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TOPPING EHA5

Yeah… it really hurt, but hey if they’re that good I can live with it, gives me time to try another bias design while I wait for them :)
 
I just realized looking at the specs that there is higher gain on the single ended RCA then the balanced XLR.........does that mean the amp will be louder if you use the RCA connection?

I just assumed XLR would be louder, anyone tested this?
 
I just realized looking at the specs that there is higher gain on the single ended RCA then the balanced XLR.........does that mean the amp will be louder if you use the RCA connection?

I just assumed XLR would be louder, anyone tested this?
The EHA5 has 6dB higher gain with RCA in to compensate for the 6dB lower signal amplitude that RCA Line out typically has, compared to XLR.

So with a typical desktop DAC (2V RCA, 4V XLR), the volume out of the EHA5 will stay the same when you switch from RCA to XLR.
 
Thanks to @Aokman for his inspiration and advice, along with @kevin gilmore for answering questions. This setup sounds fantastic. Easily puts out over 2kV down to ~13Hz with a perfect looking sine wave. 10Hz will go up to ~1400Vpp before starting to distort a little. I stopped my testing a little over 2kV, but I had more headroom left when running the AHB2 in bridged mode for most frequencies even at 2kV!

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1kHz square wave into AHB2, new transformer setup:
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1kHz square wave into BHSE (less ringing so of course the better measurement):
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As aokman pointed out, my DAC is the limiting factor, so this square wave was generated from the PC out my DAC3 B to the BHSE (1.03kV measurement) and transformer setup (1.04kV measurement). They look identical to me:
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Some 10Hz measurements:
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20Hz at 2kV:
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at no audio frequency can the eha5 generate 700vrms without the amp going into shutdown mode. bob katz and others have tested this.
the nfca modules are limited to about 4 watts of power output, and that is nowhere near enough to drive those transformers.

a pair of edcor transformers and a bias supply ends up about $450 in parts. really excellent for the price. you still need a good 60 watt power amp.
 

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Thanks to @Aokman for his inspiration and advice, along with @kevin gilmore for answering questions. This setup sounds fantastic. Easily puts out over 2kV down to ~13Hz with a perfect looking sine wave. 10Hz will go up to ~1400Vpp before starting to distort a little. I stopped my testing a little over 2kV, but I had more headroom left when running the AHB2 in bridged mode for most frequencies even at 2kV!

Made an account here purely so I could ask you what model transformers you used. I have a transformer box I built and enjoy greatly, and I used the LL1630 in mine.
I can't quite make out the model number in your picture. Also that 10Hz sine with distortion, was that the BHSE or the transformer + AHB2?
 
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Welcome to the forum! They are Lundahl LL9202 transformers.

Also that 10Hz sine with distortion, was that the BHSE or the transformer + AHB2?
All sine wave measurements posted are of the transformer setup. Of course, the BHSE can do 1500Vpp at 10Hz with a beautiful looking sine wave. Getting ~1400Vpp @10Hz from a transformer setup with a clean looking waveform is really good though; a little higher in Hz and it has more bass output than a BHSE (as the 20Hz 2kV measurement shows, was also getting a clean waveform at 13Hz@2kV). Up to you if you need the extra volume and additional bass output or not. A lot of people really like the LL1630's. As aokman shows in his video below, they are a little lacking in the low end, but otherwise have an outstandingly flat resposne without any additional components.

 
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Yeah I think the LL1630 still has its place… its insanely linear / well behaved out of the box with no resistors etc but yeah if you want more voltage swing, gotta step up to bigger options… A shame they couldn’t maintain similar characteristics to the LL1630 with more capabilities…
 
so far I see only Lundahls being used for these DIY builds. Would output Transformers meant for EL34 Amps (hooked in reverse), also be good candidates for such a build?
 
so far I see only Lundahls being used for these DIY builds. Would output Transformers meant for EL34 Amps (hooked in reverse), also be good candidates for such a build?
Im testing an Edcor output transformer currently based on a recommendation from Kevin, it definitely won’t run bare linearly like a LL1630 but it definitely has far more capabilities with some external resistors etc… Ill be doing a video on it shortly as soon as I finish my audio analyser…
 
May I ask that this thread be closed or the multitude of comments, not germane to the EHA5, be given their own thread? ESTAT amps are their own sub-species of arcana and add nothing to this particular implementation.
 
I just received the EHA5 alongside the Stax SR-X1 headphones. Bought both for under $1000 and decided to go with the EHA5 over the budget Stax amp they sell in a bundle with the SR-X1, because I wanted to used XLR connections to my RME ADI-2 DAC.
Having never heard electrostatic headphones before, here are my initial observations. Short answer: They work, they sound clean, even at the maximum volumes I'd be willing to listen. Thus it's possible to buy what sounds to me like a high quality electrostat + electrostat amp for under $950.

Details.
My standard system is the ADI-2 dac/amp powering Senn HD800 and using some 3rd party parametric EQ settings on the ADI-2, which I think yields a high quality sound. Normally fed Amazon Music at Ultra HD or HD.
My initial test of the Stax SR-X1 for a few hours was good. No equalization. RME ADI-2 fed the EHA5 via balanced inputs and XLR plugs. High power setting. Line out volume from ADI-2 at about -4db, and the volume dial about 12 oclock on the EHA5 was as loud as I'd want to listen. At that (for me) full volume I heard no distortion in either music or test tones.
The Stax headphones sounded slightly "cleaner" to me. The Senn headphones sounded a bit weightier on lower bass, but that could be because of the large shelf eq I applied to the HD800, versus no EQ (yet) on the SR-X1. HD800s to me are physically somewhat more comfortable and cooler for long-haul listening than the SR-X1s.
 
Can someone summarize in layman's terms the safety and quality of the EHA5 as opposed to something in the same ballpark like the newer Stax SR-270 (seems to replace SRM-252S)? I' m not sure if there are other sub-1000 new options or whether the 270 is meaningfully different from 252S which is what I'm using for L300 Limited, but I can tell the 252S is a limiting factor.
 
I would suggest looking into the Mjolnir Audio SRD-7 especially if you can get one with Lundahl transformers. https://mjolnir-audio.com/electrostatic-amps/

This is an ADAPTER for Stax pro-bias headphones, you connect it to a regular (speaker type) amplifier's speaker outputs, your amplifier provides the power and the SRD-7 provides the bias voltage and converts the audio power coming from your amplifier to drive the electrostatic 'phones. The Mjolnir units have a much better bias supply than the stock Stax units. And if you can get one of the SRD-7's with the Lundahl transformers you have a superior to the Stax version of this type of adapter. This will typically sound better than any of the Stax amplifiers.

An alternative would be to try to buy a used version of the KGSSHV Stax 'phones sound great on one of these.

Stax pro-bias headphones sound best with a cleaner, tighter bias supply and a drive circuit that can swing high voltage cleanly and with good slew rates, which the Stax amps don't really do.
 
Can someone summarize in layman's terms the safety and quality of the EHA5 as opposed to something in the same ballpark like the newer Stax SR-270 (seems to replace SRM-252S)? I' m not sure if there are other sub-1000 new options or whether the 270 is meaningfully different from 252S which is what I'm using for L300 Limited, but I can tell the 252S is a limiting factor.
a SRD7 replaced my blue Hawaii. If you like to listen to headphones with eq or/and on the louder side, all dedicated stax amps no matter how big will start to distort when pushed, transformers are the only solution.
 
a SRD7 replaced my blue Hawaii. If you like to listen to headphones with eq or/and on the louder side, all dedicated stax amps no matter how big will start to distort when pushed, transformers are the only solution.
What amp do you use for the SRD7? A cheap Fosi Audio FA3 gives a very good performance when changing all the op-amps for better. Amp is only 150€ but op-amps 300€ :D Sound a bit of tube and solid state, like a hybrid. The treble stays in better control. 150W/4Ohm is sufficient. I can't use High gain from the Schiit Magni when using XLR input but sound is much better than RCA input. I have the Ifi Audio iESL.. So lots of power is needed for Nectarsound HiveX.
 
What amp do you use for the SRD7? A cheap Fosi Audio FA3 gives a very good performance when changing all the op-amps for better. Amp is only 150€ but op-amps 300€ :D Sound a bit of tube and solid state, like a hybrid. The treble stays in better control. 150W/4Ohm is sufficient. I can't use High gain from the Schiit Magni when using XLR input but sound is much better than RCA input. I have the Ifi Audio iESL.. So lots of power is needed for Nectarsound HiveX.
any stereo amp with good thd+n/sinad, a gain of 30dB or more (or add preamp if needed), and about 10Watts or more into 4Ohms is all you will ever need really.
 
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Yep. I did my own testing and figured this out. All amps you can buy will clip for a split second if you play extremely dynamic tracks. Best to use high quality transformers if you never want to clip. I run two AHB2's through mine.

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You can see in this video, some of the transients go over 2kV, so I had to use two AHB2's to prevent clipping lol:

a SRD7 replaced my blue Hawaii. If you like to listen to headphones with eq or/and on the louder side, all dedicated stax amps no matter how big will start to distort when pushed, transformers are the only solution.
 
@etc6849 How loud do u listen to music? It's just crazy how much power there is for one channel. I'm happy with Fosi Audio ZA3 with paired Ifi Audio iESL. No clipping!
 
If you measure the iFi Pro iESL at low frequencies, you'll see it to has tons of distortion. As for loudness, the larger headphones like the DCA Corina or Stax X9000 have a much larger stator gap, so are harder to drive. It takes the amps I have through the particular transformers I used to hit 2kVpp. Music has transients, I don't want to ever have clipping.

If you have an oscilloscope and differential probe that can handle 1-2kV, measure the iESL... You can easily see how poor it is at low frequencies.

For example with the iFi Pro iESL at 10Hz, you get this distorted looking sinewave for L+ to L-, less than 600Vppss:
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This was with a dummy load, thinking I used 120pF, but can't remember now. I have no idea how manufacturers get away with flat out lying on their specs, it's total BS. No way would this POS do 5Hz. iFi is no better than Topping apparently.

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The bottom line is small transformers go into saturation at low frequencies like many have previously stated in this thread, you will get distorted wave forms as shown. Just because you may not be able to hear it, doesn't mean it's not there. I can promise you the bass is much better on my custom transformer setup as I've tested and own both.

@etc6849 How loud do u listen to music? It's just crazy how much power there is for one channel. I'm happy with Fosi Audio ZA3 with paired Ifi Audio iESL. No clipping!
 
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