TOPPING EHA5

[kevin gilmore]

same problem i have with toroidy transformers. shipping exceeds the part cost.

 

[Aokman]

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

 

[Svperstar]

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?

 

[staticV3]

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.

 

[etc6849]

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!

1kHz square wave into AHB2, new transformer setup:

1kHz square wave into BHSE (less ringing so of course the better measurement):

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:

Some 10Hz measurements:

20Hz at 2kV:

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.

 

[gammi]

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?

 

[etc6849]

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.

 

[Aokman]

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…

 

[the_brunx]

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?

 

[Aokman]

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…

 

[dartinbout]

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.