Used amplifiers

Time to split up the special’s page into two so one for headphones and another one for electronics.  Here I’ll list what my more unusual amplifier projects, used amplifiers that I’ve refurbished/rebuilt plus any other piece I’m selling.  Feel free to contact me at spritzer@mjolnir-audio.com if you are interested in any item here.  I will reply to every mail so if you haven’t received a reply within 24 hours then feel free to send me another email.  Email gets lost all the time or is flagged as spam.  All prices in US dollars (USD).

 

Ahhh the Stax SRM-T8000. I bought this one as the first used unit to hit the market anywhere as I just had to try the new flagship amp. I got it from Japan but we quickly figured out how change to any voltage so it is now set to 240V. This is serial number 26 so early first batch for people who care about that. It is mint in every way and while Kevin Gilmore and I have both opened it up to see what the circuit contains, it is still perfect. The screws were not in the top as Stax screws always get scratched with use so they were kept secure until the amp ships out.  It comes with everything a new amp would come with except the wait time…  😉

Price: 4600$ plus shipping

Here is one I thought I’d never sell but then again, I never use it. So this is a Stax SRA-7S which as the first popular Stax amplifier and designed for the SR-1. This was back in 1967 so before even the SR-3 or SR-X mk1 was released. It’s an all tube design and quite small for the amount of circuitry that is in it. So I got this amp from Japan and it has been completely rebuilt. The only original parts in this as the chassis, output sockets, tube sockets, amplifier PCB and the original tubes as they all measured good. The rest is all new and improved. There is a thread on head-case.org where I documented the lengthy rebuild process but basically when I got the amp it was 100V only and the power supply was basic to say the least. There was also no place to put the improved power supply so the first thing I did was to scrap the phono input as it took up so much space and was terrible to begin with. The transformer was scrapped and a new unit from Hammond was installed with the +300/+600V power supply from the Octave. The amplifier board was completely rebuilt with far better parts and moved further away from the transformer.

I really went to town here though as everything else was changed and upgraded. The front panel markings were peeling off when I got the amp so I cloned them and had my laser shop etch them onto the same plate once I had cleaned off all the old labels. The back panel RCA sockets had not aged well so I replaced them with new gold plated Neutrik sockets and redid all of the input wiring. There was a new input switch fitted plus a new volume control and balance pot, both Alps RK27. The power and mono/stereo switches were also both replaced with new units from Japan plus one output was converted to Pro bias output to make it more modern.

This amp has one unique feature which Stax stopped adding in the 70’s… it has a tone control. Basically this is a switch which has 4 settings and it increases the amount of series resistance there is inline with the output of the amp. Now the stock configuration was odd as it treated just one half of the push pull output so when I rebuilt it, it’s done right with matched sections for each output phase. Finally the amp was fitted with new feet, a proper power cable with strain relief and the top cover was powder coated. Last but not least…the knobs used on these are still being made in Japan so I custom ordered new ones as the old ones were unsightly.

The prices for these amps are crazy in Japan now even with tatty samples hitting 1000$ or more. I paid way too much for this one and the rebuilt was…insane so that explains the high price. I also kinda don’t want to sell it but that’s how it is… 😉

Price: 1900$ plus shipping

I’ve had this SRA-3S sitting on shelf for years and used it to harvest parts for the other units I’ve refurbished over the years. The plan was to just throw it away but then it hit me, I could cram some Octave V2 boards in there so that’s what this is, a single ended Octave V2 with just RCA inputs in a vintage Stax chassis. Inside, everything is new though. The only old parts being used as the output sockets, power switch and the RCA inputs. The rest is all new and given the larger size of this chassis I can use a far beefier power supply than the normal Octave V2. Much bigger caps and an oversized transformer. All the switches on the front panel beside the power switch have been disconnected and the input switch replaced with a large orange LED.

In terms of performance this is just like the Octave V2 so similar to the Stax SRM353X but more powerful and a better power supply. It can be wired to either 117V or 230V and has a hard wired power cable which I can change to a US one should the amp go there.

Price: 790$ plus shipping

This is a one off Dynalo like the other ones I’m selling but only in a project box. This case came with some laser etched markings so I just used it as a test bed for this Dynalo design. This actual amp has the brand new matched input fets which many of the future amps will use. Only other difference is the lack of markings and just one input, no loop output. Can be set to either 117V or 230V.

Price: 510$ plus shipping

 

Last updated 16.04.18

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