New: Tech 21 VT-500 Bass Amp

[Acoustic356]

I did a full video review of the various tones that you can coax out of the Tech 21 VTBass 500 here: Full Review - Tech 21 VTBass 500 | TalkBass.com

The only reason I didn't post the video here is because I also posted video revies of:

• Warwick LWA 1000
• Taurus Qube 450
• Bugera Veyron

This will allow you to do a comparative analysis of something recorded with the same camera, same room, same loop playing through the Boss RC 300 from the same bass guitar against the same cabinets.

 

[Spector2112]

I did a full video review of the various tones that you can coax out of the Tech 21 VTBass 500 here: Full Review - Tech 21 VTBass 500 | TalkBass.com

The only reason I didn't post the video here is because I also posted video revies of:

• Warwick LWA 1000
• Taurus Qube 450
• Bugera Veyron

This will allow you to do a comparative analysis of something recorded with the same camera, same room, same loop playing through the Boss RC 300 from the same bass guitar against the same cabinets.

DUDE!!
I just finished watching the whole video.
That is EXACTLY the kind of demo I have been hoping someone would do!
A million thank yous!

 

[crguti]

That looks great! Can you give us the detail on the signal path? I tried to do something similar with a VT Bass pedal and an A-B box so the signal would either go into the front end of the VT500 or would go through the VT Bass pedal and into the effects return, bypassing the front end. But when I plugged anything into the effects return, I couldn't get any signal from the front of the amp.

Thanks!

^ In my particular setup I use the Rocktron Patchmate loop 8 (the brain). The first 7 loops are for effects and the last loop is for channel switching. Then I select my presets using the Rocktron Midimate.
Signal path goes to the pedals then to the input of VT RM. Output unaffected of VT RM into input of VT-500. Both signal sends are connected to the switching loop, then the output goes to the return of VT-500 with the switch loop on.
A simplified plot of the connections is below. hope it helps

 

[aborgman]

In other words it's my understanding that if you claim a peak of double your continuous RMS output the continuous can only be a completely clean rating, mathematically. It's not possible to get any more than double the power difference clean to distorted with a cap on the instantaneous voltage.

A few things...

First, we really shouldn't talk about "RMS power", as there is no such thing. There is RMS current and RMS voltage - and the product of the two is "continuous average power"

Second - your thoughts are sort of true...

1) There is no such thing as a "completely clean" rating.

2 ) As long as your "clean" power rating is in a condition where the peak amplitude (either current or voltage, whichever applies for the given load) is at or below the max - you'll be able to get a 2x by going to a full square wave. If your clean rating is with a peak amplitude below the max, you'll be able to get more than 2x.

Say I have an amp that has the following:

8V @ 2A power rails
.1% THD at 1W
.2% THD at 2W
.3% THD at 3W
.4% THD at 4W


If I define "clean" power as .1%THD - my clean power is 1W, but I can get 8W "peak" power

If I define "clean" power as .4%THD - my clean power is 4W, but I can get 8W "peak" power.

... but I still might define my "peak" power as 6W if I wanted to.

Without test conditions and definitions, the words "clean" and "peak" could mean anything.

 

[Acoustic356]

Tech21 Facebook Page shared my review of the VT Bass 500!

 

[Downunderwonder]

A few things...

First, we really shouldn't talk about "RMS power", as there is no such thing. There is RMS current and RMS voltage - and the product of the two is "continuous average power"

Second - your thoughts are sort of true...

1) There is no such thing as a "completely clean" rating.

2 ) As long as your "clean" power rating is in a condition where the peak amplitude (either current or voltage, whichever applies for the given load) is at or below the max - you'll be able to get a 2x by going to a full square wave. If your clean rating is with a peak amplitude below the max, you'll be able to get more than 2x.

Say I have an amp that has the following:

8V @ 2A power rails
.1% THD at 1W
.2% THD at 2W
.3% THD at 3W
.4% THD at 4W


If I define "clean" power as .1%THD - my clean power is 1W, but I can get 8W "peak" power

If I define "clean" power as .4%THD - my clean power is 4W, but I can get 8W "peak" power.

... but I still might define my "peak" power as 6W if I wanted to.

Without test conditions and definitions, the words "clean" and "peak" could mean anything.

how do you get 8W from 8A and 2V swing unless you have a fully square wave? If you pull that back to 4w it's theoretically a pure sine of same 2V swing.

At that point distortion is theoretically zero.

To cheat you claim that zero point has a higher implied voltage, not lower! But that forces you to do same for the peak which is simple to prove a lie without hardly any testing gear.

 

[aborgman]

how do you get 8W from 8A and 2V swing unless you have a fully square wave?

You don't. That is why the peak is 8W.

8V/2A will drive an 8W square wave into either an 8ohm or 4 ohm load.

It will only drive a 4W sine wave.

If you pull that back to 4w it's theoretically a pure sine of same 2V swing.

At that point distortion is theoretically zero.

...but it ISN'T zero.

Distortion products start going up WAY before you get to saturation.

Here is the data sheet for a 350B tube in a single ended amplifier. It is only being driven within the "clean" region.

At 2W output "clean" - THD is 3.5%
At 9.5W output "clean" - THD is 12%

To cheat you claim that zero point has a higher implied voltage, not lower! But that forces you to do same for the peak which is simple to prove a lie without hardly any testing gear.

What?

8V@1A into a 8 ohm load is 4W sine, 8W square waving peak. This case is voltage limited.
4V@2A into a 4 ohm load is 4W sine, 8W square waving peak. This case is current limited.

If you've got a supply(and active devices) capable of 8V @ 2A - those are the power level you get.

 

[Downunderwonder]

You don't. That is why the peak is 8W.

8V/2A will drive a square wave into either an 8ohm or 4 ohm load.

It will only drive a 4W sine wave.



...but it ISN'T zero.

Distortion products start going up WAY before you get to saturation.

Here is the data sheet for a 350B tube in a single ended amplifier. It is only being driven within the "clean" region.

At 2W output "clean" - THD is 3.5%
At 9.5W output "clean" - THD is 12%





What?

8V@1A into a 8 ohm load is 4W sine, 8W square waving peak. This case is voltage limited.
4V@2A into a 4 ohm load is 4W sine, 8W square waving peak. This case is current limited.

If you've got a supply(and active devices) capable of 8V @ 2A - those are the power level you get.

Why
bring impedance into it?

Try another way of painting a picture.

I have a little solid state power amp which at full clip puts out 8w. It's not thermally stable at that level but it is at 4W. It'll do 4W all day in the sun.

It seems like you're trying to tell me it won't do a 4w sine cleanly. If It isn't clean at 4W it can't get to the 8W square signal without increasing the available voltage, however briefly you might try to qualify a burst rating.

 

[bebass]

dudes.... it's a loud amp, trust me. I play in a heavy band with a loud drummer and 2 loud guitards, and I don't need to go above half volume. At full power into a 4 ohms cab without hearing protection you can have a permanent hearing damage.

This amp is very tight and clean, but thanks to the drive, character and blend knobs you can make it sound more 'grindy' and 'tubey' if you want. As soon you start exploring those knobs you will wish to have 2 channels.
It takes pedals very well thanks to the blend knob and the combination of drive & character can go from pristine clean to fuzzy saturated tones.

I agree with your volume assessment. Good advice about hearing protection.

 

[4StringsEnough]

^ In my particular setup I use the Rocktron Patchmate loop 8 (the brain). The first 7 loops are for effects and the last loop is for channel switching. Then I select my presets using the Rocktron Midimate.
Signal path goes to the pedals then to the input of VT RM. Output unaffected of VT RM into input of VT-500. Both signal sends are connected to the switching loop, then the output goes to the return of VT-500 with the switch loop on.
A simplified plot of the connections is below. hope it helps

Thank you!

 

[aborgman]

I have a little solid state power amp which at full clip puts out 8w. It's not thermally stable at that level but it is at 4W. It'll do 4W all day in the sun.

It seems like you're trying to tell me it won't do a 4w sine cleanly.

Correct.

No amplifier can do ANY power level "cleanly". There is alway SOME distortion.

That 350B graph I posted - those are all levels within the voltage envelope. The signal is still a sine wave with no flat tops... but the level of distortion of that sine wave varies.

If It isn't clean at 4W it can't get to the 8W square signal without increasing the available voltage, however briefly you might try to qualify a burst rating.

It depends on how you define "clean". That is NOT a technical term that I as an electrical engineer would ever use without a lot of qualifiers.

Is anything up to the voltage rail "clean" no matter the distortion? It is if you choose to define it that way.

Is only the power levels you can achieve less than 1% THD clean? It is if you choose to define it that way.

 

[crguti]

someone has compared the Tech21 VT-500 and Ampeg SVT-7pro?

 

[BassByBaldSteve]

I took delivery of one two days ago and brought it straight to some gigs. First night was a little rough (though the DI was phenomenal, as expected, being a sansamp and all), but last night was killer. The more I'm learning how to dial it in, the better the sounds I'm getting. It's a remarkably powerful and versatile head. The Blend, Drive, and Character knobs alone provide one with an almost endless tonal palette from which to shape tone. I'm using it with a Berg CN112, but I'll be stepping up to a 15" of some kind shortly here. Trying out the new Ampeg flip-top, the Mesa Boogie Subway 15, and the Trickfish 112 and 115 over the next few days. So far, so good, though.

Few gripes: it's not the most stage ready head. There's no mute button and no tuner out. You can use the effects send, but the amp remains on. You can use the headphone out, but when you connect to that output the power-amp is bypassed. There's no solution other than running your signal through the tuner. Some glaring omissions, IMO. So far, so good, though. We'll see how it goes tonight.

 

[Downunderwonder]

I'm wondering if they got it to power up and down silently in the DI?

 

[agedhorse]

Distortion products start going up WAY before you get to saturation.

Here is the data sheet for a 350B tube in a single ended amplifier. It is only being driven within the "clean" region.

At 2W output "clean" - THD is 3.5%
At 9.5W output "clean" - THD is 12%





What?

8V@1A into a 8 ohm load is 4W sine, 8W square waving peak. This case is voltage limited.
4V@2A into a 4 ohm load is 4W sine, 8W square waving peak. This case is current limited.

If you've got a supply(and active devices) capable of 8V @ 2A - those are the power level you get.

This set of curves is exactly the kinds of things we look for when sorting out the cause and effect of how a particular topology might sound (or perform), and also what elements might be involved when emulating it's behavior using different approaches.

It's also a good example of why always stating power at say 0.1% or 1% THD may not accurately reflect the power an amp may be able to deliver, especially if this is the behavior that you are trying to emulate. at 1% this would appear to be a 2 watt amp, but clearly that's an absurd assertions. In fact, at 10% THD, it's a 10 watt amp and is (probably) really nice at that level for some players and tastes.

There is no "one number fits all" solution to any of these product descriptions.

 

[bebass]

...0.1% or 1% THD may not accurately reflect the power an amp may be able to deliver, especially if this is the behavior that you are trying to emulate...

Thanks for pointing this out. Most of us bass players LIKE the distortion of tube amps. And we like the purposefully designed solid state amps which emulate them.

To me, when considering the rated power of an amp, for evaluation I play it, testing it for myself, as no one standard of rating has ever appeared to give me a real feel of the amp. If it meets my needs when trying it out it has plenty of power. Very few of the modern nominal 500w rated amps will not give a person plenty of stage volume , as in way MORE than enough, when used with good cabs. And if one's cabs are not sufficient this needs to be addressed BEFORE throwing different amp solutions towards "fixing" the problem.

 

[Acoustic356]

Tech21 finally did a video demo of the head... masterfully done!

 

[Jeff Scott]

I don't get why T21NYC didn't include a real mute switch. What if the effects loop is actually being used for something?

 

[Acoustic356]

I don't get why T21NYC didb't include a real mute switch. What if the effects loop is actually being used for something?

Why no mute switch?
Why no tuner out?

My guess is that with the rack ears, they're expecting you to put it in a rack?

My signal path goes:
Bass -> Rack Tuner -> VT500

I mute from my rack... but I understand not everyone runs a tuner as an insert.

 

[BassByBaldSteve]

Anyone else get one of these? I'm curious about feedback, as I'm checking out the Mesa Subway D-800 tonight in Hollywood and might make a switch.