TOPPING EHA5

[Aokman]

Many people already use powerful amplifiers that are capable of blowing up their speakers when driven at full volume, I don’t see them stopping to use those amplifies anytime soon, they just have to be careful with the volume control or use it in low gain mode, I thought this was common sense in Audio. I don’t see why the topping EHA5 should be treated differently. Topping got a bad reputation after the L30 problem with it sometimes outputting DC instead of AC but that can’t possibly happen to the EHA5 because DC can never physically pass through a transformer let alone be stepped up by it, if it did, Tesla would have never been as famous as he is and USA would probably still be powered with Edison’s DC.

I have a Topping LA90 running my STAX converter with Lundahl Transformers and it has impressed me with its build quality and performance.

I don’t doubt Spritzers experience in the STAX arena but I would just point out he has been solely looking at the output side of the transformers from what I read. As you said the transformers already block DC by nature and there may be plenty of protection on the low voltage side in Toppings custom ICs… They seem similar to the LA90 which has plenty of protection.

As for the audio performance, still early days but yeah we know this isn’t going to complete with Lundahl transformers especially at the price point.

 

[the_brunx]

but yeah we know this isn’t going to complete with Lundahl transformers especially at the price point.

I don’t know

 

[kevin gilmore]

2 x lundahl transformers plus la90 + bias circuit is about $1100.

 

[Tim]

Will it work with the Koss E-stat? Aren't they different bias voltages?

Stax bias for pro is 580v, the Koss ESP950 is 600v. I should point out that the prior Koss e-stats had a much lower bias, I have heard that they are 400v or less. So your Koss ESP950 is safe on a Stax pro bias.

 

[Tim]

General rule of thumb, if the amps bias is the same or lower than what headphones bias is rated you generally ok. Using the reverse, higher bias amp than the headphones that have a lower bias, then you get burned and or stuck diaphragm on the stators. Sometimes even smoke!

 

[Aokman]

I tried normal bias and pro bias on my L700s when I was messing around and all I really noticed was less volume which generally translates to less dynamics. Still sounded fine honestly lol

 

[Tim]

Yeah that’s what happens when you do that

 

[Aokman]

Yeah that’s what happens when you do that

I would imagine its probably not good for them to run vastly wrong bias like normal vs pro as you would put excessive drive into the stators trying to recover the lost volume?

 

[Tim]

A pro headphone will play at normal bias,280v, just lower volume and dynamics. To the best of my knowledge, doing so should not harm the headphones.

 

[Aokman]

A pro headphone will play at normal bias,280v, just lower volume and dynamics. To the best of my knowledge, doing so should not harm the headphones.

Yeah I wouldn’t expect it to harm them at normal levels but it was always in the back of my head about what happens when you try to recover that lost volume from the lower bias as the stators would then be much higher voltage (assuming you have an amp with the stones)…

 

[Svperstar]

I ordered a a Topping EHA5 from APOS Audio last night. I'll report on it after it arrives. I have no real test gear so I can't do any real testing; I do have OmniMic and also the RightMark audio analyzer app, as well as a Scarlet A/D converter which is quite good, so I COULD do some S/N and distortion comparisons of the Carbon amp vs the Topping EHA5 acoustically using my Stax SR-007a headphones and a DIY mic coupler - not sure it would reveal much about the amps, though, as their distortion levels would have to be pretty high to show any differences between the amps through the headphones. Certainly I couldn't do any kind of meaningful FR testing with a cardboard acoustic coupler, but I think it would be possible to compare the noise and distortion through the 'phones between the two amps. And I can do a listening comparison, though actually I would be surprised if there are any audible differences . I'll post some pictures of the insides.

Do you have the Koss electro-stats and the adapter cable that allows them to run on Stax amps? Can you confirm if the Koss will work with the EHA5?

 

[jdan1457]

Can you guys recommend some good Koss adapter cables for the EHA5?

 

[kevin gilmore]

so after working on a very old stax amp, turns out that plugging a pro bias headphone into the normal bias jack results in at least 8db less volume and significant balance issues. tried with a number of different headphones. that means you have to turn up the volume a bunch which might cause damage to the headphones.

https://www.amazon.com/Koss-ESP-950...00LCKWG40/ref=cm_cr_arp_d_product_top?ie=UTF8.
this one and others like it all use the wpi male connector which does not fit well in a real stax socket. and over time will crack the socket.
probably best to make your own, you would have to 3d print the stax male jack.
chinsettawong (other site) can probably provide the appropriate print file.

there is also the issue that the koss headphone wants a 10 megohm bias resistor, and the standard for a stax jack is a 4.7 meg resistor.

 

[Soria Moria]

EHA-5 with the new Dan Clark Corina.

 

[Aokman]

I never encountered balance issues when I tried really but maybe my L700s are too new still but yeah the volume drop was very apparent.

I tried it on my SRD-7 before I build my first gen pro bias and on the SRM-1 mk2

 

[Roland301]

The modules in the EHA5 are the same ones as in the A90D since they are labeled as such in photos and the circuit board layout looks identical, so quite a bit weaker than the LA90.

The Topping measurements of the EHA5 are made with a step-down transformer placed after the step-up, which is not a realistic load. Since the amp section is A90D, the transformers are probably 1:50 ratio which means they aren't going to be very linear.

Spritzer got his unit in and measured a pretty appalling square wave coming out at listening volume. He also noted it did not get very loud and did not sound very good, barely trading blows with an SRM-252.

I would agree that the lack of output protection isn't problematic, given the transformers themselves block DC, and the amp isn't powerful enough to drive a pair of headphones to failure, regardless of the synthetic specs. The under-specced components on the bias circuit are problematic though.

RE: running pro bias cans on NB outputs - you will get sound, but your headphones will be making buzzing and squealing noises before long. Just don't do it. If the voltage is only a little off e.g. Koss/Sennheiser vs Stax Pro Bias then it's probably fine.

 

[Aokman]

The modules in the EHA5 are the same ones as in the A90D since they are labeled as such in photos and the circuit board layout looks identical, so quite a bit weaker than the LA90.

The Topping measurements of the EHA5 are made with a step-down transformer placed after the step-up, which is not a realistic load. Since the amp section is A90D, the transformers are probably 1:50 ratio which means they aren't going to be very linear.

Spritzer got his unit in and measured a pretty appalling square wave coming out at listening volume. He also noted it did not get very loud and did not sound very good, barely trading blows with an SRM-252.

I would agree that the lack of output protection isn't problematic, given the transformers themselves block DC, and the amp isn't powerful enough to drive a pair of headphones to failure, regardless of the synthetic specs. The under-specced components on the bias circuit are problematic though.

RE: running pro bias cans on NB outputs - you will get sound, but your headphones will be making buzzing and squealing noises before long. Just don't do it. If the voltage is only a little off e.g. Koss/Sennheiser vs Stax Pro Bias then it's probably fine.

Interesting, wasn't aware they were using A90D derivatives... I'm shocked they can get anywhere near enough power out for the application. The LA90 can barely get an SRD-7 or Lundahl's to the volumes needed but obviously different ratios in the OTs.

I wouldn't buy one but wouldn't mind hearing one sometime and if it pairs decently with entry level STAX for new customers to at least get a taste... Also interested in how the square wave output actually translates into the real world sound of it vs an SRD-7 with say a class D desktop speaker amp to match the price point...

Makes me want to jam some OT's in the LA90 now because it has a crapload of room in there... If only it had another 10v on the outputs without monoblocks...

 

[Roland301]

Interesting, wasn't aware they were using A90D derivatives... I'm shocked they can get anywhere near enough power out for the application. The LA90 can barely get an SRD-7 or Lundahl's to the volumes needed but obviously different ratios in the OTs.

I wouldn't buy one but wouldn't mind hearing one sometime and if it pairs decently with entry level STAX for new customers to at least get a taste... Also interested in how the square wave output actually translates into the real world sound of it vs an SRD-7 with say a class D desktop speaker amp to match the price point...

Makes me want to jam some OT's in the LA90 now because it has a crapload of room in there... If only it had another 10v on the outputs without monoblocks...

Which Lundahls do you use, out of curiosity? I'm running LL1630-PPs which are not "hard" to drive in terms of current or load behavior, but the 1:7.2 ratio requires a whole lotta gain. Getting a Purifi build to drive my setup soon which oughta suffice

Anyway, having experienced various Lambdas off various gear, I really think those looking into "entry level" stax are better served by the mid-high end Hifiman planars like XS, Arya, etc. The cheap amps really don't do them justice, and there's too much fuss with buying used old stuff. The HFM have a comparable sound signature, with better tonality and much easier amping requirements.

 

[Aokman]

Which Lundahls do you use, out of curiosity? I'm running LL1630-PPs which are not "hard" to drive in terms of current or load behavior, but the 1:7.2 ratio requires a whole lotta gain. Getting a Purifi build to drive my setup soon which oughta suffice

Anyway, having experienced various Lambdas off various gear, I really think those looking into "entry level" stax are better served by the mid-high end Hifiman planars like XS, Arya, etc. The cheap amps really don't do them justice, and there's too much fuss with buying used old stuff. The HFM have a comparable sound signature, with better tonality and much easier amping requirements.

Yup using the LL1630-PPs also which will replace my modded SRD-7... The LA90 goes just loud enough in most cases but there are some quieter tracks that I wish I had more gain for my L700s. Would be interesting to try even more power hungry estats but I did this in preparation of getting the Corina or X9000... Max gain with 10khz output peaks about 382v (763v bridged). SRM-1 mk2 was about 470v.

2 x LA90 in monoblock mode are excellent with the extra voltage output but not cost effective, super clean noise floor with no background whatsoever and plenty of punch... My goto amp is the Sony TA-N9000ES which can put out either 100Wpc or 200Wpc bridged but this is supposed to be my desk setup so the LA90 was ideal for it without dealing with class D stuff.

My biggest hope with the EHA5 is that it would open up the estat market more and get more people trying them out and more manufacturers making an entry as it feels too elitist "buy my 6k amplifier" and other cost barriers everywhere at the moment.

 

[Roland301]

My biggest hope with the EHA5 is that it would open up the estat market more and get more people trying them out and more manufacturers making an entry as it feels too elitist "buy my 6k amplifier" and other cost barriers everywhere at the moment.

Ah, then yeah hopefully there end up being more options. Estats are really not difficult or expensive to make relative to other driver types, when we are talking higher performance tiers. Those Chinesettawong clones of Orpheus and Omega from way long ago come to mind.

I just wish Topping had designed the EHA5 around a more powerful amplifier, rather than going the route they did. Or even just selling a pair of good transformers in a box, and letting people pick whatever amp they like.