monster when turned up. It was crazy powerful into just one 8 ohm cab after that. Even with everything flat and the graphic switched out, it didn't need the master at more than two or three with the gain around 1 or 2 o'clock to be shaking the room. I would have expected an SVT-3 Pro to be as powerful and more flexible tone wise.

 

Just for info, the B2RE had been through the gig wars and had a few other vibration related loose parts . The 450w output section is a beast and super powerful.

[Undertone]

Good information. Thanks.

[DGBass]

While the B2RE and SVT3-Pro do share a lot of design features like multi core connector plugs to link pre-amp and output sections they do also have slighty different layouts. If an amp is suspected of not be performing as expected and if its new, i'd contact the retailer or return it. If it was bought used, a visit to trusted tech is always worthwhile just to make sure its as it should be. Most fairly modern 300-500 watt solid state class A/B amps should be capable of sufficient loudness and power levels without having to run pre or post controls anywhere near full up to get a gig ready level of output 🙂

[acidbass]

I used a 3 PRO at a gig in Brisbane recently and found it very underpowered when used with a SVT 810.

[Bill Fitzmaurice]

18 hours ago, DGBass said:

300-500 watt solid state class A/B amps should be capable of sufficient loudness and power levels without having to run pre or post controls anywhere near full up to get a gig ready level of output 🙂

This raises the point of what pre (gain) and post (master) do. The gain knob sets the drive level. The higher it's set the greater the ability to get over-driven tones. The master sets the power amp level. The higher it's set the louder the amp goes. To get over-driven tone without excessive volume the gain is set high, the master set low. For the cleanest tones the gain is set low, the master set high. No law says you can't run the gain at full, or the master at full. You may do either, you may do neither, you may do both. Horses for courses.

From a historical context the volume knob on vintage amps equated the gain knob on modern amps. The higher you set that the greater the ability to over-drive, but it was always accompanied with going louder. The master was added to allow one to crank the gain without cranking the volume. Setting the master at full takes it out of the circuit, giving the same topology as a vintage amp.

[DGBass]

18 minutes ago, Bill Fitzmaurice said:

To get over-driven tone without excessive volume the gain is set high, the master set low. For the cleanest tones the gain is set low, the master set high.

Yep there is no law against doing either. It's up to the individual. Personally I come from an age where setting the input a bit higher to maximise the pre-amp signal( I blame those Trace Elliot LED's on my GP11 and the VU meter on my ABM's for that) and not cranking the master.  I'm really interested in getting hold of an SVT3-pro now just to see how it actually works.

[GigDudeRich]

Probably too late to this party but I've just read this and.... I had an SVT3-Pro for over ten years and it's deafening flat out. Here's what you need to know:-

Preamp is there for your drive and tone. Want more tube distortion? Up the gain. Put a RAT up front or a muff. The peak just means it's driving the valves into the region they aren't linear anymore. They can take it, they max out in a subtle and coloured way and then give that nice valve breakup sound, which is why you bought a tube amp in the first place. Try messing with it and see what it does. The ampeg is a tank. You won't break it. Otherwise get something with transistors and no variation of sound. Set right you can flip between clean and distorted just by how hard you play. I nearly always had the gain set around 60-80%, even with an active bass. Always have it set so at your hardest playing the peak light is at least flashing in and out. I've played Buck Rogers by Feeder without any drive pedal and got a pretty good approximation of Taka's quiet subtle clean and utterly ripped.

 

Set all the tone to 12 O'Clock. EQ FLAT. Always start from there. use the mid control if you need some mid scoop, but keep it subtle. Bass is, well bass-y. don't crank up the bass for volume; it will sound like elephants farting in a large hall 300 yards away. Flubby and muddy. Set to taste and sound, NOT for volume. Everything should average out around 12 o'Clock and zero dB, not all slammed fully one way or another. You can use the DI out to get a better idea of the actual preamp out sound, so stick it into an interface and check it sounds ok on some monitors.

 

FX Loop - stick your modulations here; we all like some flange, chorus or vibrato occasionally. Try to make it so they don't change the overall volume from off to on.

 

Output Section - tube gain is a voltage sag adjustment. lowering it reduces the transformer voltage supplied to the power stage tubes, meaning they saturate more quickly. This gives a warm and glowing colouration and limiting.  Think Sister Sledge or The Pointer SIsters, or maybe Bootsy Collins. Turn it to max and the two valves in the power amp section stay linear and and don't saturate (yes there are valves in the hybrid power amp stage). It's in the tech material somewhere. Turn down the Tube gain to act as a soft limiter.. around 50-70% is great for all those soul and disco bass lines. Fully up for clean dry modern power, like a trace.

 

The Graphic should have the frequency sliders set around the middle (0dB) on average too if that wasn't clear. Can't remember if the graphic has a volume slider but put it full up if it does.

 

Oh and master volume - start with it about 30% up. If you do the above first then you will be able to set the tone. Use the master volume for what its' meant for. I rarely had master volume above 50% in a rock band. There are four mosfets in there doing the heavy lifting, solid state buttons of loudness. If you get bad hiss or have them anywhere near flat out you've not set the preamp correctly, you are just amplifying the noise floor of the preamp.

 

Really hope that helps. It really helps if you find out what each part of your signal chain actually does, and is there for. Gain staging is everything.

 

BTW I had the SVT3 Pro, and ampeg 4x10 HF + 1 x 15, Run in Parallel for 4ohms. tbh the 4 x 10 was enough by it's own in most cases. My basses at the time were a charvel 3B '86 through neck, a Cort C4 Limited for the funky stuff and a Sandberg VM4 (music man sound alike, better build quality :))

Edited 5 hours ago by GigDudeRich

[BassAdder60]

I had an Ampeg SVT 3Pro and found it to be a good amp and the power was there if you pushed it 

 

Replaced it with an SVT CL 300w and felt I had everything I needed but I was young and lifting it wasn’t an issue 

 

I used a 610 cab and this helped ! Again a heavy beast but lots of speakers and everyone could hear it !