Octave V70SE to drive Martin Logan Summits?

" Optimum Load Impedance 3 - 16 ohms Nominal Speaker Impedance"

" Impedance mismatch is without consequence, as the amplifier is stable down to a 2 Ohm load."

That means that with loads below 2 Ohms amplifier may (may!) go into oscillations.

I knew a guy who try to use some medium paert amps on his Summit. Every time sound went to treble the amp shut itself off (to avoid oscillation or whatever). He bought Spectron.

" ....the Aeon is a slightly less difficult load (1.3 ohms at 20kHz, instead of 0.7 ohms)."

SLIGHTLY ? To have the same effect amp with 0l7 Ohm @ 20 kHz must deliver almost twice more more power - if load is resistive ...but if its electrastatic its reactive load so power delivery must be substantially more then x2

Regarding 70 wpc and 83 dB efficiency - there are simple relations between this numbers and maximum SPL (in dB...) available, say 10 ft from the speakers. Not only peaks of symphonic music but even drum's transients in jazz are doubful be transmitted without huge degree of distortions (Brrrrr...).
However, you can listen pop, flute concerto and such without a sweat !

Buyer beware !

What can you decipher from the following specs?

Nothing particularly conclusive.

The statement about damping factor would seem to imply that its damping factor is not particularly high, and therefore its output impedance is not particularly low. Which with the ML speaker would lessen the likelihood that the upper treble will be over-emphasized, as it might be with a solid state amp.

The reference to being able to handle speakers with impedance dips as low as 2 ohms is not particularly comforting with respect to a speaker that dips to a highly capacitive 0.7 ohms, but on the other hand the amp doesn't have to supply much energy at the upper treble frequencies where that dip occurs.

Best regards,
-- Al

Al,

What can you decipher from the following specs?

Power amplifier
Output Configuration: Push Pull, advanced Pentode Mode, Grid 2 Voltage 300 V, Idle Current
Tubes 28 mA - BIAS Low, 34 mA - BIAS High. Negative Grid Voltage separately adjustable for
each Tube. Range: -16 to -40 V, 3 turn precision regulators.
Wideband Output Transformers using Silicon steel PMZ Core, single Impedance Output.
Optimum Load Impedance 3 - 16 ohms Nominal Speaker Impedance. Efficiency greater than 83
dB. Amplifier remains stable with No Load and Output short-circuited.
Output 2 x 70 W @ 4 ohms
Frequency response 20 Hz - 70 kHz @ 40 W -1 / - 3 dB
5 Hz - 70 kHz @ 10 W - 0 / - 2 dB
THD 0.1% at 10W @ 4 ohms
Signal-to-noise ratio -100 dB / 40 W
Output Noise less than 300μV
Optimal load impedance 3 - 16 ohms
Minimum load impedance 2 ohms
Gain 38 dB
NFB 10 dB
Tube set 4 x 6550 C
Quiescent current; output tubes 28 mA - BIAS Low, 34 mA - BIAS High

Preamplifier
Input sensitivity 180 mV Line Level Inputs
Input Impedance 50 k ohms
Crosstalk input to input - 105 dB
Output Impedance Pre Out 240 ohms
Channel Balance 0.5 dB to - 70 dB on volume control
Channel Separation 55 dB
Max. Level Pre Out 5 V RMS
Tube set 1 x ECC 83, 2 x ECC 81

A FAQ about Octave amp in general:

5. What is the significance of loudspeaker impedance and efficiency?

The impedance and efficiency of modern loudspeakers is not an issue for OCTAVE amplifiers.
The often-quoted damping factor is not normally a guarantee that an amplifier will exert tight
control over the loudspeakers. In practice, speakers of 85 dB efficiency and above are suitable
for use with tube amplifiers. The high stability of the OCTAVE power amplifier technology even
allows the use of speakers whose impedance dips as low as 2 ohms.

Ciao,
Audioquest4life

As Al says, if A drives B it should also drive C does not always hold. I have Meridian 605 amps, which are 150 watt mosfets. They never had any trouble driving my Apogee Duetta Signatures, which are known as a difficult load. But they get very hot and have to be carefully monitored driving my Gamut L5s. Most would think the Apogee was the harder load but not for the Meridians; every amp -speaker interface is different.

Audioquest4life, yes I recall that discussion, in this thread. Thanks again for providing the information and the links.

That's certainly a good sign that people are happy using the amp with the Aeon, although the Aeon is a slightly less difficult load (1.3 ohms at 20kHz, instead of 0.7 ohms).

There are two concerns, as I see it:

1)Will the amp be able to handle the load?

While your B&W N800's are a somewhat difficult load, they are difficult in a different way. I found a statement in a review indicating that their minimum impedance is 2.8 ohms, and that occurs in "the power band," which I assume means the bass or mid-bass. The ML, like many electrostatics, reaches its minimum impedance at 20kHz, and that impedance is highly capacitive. On the one hand, obviously much less energy is required at upper treble frequencies than in the bass region, but on the other hand the highly capacitive nature of the load increases its severity.

2)Achieving proper tonal balance. The lower the (unspecified) output impedance of the amp, the more prominent upper treble frequencies will be. The higher the output impedance of the amp, the more upper treble frequencies will be de-emphasized. The degree to which the speaker's tonal balance will vary as a function of amplifier output impedance will be much greater than for most dynamic speakers.

So I'm not sure what the bottom line answers are, but those are some thoughts.

Best regards,
-- Al

I did a search on the Octave forum for Martin Logans, several Octave owners have tried them. ML Aeons seem to be a good match.
http://www.octave.de/forum/index.html

IMHO, if I could drive B&W N800's with Octave MRE130's, you should be able to drive the ML's. Make sure you do gte the Super Black Box though. It does make a difference.

Here is what I found on the Octave on the Octave english website about the V70SE:

"The V 70 SE, as all OCTAVE Amps, is based on the enhanced pentode configuration. This configuration ensures the absolute stability of the amplifier against the unstable impedance of the speaker. Impedance mismatch is without consequence, as the amplifier is stable down to a 2 Ohm load. An important contribution to this stability is the Single Impedance Output Transformer.

Power Output 2 x 70 Watt into 4 Ohm
Frequency Response 10 Hz - 80 kHz / ± 0,5 dB
Total Harmonic Distortion < 0,1% @ 10 Watt into 4 Ohm
Signal-to-Noise Ratio > 100 dB
Input Sensitivity 120 mV
Minimum Speaker Impedance 2 Ohm

Al,

I have chatted with you in the past about Octave products. Here is a link to the user manual for the V70SE with lots of specs:

http://www.octave.de/en/pdf/Manual_V70SE_engl.pdf

Ciao,
Audioquest4life

I second the concerns indicated by Stan and Dob about the impedance characteristics of the Summit. I've seen specs indicating that its nominal 4 ohm impedance drops to 0.7 ohms at 20kHz. That variation will make its tonal balance very sensitive to the output impedance of the amplifier, even assuming the amp can handle the load. I would not extrapolate from its performance with Dynaudio's, which have completely different (and much more benign) impedance characteristics.

I couldn't find specs on the Octave's output impedance, or damping factor (which equals output impedance divided into 8 ohms). That might be useful information if it can be obtained. Beyond that, I second the recommendation of trying to arrange in in-home trial.

Regards,
-- Al

Your Martin logan Summits is excellent speakers. However, its load at high frequencies probably 5-10 times greated then that at midrange. Thus your requirments for amplifiers must match this challange.
Buyer Be Aware

Great integrated. Can't say regarding the ML's but the V70SE handles my C1's with ease and has tremendous authority with both the KT88's and 6550's. The black box or super black will help lower the noise floor and add a hair more authority. I have the black box too.

The V70SE is fairly new and I was told mine was the first one sold in the US. I bought mine on 9-13-2010 so there may not be too many V70SE owners.

Jon-Where are you located? Your best bet is to find a dealer that will allow you to an in-home demo as there are very few units of this new model in the market. (We have customers utilizing the fantastic V70SE with both Dynaudio Sapphires and C1 but keep in mind that Tone Audio reviewed the V40SE on a pair of Dynaudio C4s with very favorable results!)

Cheers,

Tyler T. Mueller

Next Level AV-Chicago

thanks.
I have the martin logan summits and am looking if the octave can drive it. not considering mac as alternative.

A friend had them, a Mac 275 would drive them but they are a quite difficult load. the efficiency is lower than MLs rating according to test reports I have seen and the impedance is very low in the high end.