Ron's Speaker, Turntable, Power and Room Treatment Upgrades

[Ron Resnick]

I have the opportunity to purchase a pair of VTL Siegfried Series Is. I presently have VTL MB-750s, and I anticipate getting MartinLogan Neoliths in the future.

I am considering the Siegfrieds to passively, horizontally bi-amp the future Neoliths.

My view is that there pretty much is no such thing as too much power on big MartinLogan hybrid speakers. The MB-750s and the Siegfrieds should output approximately the same power.

If I wanted more low-frequency oomph or I wanted some flexibility to tinker with the frequency response of the system in my room from 23 to 400 Hz the Siegfrieds would afford me the option to experiment with driving the panels with my current MB-750s in triode mode and driving the woofers and subwoofers with the Siegfrieds in tetrode mode (twice the power of triode mode).

If I needed to tinker with the frequency response of the Neoliths from 23 to 400 Hz, with the Siegfrieds in tetrode mode I could boost both the 15" driver (covering 23 hz to 60 hz) and the 12" driver (covering 60hz to 250-400 hz (based on crossover setting)) by 3 dB, or I could boost only the 12" driver by 3dB and keep the 15" driver the same (by switching in the built-in 4 dB attenuator for the 15" driver).

For those who object to passive bi-amping — I totally understand. If MartinLogan follows its past practice it will release an active-crossover version of the Neolith. I would select that product if it is released next year.

1) Do you agree or disagree that whatever is the difference in output power between the MB-750s and the Siegfrieds it is likely to be small and inconsequential (and who knows what the sample-to-sample output variance is from even the same model)?

2) Do you agree or disagree that being able to raise by 3dB the output of a) the 12” driver or (b) the 15” driver or (c) both the 12” driver and the 15” driver might afford some useful flexibility in getting flat frequency response?

 

[Billy Shears]

Hi Ron

Horizontal Bi-Amping of the Neoliths is a great Idea. it eases the Load on the Amps if they are only driving the Stats / Woofers

Personally i am concerned about the different output . I know Audioresearch have Bi-amped Sonus Fabers with Ref 250s and DS Amps to good effect but i would stick with a more Homogenous solution. Maybe someone has actually tried mixing the VTLs and can offer some PRACTICAL experience.....

 

[microstrip]

Ron,

When passively biamping, the main issue is gain and subjective sound characteristics, power is usually not so critical, as sometimes amplifiers with the same nominal power reach very different loudness levels.

Unfortunately VTL took the specifications of their old amplifiers from their site and I can not find gain of the original Siegfried anymore. We have the measured gains of the MB750's in the Stereophile review. Please note you must compare them in the used mode - tetrode or triode, RCA or XLR input.

If gains are reasonably matched I could anticipate that using the MB750 for bass and the Siefried for the panels would sound great.

 

[microstrip]

Hi Ron

Horizontal Bi-Amping of the Neoliths is a great Idea. it eases the Load on the Amps if they are only driving the Stats / Woofers

Personally i am concerned about the different output power. I know Audioresearch have Bi-amped Sonus Fabers with Ref 250s and DS Amps to good effect but i would stick with a more Homogenous solution. Maybe someone has actually tried mixing the VTLs and can offer some PRACTICAL experience.....

The Audio Research combination was carried with the Aida's, just for the Aida downfiring sub - crossover frequency around 55Hz. It was possible because after you enter the output impedance of the tubed amplifiers and gain at the used impedance the numbers matched with the DS450. I tried the same approach with the REF150, that has different gain and output impedance and it was unsuccessful.

 

[Billy Shears]

Thanks Micro

Hence the PRACTICAL Experience......

 

[LL21]

Hey Ron,

i wonder if your option 2 (the built-in 3db attenuation feature) is similar to changing the resistors on a Wilson crossover...which apparently also result in attenuating or boosting treble or mids, etc. I think by changing resistors, one can boost/attenuate by 0.7db increments.

If this is about right, then that definitely sounds like something worth experimenting with. I think Gryphon Pendragon has some kind of 1db +/- attenuation/boost feature on their Pendragon as well. Used well, a piece of flexibility like that should be a good thing...at the same time, (as with Wilson) if used poorly, it can of course be worse.

Net, net...i'd rather have the flexibility and ensure good setup by a professional.

 

[ddk]

I have the opportunity to purchase a pair of VTL Siegfried Series Is. I presently have VTL MB-750s, and I anticipate getting MartinLogan Neoliths in the future.

I am considering the Siegfrieds to passively, horizontally bi-amp the future Neoliths.

My view is that there pretty much is no such thing as too much power on big MartinLogan hybrid speakers. The MB-750s and the Siegfrieds should output approximately the same power.

If I wanted more low-frequency oomph or I wanted some flexibility to tinker with the frequency response of the system in my room from 23 to 400 Hz the Siegfrieds would afford me the option to experiment with driving the panels with my current MB-750s in triode mode and driving the woofers and subwoofers with the Siegfrieds in tetrode mode (twice the power of triode mode).

If I needed to tinker with the frequency response of the Neoliths from 23 to 400 Hz, with the Siegfrieds in tetrode mode I could boost both the 15" driver (covering 23 hz to 60 hz) and the 12" driver (covering 60hz to 250-400 hz (based on crossover setting)) by 3 dB, or I could boost only the 12" driver by 3dB and keep the 15" driver the same (by switching in the built-in 4 dB attenuator for the 15" driver).

For those who object to passive bi-amping — I totally understand. If MartinLogan follows its past practice it will release an active-crossover version of the Neolith. I would select that product if it is released next year.

1) Do you agree or disagree that whatever is the difference in output power between the MB-750s and the Siegfrieds it is likely to be small and inconsequential (and who knows what the sample-to-sample output variance is from even the same model)?

2) Do you agree or disagree that being able to raise by 3dB the output of a) the 12” driver or (b) the 15” driver or (c) both the 12” driver and the 15” driver might afford some useful flexibility in getting flat frequency response?

Passive biamping/biwiring has sonic advantages beyond the tinkering. I don't think blending the 750s and the Siegfrieds would be a problem but you'll probably need passive attenuators to balance the levels. What I'm concerned with is if the Manleys can handle the difficult >0.5 ohm load of the Neolith .

david

 

[Ron Resnick]

Billy, Lloyd, Thank you!

microstrip, I too, have been researching the specs of the MB-750 and the Siegfried Series I and I could not find much either. Even if the Series 1 has higher output (holding tetrode/triode mode constant) the fact that the Series 1 will be driving the higher impedance cones than the lower impedance panel might offset the higher power of the Series Is. Thank you for working on this with me!

David, thank you for weighing in! I appreciate it! You raise a good question, but I seem never to mind the high-frequency roll-off due to the panel's low impedance at high frequencies. I actually have two pairs of those pretty high-quality Electronic Visionary Systems fixed-resistor attenuators from about 15 years ago.

This idea of bi-amping with the Siegfrieds appeals to me both for the passive bi-amping advantages David mentioned but also because it is the bigger transformers and more tightly regulated power supplies of the Siegfried Series 1 (continuing further with the Series IIs) which may account for some listeners' view that VTL's house sound has gotten less "tubey" over the years.

Microstrip, I like the more tubey sound of the MB-750s for the panels and the tighter, more authoritative sound of the Siegfrieds for the dynamic drivers of the Neoliths.

 

[microstrip]

Passive biamping/biwiring has sonic advantages beyond the tinkering. I don't think blending the 750s and the Siegfrieds would be a problem but you'll probably need passive attenuators to balance the levels. What I'm concerned with is if the Manleys can handle the difficult >0.5 ohm load of the Neolith .

david

The MB750s handle the SoundLabs perfectly, that also have very low input impedance at 20 kHz - similar to the Prodigy's. However it seems the Neolith is less than half that value at 20 KHz - it can risk some serious attenuation of the extreme treble when used with the VTL's that have more than 1 ohm output impedance.

The Soundlabs have treble adjustment so this attenuation can be easily compensated (but with the cost of decreasing the treble impedance ).

 

[KeithR]

What would be your plan with regards to heat?

 

[Ron Resnick]

Keith, I appreciate that question. But I already have thought of that and I have it covered.

Just outside of the listening room will be a sign:

"PLEASE CHECK ALL CLOTHES AT THE DOOR"

 

[ddk]

Keith, I appreciate that question. But I already have thought of that and I have it covered.

Just outside of the listening room will be a sign:

"PLEASE CHECK ALL CLOTHES AT THE DOOR"

Are you sure about that Ron? You're aware of the gender and the age range of your audiophile buddies!


david

 

[GaryProtein]

Keith, I appreciate that question. But I already have thought of that and I have it covered.

Just outside of the listening room will be a sign:

"PLEASE CHECK ALL CLOTHES AT THE DOOR"

I think I still have one of those from Plato's Retreat.

 

[Ron Resnick]

David, Yes, you are right. I will just have to run the air conditioning on full. : )

Gary, Plato's retreat was before my time in Manhattan!

 

[Ron Resnick]

I see the .43 ohm spec for the Neolith at 20 khz. I wonder why that design results in half the impedance at that frequency as did the Prodigy or the Monolith III.

 

[Billy Shears]

Hi Ron
Have you contacted Martin logan about the possibility of a Active Crossover for the Neos?
It would be a much cleaner solution......

 

[GaryProtein]

I see the .43 ohm spec for the Neolith at 20 khz. I wonder why that design results in half the impedance at that frequency as did the Prodigy or the Monolith III.

I'm not an engineer. Could it be the sheer size of the conductor in the stators and diaphragm?

As I recall, the impedance of the Statement E2 dropped very low at the top end also.

 

[Billy Shears]

That is a real measurement of the Martin logan Ethos. Look at the same Impedance drop to under 1 ohm at 20Khz.
I have used it with a 50 watt Push pull KT88 Copland CTA 405 Amp and prefered the 8 ohm Tap for the same reasons Ron has listed.
No doubt that affects the Frequency response. But it seems a lot more frindley than with Dynamic Speakers that have current pulling dips in the Bass region.

 

[microstrip]

I see the .43 ohm spec for the Neolith at 20 khz. I wonder why that design results in half the impedance at that frequency as did the Prodigy or the Monolith III.

The decrease of the impedance of panel electrostatic speaker versus frequency is due to its capacitive nature. Panels behave like capacitors - typical capacitance can be around 1000 or 2000 picoFarad - 10E-9 to 2x10E-9 Farad. The impedance of this capacitor in reduced by a factor approximately equal to the square of the turns ratio of the matching transformer. Most probably ML made changes to the panel capacitance - capacitance increases with area and increases with the decrease of panel spacing.

Now for the practical aspects. Measurements of large curved panels taken near field are misleading - the Stereophile review of the Martin Logan SL3 http://www.stereophile.com/content/martinlogan-sl3-loudspeaker-manufacturers-comment-part-2#KDoyier3LIxbUvG2.97debated this subject. Small changes in panel orientation can work as a powerful treble controller. It is why we have reports of excellent sounding Martin Logan panels used either with amplifier having high damping (low impedance output) or low damping (most tube amplifiers). The key points are the capacity of supplying reasonable amounts of current without distortion and proper speaker set up. As always, people must try, although I would not advise connecting the Neolith's to Futterman's ...

 

[Billy Shears]

Micro

Clear on the Capacitor analogy. I dont understand what the technical theory behind Tube Amps sounding good with logans (from practical experience) is

"The key points are the capacity of supplying reasonable amounts of current without distortion" would mean Solidstate Amp with high dampening factor.