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.