[spritzer]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif You're lucky you didn't damage anything. I knackered my 4070s with a simple mistake like that.

The 0.3mm gap should withstand some 600v and maybe slightly more so if the volume is low the phones should survive.
What did you do to the 4070 that caused them to arc?

 

[Johnny Blue]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif Interesting. The ESC-1001 isn't mains driven either, it uses batteries. You think the bias voltage is really sensitive to ripple or something? If this turns out to be the case, I think I'm going to change my amp design to support a battery supply for the bias.

Woah, guys! Don't go changing all your designs based on a 1 hour A - B comparison that I carried out yesterday!

I'm not categorical that the SRD-6 IS quieter, or sounds better. I raised the issue because I fully expected the SRD-7 to be better, and it was not clear cut. I really need to carry out a blind test, to get rid of the expectations that the SRD-7 'should' be better.

My problem here is that my lovely assistant (aka SWMBO, who would normally be pressed into service for swapping plugs from A to B for blind testing) will KILL me if she discovers that I've got another set of SRX MkIIIs. As it is, one pair of SRX MkIIIs looks much like another, and the transformer is pretty much hidden away out of sight so she (hopefully!) won't notice that there's an SRD-7 box where there used to be an SRD-6! What I cannot do, in the circumstances, is have her see the 2 boxes at once (which would obviously be necessary for blind testing)! (I hadn't seen this as a long term problem, in that it was my intention to sell the original SRX MkIIIs with SRD-6 (SB) transformer: now I'm not so sure I want to get rid of a bit of kit that may be better than its replacement!)

Anyway, apart from the mains bias issue, another factor could be that the SRD-7 didn't sound as good as it could, because it hadn't been used for a while (I'm a firm believer in things warming up/being left on). On the other hand, the SRD-6 only ever gets 'warmed up' when it's in use, it being completely passive.

In any case, I look forward to my Kiwi chums coming up with their point of view when they've made this comparison, too.

(Meanwhile, I have to agree with the 17 year-old kid in the US who's supposed to be swotting for his O-levels [Azure?]: this site is very addictive! I'm even checking it out BEFORE I get round to lookng at pictures of women without any clothes on... )

 

[Carl]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif The 0.3mm gap should withstand some 600v and maybe slightly more so if the volume is low the phones should survive. What did you do to the 4070 that caused them to arc?

Well, I'm not 100% sure, but in retracing my steps I'm pretty sure I've worked out how I did it.

Somehow I managed to discharge the stators (don't ask me how; it was morning), and I turned the volume up to a listening level, fine but a little crackly, but then the stators came up to charge again. There was a few seconds on corona and ozone before I turned things off. Important lesson; don't opperate expensive electronic equipment while half-asleep.

 

[feckn_eejit]

Johnny, I am also a big believer in gear warming up but I find it hard to figure out what warms up in the SRD boxes... I do believe the earspeakers need some time to build up a proper bias charge in the diaphragms, but the SRD boxes themselves are extremely simple...

 

[Johnny Blue]

Quote:

Originally Posted by feckn_eejit /img/forum/go_quote.gif Johnny, I am also a big believer in gear warming up but I find it hard to figure out what warms up in the SRD boxes... I do believe the earspeakers need some time to build up a proper bias charge in the diaphragms, but the SRD boxes themselves are extremely simple...

Hello, mate! It was your post on the SRD-7 hot wiring that led me down this path in the first place! I only got the SRD-7 because it'd be easier to hot wire than the SRD-6...

As regards your point about the earspeakers building up a proper bias charge: surely if the SRD-7 box is left 'On', and the SR-X MkIIIs are plugged into it, they'll be 'charged' all the time?

 

[Carl]

Quote:

Originally Posted by Johnny Blue /img/forum/go_quote.gif As regards your point about the earspeakers building up a proper bias charge: surely if the SRD-7 box is left 'On', and the SR-X MkIIIs are plugged into it, they'll be 'charged' all the time?

Yes, that is correct.

 

[spritzer]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif Well, I'm not 100% sure, but in retracing my steps I'm pretty sure I've worked out how I did it. Somehow I managed to discharge the stators (don't ask me how; it was morning), and I turned the volume up to a listening level, fine but a little crackly, but then the stators came up to charge again. There was a few seconds on corona and ozone before I turned things off. Important lesson; don't opperate expensive electronic equipment while half-asleep.

Nasty

Did Stax make you pay for the repairs?

 

[Carl]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif Nasty Did Stax make you pay for the repairs?

Yes, yes they did. The damage wasn't bad enough for them to consider it worthy of fixing, and not wanting to get them back only to send them back to Japan for a second time, I just gritted my teeth and paid for new drivers.

At least it's fully operational now, and I learnt a good lesson about not killing it with St. Elmo's fire.

 

[spritzer]

Bastards, though it isn't really fair to them to pay for our mistakes. One good thing about this is you could then probably answer the question if they use 404 drivers or do they use special ones.

 

[Carl]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif Bastards, though it isn't really fair to them to pay for our mistakes. One good thing about this is you could then probably answer the question if they use 404 drivers or do they use special ones.

Oh, I most certainly opened them up for a look after I popped them. Yup, the red 404 drivers alright.

When I get a few more specimens to work with I plan to A/B some different lambda drivers in there to see how it sounds (a world first!).

 

[jigster]

Well, after running both the 404 and the Lambda Pros for about 20hrs each, played them off the 006t. The Lambdas seem harder to drive than the 404. At the same volume level the 404s seem a lot louder. Perhaps the Lambdas havent been run in enough? Anyway, build wise the 404s were more comfortable, the pads were much softer. Could this be because the Lambdas were never used for a substantially long time, so the pads could have hardened somewhat. There seems to be a problem (don't know if you'll call it a problem) with the Lambdas, the left channel is softer than the right. Had to turn the right up another 10-15 degrees on the volume pot to right the balance. Could there be something wrong with the left driver? There also seems to be a bit of static on the Lambdas... dang, hope its nothing wrong with it.

Impressions. Not good at describing what I hear but will do my best.
I felt that the 404s were warmer. Both lack bass, could be tighter. The lambdas seemed harsher on the highs (when I listened to Norah Jones "Seven Years" during the guitar plucking section), perhaps the warmth of the 404s made me think the Lambdas were harsher? I found the 404s more "coloured", the Lambdas sounded more "neutral". On the whole, preferred the comfort of the 404s and the sound of the Lambdas but I'd be torn to decide which to let go.

The 006t seemed to lack juice when driving the Lambdas, even when I turned the volume pot to the highest, it wasn't that deafening unlike the 404s. Will try them on the SRM-1/MKII later to see if it makes any difference.

 

[Carl]

The earpads are only celotaped on, so you can swap the Lambda Pro's and 404's earpads should you so desire.


You turned the volume pot up to max?

 

[spritzer]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif Oh, I most certainly opened them up for a look after I popped them. Yup, the red 404 drivers alright. When I get a few more specimens to work with I plan to A/B some different lambda drivers in there to see how it sounds (a world first!).

Cool, glad that's settled. I was going to recable all the Lambdas and compare them but I will only do that if I have two of every thing so it will have to wait.

Quote:

Originally Posted by jigster /img/forum/go_quote.gif Well, after running both the 404 and the Lambda Pros for about 20hrs each, played them off the 006t. The Lambdas seem harder to drive than the 404. At the same volume level the 404s seem a lot louder. Perhaps the Lambdas havent been run in enough? Anyway, build wise the 404s were more comfortable, the pads were much softer. Could this be because the Lambdas were never used for a substantially long time, so the pads could have hardened somewhat. There seems to be a problem (don't know if you'll call it a problem) with the Lambdas, the left channel is softer than the right. Had to turn the right up another 10-15 degrees on the volume pot to right the balance. Could there be something wrong with the left driver? There also seems to be a bit of static on the Lambdas... dang, hope its nothing wrong with it. Impressions. Not good at describing what I hear but will do my best. I felt that the 404s were warmer. Both lack bass, could be tighter. The lambdas seemed harsher on the highs (when I listened to Norah Jones "Seven Years" during the guitar plucking section), perhaps the warmth of the 404s made me think the Lambdas were harsher? I found the 404s more "coloured", the Lambdas sounded more "neutral". On the whole, preferred the comfort of the 404s and the sound of the Lambdas but I'd be torn to decide which to let go. The 006t seemed to lack juice when driving the Lambdas, even when I turned the volume pot to the highest, it wasn't that deafening unlike the 404s. Will try them on the SRM-1/MKII later to see if it makes any difference.

I'm afraid that there is something very wrong with the Lambdas. It's hard to tell without opening them up but try leaving them plugged in and playing music for 24 hours and see if they improve. That has fixed some bias issues in the past but it isn't a sure fix.

 

[Snacks]

Quote:

Originally Posted by Carl /img/forum/go_quote.gif Yes, yes they did. The damage wasn't bad enough for them to consider it worthy of fixing, and not wanting to get them back only to send them back to Japan for a second time, I just gritted my teeth and paid for new drivers. At least it's fully operational now, and I learnt a good lesson about not killing it with St. Elmo's fire.

Carl - It's an enclosed 404 driver; please tell me that you took pictures of the insides.
How much did the drivers cost to replace?
Were you able to locate any ports, etc., for air to escape?
Did STAX use any sort of dampening material for the 4070?

 

[Carl]

Quote:

Originally Posted by Snacks /img/forum/go_quote.gif Carl - It's an enclosed 404 driver; please tell me that you took pictures of the insides.

Nope, but the image is burned into my mind.

The housing is more clever and interesting than the driver though.

Quote:

How much did the drivers cost to replace?

About 3/5th the price of a brand new 404.

Quote:

Were you able to locate any ports, etc., for air to escape?

Yup, they're ported. Guess where the port is.

Quote:

Did STAX use any sort of dampening material for the 4070?

Certainly, being a dipole they'd be silly not to. There was less of the stuff than I was expecting, though.