Members Phantasm Posted May 26, 2007 Members Share Posted May 26, 2007 Ok, I bought a used Ampeg SVT-2pro. It sounds like it should and all's good with that. However, through my Eden 410XLT it makes the speakers jump quite a bit even if i cut the lows out. I'm going to try another cab in a bit, but compared to all the other amps I own it's making the speakers jump a considerable amount more. It's a 4ohm cab and I have the head set to 4ohm. Is this a normal thing, or is there a possibility there are tubes or something electrical I should have checked? I've been a SS guy for years so I'm not sure what's normal. Link to comment Share on other sites More sharing options...
Members Deacon_blue Posted May 26, 2007 Members Share Posted May 26, 2007 Are you sure your cab is 4 ohms?Specs for a new one is 8, I believe. Link to comment Share on other sites More sharing options...
Members Phantasm Posted May 26, 2007 Author Members Share Posted May 26, 2007 It's definately a 4-ohm cab. Link to comment Share on other sites More sharing options...
Members hasbeen Posted May 26, 2007 Members Share Posted May 26, 2007 it sounds like a dampening issue to me; which is not uncommon with some tube amp designs. Link to comment Share on other sites More sharing options...
Members Phantasm Posted May 26, 2007 Author Members Share Posted May 26, 2007 it sounds like a dampening issue to me; which is not uncommon with some tube amp designs. Is this something that needs to be fixed, or is it just the nature of the beast? Link to comment Share on other sites More sharing options...
Moderators Kindness Posted May 26, 2007 Moderators Share Posted May 26, 2007 If that's the problem (it was my guess too), it's the nature of the beast. There are some amps and cabs that don't match up well as far as damping is concerned. Make sure you are listening to your cabinet, not just looking at the excursion. If you are reaching the excursion limits of the drivers, you will hear it. If you still aren't loud enough at that point, you need to pair a different amp and cab to accomplish your goals. If the speakers are dancing, but everything sounds good, don't worry too much. Link to comment Share on other sites More sharing options...
Members Phantasm Posted May 26, 2007 Author Members Share Posted May 26, 2007 Thanks for the advice, guys. I'm usually a Solid State guy but I figured I'd give tube amps another shot in an attempt to redeem themselves from the pain and suffering they caused in my formative bass years... If I switch over to my Henry 8x8 there's a lot less speaker movement. I've got a Bergantino NV610 that I'll probably give a shot also since it sounds like there's nothing's wrong with the tube amp. Also, I didn't hear anything bad when the speakers in the Eden were jumping, just they were flapping around like I had never seen before with my Ampeg B2R, SWR 350, or GK 2001RB. After over 10 years of use, it was kind of a shock! Link to comment Share on other sites More sharing options...
Members der oxenrig Posted May 26, 2007 Members Share Posted May 26, 2007 That amp is supposed to be the {censored} with the NV610. Give it a shot. Link to comment Share on other sites More sharing options...
Members oldivor Posted May 26, 2007 Members Share Posted May 26, 2007 That amp is supposed to be the {censored} with the NV610. Give it a shot. What have you done with Sean? An Ampeg with 10s? Link to comment Share on other sites More sharing options...
Moderators Kindness Posted May 26, 2007 Moderators Share Posted May 26, 2007 Do it and give us a report about how differently the amp responds with the different cabinets. Link to comment Share on other sites More sharing options...
Members TimmyP Posted May 26, 2007 Members Share Posted May 26, 2007 Plug one of your other heads into the Eden cab and set the volume at a pleasant level. Grab the B (or E if a 4 string) and wiggle it back and forth. See how much the speakers move. Now hook up the Ampeg, adjust for a similar volume, and wiggle the string. If the cones move a lot more, have the local amp guru decrease the value of the coupling caps to take out some of the extreme low end. (This will have a much different effect than using the EQ.) Link to comment Share on other sites More sharing options...
Members hasbeen Posted May 26, 2007 Members Share Posted May 26, 2007 Is this something that needs to be fixed, or is it just the nature of the beast? nature of the beast with some tube amp designs. This is why some tube amps for "loose" or "pillowy". This effect can be more obvious when the amp is used through a ported cabinet vs. a sealed cabinet. Just of note: It could also happen with SS amps too but it isn't as common. Link to comment Share on other sites More sharing options...
Members Rippin' Robin Posted May 26, 2007 Members Share Posted May 26, 2007 nature of the beast with some tube amp designs. This is why some tube amps for "loose" or "pillowy". This effect can be more obvious when the amp is used through a ported cabinet vs. a sealed cabinet. Just of note: It could also happen with SS amps too but it isn't as common. I've never quite understood the 'dampening' factor... In layman's terms... When an amp puts power onto a speaker, it moves forward. When the speaker moves backwards again, this creates power that goes in the reverse direction and has to be sucked up by the amp Is the dampening factor the ability of an amp to suck up the 'returned' power Link to comment Share on other sites More sharing options...
Members L. Ron Hoover Posted May 26, 2007 Members Share Posted May 26, 2007 I've never quite understood the 'dampening' factor... In layman's terms... When an amp puts power onto a speaker, it moves forward. When the speaker moves backwards again, this creates power that goes in the reverse direction and has to be sucked up by the amp Is the dampening factor the ability of an amp to suck up the 'returned' power No, that's the damping factor. I'm not sure what the dampening factor is but I think it has something to do with moist towelettes..... (Sorry Roger, it was too good to resist ) Anyway, what generates the reverse current is the movement of the coil in the magnetic field. If you move a speaker cone by hand, you'll generate it. Damping factor is a measure of an amp's ability to deal with that and with the other impedance variances inherent in speakers. It's actually the ratio of the amp's output impedance to the impedance of the load, so higher damping factors equate to lower output impedances. The lower an amp's output impedance is the more it acts like an ideal voltage source, which means the output voltage will stay the same no matter what the load impedance is (at a given level). Higher output impedances allow the output impedance of the amp to form a voltage divider with the impedance of the driver which allows the output voltage of the amp to vary with the varying impedance of the drivers. This is especially noticeable at the big impedance dips and peaks in the low end of a ported cabinet and an amp with low DF can sound 'bloaty' at low frequencies. However, I'm not sure that this is the issue here but I'm not sure it isn't. Eden's drivers are designed to be high excursion and in my experience they move a lot no matter what amp is driving them. The DF of big push-pull tube amps is high enough that it shouldn't make that huge of a difference. Perhaps the 2-pro has a response peak below the tuning frequency of the cab, which would cause lots of excursion. I've driven the 410XLT with my SVT and noticed a lot of excursion but no more that I noticed using a WT-800.... The combo of SVT and 410XLT actually sounds deluxe, but not as deluxe as it sounds with the NV-610.. Barring an old square back 810, that is the cab for an all tube SVT. Link to comment Share on other sites More sharing options...
Members hasbeen Posted May 26, 2007 Members Share Posted May 26, 2007 No, that's the damping factor. I'm not sure what the dampening factor is but I think it has something to do with moist towelettes..... (Sorry Roger, it was too good to resist ) Anyway, what generates the reverse current is the movement of the coil in the magnetic field. If you move a speaker cone by hand, you'll generate it. Damping factor is a measure of an amp's ability to deal with that and with the other impedance variances inherent in speakers. It's actually the ratio of the amp's output impedance to the impedance of the load, so higher damping factors equate to lower output impedances. The lower an amp's output impedance is the more it acts like an ideal voltage source, which means the output voltage will stay the same no matter what the load impedance is (at a given level). Higher output impedances allow the output impedance of the amp to form a voltage divider with the impedance of the driver which allows the output voltage of the amp to vary with the varying impedance of the drivers. This is especially noticeable at the big impedance dips and peaks in the low end of a ported cabinet and an amp with low DF can sound 'bloaty' at low frequencies. However, I'm not sure that this is the issue here but I'm not sure it isn't. Eden's drivers are designed to be high excursion and in my experience they move a lot no matter what amp is driving them. The DF of big push-pull tube amps is high enough that it shouldn't make that huge of a difference. Perhaps the 2-pro has a response peak below the tuning frequency of the cab, which would cause lots of excursion. I've driven the 410XLT with my SVT and noticed a lot of excursion but no more that I noticed using a WT-800.... The combo of SVT and 410XLT actually sounds deluxe, but not as deluxe as it sounds with the NV-610.. Barring an old square back 810, that is the cab for an all tube SVT. hey, I never let my old Trace HexaValve eat a lobster dinner without those. It leaves them refreshed and lemony. Just unplug the amp before application. Link to comment Share on other sites More sharing options...
Members hasbeen Posted May 26, 2007 Members Share Posted May 26, 2007 Yes.....that is correct. I don't know why it is a problem with some designs an not others. I use a Sadowsky SA200 (tube amp) with two different ported cabs and never a problem. Also, a Trace Hexa and SVT-CL....same thing.....no problem. I will say that my SS amps are certainly "faster" all around, but not to where you'd say the tube amps were "under-performing".....just different. I've never quite understood the 'dampening' factor... In layman's terms... When an amp puts power onto a speaker, it moves forward. When the speaker moves backwards again, this creates power that goes in the reverse direction and has to be sucked up by the amp Is the dampening factor the ability of an amp to suck up the 'returned' power Link to comment Share on other sites More sharing options...
Members Phantasm Posted May 26, 2007 Author Members Share Posted May 26, 2007 Do it and give us a report about how differently the amp responds with the different cabinets. I'm going to try to get this done over the weekend. So far the Eden 410XLT jumps a lot more than I've seen it jump with other amps and the Henry 8x8 is a lot more in control. I'll hook it up to the Berg next. Link to comment Share on other sites More sharing options...
Members bassman1956 Posted May 27, 2007 Members Share Posted May 27, 2007 Question for Hasbeen, L.Ron...Is this what the Traynor YBA200 "resonance" knob is for? Link to comment Share on other sites More sharing options...
Moderators Kindness Posted May 27, 2007 Moderators Share Posted May 27, 2007 That is what the resonance control is intended for, but I don't have any personal knowledge of how it works, whether it actually influences the output impedance or whether it is just a simulation. Link to comment Share on other sites More sharing options...
Members bassdudeguy Posted May 27, 2007 Members Share Posted May 27, 2007 F.A.Q????? Link to comment Share on other sites More sharing options...
Members bassman1956 Posted May 27, 2007 Members Share Posted May 27, 2007 That is what the resonance control is intended for, but I don't have any personal knowledge of how it works, whether it actually influences the output impedance or whether it is just a simulation. Have had some luck dialing it in. Best at 0 in the house. At Mike N Denise's, had it about 4. In a friend's garage, playing to the open cornfield, it didn't seem to matter... Then again, those Mesa's can take every ounce the Traynor can throw at them. Link to comment Share on other sites More sharing options...
Members hasbeen Posted May 27, 2007 Members Share Posted May 27, 2007 Question for Hasbeen, L.Ron...Is this what the Traynor YBA200 "resonance" knob is for? to be contrite....I don't know. I've haven't read their manual or seen a schematic. If it acts as an ultra-low or sub type thing, it will certainly affect how a speaker jumps around. My Sadowsky amp has a "bottom" control. It really adds some nice depth....it's around 40hz. If I get silly with it, it will sure make my speakers jump too. Link to comment Share on other sites More sharing options...
Members L. Ron Hoover Posted May 27, 2007 Members Share Posted May 27, 2007 Question for Hasbeen, L.Ron...Is this what the Traynor YBA200 "resonance" knob is for? Yup. As far as I know the way it's done is that they vary the amount of negative feedback in the power amp stage, which affects the output impedance (and voltage gain) of the power stage. More feedback gives lower output impedance (higher DF) while less feedback results in more. Link to comment Share on other sites More sharing options...
Members L. Ron Hoover Posted May 27, 2007 Members Share Posted May 27, 2007 hey, I never let my old Trace HexaValve eat a lobster dinner without those. It leaves them refreshed and lemony. Just unplug the amp before application. Link to comment Share on other sites More sharing options...
Members Marw|n Posted May 29, 2007 Members Share Posted May 29, 2007 I have a similar problem! my amp setup is a Carlsbro top 50 tube amp into a Eden 1x12 and the speaker cone moves alot. And recently i played a rock gig where the speaker started farting when playing really low notes at high volumes. So i guess the speaker can Link to comment Share on other sites More sharing options...
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