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 21 
 on: October 25, 2018, 11:43:13 am 
Started by afterlifestudios - Last post by afterlifestudios
Just an update:
I replaced the two 47uf 25v electrolytic (coupling?) caps.  So far so good!  The noise is gone.
I used the only caps I could find that were physically small enough, which were Vishay MAL203036479E3  and only 85c rated.
Do these appear to be ok?
https://www.digikey.ca/product-detail/en/vishay-bc-components/MAL203036479E3/BC5237CT-ND/8557366

All tighter spec'd and higher temp caps I could find had too large a diameter to fit.  (I know for sure because I tried some...)

The other thing is that the measured capacitance on these caps is higher than rated, (about 62uf each), but I guess that's not a bad thing in this application?

I

 22 
 on: October 22, 2018, 03:27:11 pm 
Started by Ernie Black - Last post by Ernie Black
IMPORTANT NOTICE

We will be upgrading the PSW forums server, commencing Tuesday October 23 at 1 am. The purpose of this upgrade is to increase server memory, RAM, and output. Over the past day, we have experienced temporary outage as the server ran out of available memory; this also occurred briefly in September. We will be adding 100 GB of memory, plus bumping the RAM from 12 to 16 GB and increasing output to 6000 Mb/s. The forums may be unavailable for up to three hours (although we expect a shorter timeframe).

Thank you.

 23 
 on: October 15, 2018, 07:01:03 am 
Started by John diggs - Last post by Timjag
I wouldn’t! I was being silly, I guess the humour was lost in text. I did buy 4 that were ex-BBC 2 of which were Cs and two As. From what I heard they bought a lot.

 24 
 on: October 15, 2018, 12:58:48 am 
Started by John diggs - Last post by klaus
How would you know its a 'c' version displayed in the video?

 25 
 on: October 14, 2018, 05:41:45 pm 
Started by John diggs - Last post by Timjag
I was just thinking of asking you about that klaus. Was there a reason that AKG used 5 volts for the 7586 tube? It quite clear on every data sheet I’ve seen that it’s requires a regular 6.3v 135mA supply. Was it a heat issue, being inside a metal tube and not wanting to burn David Bowie’s hand on totp  or something?(joke!)

Here he is doing the magic with one!

https://m.youtube.com/watch?v=yEmGQYCuc6M



 26 
 on: October 01, 2018, 06:21:20 pm 
Started by BluegrassDan - Last post by Kai
I consistently prefer the long body over the other two, where the nuvistor I like the least, sounds like I a later U87 with its balls cut off ;D

But.... with the throat like this you better don't sing or your voice will stay like this.

 27 
 on: October 01, 2018, 12:10:54 am 
Started by BluegrassDan - Last post by klaus
I am not sure whether you know my attitude about sound samples. I find them unreliable in so many ways, and not representative of how we use these mics, and therefore unsuitable for any serious analysis.

The first thing I would do is authenticate the capsules: if you want to know whether they are original, you need to open the baskets, take close-ups and post them. Anything short of that is speculation not helpful in your query.

As far as the sound of original Berlin-M7 goes: I have not encountered a single one in the last five years that still performed at the noise floor or full bass response of a healthy M7.

 28 
 on: September 30, 2018, 08:51:49 pm 
Started by BluegrassDan - Last post by BluegrassDan
Hello all,

I worked today with three U47s and did some comparisons.
  • Short-body with Nuvistor and K47
  • Short-body with VF14 and M7, recently recapped (serial 4825)
  • Long-body, nickel grill with VF14 and M7 (serial 2007)
Regarding those two with proper VF14s and M7 capsules, is it remotely possible that original M7 capsules of these ages could still be in good usable condition, i.e., not deteriorated? Do you hear anything suspect of deterioration in these samples?

Audio samples are available here (I'm singing two of the three clips, and I have had bronchitis for two weeks - please overlook the horseness: https://www.dropbox.com/sh/b57mjka0kcr7s3q/AACeTLtCmkecR0kpBlvJS7nsa?dl=0

Thanks in advance,
Dan

 29 
 on: September 29, 2018, 07:55:47 pm 
Started by afterlifestudios - Last post by Kai
 Sorry, I am still not in my studio to have a look.
Of course any of the transistors can have gone wrong too.
To find out which one you can short the interconnects to ground one by one using a small film cap of about 1uF, until the noise disappears.
Always connect this cap before applying voltage or you can kill a transistor.
But giving the elko a shot doesn't hurt, for testing put in anything you have lying around, even the value does not need to be exact, it just has to meet the voltage specs.
From my remembrance it wasn't the electrolytics but the styroflex that was broken, but I am a bit unsure, I thought it wasn't styroflex but something different.  I am sure it was not the glass C!
Might have something to do with the fact that I repaired the transformersless versions, which uses a higher voltage of 120V instead of 48V, so some parts may be different.

For ordering the caps: something decent like Panasonic, 105°C, lo ESR.
I am not the right person to comment on the sound of parts, that's Klaus's speciality.

 30 
 on: September 29, 2018, 01:20:13 pm 
Started by andrespoll - Last post by klaus
Wire suppliers change. That's the only difference, aside of slightly less flex in the wires with red jackets.

I will look up the period when red, instead of yellow capsule lead-out wires were used on K87/870 and post here later this weekend.

 

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