Hello kind and wise sirs, the following problem has been briefly touched upon, but, as far as I could find, in a rather nonspecific manner.
I hope to build an amplifier that will drive low impedance speakers, ESLs, and specifically, Martin Logan Summit Xs. Mr. Pass being the nicest, kindest and wisest guy in audio, using his designs would make me happy.
The speakers impedance curve looks like this:
The impedance goes down to 2 Ohm above 6kHz and touches on maybe 0.7 Ohms at 20kHz.
Sensitivity is rated at about 91db/Wm
As my limited understanding has it, this requires the amplifier to be able to deliver lots of current into low impedance loads.
Also, given the varying impedance, some voltage oomph will be beneficial too? Regarding listening levels, I don't intend to drive them at party levels, they are electrostats after all.
All this leaves me with three options, as I see it:
(as an aside, I already have two 400VA +-24V power transfomers, so this reflects in my thinking🙂
1. Burning Amp 3 with complimentary output stages, 6 deep output stages per side, monoblocks of 5U 500mm cases each for maximum of heatsink
Question: There's a lot of discussion about the source resistors, they are supposed to be 1 Ohm for the 6 pairs. Would there be any benefit for current delivery in going to lower values for the source resistors, given the constraints of heat/power dissipation?
2. F5 Turbo V2 - as Mr. Pass says clearly, greatly improved current delivery vs F5. On a plus, it would be possible to build this in one dual mono 5U 500mm chassis.
Question: How does the output stage compare to the BA3 PP in current capability?
3. Going all the way with an F5 Turbo V3, monoblocks in an 5U 500mm chassis each, transformers paralleled for 800VA.
Question: Is there a tangible advantage over the F5V2 or BA3 for my use case?
Just going by the expected power supply capacity/rating, if my understanding is correct, F5V3 should have by far the highest output potency. Does that mean best in my case? Complexity is also highest though.
The amount of knowledge and support here is amazing. Please advise me kindly or harshly, anyhow, as I am in way over my head, no matter what 🙂
I have parts already for the BA3 (which was my original plan before acquiring the speakers), but having gone all out on the speakers, I really want to do them justice.
I hope to build an amplifier that will drive low impedance speakers, ESLs, and specifically, Martin Logan Summit Xs. Mr. Pass being the nicest, kindest and wisest guy in audio, using his designs would make me happy.
The speakers impedance curve looks like this:
The impedance goes down to 2 Ohm above 6kHz and touches on maybe 0.7 Ohms at 20kHz.
Sensitivity is rated at about 91db/Wm
As my limited understanding has it, this requires the amplifier to be able to deliver lots of current into low impedance loads.
Also, given the varying impedance, some voltage oomph will be beneficial too? Regarding listening levels, I don't intend to drive them at party levels, they are electrostats after all.
All this leaves me with three options, as I see it:
(as an aside, I already have two 400VA +-24V power transfomers, so this reflects in my thinking🙂
1. Burning Amp 3 with complimentary output stages, 6 deep output stages per side, monoblocks of 5U 500mm cases each for maximum of heatsink
Question: There's a lot of discussion about the source resistors, they are supposed to be 1 Ohm for the 6 pairs. Would there be any benefit for current delivery in going to lower values for the source resistors, given the constraints of heat/power dissipation?
2. F5 Turbo V2 - as Mr. Pass says clearly, greatly improved current delivery vs F5. On a plus, it would be possible to build this in one dual mono 5U 500mm chassis.
Question: How does the output stage compare to the BA3 PP in current capability?
3. Going all the way with an F5 Turbo V3, monoblocks in an 5U 500mm chassis each, transformers paralleled for 800VA.
Question: Is there a tangible advantage over the F5V2 or BA3 for my use case?
Just going by the expected power supply capacity/rating, if my understanding is correct, F5V3 should have by far the highest output potency. Does that mean best in my case? Complexity is also highest though.
The amount of knowledge and support here is amazing. Please advise me kindly or harshly, anyhow, as I am in way over my head, no matter what 🙂
I have parts already for the BA3 (which was my original plan before acquiring the speakers), but having gone all out on the speakers, I really want to do them justice.
go with BA3
easier to build, good current capability
comparable (sized) F5T is risky business
easier to build, good current capability
comparable (sized) F5T is risky business
I ran a pair of ML Requests with a F6 and it did surprisingly well. I don't know how the load compares to the Summit X. However, I believe the Requests have a similar impedance curve. I got pretty loud without any noticeable clipping etc. I believe clipping isn't an issue for ESL's unlike speakers with voice coils. It was a little thin on the bottom compared to a higher wattage amp that I have.
From what I have been told (have a lot of the parts but haven't built it yet) the BA-3 amp is supposed to be better suited for rock type music when you compare it to other Firstwatt models. The benefit of a ESL is its ability to reproduce detail. This is just going off what I have read. Maybe look into listening impressions before you commit.
From what I have been told (have a lot of the parts but haven't built it yet) the BA-3 amp is supposed to be better suited for rock type music when you compare it to other Firstwatt models. The benefit of a ESL is its ability to reproduce detail. This is just going off what I have read. Maybe look into listening impressions before you commit.
Hello sti571,
your ML Summit X has an actively driven bass department (2 x 10inch bassdrivers). Crossoverfrequency is at 270 Hz.
So, your amp has not to drive the lowest bass-region.
An impedance of 0,8 Ohm at 20kHz is coming close to a short.
The sensitivity is at around 91 dB / W / m. Not bad for an ESL.
I have a slight tendency to recommend the BA-3 over the F5T V3. Both amps sound great.
I prefer the BA-3 in the bass-region over the F5T V3. But this doesn't come into account because of the
implemented bass-amp in your ML Summits.
My experience with my F5T V3-monoblocks is, that they sound very analytic and clear (although this is slightly adjustable on the frontendboards). This can be a tad too much with a very analytic sounding ESL.
My Audiostatic ES300R sound very good driven from my F5T V3-monoblocks. They sound also very good
driven by the BA-3-amp. Although my preferred combination is F5T V3-monoblocks driving the ESLs,
BA-3 driving the subwoofer (crossoverfrequency at 80 hz).
And I agree with the statement of ZenMod, that the BA-3 seems easier to build. Both amps need some patience for the biasing-procedure.
Hmmm? 🤔
Is that a help? - Not really.
Cheers
Dirk
your ML Summit X has an actively driven bass department (2 x 10inch bassdrivers). Crossoverfrequency is at 270 Hz.
So, your amp has not to drive the lowest bass-region.
An impedance of 0,8 Ohm at 20kHz is coming close to a short.
The sensitivity is at around 91 dB / W / m. Not bad for an ESL.
I have a slight tendency to recommend the BA-3 over the F5T V3. Both amps sound great.
I prefer the BA-3 in the bass-region over the F5T V3. But this doesn't come into account because of the
implemented bass-amp in your ML Summits.
My experience with my F5T V3-monoblocks is, that they sound very analytic and clear (although this is slightly adjustable on the frontendboards). This can be a tad too much with a very analytic sounding ESL.
My Audiostatic ES300R sound very good driven from my F5T V3-monoblocks. They sound also very good
driven by the BA-3-amp. Although my preferred combination is F5T V3-monoblocks driving the ESLs,
BA-3 driving the subwoofer (crossoverfrequency at 80 hz).
And I agree with the statement of ZenMod, that the BA-3 seems easier to build. Both amps need some patience for the biasing-procedure.
Hmmm? 🤔
Is that a help? - Not really.
Cheers
Dirk
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Hi Dirk,
thanks for your input. I do appreciate it. And nice amps 🙂. The bass section is active, yes; although one might hope that some general kind of sound signature is transmitted via sub amps as well.
Right now, I will be taking ZM's advice - BA3 -- planning for monos with 6 pairs per channel, biased for a dissipation of 200W each (as I already have two 400W transformers). I got some F5T boards ordered though... just in case I get an itch later... 😉
And to also take into account Mike's concerns I am building an M2X right now, just to get a hang of it - should play nice with my father's Harbeth P3ESRs.
Thank you all for your input,
jan
thanks for your input. I do appreciate it. And nice amps 🙂. The bass section is active, yes; although one might hope that some general kind of sound signature is transmitted via sub amps as well.
Right now, I will be taking ZM's advice - BA3 -- planning for monos with 6 pairs per channel, biased for a dissipation of 200W each (as I already have two 400W transformers). I got some F5T boards ordered though... just in case I get an itch later... 😉
And to also take into account Mike's concerns I am building an M2X right now, just to get a hang of it - should play nice with my father's Harbeth P3ESRs.
Thank you all for your input,
jan
I am Jealous. Those Harbeths are beautiful! M2X is on my list of things to build. However, my list of things to build is about 100 items long... 😳
Let us know of what you think of the BA-3 when you get it done 🙂
Let us know of what you think of the BA-3 when you get it done 🙂