[Chefguru]

Ahuh…. I keep hearing such things then you try to decide what direct drive amp to buy and the crap fights begin about what direct drive amp. KHSSHV, BHSE, Z10e and god knows what else and no one was willing to subject one to analytical measurements vs a high end transformer setup, let alone each other…

I have 2 transformer setups and counting now and 3 high end amplifiers and still haven’t got near the price of a BHSE alone…

Whatever floats your boat I guess but I'm betting you cannot hear any difference between a reference direct drive amp and a high end transformer setup in a blinded comparison. Then again Im expecting all the usual audiophile caveats at that point of “your source isnt good enough” you need “better estats” “you cannot measure the differences analytically”

One thing that doesn't get talked about enough when these conversations come up is that some of the direct drive amps have a bit of coloration added to the sound due to the mosfet translation stage; the BHSE / T2 for instance. I love both amps, and it actually can work in favor of the modern stax sound (x9k,009) but yeah... still. T2 sort of have the "excuse' for being so noisy, and dealing with the core circuitry in-stability since it's the closest amp that can get a headphone to the max Vppss threshold (I suppose until Kevin completes the D&G).

This part of why I prefer the all-tube megatron for the "fun amp" in the arsenal and the carbon as the go-to for a very clean no mosfets/no servo type situation. To me, those are the flagship amps that justify the leap, plus I only own estats so yeah that too

 

[Svperstar]

all these transformer things are just a cheap way to listen to hp, hold out until waiting for a package with a real amplifier like Megatron or Carbon

After listening to them just once - you will no longer want to return to transformer boxes

It makes sense to use transformer boxes with something cheap like cheapest lambda series if the main goal is to save as much money as possible

There was a 4 way blind test on Headfi in like 2012 or so between 4 estat amps. All 4 people voted a Stax 007 tube amp dead last and a transformer box first place. I do think the transformer box was powered by a $5,000 speaker amp tho.

Also there is the YouTube video of the guy who made his custom transformer setup that pushes 800 volts.

Dunno if it's as simple as saying all transformer boxes suck

 

[myheadHz]

IIRC the SRD-X Pro uses the actual headphone signal to generate the 580v bias which is pretty poor design.

SRD-7 doesn't do this and has bigger/better transformers but is still not optimal, you'll get some roll off above 15khz with the SRD-7 as the transformers saturate. It's possible you may actually find this enjoyable but yeah, it's not accurate. One thing you should do with the SRD-7 that helps a lot is remove the thermistors and replace with resistors since they add unnecessary distortion in the signal path. Takes 15 minutes with a soldering iron. I go over the process starting with this post: https://www.head-fi.org/threads/the-stax-thread-iii.677809/page-1605#post-17658579

Only way to get "optimal" performance from a transformer is DIY using something like Lundahls or Edcors. Reason I put optimal in quotes is some would still argue it's suboptimal due to some odd transformer effects but you can at least get big voltage swings and flat frequency from a large enough and well built enough transformer.

You could also buy an SRD-7 already modded with Lundahl transformers from Mjolnir Audio if you're ok spending $1500 instead of the $500 to do it yourself.

I've not opened mine up, but I'm pretty sure it's not self-biasing. It needs to be plugged in for one, and doesn't have the behaviours of the SRD6 (which is self-biasing), namely fade-in after quiet sections and less/none channel imbalance on some of my older stax (which start with imbalance on the SRD6 although tend to balance out after a while) which I attribute (rightly or wrongly) to the charge getting big enough.

I wonder what protection SRDX-pro uses, as it is later than the SRD7 I think, and iirc, I read that thermistors were replaced as a means of protection on the later models?

I will be buiding my own energiser some point soon, have a stack of Stax energisers ripe for repurposing (ergo the transfomers) but want to build my own bias circuit (probably cockcroft ladder like the stax ones), I'm just curious if this is worth it with the SRD6/SRD4 boxes I have or if I should look for SRD7 transformers, or not bother at all and go full on Lundahl or equiv. Currently thinking the latter.

all these transformer things are just a cheap way to listen to hp, hold out until waiting for a package with a real amplifier like Megatron or Carbon

After listening to them just once - you will no longer want to return to transformer boxes

It makes sense to use transformer boxes with something cheap like cheapest lambda series if the main goal is to save as much money as possible

I dunno, cheap way yes, but also opens up the the myriad of amps out there that can be used and ime a lot of them are better than Stax amps I tried. I've not much experience with Stax amps, although the 3 I have heard (006T, 007T and 313) were floored by even a midfi 80's sony amp using the same DAC and left me somewhat underwhelmed compared to other amps using SRDX-pro (and even SRD6).
Stax amps seemed to be generally great at the top end and give a wonderful airy-ness, but not anything I have heard some other amps do, and the low-end presentation of the stax amps I have tried does a disservice to the stax transducers imo. As they can do bass, and oodles of it well textured and bodied, which seems to be a common misconception about estats in general floating around tinterwebs, which I am starting to wonder is down to the fact that everybody listens via Stax amps? idk? (something I fell victim to, but had my jaw hit the ground when I first heard estat bass). And I listen to a lot of dnb

The chain I current have even makes the SR-X mk3 give thunderous well extended bass (which is contray to all online opinions of SR-X low-end presentation). While I think most of this came further upstream (from the DAC), the stax amps seemed to loose a bit of this compared to other amps which retained and even 'amplified' this part of the FR (I use tone controls, not software EQ though). I also regularly listen to L500 and Sigma NB (the latter of which is starting to mould to my head ) to very satisfying results with this setup. Can it be better with Carbon/KGSHV? most probably? How much better... dunno...

I agree with Padam, they can't really be judged as standalone since they are completely dependant on upstream (source and amp), and I am sure even the ultimate transformer box would introduce some degradation (it's after all another component in the signal path, including cabling, and every transformer introduces noise of some type) but it's overall negative impact is another matter. It does sound like Lundahl etc surpass the Stax transformers and are the components to aim for to mitigate any degradation.

Granted a high end Carbon/KGSSHV etc may sound exceptional, and one day I will look forward to get round to building one (I do like my normal bias phones though so would need a NB bias circuit in it), however I am not in the camp that there is a direct correlation between price and sound as I have paid far too little to hear some of the best sounding audio that I have experienced (some vintage stax gear included), and so far been a bit underwhelmed by the 'cheaper' stax amps I have heard so I'm not convinced it would be 1000's of monies better... although I do think (hope) it would sound better. In the mean time there are decades and huge numbers of exceptionally good amps out there which I suspect would pair incredibly well with Stax headphones. Ime Stax headphones have a much bigger spectrum of how they respond/behave to differering chains, like no other headphone I have expereinced... they can literally sound completely anemic, and other permutations result in absolute sonic bliss... all via my lowley SRDX pro.

 

[aokman]

I will be buiding my own energiser some point soon, have a stack of Stax energisers ripe for repurposing (ergo the transfomers) but want to build my own bias circuit (probably cockcroft ladder like the stax ones), I'm just curious if this is worth it with the SRD6/SRD4 boxes I have or if I should look for SRD7 transformers, or not bother at all and go full on Lundahl or equiv. Currently thinking the latter.

Look into other / safer alternatives that use DC-DC sourcing and are completely seperate from mains. It solves any potential hum / ground loop issues, safer and much cleaner (in my testing anyway). Everyone seems to overlook how important the bias is to the sound also, it is the reference for which everything else acts against and any bias noise will leak into the final sound. I did a video on my first attempt and second attempts using the STAX design then finally a DC-DC converter which was still better than anything STAX used in the SRD-7 etc, but taking it further now.

How STAX got away with such things even back in the day is scary to me. At the absolute bare minimum, you need an isolation transformer in place for the bias.

 

[aokman]

There was a 4 way blind test on Headfi in like 2012 or so between 4 estat amps. All 4 people voted a Stax 007 tube amp dead last and a transformer box first place. I do think the transformer box was powered by a $5,000 speaker amp tho.

Also there is the YouTube video of the guy who made his custom transformer setup that pushes 800 volts.

Dunno if it's as simple as saying all transformer boxes suck

I think most people making such claims have only heard an SRD box / AC derived bias system. Ill happily bring all my transformer setups to any audio meets in AUS when they’re finished with some fine Japanese amps to drive them if they want a real comparison…

I think a couple posh Lundahl amorphous core transformers being driven by my NEC A-10X monoblocs will be the end of the road for me. The Sansui 907MR with loudness button is still my personal favourite though even though it ain't reference…

 

[kevin gilmore]

in the usa at least stax got away with direct ac mains to the transformers because of the polarized ac plug.
bad idea. but legal 30 years ago. lots of tube type televisions with hot chassis did the same thing. also a bad idea.
but cheap. Zenith was the only manufacturer that used an isolation transformer. weighed 15 lbs.
for transformer boxes the way to go is one of the high frequency switchers you can find on ebay cheap.

edit: its actually more like 50 years ago.

 

[KDS315]

Never understood it took the US that long to introduce a PE (protective earth) wire on their AC power supply outlets and one way only fitting AC plugs; that’s long been a standard here in the EU.

 

[Tachikoma]

all these transformer things are just a cheap way to listen to hp, hold out until waiting for a package with a real amplifier like Megatron or Carbon

After listening to them just once - you will no longer want to return to transformer boxes

It makes sense to use transformer boxes with something cheap like cheapest lambda series if the main goal is to save as much money as possible

Have you actually tried a decent transformer box (not an srd-6 or srd-7)? I owned a kgsshv carbon and tbh, the transformer box + amp was every bit as good, if not a little better.

 

[icnaiwhimor1975]

I think everyone will still have their own opinion

Has anyone actually tried to measure slew rate in transformer boxes?

I seriously doubt that any of them can approach 100 volts per microsecond, as kgsshv carbon does

 

[DougD]

I am far too ignorant to contribute to the transformers vs the bespoke e-stats amplifier discussion but I do want to express appreciation for all of you who invest your passion, intellect, time & money into the eternal quest to push the boundaries of what's possible.

 

[Chefguru]

The transformer box situation is not that controversial. A well made Lundahl transformer box is $1500~ and the cost of a proper speaker amp for the job is $2500+ (used) which basically works out to the same price as a new carbon (actually Dukei, Soren and other builders make carbons for under $4k). Carbon is going to do a better job since it’s a more optimal solution, but if you already have the speaker amp it makes sense to save some dough.

Megatron/T2 offer some benefits beyond the above either in topology or power.

And then all of the cheaper options (e.g. kgsshv, KGST) are essentially better choices if you don’t already own a speaker amp.

The headamp BHSE is probably the most controversial at this point given how much the price has risen over the years. That said, it’s an extremely well built amp and the golden standard for 10+ years now.

 

[etc6849]

This is what I had a picture of from before when I was comparing the two; while feeding each from a signal generator. Note the small amount of ringing on the transformer setup is negligible in my opinion as both setups ring when my DAC is used.

BHSE (800V/15us) = 53.3V/us

Transformer setup (800V/10us) = 80V/us

I think everyone will still have their own opinion

Has anyone actually tried to measure slew rate in transformer boxes?

I seriously doubt that any of them can approach 100 volts per microsecond, as kgsshv carbon does

 

[etc6849]

Could be, but I need to have someone in South Carolina bring one by for me to try out. There needs to be a measurable improvement too, plus I need to get one at a fair used price.

No way would I shell out $6900 plus shipping for one without seeing published measurements like Benchmark does in their manuals.

I did buy a BHSE, but only because it was used and I can always get my money back on it due to its reputation. How much could I resale a $6900 Carbon CC for? Like $2800-3500? That's over a 50% loss if I don't like it. No thanks.

Carbon is going to do a better job since it’s a more optimal solution, but if you already have the speaker amp it makes sense to save some dough.

 

[aokman]

The transformer box situation is not that controversial. A well made Lundahl transformer box is $1500~ and the cost of a proper speaker amp for the job is $2500+ (used) which basically works out to the same price as a new carbon (actually Dukei, Soren and other builders make carbons for under $4k). Carbon is going to do a better job since it’s a more optimal solution, but if you already have the speaker amp it makes sense to save some dough.

Megatron/T2 offer some benefits beyond the above either in topology or power.

And then all of the cheaper options (e.g. kgsshv, KGST) are essentially better choices if you don’t already own a speaker amp.

The headamp BHSE is probably the most controversial at this point given how much the price has risen over the years. That said, it’s an extremely well built amp and the golden standard for 10+ years now.

It depends where you live in the world… A BHSE costs 10kish in AUS, I built my first Lundahl 1630 setup for a but less than 1k and my Sansui Alpha 907 amp was $2500 (which will actually appreciate in value and is rare).

KGSSHV Carbon plus shipping and duties will be about 12k to Australia. That is before we get to resale value where anything estat related in Australia has abysmal resale value and you simply won’t sell it again for anything less than a 30-40% loss, if it ever sells.

Anyways buy whatever you want, im not saying one is better than the other but people need to stop crapping on transformers as some sort of poor man’s inferior attempt. They offer things direct drive don’t have either…

The reason I wont buy direct drive is because its all hearsay, no analytical measurements, clones everywhere and infighting over what is best and I don’t gamble with that sort of money on something that is basically a boat anchor if I don’t like it in Australia…

 

[aokman]

I think everyone will still have their own opinion

Has anyone actually tried to measure slew rate in transformer boxes?

I seriously doubt that any of them can approach 100 volts per microsecond, as kgsshv carbon does

I will do some testing on this also but yeah transformers are all going to be different but that was the whole point of my journey into them anyways… my best amp is rated at 200v/microsec but I have all manner of amps in the shop currently with no listed specs like the NEC A-10X (High Current), Yamaha B-6 (X-Power Pyramid of Doom) and a couple Sony VFETs so happy to throw them all into the mix also.