Official 33609 builder's tread. See 1st page for updates.

[Yellowguy]

I am very hesitant about using the cheapo switches for the gain make-up. This switch is effectively in the audio path.
Are there any alternatives?

 

[Jim50hertz]

http://www.technicalaudio.com/reading/neve_xfmrs/neve_edo7113.html

Looking at the data sheet here, if one wires an LO1166 primary in parallel and the secondary in series it should be usable in this circuit, or am I missing something?

 

[PimD]

That's what i thought yeah.
and Takey said this

T3 is step-up transformer 70:600 / ~1:2.5 (+8dB) TF12009, L1173 or similar.

So looks like aLO1166 as 50:600 would work too. +10dB instead of +8 dB (but that could compensated with trimpot RV1)

So seems good too me.
Or does anyone know why it wouldn't work???

 

[Yellowguy]

[quote author="PimD"]
So looks like aLO1166 as 50:600 would work too. +10dB instead of +8 dB (but that could compensated with trimpot RV1)

So seems good too me.
Or does anyone know why it wouldn't work???[/quote]

It might load the output stage to hard?
I can't think of any other potential problem.

 

[PimD]

Okay cool, well i can just try it, have one here so could try easy (only need too dive into measuring with transformers and all)

and then a question for igor.
Which Transformer has the biggest impact on the total sound.
because i may want too make it switchable between a cheap OEP, and an other one. (possible of not??)

Want too do this because i will first buy the OEP's, and later (when the money ship comes in) buy some better transformers.
And then it would be nice too have a choice for different flavours.

 

[Igor]

I am very hesitant about using the cheapo switches for the gain make-up. This switch is effectively in the audio path.
Are there any alternatives?

Grayhill have same pinout switches, don't know exact cat. nr.
(edit: checked, this is C&K, not Greyhill)
There's goldplated Lorlins as well. I'll be in for 30-50 if someone
organise groupbuy for pcb version.
But, if you looking on schematic, RV1 trimpot affects audio
more than gain switch...
This way we can went in total audiofullery and...finnish the unit with
top MonsterCables 99,999999 puremonocristallic copper or something
like this. For me, it's OK, there was time when ESL63 at home
were connected with crazy good quality military silver-plated teflon cables

Which Transformer has the biggest impact on the total sound.
because i may want too make it switchable between a cheap OEP, and an other one. (possible of not??)

Depends on level you feed into compressor.
If 0dbfs=+18, i.e. very hot, input OEP will saturate very hard.
Interstage OEP cuts a bit lows and adds more phaseshift on highs than Marinair/Beclair.

IMHO, worthy to try ungaped (2567 iirc) version of lo1166
at output connected pri's in series, there's still enough headroom,
just re-calculate resistors values at gain switch and test. Will do this week.
I just asked a friend to wound me 1:2.5 trunnys on HI-B C-core
which I love for sound. This size bobbins are too big for my winding machine.
But hey, there's a lot of other substitutes, API output clone will fit,
Cinemag and Edcore have 1:2 outputs too.
Just...you know, as someone wrote there, mind is like parashute

 

[PimD]

I guess i will try the CA-18-VTB9057 (ungapped 2567) then. Wired Pri - Series, Sec - Series (200:600 +4dB)

And i will use the OEP on In and Interstage, and maybe make the input so i can switch it (in a later stage)

 

[Yellowguy]

[quote author="Igor"]
But, if you looking on schematic, RV1 trimpot affects audio
more than gain switch...[/quote]

I can see what you are getting at :wink:
However, the trimpot is set once and then left there. Maybe recalibrated once every 2 years, if ever.
The gain switch (that is in the audio path just as much as RV1, it's in the negative feedback loop of the output amp) will be used on a regular basis. As soon as it starts to get worn or oxidated, we will be getting loud cracks and pops or dropouts when adjusting it. This could happen pretty fast

Now let's not get into the exotic cable debate, nothing good ever comes from it :green:

/Marco

 

[Yellowguy]

For Grayhill switches, is this the one? Farnell code 1190385

 

[Igor]

For Grayhill switches, is this the one? Farnell code 1190385

No, this one won't fit.
Sorry, it is C&K, my bad sectors
http://www.ck-components.com/media/pdf/catalogs/Rotary_Switches/A_Rotary_August_2007.pdf

Manufacturer: C & K

Order Code: 1701630

Manufacturer Part No: A11215RNCQ

Igor wrote:
But, if you looking on schematic, RV1 trimpot affects audio
more than gain switch...
I can see what you are getting at
However, the trimpot is set once and then left there.

Hey, but this affects sound more than switch!

Potentiometers DO distort, audio is chaotic (pulse randomal) signal,
it is never sinwave, etc.

I am OK with this trimpot there, even in case my ESL-63's were connected with very freaky cables

IMHO just use Lorlin, type in BOM is shorting (make before break),
made in UK, very good contact quality till you put this in smoking room
(as all silverplated contact switches).
Don't use Alfa chinese replacement. These no good.

 

[Yellowguy]

[quote author="Igor"]
IMHO just use Lorlin, type in BOM is shorting (make before break),
made in UK, very good contact quality till you put this in smoking room
(as all silverplated contact switches).
[/quote]

Ok Igor, I will just have to trust you on this!

Another thing that I'm not clear on: Is there a PS board in the kit, or do we have to make up our own here?

/Marco

 

[PimD]

[quote author="Yellowguy"]

Another thing that I'm not clear on: Is there a PS board in the kit, or do we have to make up our own here?

/Marco[/quote]

And if so could you include the parts in the BOM??
And also the parts for the BA340 (or at least the farnell part numbers for tr1 - tr 7)
Want too order the parts asap.

And again, thanks for making this possible :green: :thumb:

 

[Igor]

Order Code: 9207104
Manufacturer Part No: BC461

Order Code: 356992
Manufacturer Part No: BC441.

Order Code: 1017657
Manufacturer Part No: BC184C

Order Code: 1017665
Manufacturer Part No: BC214

 

[Igor]

BA 340 BOM

RESISTORS
1 5k trimpot bourns 25t RV1
2 1R5 R-EU_0204/5 R13, R14
1 2K2 R-EU_0204/5 R7
1 2K7 R-EU_0204/7 R5
1 10K R-EU_0204/5 R11
1 15K R-EU_0204/5 R16
1 18K R-EU_0204/5 R2
1 36K R-EU_0204/5 R1
1 47K R-EU_0204/5 R6
1 47K R-EU_0204/7 R3
1 150 R-EU_0204/5 R10
3 560 R-EU_0204/5 R8, R9, R12
SEMICONDUCTORS
2 BC184. BC184. TR2, TR3
1 BC214 BC214 TR1
3 BC441 BC441 TR5, TR6, TR7
2 BC461 BC461 TR4, TR8
1 GE AA144 D3
2 SI 1N4148 D1, D2
CERAMIC CAP
1 10n C-EU075-032X103 C5
ELECTROLITHIC CAPS
1 10uF CPOL-EUE2.5-6 C2
1 22uF CPOL-EUE2.5-6 C1
POLY OR COG
1 220p C-EU050-024X044 C3

 

[Igor]

Another thing that I'm not clear on: Is there a PS board in the kit, or do we have to make up our own here?

Included. Will post schem and layout within some days.

 

[Yellowguy]

[quote author="Igor"]
Included. Will post schem and layout within some days.[/quote]

Beautiful! :thumb:
I can't wait to get started, when can we expect the pcb's?

 

[Igor]

I expect to get pcb's from manufacturer on 20-22 feb.

 

[waldorfcave]

What kind of meter do we need :?:

 

[PimD]

Take a look at the second page of the BOM, which can be found on the first page.
But it's a Sifam AL19

 

[Igor]

More pics uploaded.
See 1st page.