TEN81 2009 PROJECTS

[kazper]

If your lacking the pins some Millmax ones will work, just measure the hole with a drill bit or caliper and then look up the cup to match and a pin for the cup.

Tommy supplied the pins for a few bucks extra with the PCB's back in the day.

BTW those semiconductors look like the ones from the prior GB I did. Make sure you use the higher gain -5 or -6 on the 341. (if it works leave as is)

I also noticed the same thing in regards to the values on the main pcb... and did the same thing and used the values from the manual.

Kaz

 

[Wonderlandaudio]

Regarding the 15K resistor, that´s obviously a mistake in the drawing, as that resistor sets the gain of the B338.

The 30K resistors changed for 15K... could be possible only in case 3k6 resistors hanging on pin 7 of those 338´s were shorted to ground. Otherwise those stages wouldn´t be unity gain with the pot set to zero.

The other resistors involved are JUST the resistors that set the Q, or bandwidth.
With those mods it seems like the reissue, with Q set to lo, has the same Q as the vintage set to hi Q. That makes me think another kind of Q switching was used, like putting a resistor in series instead of bypassing it.

Kazper I will email you today...

 

[kazper]

Cool, hopefully you got your goodies by now. I got a package back from France this last week. It was beat to hell with a hole in the side and were lucky because I bagged everything so nothing was lost.

Going to get it reshipped today.

I'll have to pull out the schematics and see if I can understand what you just said.

Kaz

 

[Wonderlandaudio]

Anyone has the reissue schematic? The manual in AMS´website has the old one copied-pasted.

 

[RedNoise]

http://www.keepandshare.com/doc/view.php?id=1236466&da=y

I don't know if it is the reissue schematic but I hope this help.

 

[Wonderlandaudio]

http://www.keepandshare.com/doc/view.php?id=1236466&da=y

I don't know if it is the reissue schematic but I hope this help.

The oldie... Thanks anyway

 

[Wonderlandaudio]

The other resistors involved are JUST the resistors that set the Q, or bandwidth.
With those mods it seems like the reissue, with Q set to lo, has the same Q as the vintage set to hi Q. That makes me think another kind of Q switching was used, like putting a resistor in series instead of bypassing it.

Kazper I will email you today...

What I mean is Q of an RLC circuit like this is directly proportional to R. I´ll use the lower presence assy, which seems clearer:
The R of the RLC circuit for each frecuency, in Hi Q mode, is the sum of the fixed resistor 6K2 plus:

- 3k6 for first 2 bands
-3k3 for the next 2
-3k3 for the next 3
-3k0 for the next 3

In lo Q mode, 6k2 is shorted so 3k6, 3k3, 3k3 and 3k0 are the Q resistors

In the reissue, 6k2 becames 2K0.
- 1k6 for the first 2 bands, which in hi Q mode makes for R= 2k0 + 1K6 = 3K6 ( the vintage value!!) ;D
- 1k3 for the next 2 bands, which in hi Q made makes for R= 2k0 + 1K3 = 3K3 ( the vintage value!!) ;D
- 1k3 for the next 3 bands, which in hi Q made makes for R= 2k0 + 1K3 = 3K3 ( the vintage value!!)  ;D
- 1k1 for the next 3 frecs, which in hi Q made makes for R= 2k0 + 1K1 = 3K1 ( the vintage value!!, well almost 3k0 )

 

[Wonderlandaudio]

"wonderland"
what reissue do you mean?
1997 ?

???

6T9R

I guess that´s the one with the mods being discussed, but I´m afraid I´m not familiar with the reissues

 

[EKADEK]

i think that wonderland has cleared up a big question/issue.
and yet im not sure that we are talking of the same resistor mistake.
im NOT referring to the gain set network hanging off pin 7 of b338.  that is ok . a big electro and 3k6 in series to ground.


it was the 15k eq stage gain  bridging  resistor that was definitely an error.  okk..

"that 15k resistor was r52 in the original b312. it feeds out of the lo mid amp to the bass amp across the bass eq network. it is marked as r74 on the  rev7 layout."

it HAS been corrected in the rev8 pdf. yeh.

AND a reissue (1997.. doesnt really matter when) was modified to be tighter Q than the original design. and those AMS alterations were transferred to the tommytones and REV7/8 documents after the reissue was marketed.  what for? ..  hype. something "new and fabulous improved from vintage design" . well.  

i personally like the wide bandwidth setting. its like a broadsword. effecting a wide frequency range for a subtle overall spectrum eq. and the tighter eq setting is damm bitchy. damm bitchy enuff anyways. why would i want to have bitchier than that? .  with a wide/tight option rather than tight/tightest option. my trousers will always fit .  

 

[Wonderlandaudio]

AND a reissue (1997.. doesnt really matter when) was modified to be tighter Q than the original design. and those AMS alterations were transferred to the tommytones and REV7/8 documents after the reissue was marketed.
what for? ..  hype. something "new and improved vintage design" . well.  

The thing is I´m not sure they wanted to make it narrower bandwith till I see the schematic. The fact that those changes match perfectly with the Q of the vintage one makes me think a resistor in series may be mounted in the Q switch...
Anyway, for those interested, Q at all 20 mid frecuencies in the original 1081 are ( from 8,2 Khz to 220Hz ) ( and at full boost... ):

LO Q: 0.41, 0.50, 0.41, 0.45, 0.35, 0.42, 0.50, 0.41, 0.49, 0.60, 0.34, 0.41, 0.30, 0.37, 0.26, 0.32, 0.38, 0.29, 0.35, 0.42

IN OCTAVES: ( rounded to 1 decimal ): 3.0, 2.5, 3.0, 2.8, 3.3, 2.9, 2.5, 3.0,2.6, 2.2, 3.4, 3.0, 3.7, 3.2,4.0, 3.5, 3.1, 3.8, 3.4, 2.9

That´s why it sounds so musical

 

[SIXTYNINER]

EKADEK

Congrats and welcome to the elite 1081 builders club! Nice to see some more folks finishing this project.
I really like those switches they look very slick.

Chuck

HI CHUCK
please have you some help to give about
parts sources like STYROFLEX and foil capacitors ecc...?
6T9R

 

[SIXTYNINER]

"wonderland"
as "Q" do you mean
"Bell" in parametric eq as in follow picture?

 

[SIXTYNINER]

Complete specs about resistors values sourced
and compared between original 1972/74 , 1997 , and rev 7/8
schematics and part layout

 

[EKADEK]

. the wiring is evil.  but i think that the bass Q switch essentially disconnects the wiper from getting directly connected to the input of A7 bass amplifier. the wiper is still direct joined to the switching eq tho . . thats the wire that i found to be missing in rev7 AND the switch wiring diagrams that guided me. just one wire. a wire that goes from the gp1 on the bass gain pot back to pin 80 of the board.  and also joining gp1 to position 1-off of the unshorting switch. that wire is the 'other' side of the eq. without it the control of bass was totally weird. does my describing make sense.?  the original EK20050 diagram shows it as wire A. heres a photo of the switch diagram that works proper.. compares perfectly with the original.
http://ekadek.com/wp-content/uploads/2009/06/ekten825.jpg

 

[Wonderlandaudio]

"wonderland"
as "Q" do you mean
"Bell" in parametric eq as in follow picture?

Well... You know Q is a way to measure the bandwidth of a filter. But the smaller the Q, the wider the bandwitdh.
The EQ in your picture has a Q of 0.4 fully counterclockwise ( around 3 octaves ), the wider setting. Fully clockwise it raises Q to 4, which means it narrows the bandwidth to a hair less than 1/3 octave

 

[SIXTYNINER]

a my friend that have seen the brain of latest orignal 1081
said me that neve have changed some detail on pcbs
for use bc184L and some other part ,
(... i think can be better we stay on the "vintage" style for now)

 

[Wonderlandaudio]

. the wiring is evil.  but i think that the bass Q switch essentially disconnects the wiper from getting directly connected to the input of A7 bass amplifier. the wiper is still direct joined to the switching eq tho . . thats the wire that i found to be missing in rev7 AND the switch wiring diagrams that guided me. just one wire. a wire that goes from the gp1 on the bass gain pot back to pin 80 of the board.  and also joining gp1 to position 1-off of the unshorting switch. that wire is the 'other' side of the eq. without it the control of bass was totally weird. does my describing make sense.?  the original EK20050 diagram shows it as wire A.

The high and lo eqs are a whole different scenario. They dont have a Q switch but a shelf-peak switch

 

[Wonderlandaudio]

a my friend that have seen the brain of latest orignal 1081
said me that neve have changed some detail on pcbs
for use bc184L and some other part ,
(... i think can be better we stay on the "vintage" style for now)

Neve also used BC184L´s in the early days... There´s a common thinking those are kind of modern. They just have a different pinout

 

[Wonderlandaudio]

Complete specs about resistors values sourced
and compared between original 1972/74 , 1997 , and rev 7/8 schematics
and part layout

So who changed the Q resistors? MAy I understand reissues have the same values( apart from that 4K3-3K9 issue that has no effect).
Also, for people trying to make one of those, 3k5 resistors noted hanging from some 338´s pin 7 are 3k6 ( the E24 value...). 2800pf styroflex capacitors cant be found as commercial values ( 2700pf). Also my schematics say 2700pf anyway.

 

[EKADEK]

heres the jpg from my wall with the bass switch stuff.  when the bass shelf/peak switch  is open -  the middle section of caps are what is feeding the wiper of the gain pot back to the amp . when the switch is closed. that cap network is  shorted out. alla a normal shelving style. (im actually not so sure of my explaining/thinking out loud on this point)

http://ekadek.com/wp-content/uploads/2009/06/ekten826.jpg    bass amp
http://ekadek.com/wp-content/uploads/2009/06/ekten825.jpg    bass switch