I HATE MY SVT HEAD!!

[TheDirtyLowDown]

1. I'm always happy to play through one when someone else does the heavy lifting. It feels like a luxury because there's no way I'm dragging that kind of weight around on my own any more... and
2. I'm always happy to record through one.... but
3. For the middle-to-low end live sound environment in which our band lives, there are so many other variables (the room, the setup, the onstage sound, etc) that I just don't hear enough benefit when compared to what I get from my lightweight amp (now a Quilter BB800). I'm know the SVT sounds better, and looks better, and is groovier. But, frankly, in most of our live sound setups (about 75% of which we schlep in and set up and tear down and schlep out) I can't really hear enough of a difference to make it worth the weight. Further up the food chain it's a different story -- you've got roadies and better sound crew and real sound checks and all that good stuff. But as you get closer to the bottom of the tank... well, for me, I'm happier if I can load in with 2 trips and not be tired from the lifting.

 

[Wasnex]

View attachment 4088331

The difference between 300 and 350W is only 0.67dB which you will not be able to hear.

It's true that watts = watts. But two amps with the exact some power rating may not play at the same volume. The rating of an amp doesn't really necessarily tell you how loud it can play. It just says how many watts it's supposed to make at a certain distortion rating. This can be chosen in somewhat of an arbitrary manner.

Per the tech manual, vintage SVTs are supposed to make 300W at 3% THD, but it seems rare for SVTs to pass this standard. I believe Ampeg has changed the standard for modern SVTs to 300W at 5% THD. AFAIK the output section has not really been changed in a way that would degrade the power or distortion.

Here is a bench test for a SVT CL that shows ~240W at ~6% THD and ~340W at ~11% THD (see 10:06). Maybe it has crappy tubes as I believe SVTs typically make about 265-270W at 5%

I think most people report that an SVT sounds louder than a PF350...perhaps that says something about how these two amps overload. A PF350 should make 350W at 4 ohms, but it may not much more. As I have shown above, SVTs don't typically make their rated power/distortion spec, but they do make more power than they are rated for.

If you don't mind a bit of distortion, and SVT should make a bit more than 350W...however at some point as the distortion rises, you may actually notice the SPL going down instead of going up. This is because the power supply is sagging, so less voltage is delivered to the speakers. Explanation: Once the amp starts clipping, the increase in power comes from increasing the duty cycle instead of increasing the voltage...but the speaker needs more voltage to play louder.

Also, let's keep in mind, it's not a valid comparison unless both amps are driving the same type of speaker. If you are comparing a SVT pushing an 810E to a PF350 pushing a SVT-212AV, it's not a very fair comparison.

My Experience:
I own two vintage SVTs, and my GK 700RB which is rate at 380W at 4 ohms is noticeably louder. My Ashdown CTM300 also sounds slightly louder than my SVTs. My Trace Elliot V6, Reeves 400, and Ashdown 427 are even louder. My GK 700RB hangs pretty well with all of these amps.

Some of my more powerful solid state amps seem to be practically idling when my loudest tube amps are maxed out. By this time, the volume is way louder than I have ever needed; so it really doesn't matter. I can get the job done equally well with tube watts or solid state watts.

 

[Wasnex]

So what is 'being louder' if it isn't sounding louder? To my measurement device (my ears) its way shagging louder.

There is definitely a difference between perceived louder and measured louder. I suspect perceived louder in this case has to do with the fact that distortion shifts some of the energy from the lower part of the frequency spectrum to a higher range where your ears are more sensitive.

 

[drumvsbass]

Put a PF-350 head on top of an 810 cab and tell me honestly that it can do battle against 3 triple rectifiers in a metal context. That's a joke. I know for a damn fact it can't, I flatlined an SVT 4 Pro and it was almost enough, and yet my SVT-CL I got barely to 4 and it was crushing the band. So do tell what voodoo that is. Same Cab, Same room, same band, different heads with apparently way MORE wattely watts (4 pro is 1600 lol) getting crushed. Meters and scopes and Blah blah blah. Hey I used one in the REAL world, in a situation where these other heads couldn't deliver. It's louder. Period.

I can even double down on this, a few years ago I had switched from the PF-500 head to the PF-50T Same settings, almost same volume, better tone by far. 450 watts difference I should have been unable to hear myself in a band context.

 

[Mastermold]

Putting your SVT on a shorter cabinet (like the 212 AV) solves much of the lifting issue people don't like with the 810.

I still use my SVTs every chance I get, nothing sounds as good to me.

 

[Plain Old Barry]

There is definitely a difference between perceived louder and measured louder. I suspect perceived louder in this case has to do with the fact that distortion shifts some of the energy from the lower part of the frequency spectrum to a higher range where your ears are more sensitive.

View attachment 4088439

Good ol' Fletcher-Munson...

 

[Wasnex]

@Jim C

Have you tried running your SVP-CL into your SVT Power Amp In. The idea is to see how true it is to channel one of the original preamp.

I have the SVT 8-Pro and the preamp is based on the SVP-CL. I think it sounds a lot like my vintage SVTs, especially if I dial in just a touch of the Power Reduction circuity, but it's not exact.

To me the biggest difference is the way the bass control acts. The manual for the SVTs say the bass control works at 40hz. The SVP-CL and SVT 8-Pro say the control works at 20hz, and my ear tells me it is tuned to a lower frequency as the manuals suggest.

The schematics appears to be very similar. There is an extra 50pf capacitor in the modern preamp. Also, it looks like the capacitor values are inverted on the treble side of the circuit. Notice where the 47pf and 470pf caps are in each circuit. There is small variances in some of the resistor values as well.

SVT 8-Pro

SVP-CL

Vintage SVT

To my ears the Mids and Highs of the SVT 8-Pro are pretty close to the sound of my vintage amp. But the low end is significantly different. The bass control does not seem to reach high enough into the low mids to create the authentic sound and feel. Perhaps I could get closer with a parametric EQ pedal.

I can dial the lows of my Mesa Titan in closer to an SVT, but it does not really have the same mids and highs. The Titan is in a Bronco headcase...and it's a pretty big and heavy package as well.

 

[Plain Old Barry]

Put a PF-350 head on top of an 810 cab and tell me honestly that it can do battle against 3 triple rectifiers in a metal context. That's a joke. I know for a damn fact it can't, I flatlined an SVT 4 Pro and it was almost enough, and yet my SVT-CL I got barely to 4 and it was crushing the band. So do tell what voodoo that is. Same Cab, Same room, same band, different heads with apparently way MORE wattely watts (4 pro is 1600 lol) getting crushed. Meters and scopes and Blah blah blah. Hey I used one in the REAL world, in a situation where these other heads couldn't deliver. It's louder. Period.

I can even double down on this, a few years ago I had switched from the PF-500 head to the PF-50T Same settings, almost same volume, better tone by far. 450 watts difference I should have been unable to hear myself in a band context.

Stick a compressor or dirt box in front of the SS amps...

 

[bassfreakah]

there is nothing like the real thing!!!!!!!!!
ALL tube svt and 810 flat back!!!

 

[Funk With Me]

P.S. . . . Nobody gives a "poopie" about my tone except for me and maybe some other bass players.

For me it's important. I play because I love to play. The better it sounds the more fun it is.

 

[Jim C]

@Jim C

Have you tried running your SVP-CL into your SVT Power Amp In. The idea is to see how true it is to channel one of the original preamp.

I have the SVT 8-Pro and the preamp is based on the SVP-CL. I think it sounds a lot like my vintage SVTs, especially if I dial in just a touch of the Power Reduction circuity, but it's not exact.

To me the biggest difference is the way the bass control acts. The manual for the SVTs say the bass control works at 40hz. The SVP-CL and SVT 8-Pro say the control works at 20hz, and my ear tells me it is tuned to a lower frequency as the manuals suggest.

The schematics appears to be very similar. There is an extra 50pf capacitor in the modern preamp. Also, it looks like the capacitor values are inverted on the treble side of the circuit. Notice where the 47pf and 470pf caps are in each circuit. There is small variances in some of the resistor values as well.

SVT 8-Pro
View attachment 4088449

SVP-CL
View attachment 4088483

Vintage SVT
View attachment 4088467

To my ears the Mids and Highs of the SVT 8-Pro are pretty close to the sound of my vintage amp. But the low end is significantly different. The bass control does not seem to reach high enough into the low mids to create the authentic sound and feel. Perhaps I could get closer with a parametric EQ pedal.

I can dial the lows of my Mesa Titan in closer to an SVT, but it does not really have the same mids and highs. The Titan is in a Bronco headcase...and it's a pretty big and heavy package as well.

I can try that this week.
You had mentioned the 20 Hz. for bass center freq. of the 8 Pro which has kept me from looking at them.
Have you tried a HPF to clean up the low end?

 

[Wasnex]

Put a PF-350 head on top of an 810 cab and tell me honestly that it can do battle against 3 triple rectifiers in a metal context. That's a joke. I know for a damn fact it can't, I flatlined an SVT 4 Pro and it was almost enough, and yet my SVT-CL I got barely to 4 and it was crushing the band. So do tell what voodoo that is. Same Cab, Same room, same band, different heads with apparently way MORE wattely watts (4 pro is 1600 lol) getting crushed. Meters and scopes and Blah blah blah. Hey I used one in the REAL world, in a situation where these other heads couldn't deliver. It's louder. Period.

I can even double down on this, a few years ago I had switched from the PF-500 head to the PF-50T Same settings, almost same volume, better tone by far. 450 watts difference I should have been unable to hear myself in a band context.

It's a valid comparison if you switched heads in the same rehearsal.

SVT crushing three Triple Rectifiers...maybe if the guitar players were humoring you. I have a couple of vintage Marshall 100W heads and a 1960AX/BX full stack, and IMHO my SVTs have no chance against this rig unless the guitar player uses some degree of self control.

FYI the settings on an amp have nothing to do with how loud it will play. Two amps that have knobs numbered from 1-10. One amp may max out at 4 and the other may max out at 7. Use a different bass and the the first amp may max out at 5 and the second amp at 7.5.

I really can't say how loud a PF350 will play since I haven't used one personally. But as I said previously, my 380W GK 700RB is louder than my SVTs. It's not a huge difference, but it is louder.

The funny thing is I an SVT into an 810E never really seemed all that loud to me. Louder than I actually need yes, but brutally loud or bone crushingly loud. Absolutely not.

 

[Altitude]

They will continue to be the darlings of recording studios for ever and ever. But the only way I'm playing one on a gig is if it's backline. Or, I guess, if Lenny Kravitz hires me and tells me he demands that I play a 4-string bass through an Ampeg.

I do love the way they sound. Actually didn't get into them until my 40s, is the odd part.

 

[ashtray]

I'm going to get dragged for saying this, but for gigging, "close enough" is usually "good enough". Those subtle nuances that make something sound amazing to us are just lost in the mix, and even when they aren't, they just aren't noticed by other people - even fellow bass players!
Now - I'm not saying bad tone is acceptable! I'm saying that one tone that gets you 90% the way there won't sound any different to everyone else. So the big guy can stay at home, and you can gig the lightweight smaller stuff without any real loss.
The flip side though is that YOU can hear the difference, and you can enjoy the amazing tones at your gig. But no one else will really notice.

 

[JMarkD]

I hate mine too. Mainly because it doesn't work and even if it did I can't lift it. When it did work I loved it. Sadly I don't see the point of fixing something I won't ever use (I really can't lift it). It's a 70's blue line Magnavox and if anyone wants it and you are in central Fl just come by and get it. Don't know what it would take to fix, might be cheap, might be expensive. Heck the old tubes in it might be worth more than the amp. I would love for it to go to a good home, or at least to someone who could use it (and lift it).

 

[Wasnex]

I can try that this week.
You had mentioned the 20 Hz. for bass center freq. of the 8 Pro which has kept me from looking at them.
Have you tried a HPF to clean up the low end?

I don't own an HPF pedal. Pretty sure the 8-Pro has a built in fixed HPF.

The SVP-CL manual says exactly the same thing as the 8-Pro manual:

9. BASS:Use this control to adjust the low frequency output level. This control provides +17/-13dB at 20Hz
​

The controls may actually work exactly the same, the 20hz could be just where they took the measurements.

From the vintage service manual:

 

[Jim C]

Does it sound like the center freq is that low; or in another words, does it sound like mud and speaker overextension when turned up? 20 Hz. is flat out ridiculously low.
No way that my SVT-CL has a center freq that low and just found this online for the current SVT-CL

BASS: Use this to adjust the low frequency level of the amplifier. This provides up to 12 dB of boost, or 12 dB of cut at 40 Hz. The low frequency output is flat at the center position.

 

[Jefenator]

You're making me regret having just traded in my vintage V-4B.
Like you I have that SVT-IIP preamp. It does sound great with a solid state power amp but I must concur that the pairing really does not replicate the true all-tube experience.
I still have a Sunn 200s for smaller rooms. Definitely not ruling out one of the modern, less cumbersome "lunchbox" style tube heads. (Love to find something practical enough for Jazz gigs - tube power can be a real delight for upright bass.)

 

[Wasnex]

Does it sound like the center freq is that low; or in another words, does it sound like mud and speaker overextension when turned up? 20 Hz. is flat out ridiculously low.
No way that my SVT-CL has a center freq that low and just found this online for the current SVT-CL

BASS: Use this to adjust the low frequency level of the amplifier. This provides up to 12 dB of boost, or 12 dB of cut at 40 Hz. The low frequency output is flat at the center position.

This post has some low rez scans of an old magazine article that show the response plots for the vintage SVT's tone controls: Totally transparent combo bass amp?

Here are the relevant plots for the bass control...plot with the big hole in the middle is with the Deep switch engaged.

 

[Wasnex]

Does it sound like the center freq is that low; or in another words, does it sound like mud and speaker overextension when turned up? 20 Hz. is flat out ridiculously low.

I feel like I have to run the Bass control higher on the SVT 8-Pro to get the same perceived level of bass. I suspect much of the range of the control is cut off by an HPF. Also I don't feel like it reaches as far into the low mids as the Bass control on my vintage SVTs.

The sound is not really muddy, it just doesn't seem to authentically do that thick low mid push that SVTs are known for. But perhaps some of that is built into the power amp. I have read that the V4B power amp is almost perfectly flat and the SVT has a very small mid-band hump centered around 400hz. Perhaps my 8-Pro power amp is just super flat so I am missing the gentle hump in the low mids.

The SVT 8-Pro is still an incredible amp that comes pretty darn close to sounding like a real SVT IMHO. I think with just a little bit of EQ I might get even closer, but I have held of on buying an Empress ParaEQ for too long, since they appear to be discontinued.