Stax SR-L300 Impressions Thread
Sep 4, 2020 at 5:30 AM Post #1,021 of 1,126

Tugbars

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Thanks for your input guys. I have what's probably a bottom-of-the-barrel energizer, a good condition but very old SRM-1 MK2. Soundstage and details are decent, but dynamics and bass just suck. I've recently acquired a very powerful speaker amp, it's actually a 5.1 channel A/V receiver with a great headphone amp too, Kenwood VR-406 putting out 500W; 100W per channel. I'm looking for much improved dynamics and maybe bass, or I could boost by EQ - so would you still recommend the SRD-7 transformer?

The owner of Mjolnir doesn't seem to be able to get any Lundahl transformers now, probably why he didn't answer when asking him twice about any differences in sound. Is there any Lundahl energisers I can find from another company?

You can build your own energizer if you have a little bit of experience in soldering. Energizers are extremely simple: An Input protection circuit + transformers for channels + transformer for bias. That's all. http://www.audiodesignguide.com/my/stax_transf.html you can check the circuitry here. What Birgir claims is that he custom ordered his own lundahl transformers which are perfectly designed for driving electrostatic headphones. The winding rate of birgir's transformers is 1:17, That's all I know. If you don't aim for absolute perfection, you can just pick required transformers recommended in the circuitry schema.
 
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Sep 4, 2020 at 1:09 PM Post #1,022 of 1,126

armani006

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Sep 5, 2020 at 1:59 AM Post #1,023 of 1,126

DecentLevi

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Transformers ideally should have very low winding rate. In SRD7 boxes, relatively the winding rate is higher than lundahl transformers. What does that mean? That means, due to parasitic capacitance and other factors, treble extension and treble clarity of SRD7 boxes are seriously worse than lundahl transformers. Lundahl transformers can deliver absurd amount of current too, 45ma if i remember right.(can result in better dynamics in theory) Stax energizers can't even come close. If you have the budget, SRD7 boxes are just waste of money compared to lundahl energizers. I tested both and compared to my KGSSHV Carbon too.(a Krell KSA 200 class A amp used in the tests)
Well you've sold me on the need for Lundahl in the design. I'm assuming it wouldn't make any difference if using a Lundahl tube / speaker amp going into a non-Lundahl Mjolnir SRD-7 transformer unit?
Oh, I had a 3-month experience with the transformer (Mjolnir srd-7) route, you need to try many amps to get the sound you are looking for, as more amp match poorly with srd-7 than good amps. I have tested over 10 amps ranging from 1000$~3000$ but only 2 matched well. The transformer could not drive 007. In terms of sound, you get a huge dynamic punch and rumbling bass, with very little details loss, and transparency, but the soundstage was really smaller than a standard amp, you feel you are listening to a speaker further away from you and the sound is not intimate as a standard amp. Lundahl is more transparent than srd-7 as Mjolnir himself told me, which is a very good thing! Overall srd-7 + 1400$ dollar amp was equal or just a little better than 323s. If you already own a high-end with allot of wattage speaker amp or want higher dynamics or want to match and try different sounds then the transformer is the way to go. If you already own a standard Stax amp, it is not worth buying srd-7 for an upgrade and kgsshv route is better ...
Interesting, would you be able to speculate if possibly a Lundahl version of the Mjolnir SRD-7 may have a better than your 2/10 ratio of pairing with more speaker amps? And when you said Lundahl was more transparent than SRD-7 are you referring to a Lundahl SRD-7, or an entirely different Lundahl transformer?
 
Sep 5, 2020 at 2:21 AM Post #1,024 of 1,126

DecentLevi

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You can build your own energizer if you have a little bit of experience in soldering. Energizers are extremely simple: An Input protection circuit + transformers for channels + transformer for bias. That's all. http://www.audiodesignguide.com/my/stax_transf.html you can check the circuitry here. What Birgir claims is that he custom ordered his own lundahl transformers which are perfectly designed for driving electrostatic headphones. The winding rate of birgir's transformers is 1:17, That's all I know. If you don't aim for absolute perfection, you can just pick required transformers recommended in the circuitry schema.
Thanks. I've looked over the formula, looks like I'd need 2x transformers for channels and 2x for bias (unless I'm reading this wrong?), which comes to about $900. But I didn't seem to notice any input protection on the webpage or what's needed for that.

And does anyone know if the above DIY transformer would sound better/worse than a Lundahl SRD-7?

I would also need a chassis, input/output connectors, etc. and don't have any tools. Maybe someone here could put one together for me?
 
Sep 5, 2020 at 2:18 PM Post #1,025 of 1,126

VRacer-111

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Hey @VRacer-111 I think it was you who introduced me to the idea of getting the SRD-7 from Mjölnir Audio as an electrostatic transformer box that's powered by a speaker amp, as an alternative to an e-stat energizer. I'm thinking to go that route very soon. After contacting them though he said he's experiencing a supply chain issue with Lundahl transformers, so I'd have to get the standard SRD-7 for the time being. Have you any 1st / 2nd hand knowledge of any difference between the Lundahl vs. standard versions sound-wise?

Have no first hand experience with Lundahl transformers, was really interested in trying one though. I will say the Mjolnir modded SRD-7 with my NAD C275BEE Class A amp (150W continuous rated output @ 8ohm with +/- 0.1dB 20-20kHz frequency response, THD of 0.008%, and SNR of 123dB) is an improvement over the SRM-323S I originally had and it really powered the SR-007 and SR-009 well, subbass on the 009 was outstanding, not 007 level but very close. Everything I've heard about the Lundahl transformers would make them what you'd want to go with if you are looking to go transformer route since they will help bring out vocal and treble detail and soundstage more than the SRD-7 transformer. I was more than pleased with my Mjolnir SRD-7 and NAD C275BEE setup, but was planning to go to a Lundahl transformer setup until I decided to sell off all my estat gear (for debt reduction reasons.)

A Lundahl transformer mated to the NAD C275BEE is the way I'd go if I ever got back into estats, should have same great low frequency presentation but better/improved everything else.
 
Sep 5, 2020 at 4:46 PM Post #1,026 of 1,126

Makiah S

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Sep 5, 2020 at 10:08 PM Post #1,027 of 1,126

DecentLevi

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Have no first hand experience with Lundahl transformers, was really interested in trying one though. I will say the Mjolnir modded SRD-7 with my NAD C275BEE Class A amp (150W continuous rated output @ 8ohm with +/- 0.1dB 20-20kHz frequency response, THD of 0.008%, and SNR of 123dB) is an improvement over the SRM-323S I originally had and it really powered the SR-007 and SR-009 well, subbass on the 009 was outstanding, not 007 level but very close. Everything I've heard about the Lundahl transformers would make them what you'd want to go with if you are looking to go transformer route since they will help bring out vocal and treble detail and soundstage more than the SRD-7 transformer. I was more than pleased with my Mjolnir SRD-7 and NAD C275BEE setup, but was planning to go to a Lundahl transformer setup until I decided to sell off all my estat gear (for debt reduction reasons.)

A Lundahl transformer mated to the NAD C275BEE is the way I'd go if I ever got back into estats, should have same great low frequency presentation but better/improved everything else.
Oh you've sold off your whole e-stat system? And by Lundahl transformer are you referring to a DIY one like linked above, or a Lundahl version of Mjolnir SRD-7 - if that even exists?

In terms of a standard Mjolnir SRD-7 I'm operating under the assumption that a good amp pairing would be too difficult to find. But then there's a small possibility of just taking a slimmed-down rig with the transformer down to a used music equipment store and testing it out with a bunch of random amps until I find a good pairing. In terms of NAD C275BEE, it seems a little steep on cost, especially considering it has only a single output and doesn't even throw in a bonus headphone output.
 
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Sep 6, 2020 at 4:29 AM Post #1,028 of 1,126

armani006

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Sep 6, 2020 at 6:49 AM Post #1,029 of 1,126

Tugbars

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Oh you've sold off your whole e-stat system? And by Lundahl transformer are you referring to a DIY one like linked above, or a Lundahl version of Mjolnir SRD-7 - if that even exists?

In terms of a standard Mjolnir SRD-7 I'm operating under the assumption that a good amp pairing would be too difficult to find. But then there's a small possibility of just taking a slimmed-down rig with the transformer down to a used music equipment store and testing it out with a bunch of random amps until I find a good pairing. In terms of NAD C275BEE, it seems a little steep on cost, especially considering it has only a single output and doesn't even throw in a bonus headphone output.

ideally, you need a load invariant amp. Threshold amps with Statis topology, Sunfire, some of Krell amps, Nakamichi amps with Statis topology etc. Check for load invariant amps on google.

Amps which are designed to drive "unusual" loads is what you need basically.
 
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Sep 6, 2020 at 3:42 PM Post #1,030 of 1,126

VRacer-111

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Oh you've sold off your whole e-stat system? And by Lundahl transformer are you referring to a DIY one like linked above, or a Lundahl version of Mjolnir SRD-7 - if that even exists?

In terms of a standard Mjolnir SRD-7 I'm operating under the assumption that a good amp pairing would be too difficult to find. But then there's a small possibility of just taking a slimmed-down rig with the transformer down to a used music equipment store and testing it out with a bunch of random amps until I find a good pairing. In terms of NAD C275BEE, it seems a little steep on cost, especially considering it has only a single output and doesn't even throw in a bonus headphone output.

All my estats and the Mjolnir SRD-7 were sold off, kept the RME ADI-2 DAC and NAD C275BEE. I was wanting the Mjolnir Lundahl, like the design and know it fits perfectly size-wise with the RME ADI-2.

I bought my NAD C275BEE way back before I got into headphones for driving my mains in my HT setup (using NAD T747 receiver as pre-amp going to the 2-channel C275BEE and 5-channel T955 amps.) Got it refurbished from authorized dealer (as I did for all my NAD gear) for many hundreds off, paid around $900 for it. When getting into estats I originally really wanted the Octave II prototype Birgir had listed, but when contacted him about it someone had just bought it. Then I really wanted to go SRD-7 route since that was next cheapest and had the NAD C275BEE amp which I really like. Was hesitant because of concern with what Birgir listed about amp topology that could damage the SRD-7, but he said the NAD C275BEE would work fine with it, which was relief to me and pushed me to going that route.

Headphone outs on stereo amps generally really suck for sound quality, most any inexpensive $100 headphone amp is better. Best thing to do if you want an all in one headphone rig that can cover dynamic, planar, and electrostats is use a headphone DAC/amp as preamp for the stereo amp to power the estats. Plug your dynamics/planar magnetics into the DAC/amp when you want to use them.

The Mjolnir Audio SRD-7 and RME ADI-2 make for a great stack...

i-9Jrtfsw.jpg
 
Sep 7, 2020 at 12:42 AM Post #1,031 of 1,126

DecentLevi

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ideally, you need a load invariant amp. Threshold amps with Statis topology, Sunfire, some of Krell amps, Nakamichi amps with Statis topology etc. Check for load invariant amps on google.

Amps which are designed to drive "unusual" loads is what you need basically.
Thanks, but your suggestion seems abstract to me. I could only find a few of those online, but of those I didn't see any with Stax compatible outputs. Maybe you meant those as a speaker amp to drive the likes of the SRD-7?

All my estats and the Mjolnir SRD-7 were sold off, kept the RME ADI-2 DAC and NAD C275BEE. I was wanting the Mjolnir Lundahl, like the design and know it fits perfectly size-wise with the RME ADI-2.

I bought my NAD C275BEE way back before I got into headphones for driving my mains in my HT setup (using NAD T747 receiver as pre-amp going to the 2-channel C275BEE and 5-channel T955 amps.) Got it refurbished from authorized dealer (as I did for all my NAD gear) for many hundreds off, paid around $900 for it. When getting into estats I originally really wanted the Octave II prototype Birgir had listed, but when contacted him about it someone had just bought it. Then I really wanted to go SRD-7 route since that was next cheapest and had the NAD C275BEE amp which I really like. Was hesitant because of concern with what Birgir listed about amp topology that could damage the SRD-7, but he said the NAD C275BEE would work fine with it, which was relief to me and pushed me to going that route.

Headphone outs on stereo amps generally really suck for sound quality, most any inexpensive $100 headphone amp is better. Best thing to do if you want an all in one headphone rig that can cover dynamic, planar, and electrostats is use a headphone DAC/amp as preamp for the stereo amp to power the estats. Plug your dynamics/planar magnetics into the DAC/amp when you want to use them.

The Mjolnir Audio SRD-7 and RME ADI-2 make for a great stack...

i-9Jrtfsw.jpg
Wow I bet you must miss your e-stat system, even with a good standard headphone setup. Funny you mention the headphone outputs on speaker amps suck - seems more of a statement specific to certain brands/models, because as I read your post I'm actually listening to the headphone output of a Kenwood VR-406 which is a 5.1 channel A/V speaker amp I chanced upon, which happens to have an absolutely f-a-n-t-a-s-t-i-c headphone output. So much so that I would comfortably put it up against the Rangarok 2 amp. It's transparent, organic, holographic and pairs great with all low/high-Z headphones open/closed and seems to have infinite reserve of dynamic capabilities. Well my unit is coaxed along quite nicely by sorbothane dampening underneath and ferrite-chokes on the AC cable, along with fantastic upstream gear including Qutest DAC with custom DC LPS for cleaner power, DI-20 DDC (audio interface) and top RCA cable (Neotech Nei-2001 UP-OCC single-crystal silver cable). I'm aware Kenwood is probably not even a recognized 'audiophile' brand but I just came across it by random chance and it's up there with some of the best things I've heard after 12 Head-Fi meets / CanJams and I got it for free. There are other newer models than VR-406 and they're cheap used. This headphone amp outclassed/outdone my Quad PA one + tube headphone amp, which was already better than the Feliks Audio Euforia, which was already better than the Feliks Audio Elise, which was already better than my former Garage 1217 Ember amp. It looks like you have Garage 1217 amps. For me this is quite a few significant steps up the audio latter.

For the Stax system, I'm now considering either a Stax SRM-717 or 727II, which on the new Stax Thread they said the 717 is warmer and 727II is better overall. They also recommended one with tubes internally called SRM-T1.
 
Sep 7, 2020 at 3:46 AM Post #1,032 of 1,126

Pahani

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Have no first hand experience with Lundahl transformers, was really interested in trying one though. I will say the Mjolnir modded SRD-7 with my NAD C275BEE Class A amp (150W continuous rated output @ 8ohm with +/- 0.1dB 20-20kHz frequency response, THD of 0.008%, and SNR of 123dB) is an improvement over the SRM-323S I originally had and it really powered the SR-007 and SR-009 well, subbass on the 009 was outstanding, not 007 level but very close. Everything I've heard about the Lundahl transformers would make them what you'd want to go with if you are looking to go transformer route since they will help bring out vocal and treble detail and soundstage more than the SRD-7 transformer. I was more than pleased with my Mjolnir SRD-7 and NAD C275BEE setup, but was planning to go to a Lundahl transformer setup until I decided to sell off all my estat gear (for debt reduction reasons.)

A Lundahl transformer mated to the NAD C275BEE is the way I'd go if I ever got back into estats, should have same great low frequency presentation but better/improved everything else.
Aww man, sorry to hear you sold your Stax gear, but I completely understand!

At least you still have your Purplehearts, I listen to mine on a daily basis and use my L700's for special occasions :) PH's are on the short-short list of headphones I'll never sell.
 
Sep 9, 2020 at 8:39 PM Post #1,033 of 1,126

VRacer-111

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Wow I bet you must miss your e-stat system, even with a good standard headphone setup. Funny you mention the headphone outputs on speaker amps suck - seems more of a statement specific to certain brands/models, because as I read your post I'm actually listening to the headphone output of a Kenwood VR-406 which is a 5.1 channel A/V speaker amp I chanced upon, which happens to have an absolutely f-a-n-t-a-s-t-i-c headphone output. So much so that I would comfortably put it up against the Rangarok 2 amp. It's transparent, organic, holographic and pairs great with all low/high-Z headphones open/closed and seems to have infinite reserve of dynamic capabilities. Well my unit is coaxed along quite nicely by sorbothane dampening underneath and ferrite-chokes on the AC cable, along with fantastic upstream gear including Qutest DAC with custom DC LPS for cleaner power, DI-20 DDC (audio interface) and top RCA cable (Neotech Nei-2001 UP-OCC single-crystal silver cable). I'm aware Kenwood is probably not even a recognized 'audiophile' brand but I just came across it by random chance and it's up there with some of the best things I've heard after 12 Head-Fi meets / CanJams and I got it for free. There are other newer models than VR-406 and they're cheap used. This headphone amp outclassed/outdone my Quad PA one + tube headphone amp, which was already better than the Feliks Audio Euforia, which was already better than the Feliks Audio Elise, which was already better than my former Garage 1217 Ember amp. It looks like you have Garage 1217 amps. For me this is quite a few significant steps up the audio latter.

For the Stax system, I'm now considering either a Stax SRM-717 or 727II, which on the new Stax Thread they said the 717 is warmer and 727II is better overall. They also recommended one with tubes internally called SRM-T1.

That's why I put 'generally' in my statement. Most all the receivers I've ever tried (including my NAD) have had sucky headphone outputs, can't think of one I would want over any headphone amp I've had. I know some vintage / older units do have decent headphone outs. There are certain gems out there and sounds like the Kenwood VR-406 you have may be one.

As for the estat system, I actually am not really missing it. Very content with the modded TH-X00 Purpleheart and Koss PortaPros (which are actually my main daily drivers). The estat system definitely had top level of speed, detail, and clarity, but I honestly prefer listening to music on warm, bass heavy, colored dynamic cans. I found with the estats I would just pick apart the music and not relax and enjoy it. My favorite combo right now is my work rig which is modded Porta Pro running from laptop -> old Audioquest DFR -> Schiit Loki -> Project Ember with E-H 6H30Pi tube.
 
Oct 2, 2020 at 6:12 PM Post #1,034 of 1,126

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Hi guys!-) I've gone bonkers on headphonology last 8 Months or so. No system to it. Just bought stuff as it came along impulsively. A craving and a quest. Sold of two HD650, and kept my HD58X for walking. Found AKG K340, and the first model B&O made. U70, planars from 79/80 that sound amazing on my Atrox V 2, (a Norwegian garage-made amp that drives anything). Audeze LCD 2 came along, and Quad Era 1. Got both 32 and 250 Ohm drivers to Beyer T70, but they are hiding under some old Koss among debris and cables and whatnot, but STAX...! Found SR 5 w SRD 7 and forgot I wore them so wrenched teh cable and damaged the 5. An old enthusiast audiophile fixed them pro for me and I got a real good deal; (I think) on L300 new for 300$ w the usual 5 year Norwegian warranty. Ordered an SRM 717 from Japan that arrived, and they really drove my L300 to a different level. Modded w SoCas, Dekoni Beyer pads, then the fenestrated pads from the Quad Era 1, and then back to original Stax plastic again. Came here looking for a bluetack mod or something to tighten up the bass. Not sure what I'll find. Comradeship perhaps? I have my eyes on a L700, but might have driven the owner away with a bid to low for his sense of dignity. (He has them listed at 950$ and I offered 750, later 850). There is also a 007mk2 out there for 1180$ now. (I am converting roughly ten kroner to the dollar here). I have a feeling the 700 will shine with the 717, while the 007 will not reach its full potential there. Is maybe a second hand KGSSHV somewhere for 1500$ as a final mad starburst before credit card debt, and the needs of my poodle princess puppy Pippi overtake this madness. Any advice? As to direction here? Havent listened to my planars since the 717 landed. Will get a Nakamichi IA w Statis design by Nelson Pass tomorrow, and maybe the SRD 7 will shine through? I am not ready to sell them all. Those I dont use anymore, or use right now, or simply dont use enough, or whatever. They have become my preciouses. My dining table floweth over. Not ready for Audioholics Anonymus I rather ask for user advice. Where to score next.
 
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Oct 27, 2020 at 12:27 PM Post #1,035 of 1,126

alfmoonspace

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I have noticed a bit of clipping with my 252S - could you guys lean me over to an upgraded energizer besides the 353x? Or is that the one to get?
 

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