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Stax SRM1 Mk2 new lease of life

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HI everyone,

I have own the Stax Lambda Pro since the early to mid 80s and I purchased it brand new at Encel HiFi in Richmand for under $1500. At the time I dont think there was anything that was analytical, neutral and transparent on the market that could produce the SQ i need. For those who know me I want to hear everything a recording has to bring to the table, I dont care if its s--t I want to hear it as it is, I dont need euphonic liquid reproduction, I want to be able to hear evey stuff up a musician has made or the edginess of a voice or the metal string edged as it is plucked. So the only way to get there was to get the Stax and so I did!

This redefined the equipment I needed and I had to rewrite the pages to get a speaker system that can be as transparent as these cans, so at the end of 2 days listening, the whole record collection had to go. Why? I still have LPs and the LP12/ittok/ATOC9 II to this day, I cant stand the SCP, stylus contact distortion and effort you need to maintain vinyl. Digital, although not as dynamic, produced the SQ that when a passage is quite, its quite! Secondily digital is boring because it doesnt introduce the distortion through stylus and press errors. Thats my findings and I'm not here to discussed the A vs D debate! OK :D

After 30yrs this SRM1 MK2 head amp that is required to drive the Lambda Pro started to produce low level hum when I was living in Altona Meadow. And that 5yrs ago! I dont get to listen to the Stax that often so it didnt worry me because you cant listen for long if you want to prolong your hearing. The max time I spend on a session is no more than 40min.

A few months prior, I turned it on and to my horror I couldnt believe the level of hum & static. I had opened it up and this thing is still in A1 condition, no heat marks or worn components that subjected to heat, no dry joints. Very basic and nicely built, just a reminder that this is a pure class A amp and it runs HOT!

On Xmas eve, I ordered all 4 electrolytic caps, 3X 220uf/450 1X35/470uf through Element14. Today the 3X220uf/450V Panasonic arrived at the local newsagent via TOLL, and the 35/470uf are on back order!!!!!

After an hours work I put them in and walla, the hum and static is no more.

The SQ also improved and the dark silent passages are a pleasure to listen to; silence is deafening!

I could still improve this as the bias and offset needs to be done properly and Im still waiting for the 470uf/35V cap to arrive. But trolling through other forums I cant seem to pin point the procedure of setting up the bias properly, as a glorified cleaner, its best to leave it alone.

The new Panasonic 220uf/450V 105C are half the height as the the ones in the unit. Get this the old caps out of the unit measures just under 100uf accoring to the Fluke.

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Edited by pchan

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Well done.It sounds like your investment all those years ago was a very worthwhile one. Enjoy!

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Lovely pchan! Always wanted to hear a Stax setup:)

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Lovely pchan! Always wanted to hear a Stax setup:)

You are very welcome to have a listen to the Lambda Pros Migasson, but I think you will be dissappointed. I was quite surprised just how far normal cans have come. The Lamdba Pros do have the edge on speed, but the dynamic of your T90 redefined the bar. I mean we are looking at almost 30yrs!

Unfortunately I am not aiming high for the 009. There are no dealers in Melb that can give a demo on it and its too costly to just buy a pair! I found out that the SRM 1 MK2 can drive all the latest Stax, so thats a good thing and thats why I decide to recap it. But from what I have found out the 007 II and the 009 are just musical and are not as detail in the micro dynamic dept. Apparently the 407/507 are a better option interms of micro dynamics. This is where the HD800 excel, feed it with an amp such as SPL, and it delivers the goods, it also make the music come alive!. Im waiting for Jaben Audio to stock the T90 and then I'll do another shootout.

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That should be interesting!! I've just finished another session, and the T90/WA22 is just simply amazing:) it's just sooo transparent. I can listen for ages, and not get any fatigue. Approx. 25 hours so far. Tube rolling and a balanced phono stage next on the agenda. Sorry to hijack your thread, just a little gobsmacked, and cheers for the offer:)

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Yes nice work. All electros should be replaced after 10 years IMO, regardless whether it is solid state or vacuum tube. You could look at coupling caps as well. I'm looking to upgrade my 007t with Auricaps because they're such a good price to perfrmance ratio. I used them in an SP-8 refurb & they are quite a transparent capacitor

 

 .... I have the 407's through 007t 11 tube amp & I can listen for hours without any fatigue. I think the 407's are one of the best values in H/phones especially if you get em from japan. The 007t 11 is a 100v unit ... you can buggarise around & find the primaries to make up 240 but why bother ... I got an oversized torroid that has 240v primary & 100v secondary & added some line purification network & its a winner. Its the best balanced H/phone rig I've heard.

 

I would disagree about the lack of micro-detail with the 007t 11 + 407's ... swap out the existing tubes for the brimar equivalents .... mmmmmm forget the number but they are a small bottle like a 12AX7. Check out the audio salon called ???? **** its old timers kickin in .... anyway his name is kevin & he has a knack for finding good tubes ... ah ... its Upscale Audio. but don't buy them from kevin ... do a search & you'll find em at a cheaper price.

 

Your post also raises another important point about what's new should be better .... well not necessarily .... the BS bucket certainly fills up quicker with comments from corrupt & compromised "reviewers" in audiophoole mags, but who takes notice. They're a useful pointer but certainly not the last word. If the circuit dynamics are there - such as in the SP-8 - then prudent replacement of parts such as rectifier diodes, some resistors, storage caps & coupling caps. Also the old alps pots don't really cut it next to a good stepped attenuator. Good quality Hook-up OFC solid core wire + twisted pair/shielded good quality internal wiring such as Vdh Flexicon (originally developed for studios use inside desks & outboard gear & only about $12/m) is worth pursuing if you have the time.

 

I've just refurbished an SP-8 MK 2 and I sold my CJ & CAT Sig MK 3 it turned out so good ... well there's not a lot in it & I could live with any of them, but hooked up to a SE 845 power amp the sound from the SP-8 is very beguiling & easy to listen to .... and it has that "BIG" ARC 80's sound that creates a palpable sound stage. With 4 x Tele ECC803S Frame Grid tubes from the 60's + US Navy 7308's the SP-8 has increased speed to match even the OTL's. Replacement of the PS Spragues with Mundorfs & doubling the capacitance was also very worthwhile.

 

So yes its worthwhile to consider the older gear if you're willing to put a little time & effort to bring it up to spec

 

cheers .... cb

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Does anybody have the pin-mapping on the outputs?

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