spritzer

Yes and no. It will always be way over spec just to be safe.

I'm only talking about using the basic ESX circuit so the output tubes will be ECC99 with ECC81 drivers. The psu will be something simple which does the job but follow the same lines as the latest stuff from Kevin. I like the idea of using a separate psu for the bias supply with it's own regulation and it would be easy enough to just add a couple of voltage divider spots onto the board for 230V and 500V output so no adjustment necessary. Since we are probably going to need a custom transformer then we can do pretty much anything from the simple N- and P-channel affair in the old KGSS article to a version of the BH psu with split secondaries. A delay line could be added but it just adds cost and really isn't needed.

A ESX would be simpler to build than a BATE and the lack of capacitors would make all the crazy people out there happy. I like the ESX because it uses so few parts and while the whole cross coupled thing looks complicated, it really isn't in a way and people never need to know how it works. Well that and it sounds amazing once it is up and running properly. The balanced inputs are "free" here and having guided dozens and dozens of people through amp builds they have never caused any issues. Not much difference between a dual pot and quad pot and steppers are cheap on ebay. The ESX amp circuit is cheap to build so only a few $ in resistors and tube sockets plus four 2$ caps and that's it. 10W plate resistors would be pretty expensive so a simple 10M90 CCS isn't that much more expensive with much better performance. A spud... yeah let's class that with KG's gas tube amp...

It's a speaker amp driving stepup transformers. Since they have no detail at all about the amp then it's probably one of those things which can't see the light of day. The awesomeness and magic would disappear once people know what a POS it really is...

30-40K Yen. We really need to beat some sense into them about those bloody AA's. Hello Li-ion...

I think Steve nailed it!! Paging Dinny, paging Dinny to the Mafia DIY section...

Think RWA with silver transformers and the snake oil piled on thick.

I've been giving this some thought and perhaps the best candidate for rework would be the ESX circuit. Three stages, mostly DC coupled and arguably, one of the finest tube circuits I've ever seen. The money we save on the various caps can be spent on a CCS for the output and even for the front end as well. With a C- supply there will be no offset issues and with a PSU of say +/-300V it will be a very capable amp. This is naturally a Stax circuit so I see no better way for the Mafia to show it's gratitude for 50+ years of great products but by reworking one of their designs. Here is the basic design: http://www.bonavolta.ch/hobby/en/audio/hdgsta.htm Now the issues, there is no transformer out there which meet the required specs, two filament windings, bias tap and the right HV voltages. Not a big deal though since people like SumR and Edcor could have a fixed design on their books which people can just order. Same wires every time etc. The second is what parts to use. ECC81 and ECC99 are the obvious choices and the resistors can be what ever that fits but the CCS is a bit of a challenge. I'd really like isolated parts to make assembly easier (no high voltage pads etc, required) but I'm coming up empty. 2SA1968 is an obvious choice but there is very little stock left and I'm not dipping into my stock to supply a group build. Any ideas for a suitable part?

Yeah, it's just too stupid. Only the T2 and BHSE can dig up this level of detail. What other top amps though, the WES with way too many caps in the signal path and a horrible design or the A-10 which reaches 5% THD a low levels and just keeps on rising? Fucking idiots...

I'm not the biggest fan of "balanced at any cost" but it really must be balanced for the audience but also being able to be used SE. No half-assed designs here like the WES and A-10. I'd really like to take a crack at "the ultimate" diff amp but it looks like 3 stages is the minimum we can go for. Even with a ECC83/ECC99 combo it simply doesn't have enough gain. Less volume means less good amp to a lot of people... Edit. You wouldn't believe just how much willpower it took to keep my Baldur SE only when the balanced input is better in every way.

Perfect excuse to fire up the BHSE...

That one should be close to the final version but I think we settled on +/-350V rails in the end.

I like that Frank, nice and simple. Have you ever messed with feedback in these amps? I used 150K and 1uf/630V in one of my Egmonts and it really helped stabilize it. I really like the idea of taking the diffamp to the max to see just how good it can be made. If we can find cheap chokes then I'm all for it but a simple pass transistor with a zener reference would probably be cheaper and easier to deal with. Even better to use isolated parts to kill any chance of shorts. Balanced input is a must have for the amp to be taken seriously and it really must have too much gain for the "MOAR LOUD!!!" people out there so ECC83 drivers with a bypass cap on the cathode. The idea is to try and make a high voltage amp anybody can build and be as cheap as is possible. It would also be a nice reference point to compare against the commercial amps. I think less than 400$ would be easy to reach with say 80$ for a transformer, 30$ for the PCB's, 50$ for the tubes and the rest for assorted parts. Not posted but I should have it somewhere, at least one version of it. That version is just a SRM-007t front end and a 6S4A with a 10M90 CCS and a trimmer+resistor on the cathode. I used Marc's Vulcan PCB's and modified them to become a KGST.

They are really something but the headband needs to be improved. I've been thinking about something like the LCD-2 approach, thin layer of memory foam to make them useable but can't find anything locally.

Very nice indeed!!!

Use a transformer to step down and another one to step up again? Nahh, even an Egmont would be preferable to that.. For the amp I'm leaning towards something simple like a quad of ECC8*'s feeding a pair of ECC99's. ECC99's need to be left floating so two filament windings at a minimum. Nothing else out there which fits "cheap, high voltage and reasonable power" though and we really could look into CCS loading the output tubes, hell CSS load the lot of them given the low currents involved. It just has to be weighed as a cost vs. performance issue.

This one will not sound like any 300B amp, that's way too much distortion for us. A triode is still one of the best ways of amplifying ever invented so why not cram three of them per phase for a brilliant cheap-ish amp. I've also been brainstorming recently with Kevin about making a true Volksamp for the people. Basically, what is the cheapest amp we can build without sacrificing our level of quality while having some strict design guidelines. This just expands on my vision at the start of the Exstata project but naturally learning from that clusterfuck. The BATE is an excellent amp but it's PSU is highly advanced and requires some advanced assembly with the correct parts (i.e. use the correct insulators or you will have trouble) and it uses tubes which are out of production. I want something which has all the parts in current production and easy to source, using a transformer which is available off the shelf at 117/230V and should just work if all the parts are in the correct spots and face the right way. Hell, I might even write up a "how to" guide for this one... Any ideas for good tubes or topologies are welcome... Ohh and then there is that truly insane idea, making a 'stat amp with miniature tubes. It would technically be portable...

Nothing wrong with running the wires underneath PCB's but stay clear of AC lines and use wire with ample insulation. I also hope you aren't running the amp with the transformer sitting on the metal chassis? I would recommend placing a rubber pad between them just to be safe.

Time for an update, the BATE prototype PCB's landed here yesterday so naturally I started assembly... http://i.imgur.com/dLaky.jpg http://i.imgur.com/0QITM.jpg Warning KG sized pics. I'm missing some parts so it won't be ready until Fedex shows up but it will be a neat little amp.

I have an even better way, just swap one phase from left to right at the Stax plug. Instant crossfeed!!!

Going on what few internal pics of the Pawel stuff there are it does look like a clone of the Stax circuit adjusted for the newer sets. They also had some amps but who knows what's inside...

The TTVJ amp works well because Pete knows his stuff. The gimmick comment was aimed at ALO since it is bound to be badly built garbage. Just look at the Rx, sounds like shit and they are up to Mk3 now because they can't seem to fathom that li-ion batteries do not behave as alkaline's. You can't just wire them with a CT and expect it to work...

Get the SR-009 then...treble head...

There were plenty of tubes designed to work at low voltages and made super small but using tubes is just a marketing trick. "Hey this one is different!!!" Then you ALO to the mix and it's probably horrible in every way.