Ampeg Upgrades?

[Hansomatic]

I bought a '67 Portaflex and was blown over by the tone. I immediatedly sold my SWR Super Redhead and bought an Ampeg SVT-VR and an SVT-610 cab - both made in the USA.

The ports in my cab had to be re-glued almost immediately. When I pulled some of the speakers out to access the port tubes, I was shocked by their wimpy construction and teeny magnets.

Long story short, the tone I'm getting is warmer, but the bass response needs to be tightened up on this rig. So the question is...

"What speaker and or tube mods have you guys done or seen done that would tighten-up and speed up the bottom end on this rig?" For context of my full rig, I play Ken Smith BSR5 EGs.

 

[rodl2005]

I found that the Ampeg All tube amps- IMHO the best of their line- sound BEST thru non-ported cabs. I had a SVT410HLF & while it did go DEEP-very- when I played the same amp(SVT2) thru a homemade sealed 4x10" i had it seemed tighter & punchier. So I bit the bullet -sold the 410HLF & got a Bergantino NV610 & haven't looked back!

Though - this is MY EARS evaluation- sure, many agree & I'm sure many do not!

 

[Mike Chini]

I found that the Ampeg All tube amps- IMHO the best of their line- sound BEST thru non-ported cabs. I had a SVT410HLF & while it did go DEEP-very- when I played the same amp(SVT2) thru a homemade sealed 4x10" i had it seemed tighter & punchier. So I bit the bullet -sold the 410HLF & got a Bergantino NV610 & haven't looked back!

Agreed. I went with a Sadowsky 4x10 to match with my V4b and it sounds fantastic.

 

[rodl2005]

The Sadowsky 410 is ported tho IIRC???? Tho IS designed by Mr Bergantino & designed to be used w/ tube amps! & again IIRC to sound a bit like a sealed cab! Glad U like it!

 

[Hansomatic]

Anyone have a speaker upgrade recommendation? Personal experiance is especially helpful.

 

[eedre]

I found that the Ampeg All tube amps- IMHO the best of their line- sound BEST thru non-ported cabs. I had a SVT410HLF & while it did go DEEP-very- when I played the same amp(SVT2) thru a homemade sealed 4x10" i had it seemed tighter & punchier. So I bit the bullet -sold the 410HLF & got a Bergantino NV610 & haven't looked back!

Though - this is MY EARS evaluation- sure, many agree & I'm sure many do not!

+1

Except my experience is with the 410HLF to the 810E. Sealed sound is much better.

 

[One Drop]

Sell the Ampeg 6x10 and get a Bergie NV610. You'll never look back.

 

[anderbass]

Anyone have a speaker upgrade recommendation? Personal experiance is especially helpful.

If you post your internal cab dimensions with detailed info about the port(s) and any possible internal cab dividers, some of our tech-savvy members could probably work up some informed replacement speaker recommendations for ya.

 

[Jazzman]

Sell the Ampeg 6x10 and get a Bergie NV610. You'll never look back.

Exactly. The NV610 has no rivals in the sealed category.

 

[Hansomatic]

OK... I think I have a solution to tighten up the low-end response and lower the overall input gain. Here's what I have decided to do...

1) I am doing to mod my SVT-VR to go back to the original design which uses 12DW7 preamp tubes. I lifted these mod notes from another thread. PLEASE let me know if you have more accurate info:

"Replace V1 with a 12DW7

Then swap R6 to 47k from 220k and R25 to 1.5k from 4.7k"

2) I am going to upgrade the speakers from the junk that is in my SVY610 cab to the Celestion BN10-300X (with neo magnets).

Thoughts????

 

[JimmyM]

I think you will do better with the speaker mod than the amp mod. A 12DW7 is half of a 12AX7 and half of a 12AU7, so I don't think you will get any significant improvement in tone with the 12DW7 mod.

 

[coreyfyfe]

Anyone have a speaker upgrade recommendation? Personal experiance is especially helpful.

when i had my 610hlf i used it with eminence bp102s. the caveat there is that the bp102s are 8 ohm speakers, and the 610hlf's original speakers are 6 ohm (wired series-parallel to get 4 ohms). you'd have to find someone who makes either 6 ohm speakers (or 24 ohm speakers like the berg cab) to get a 4 ohm load.

that being said, i ran my cab at 5.33 ohms with my svt-cl and didn't have an issue. i ended up getting rid of the whole thing for a v4/sealed 4x10. easier to move with my small car.

 

[BassmanPaul]

OK... I think I have a solution to tighten up the low-end response and lower the overall input gain. Here's what I have decided to do...

1) I am doing to mod my SVT-VR to go back to the original design which uses 12DW7 preamp tubes. I lifted these mod notes from another thread. PLEASE let me know if you have more accurate info:

"Replace V1 with a 12DW7

Then swap R6 to 47k from 220k and R25 to 1.5k from 4.7k"

2) I am going to upgrade the speakers from the junk that is in my SVY610 cab to the Celestion BN10-300X (with neo magnets).

Thoughts????

And of course you have modeled the cabinet and speakers to ensure that they will actually work together? You cannot just stick any driver of your choice into that cabinet and expect it to be compatible.

Your tube swap will give you less gain and, assuming the VR is similar to the SVT, it sounds like the reverse of Ampeg's mod to 12AX7s when the 12DW7 became unavailable.

Paul

 

[Psycho Bass Guy]

1) I am doing to mod my SVT-VR to go back to the original design which uses 12DW7 preamp tubes. I lifted these mod notes from another thread. PLEASE let me know if you have more accurate info:

"Replace V1 with a 12DW7

Then swap R6 to 47k from 220k and R25 to 1.5k from 4.7k"

Thoughts????

I don't think that's a mod for the SVT VR, but rather for the MTI and early SLM SVT's that used 12AX7's instead of 12DW7's. The VR is was designed with exactly the same gain staging as the original according to Jerrold Tiers. That means the functions of a 12DW7, which is half 12AX7 and half 12AU7, have been split and shared among 12AX7 and 12AU7 's in the VR. IOW, what you are proposing is a step AWAY from SVT tone and probably won't well well anyway.

If you want a meaningful mod that WILL make a difference, have your tech sub 12BH7's for the 12AU7 driver tubes.

 

[Hansomatic]

I don't think that's a mod for the SVT VR, but rather for the MTI and early SLM SVT's that used 12AX7's instead of 12DW7's.

Ok. Any ideas how to bring the SVT-VR back to true Blue Line specs, tubes included?

The VR is was designed with exactly the same gain staging as the original according to Jerrold Tiers. That means the functions of a 12DW7, which is half 12AX7 and half 12AU7, have been split and shared among 12AX7 and 12AU7 's in the VR. IOW, what you are proposing is a step AWAY from SVT tone and probably won't well well anyway.

The signal from my Ken Smith basses to the amp is too hot - even in passive mode. I am hoping (by putting the 12DW7's into the circuit) to be able to drive my bass harder without clipping the preamp.

If you want a meaningful mod that WILL make a difference, have your tech sub 12BH7's for the 12AU7 driver tubes.

What is the typical effect of this mod?

 

[Hansomatic]

And of course you have modeled the cabinet and speakers to ensure that they will actually work together? You cannot just stick any driver of your choice into that cabinet and expect it to be compatible.

Modeled the cabinet? I am a musician, brother... not an engineer. I'm lucky to accomplish a string change without screwing somthing up. Any guidance you offer, I'll gladly accept. But if you don't mind, I could do without being berated.

I realize that I am grasping at straws by looking into a speaker change with such haste, but surely a better made speaker will help eliminate the floppy bottom end of this rig.

The 12DW7's should cut the hot signal from my bass - even in passive mode - but those cheap ass speakers MUST have some impact here.

 

[Psycho Bass Guy]

Ok. Any ideas how to bring the SVT-VR back to true Blue Line specs, tubes included?

If yours is the first generation US-made VR, removing the volatge protection relay (which has proven defective in many) and swapping the driver 12AU7's for 12BH7's will give you the exact SVT circuit. There is NO difference attributable in an Ampeg with a blue-lined faceplate. There were a few early circuit revisions, but none of them correspond directly to any cosmetic change or cause any audible difference in tone. IOW, the whole "blue-line" thing is made up dealer/collector BS.

The signal from my Ken Smith basses to the amp is too hot - even in passive mode. I am hoping (by putting the 12DW7's into the circuit) to be able to drive my bass harder without clipping the preamp.

Just turn your bass down. There is no benefit to running an active bass at full output and the SVT's preamp is VERY gainy. If you want to decrease gain, sub 12AU7's for the 12AX7's in the preamp, but I doubt you'll like the results. It won't hurt anything though.

What is the typical effect of this mod?

Some disagree, but I say it gives the power amp a more dynamic response and more clean drive.

 

[Hansomatic]

If yours is the first generation US-made VR, removing the volatge protection relay (which has proven defective in many) and swapping the driver 12AU7's for 12BH7's will give you the exact SVT circuit.

Ok... thanks for the info. That leaves me with 2 questions:
1) Isn't a 12DW7 required somewhere to duplicate the exact circuit?
2) My SVT-VR is US made, does that make it 1st generation or were there multiple iterations made in the US?

 

[JimmyM]

I can't answer your two questions, but I totally advise against modding it if it's a US VR. It'll be worth a lot more in the future unmodded and your gains will be mostly in looks only. If you want an SVT with 12DW7's, there are plenty out there that cost less than the VR.

 

[megadan]

1) Isn't a 12DW7 required somewhere to duplicate the exact circuit?

As stated above, a 12DW7 is just half 12AX7 and half 12AU7, so it is there in the circuit, just in the form of two tubes instead of one.