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The Lab / Re: Neumann PsvB schematic/infos request
« Last post by Khron on Today at 12:59:46 PM »
Is yours faulty? Or are you aiming to "clone" one for yourself? Or..?
The Chamber / Re: Polycarbonate Film Caps
« Last post by abbey road d enfer on Today at 12:50:03 PM »
There is one element missing in this discussion: the application.
If I understand correctly, the OP wants ocupling caps for tube amps, a position where good practice imposes very little AC voltage across the caps (as opposed to filters where some caps are submitted to voltages almost equal to the incoming signal).
The traditional approach has considered only the LF response, resulting in the 10x rule of thumb (make every capacitor 10 times biggere than the -3dB calculation result).
This is an ancient rule that did not take distortion into account.
Let's take the case of a 10k load. The cap value for -3dB at 20Hz is 0.8uF.
The rule of 10x says 8uF.
The voltage across the capacaitor at 20Hz is 1/10 of the incoming voltage. This is enough to generate significant distortion, indeed with variable results depending on the technology.
This is a case where I would use a 100uF electrolytic capacitor. Measurements have shown that the capacitor's contribution to distortion is hardly measurable.
Now in the particular case of the coupling capacitors between the PI and the output tubes, the typical value for the grid leak resistors is 220k.  [email protected] results in 36nF. Applying the 10x RoT gives 0.36uF.
Applying another 10x coefficient would result in 3.6uF, which is likely to be a huge size and create other problems (parasitic coupling).
Apparently, Cyril Bateman, in his seminal paper, didn't publish any measurements for PC capacitors, but he clearly wrote that PPS is capable of much lower distortion.
Apparently, the highest value in 400V is 1.8uF, so putting two in parallels would just clinch the deal.
Now there may be some consequences regarding the stability of the amp; ground circulation would need critical attention.

I have read through this entire thread and now I’m really worried about building these. I bought 2 sets of PCBs and front panels from, in and out Lundahl trafos and grayhill switches. Have spent a lot but I’m wondering whether to cut my losses as there really aren’t many successful builds of this and I’m still confused as to the relay issue (some say 5v ones don’t work and need 12v). I would like to know if there’s anyone here with successful build please who can answer the relay question and link to one that works?  Completed builds on this thread seem to teem with issues. Thanks!
Filters/Equalizers / Re: Studer 169 EQ in API 500 format
« Last post by Ricardus on Today at 11:54:31 AM »
Hi everyone, I tried to look into the 26 pages here but I can't find what I'm looking for. Anyway if somebody can help would be appreciate it!
I started putting together my first Eq, with the Neutrik transformers, and I'm looking at the schematics plus at the pictures with the layout values. There are something that confused me :-[...
For example:
- on the schematics R22/R23 are 10ohm on the layout 1K6.
- on the schematics C1-C2-C8-C10-C14 are 47 pF on the layout C1 is not even marked.
- on the schematics R1 is 20K on the layout is not even marked
- on the schematics R24/R25 have not value on the layout one is 15K the other a wire jump.

Well you get the point. I don't know if there are any other cases but which one should I follow? there are any update maybe that I missed out?

Thanks folks

 I built from this source and things seem to be OK.
Hi Everybody,

Since the Banzai KM84 Clone project is going through the 2 batch, I wonder if we should start another groupbuy for the Haufe BV107?

@rainton would you possibly again carry out a round?
For all those who are also interested, please write briefly in here.
i would be in for a Pair!

Can someone please also write in here how they sound compared to a Cinemag or the other options available? :-)

Many Thanks

Studio A / Re: Need Piano Advice
« Last post by fazer on Today at 11:12:12 AM »
Piano pegs find a resting place so the more you keep them in tune the more they stay in tune.  At least that’s how it was explained to me.   I have owned a Yamaha C7 since 1981.  Keeping them tuned and for me that means before any recording session is just how it works.   My experience has been that most concert pianist have a tuner they prefer as well as a piano that they choose to play on.   The room it’s in is very important.  My previous hose had an 18 ft ceiling and very large open areas that help the sound of the piano.   I currently live in a house with 8’ ceiling and have my piano In Storage to be moved hopefully next month.   I kind of wish I could change over to an upright grand as already mentioned but plan to move it to my walkout basement studio.   The temperature will be stable but the sound will never be the same.  It will be ok for rock and roll.   Grand pianos have maintained prices to some degree but small uprights you can’t give away.  A 9foot Bechstein is the finest  piano I’ve ever recorded.   Players would fall in love with that sound.  It had such an inspirational sound and great action.   
The Lab / Re: Help with Capacitor Choice
« Last post by dukeofearl on Today at 11:04:20 AM »
maybe it's a dumb question but is there any chance the leads wouldn't reach if the holes are 45mm apart?
Sorry to be slightly off topic here... Does anyone know if much of the same information for the PM-1000 also applies to the PM-430?  I have one sitting in my studio that is like 75% functional, but I haven't looked too deeply into fixing/modding it as I'm somewhat intimidated by something as large as [even a relatively simple] mixer like this.  Is the 1000 just a big brother?

I'm aware of Humner's beautiful work on his 430, but unfortunately the discussion on that one was not specific enough for me to find a real jumping-off point for looking at my own.

Looking forward to checking out OP's videos!
Black Market / Re: FS: EU: 2X Haufe RK173 = 60 € + ship
« Last post by musikorta on Today at 10:57:07 AM »
Have you four pieces for me? How much would the shipment cost to Spain (C.P. 48289)?
Brewery / Re: Words
« Last post by JohnRoberts on Today at 10:42:05 AM »
Sadly the public respects the opinion of actors and athletes more than it should...   Maher is providing entertainment not wisdom.

I am not religious, and there are a long list of bad things done in the name of religion, but in my judgement most modern religions are a positive organizing force in the lives of the masses. Sadly religion is under attack by some progressives.

I am not comfortable debating individual's personal religious beliefs. For years I had a sweet old neighbor (now RIP) who was constantly proselytizing me to go to church with him. I graciously but firmly declined. I am glad he was able to die peacefully with his belief system intact. 

Years ago I wrote a letter to the editor in my local newspaper defending teaching evolution in the schools. After my letter was published some lost soul called my home phone number asking me to explain why his minister was telling him a different story. I told him to ignore me and listen to his minister, otherwise I would never be free of him. That is exactly the kind of person who needs religion to guide his personal life. I don't want to take that away from them, or replace religion with some alternate government dogma.


PS: I read the Oreilly/Dugard book "killing Jesus" and it was an interesting read.
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