spritzer

I was sent this and it was posted on SBAF so one can expect the level of discourse over there: There is so much here that I don't even know where to start. First off, they claim this circuit is "unique"...well it isn't. Old as the hills this one, same as the old TubeCad stuff, the Rudistor amps, the prototype Schiit built, that Trilogy H1 piece of shit and I've been building similar amps for the last 15 years. Stax also released something similar in the 60's so no...not unique. The amp circuit is simple and works well enough for a cheap amp so nothing wrong with that. I also like that they used a CCS on the front end (though they claim it is on all stages but that's not true) but my issue is with the PSU and the bias supply. What an utter clusterfuck.... The circuit requires a bipolar PSU so with a center tap transformer the bias supply can be a bit tricky but simple to solve really. I just don't understand what the hell they did with that delay circuit. It's just adding tubes because... tubes? Makes no sense at all. The bias supply seems to be driven off a tap for some reason. Also, those ballast resistors look like RN55 units and they are nowhere near adequate for the job. Smaller issues, twisted output wires are a no no, not sure what's up with those output "sockets" and an unregulated heater supply is never a good idea. Still I like the colors. Might have to do something like that...

As it sits now, this will be a step down from the 252S.

I love the look of that Denon amp. Class A too...

There were pictures of him in a robe preaching to us mere commoners so yeah...

Funny enough I was buying some din plugs for the Monolith electrostatic headphones at the local store this week. They only found the metal ones and asked why I was insisting on the all plastic units... 😂

First time I heard it I wondered if Cavalli was on crack... then I saw his websites where he was a "leader of men"...

It's been quite a while since somebody has come in and told us to just ignore everything even close to negative because it "sounds good". Sure, good for you but those of us who have been here a while know that was also said about other amps which turned into an absolute clusterfuck so yeah, keep that in mind. So a couple of things things, this amp doesn't swing enough voltage to really work. Even the SRM-252S has +/-250V rails and that is really the absolute minimum for this role. Only the utter dog turd that is the SRM-D10 uses +/-200V rails but then again, the off the shelf opamps it uses can't handle any more. Now the issue is just how much volume are you using and is the amp clipping. Setting aside the issue of headroom, can the amp handle normal transient swings? Second, what does it bring to the table that a SRM-353X doesn't do and better?

Minus bias has often been tried and well... it never works. Enough issues with electrostatics even if they aren't a magnet for dust. Next step would be a whole new output stage for that amp to minimize the output capacitance as mosfets just don't work in this role. Drop the load resistors for a CCS and the amp should perform a whole lot better.

The bias supply is also the incorrect polarity and I for one would completely redo it. It has enough headroom to regulate it or do a better voltage divider and a dedicated ballast resistor on it. The output devices are also mehhh at best. Output capacitance is 106pf which means the output of the amp is higher than the headphones. The Cob should be as low as possible so this is a problem and will severely color the sound. Think Cavalli Liquid Lightning

It wouldn't surprise me that this comes from JR Audio. Same crappy wiring as they use and other silly build ideas. They have also been cloning my amps in the past.

This one came to an end this week as I finally got round to turning the amp on and testing it. Busy summer and all that but here is what this should have been in the first place: Old school KGSSHV build only using the input sockets on the back, that swanky gold IEC and the volume control. The rest was all garbage...

The ESP6,7 and 9 were all single ended so the amp won't like that at all if you've somehow connected the back stators together. You can isolate them though as I did back in the day on my esp6's.

I wasn't sure about posting this but it kinda had to be done. Pic is from HF and the usual nonsense in the peanut gallery there: So this is the Sirrah V3 from high-amp.de...aka yet another slight twist on the Stax SRM-1 Mk2 or derivatives. For me it is just the build here and well... the total shitbox we have here. First off, what's up with all the hotglue? As somebody who has built hundreds of amps at this point... I don't even own a hotglue gun nor would I ever think of using this crap. Some other goodies, top of the transformer sanded for it to fit in the chassis, no insulation on the mains plug which means this would fail even the basic CE tests, nice bit of cloth underneath the pot there to presumably stop it from shorting something on the board and I just love all the transformer leads, not twisted in any way, coming really close to the input wiring. The hand cut heatpads on the output transistors are also nice and I very much doubt that tiny ballast resistor for the bias supply is rated to 600V.... On top of that, look up the design of this thing. Basically a SRM-212 with a full size power supply and some things changed. +/-200V rails, no CCS for the VAS stage and very little power.

Seconded

Yup, that is the same as on mine. I'm just going to order a custom made transformer which will also allow me to have some fun with the amp over all.

It's worse on the 006tS I just got, there is only a 100V winding and nothing else. The cut wires can usually be restored with some precision surgery but with just one winding, nothing can be done except a new custom made transformer.

Post some pictures of the inside towards the back of amp as there is no single way to convert them.

There is nothing wrong with DIY and we try to make the PCB's as simple as they can be but it is a whole other matter to sell that DIY design after butchering the basics...

Ahh my ebay feed is such a rich source of crap. Now this: https://www.ebay.com/itm/184390225946?_trksid=p11021.c100851.m5053&_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20170803121420%26meid%3D7c8a959dd9b44639b572f30ba9d29c74%26pid%3D100851%26rk%3D4%26rkt%3D4%26mehot%3Dnone%26b%3D1%26sd%3D143674134487%26itm%3D184390225946%26pmt%3D0%26noa%3D1%26pg%3D11021%26algv%3DDefaultOrganic&ul_noapp=true Pics here for when the listing goes down. Standard KGSSHV but with a few twists: Notice that their are no terminal blocks which is bad but one bonus, this amp will kill your headphones. Can anybody spot it? It's not the twisted output leads which are a terrible idea... The bias is tied to the "bias tp" which is just for measuring the bias... before the ballast resistor!! So yeah, no ballast so say goodby to your diaphragms.

Stax SRM-1 Mk2 and upwards.

I'm not sure where I wrote down the pinout for the Monoprice headphones so I'll have to dig through my archives to see if I can find it. If I find it then I can make adapters as soon as the local store opens up after the long holiday here. As for getting the most out of these, an amp upgrade would be the first port of call.

All Stax are balanced and even if an amp has two outputs... they are wired in parallel with both channels at both sockets. What benefit could be had from this is very dubious.

I agree, those are very nice indeed. Could be old stock but I doubt it. Most likely Stax just enjoy messing with us...

Is it a Mk2 or an A unit? Also, this week in stupid: https://www.ebay.de/itm/124250502104?ul_noapp=true Here are the pics in case the listing is taken down: So somebody chopped off the Stax plug on a Mk1 and fitted two for dual mono... why I don't get but then stupid is hard to understand.

Good point so the empty warranty card points to a Japanese unit and the sellers who export never fill out the warranty cards.