The Stax thread (New)

[Clean6eR]

suggest you measure the output voltages of the switcher. + and - 250 or so

i think im measuring the wrong thing but the switch on the front is just taking the 14v from the psu? where do i find the switcher? (im pretty poor with electronics but am happy to learn things!) is it one of the transistors? if so which one?

i i measured the two transistors i soldered in, they are 14v too and the PWM chip i added i measured the ground and ref out (14v) and vcc(14v too)




i measure the two transistors in blue on the right and got 14v

i measured the two red points and the red and blue point on the pwm IC and got 14v

 

[kevin gilmore]

The voltage on the 250v caps.

But easier is to just measure the bias voltage on the stax jack. Should be around 300v with a 10Meg ohm meter. Measure to Rca input ground.
If its zero the high voltage supply is not working.

 

[Clean6eR]

The voltage on the 250v caps.

But easier is to just measure the bias voltage on the stax jack. Should be around 300v with a 10Meg ohm meter. Measure to Rca input ground.
If its zero the high voltage supply is not working.

After checking the right stuff (Bias and the caps) none of them are pumping anything out, they have a small value like 1-2 mv then drop to zero.

This sounds like bad news... anything i can do?

and thank you for taking the time to help.

 

[kevin gilmore]

Replace the sg3524

 

[Clean6eR]

Replace the sg3524

The one that was originally in there had

3524D
JRC A4011A

written on it.

then one i put in is in the above picture saying

SG3524N

have i just bought the wrong replacement?

• when i broke it at the start i searched the net and found your advice to replace two transistors and the SG chip. i found a link in this thread on where to buy both parts and did.
• the transistors turned up first but didnt have the EXACT same numbers on them as each other, they were soldered in first.
• i then tried the amp with just those two things replaced and nothing improved, then the SG chip turned up and i swapped that in, still nothing changed.

could the old busted IC taken out the new transistors then when i put the new IC (SG) they crapped that out too?

it seems like that may not have happened as the transistors are measuring 14v on one leg and 0L on the other (this suggests they work?)

I'm on the hunt for another IC to see if replacing it clears everything up (im in the UK so will start looking in rapid electronics as they are close to me...)

i'd be well happy if i get this working, i wont be selling it either, it will be my proud amp!

I was going to try one of your KGSSHV amps but thought i should fix this first, given how little I'm understanding here i think i might be better to start saving LOTS of money for one of spritzers made ones...

 

[thinker]

 

[kevin gilmore]

you are unlikely to fix this with just a voltmeter.
borrow an oscilloscope and see whether there are switching outputs from the pwm chip
if desperate put the voltmeter on ac and troubleshoot that way

 

[Clean6eR]

you are unlikely to fix this with just a voltmeter.
borrow an oscilloscope and see whether there are switching outputs from the pwm chip
if desperate put the voltmeter on ac and troubleshoot that way

WOW they aint cheap! just went to our science lab to borrow one and it came out on a trolley! (i think they will miss it if i cart it to the bus) I'm looking up buying one cheaply online but they seem not the cheapest of tools.

I will try the ol wait for replacement parts and try switching them out one more time, this time paying uber attention to the solder work, then when it fails bring it in to work after the holiday to use the expensive stuff.

thanks for the help, I'll let you know how it goes, really looking forward to comparing it to my 006t

 

[Clean6eR]

 

[Clean6eR]

sometimes being an idiot can reap such joy

so, looked at IC and found one leg i hadn't soldered to the board!!!

shes working!!!! the red light came on and a smile roused, plugged in my beater sr202's and the above happy elephant picture was the best way to illustrate my feelings.

ill post my comparison after i have had some time with it.

thank you KG and the others who have given me there help and time.

YAY again!

now i have LOADS of chips incoming but i can drown out my stupidity with music so all is well


UPDATE:



Gear:
sr Gamma normal
Lamba normal bias (not sure what they are)
sr 202
sr 307
sr 507
srm 006t
srm xh
marantz pm 7005
senhiser hdvd800

dac choice:

As the 006t is balanced in I thought trying my dacmagic 2i or hdvd800 would be comparing as they have balanced out. the dacmagic sounded scratchy and brittle so i took the hdvd800 into the comparison. when listening to it in the comparison i felt it was soft and warm sounding, I felt like i could fall asleep listening to it. This is not what i like from my music.

I thought i'd try all my dacs out and ended up REALLY liking the marantz pm7005. it was peppy sounding, details are more obvious but still sit in the soundscape and are not compressed into a lump of noise (i have a ad1955 based yulong dac that does this, it has electrical noise at EXTREME volumes)

I am going to start looking for balanced and highly resolving and spacious sounding dacs but for now the marantz is the best of my situation for dac duty, I'm open to suggestions.

ear speaker choice:

I remember getting into headphones and this site and the first time i got what i thought was a high end set of phones in the k701. The way i was hearing things i hadn't known was in the songs i loved and they sounded like they were in the room in there own odd places. It was a holographic experience that i fell in love with.

Getting the ad700 at first the searing treble amazed me, like a cloth getting removed from the sound, but the airy and strange positioning or location of the k701 i didn't find as captivating with the ad700. I wanted the resolution and bite of the ad700 with the giggles of the k701's positioning. Saved hard, got deal on ad2000 and detail went SILLY! but the sound-stage was non existent they were like an immediate and in my face sound but that detail!!!! This was a mistake buy. I ended up with the hd800 and pretty much had what i was after, then i got the gamma normal bias and a srd-6 and hooked it up to a cheap diy t amp. VERY different sound, like how the Denon D2000 had a new style with its biocelouse driver(gave a different "type" of sound) i was interested...

Bought all the stuff i listed at the top and now I'm comparing the two amps, i struggle to tell massive differences between the 202 307 and 507, the normal bias ones are very relaxing sounding and special but i can't use them for this comparison as they are normal bias. I will be using the 507 because they cost the most to be honest, i will need to compare the ear-speakers more in the future.

The Amps;

SRM-006t:

Never brittle or harsh sounding, artists and instruments all sound in a location and none right on top of me. Times when a sparkle or crash happen in a location i don't expect it grabs my attention but its done in a subtle and classy fashion, makes me smirk and think "niceee"

SRM-Xh:

Faster faster! things overall are closer to me, the vocals on some songs feel on top of me but with that all detail seems more etched or present (reminds me of my grado sr323) fun and instantly gratifying, rarely the sparkles or crashes occur but when they do i feel they are further out of place which again engages more.

Comparison:

Well its big warm and spacious with more bass presence on the 006t or faster more etched but in my head fun from the Xh. the 006t has more bass but i feel like its less controlled than the Xh which is odd given the power difference, doh! my dream is the combination of two! don't think tubes are for me but this little Xh as fun as I'm finding it lacks the open air and distance i crave.

might try new dac first then look at better amp for these

thank you again for helping me fix my Xh, i might just use this instead of my 006t as its less hassle, space, power and i prefer the immediate sound of it

 

[Vesperaudio]

Just wanted to inform everyone, we have lambda custom earpads available now.

 

[Keithpgdrb]

Just wanted to inform everyone, we have lambda custom earpads available now.

Do you have them to fit the original sr lambdas? Normal bias

 

[Vesperaudio]

This pair was designed for L700. If you mean adhessive mounted SR507 order is also possible.

 

[ml48]

Hi,can anyone help with problems I have with a first version of the srm-1 mk2 stax amp.The offset stays around -120v and adjusters have virtually no affect and the balance of the right channel stays around -30v with adjuster hardly changing this voltage.I have changed all the electrolytic caps but not the blue and brown film caps.All the resistors seem to have the correct value.The bias voltage is 175v,is this ok the resistor value is 3.3m which I think is wrong.

 

[JimL11]

This is an old thread, you really need to post this on the Stax thread III.