Kerry
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Posts posted by Kerry
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I got my boards today
Thanks Lil'knight for organizing this and Deepak for helping out with the shipping.
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I should have the boards in the next few of days and I'll take a look.
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Got the input section, +/- 15V and 30V supplies done
Here's what I've got so far. I'm using the 30V supply to bottom of the 425V supply to create a -455V line for the negative rail.
The input section came up perfectly. I've tied the output (drain) of the K216 to some 10K resistors against the -15V rail just to test. This would represent the top of the batteries. The DC is sitting at 9.3V. Seems about right.
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Sorry, I should have posted on the "Discussion on the design of the T2 & other circuitry"
Posted response on the other thread
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From T2 Thread...
I have no idea that use semis for first stage is good or bad for the sounds.
Article from MJ 1995/5 (Page 37)
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“The first stage is a cascaded differential circuit that uses two 7308 tubes that are equivalent to the 6DJ8. A transistor constant current source was added to both the plate load and the cathode. The supply voltages for this differential circuit are +250V and -600V.
The reason tubes are used for the first stage is to avoid thermal related parameters. If semiconductors were used in this circuit, the junction temperature would be influenced by the current. It would be easy to unbalance the differential circuit when the current changes. However by using tubes, the temperature is already biased by heaters so regardless of changes in current, the operating parameters will be very stable. These tubes are covered by metal shielding caps.”
I'm not sure of the sound either. I've used this front end on a dynamic amp with a T2 topology. It sounds really good
I'm building this in a way that I can try different front ends. I'm not trying to replicate the cascode with semi's. It's closer to a BH front end, but using the T2 active batteries to translate to the bottom rail instead of the current tunnel. From there back it is very similar to the T2.
The idea was to experiment and come up with a poor man's T2. I've dropped the voltage down a bit too so I can use a simple current source (IXCP10M90S) on the output stage. I can probably go a bit higher on the voltage, but want to hear it first.
I've almost got the front end finished, but I've still got more work to do on the power supplies (still need to build 30V, -425V and 160V supplies) before I can build the output stage.
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I think I've posted the full schematic before, but here it is again.
I'd love comments
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I used MCM to source some K216s and they were legit. I bought a 10 of the J79s from BDEnt. Interestingly I got 10 pairs. I was going to order some of the K216s, but then they ran out. Summer sale I think
On another note...
I've been playing with designing an SS front end and I've posted my first component (active batteries) in the T2 design and other circuitry thread. I'll keep my progress of this in the other thread.
For anyone interested here's the link:
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I was just playing with building a solid state front end for the T2. I was having some issues simulating the batteries because the LT1021 was not behaving well. It wants about 1.5mA of current, but the pass transistor was taking all the current in the models so it would never get to 10V.
I wanted to see how this behaved in real life so I built two batteries that I'll use in my prototype amp. They will need to be set at 444V for my purposes.
Here's the scematic...
and here's the prototype...
After adjustment, they come up at 444V and stay there. Very solid. I've had them on the scope and didn't see any issues yet.
I'll still need to see if it behaves with the K216 on top and current sink on bottom.
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Would definitely be interested in that. Thanks Deepak.
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I got the Arduino Uno board (part # 782-A000049) on Mouser. I would also recommend using a rotary encoder, since there are already coding examples for using one on this thread. I don't have a part number for the rotary encoder handy. Maybe someone else can supply that.
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Kerry, regarding the programing of the board, do they come pre programed or do we need to buy the arduino board to program the IC?
To use a simple pot to control the att, does it need programing?
Could you elaborate a bit more on this?
The attenuator boards don't come with processors, so you need an arduino board or something to control it. The programming is then loaded into the controller board which connects to the attenuator(s).
The boards will only work with a digital controller. You have an option of using a rotary encoder (see code above) or an analog POT to provide input to the controller board.
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Looks like no more kits.
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So in the end, I ended up putting in more money than I wanted to in this project. I'm not too far from break-even if you count the extra parts I have.
I was thinking of selling off a couple of kits (board + parts, not assembled) for $85 each + shipping just to pull some money out of this project. I could sell off up to 4 kits.
I'm not upset if I can't since I'm sure I will use them over time.
PM me or Post on this thread if you are interested.
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Here's the actual BOM I used to order:
Quantity Ref Def Item Description Mouser Digikey
2 PCF8574AN 595-PCF8574AN 296-13106-5-ND
2 ULN2803AN 595-ULN2803AN 296-19046-5-ND
8 G6SK-2F-DC12 653-G6SK-2F-DC12 Z2666-ND
1 ID 1x3 Pin Header - .1" 571-5-146276-3
1 Mini Jumper 151-8010-E
2 Terminal block 651-1935190
2 PCF8574AN DIP-16 Socket 4816-3004-CP
Resistors
2 3.3K Resistor Pack 71-CSC09A01-3.3K
2 Pullup 3.3K Pullup Resistors CRCW12063K30FKEA
Input Z = 24K
Qty, Ref, Value, Part #
2 RP7 15 PFC-W1206R-03-15R0-B
2 RP6 619 PFC-W1206LF-03-6190-B
2 RP5 4530 PFC-W1206LF-03-4531-B
2 RP4 15800 PFC-W1206LF-03-1582-B
2 RP3 41200 PFC-W1206LF-03-4222-B
2 RP2 93100 PFC-W1206LF-03-9312-B
2 RP1 196000 PFC-W1206LF-03-2003-B
2 RP0 402000 PFC-W1206LF-03-4023-B
2 RS0 1330 PFC-W1206LF-03-1331-B
2 RS1 2610 PFC-W1206LF-03-2611-B
2 RS2 4910 PFC-W1206LF-03-4991-B
2 RS3 8870 PFC-W1206LF-03-8661-B
2 RS4 14300 PFC-W1206LF-03-1372-B
2 RS5 20000 PFC-W1206LF-03-2002-B
2 RS6 23200 PFC-W1206LF-03-2322-B
2 RS7 23700 PFC-W1206LF-03-2372-B
2 RT 24300 PFC-W1206LF-03-2432-B
Capacitors
2 100uF 661-EKZE250ELL101MH0
EDIT:
The three pin header was a bit tall and I had to trim it down.
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Here's the list of what is shipped:
Name - Assembled - Bare Boards
Beefy - 0 - 4
blubliss - 4 - 0
cetoole - 0 - 10
chinsettawong - 2 - 0
deadlylover - 0 - 6
deepak - 2 - 2
DouglasQuaid - 2 - 2
Driftwood - 4 - 6
dwhat - 4 - 0
el_doug - 2 - 0
Fing - 2 - 0
Fitz - 0 - 4
Flyingsparks - 0 - 4
guzziguy - 2 - 0
Horio - 0 - 2
Jezz - 2 - 2
jgazal - 2 - 0
johnwmclean - 0 - 2
Kerry - 2 - 10
kevin gilmore - 4 - 4
luvdunhill - 0 - 2
manaox2 - 2 - 0
MASantos - 2 - 2
Max - 1 - 0
minivan - 2 - 0
n3rdling - 4 - 0
nattonrice - 0 - 4
Nebby - 4 - 0
Pars - 0 - 2
Samuel - 2 - 0
Shaman - 0 - 2
tcpoint - 0 - 2
Vortex - 0 - 10
EDIT:
Got the last two out as well:
spritzer - 4 - 0
ujamerstand - 4 - 0
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I've got just about everything shipped. Two more to go, which I'll get out early next week.
I wanted to beat the hurricane before Manhattan floats away
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Just wanted to post where I'm at with testing/shipping. Here's everything shipped. I should have some time this weekend to get through some more testing.
Name - Assembled - Bare Boards - Shipped
Beefy - 0 - 4 - S
blubliss - 4 - 0 - S
cetoole - 0 - 10 - S
chinsettawong - 2 - 0 - S
deadlylover - 0 - 6 - S
deepak - 2 - 2 - S
DouglasQuaid - 2 - 2 - S
Fitz - 0 - 4 - S
Flyingsparks - 0 - 4 - S
Horio - 0 - 2 - S
johnwmclean - 0 - 2 - S
kevin gilmore - 4 - 4 - S
luvdunhill - 0 - 2 - S
nattonrice - 0 - 4 - S
Pars - 0 - 2 - S
Shaman - 0 - 2 - S
tcpoint - 0 - 2 - S
Vortex - 0 - 10 - S
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Here's the code I used for the rotary encoder and the Uno board:
#include "Wire.h"
// Set up the Variables
int state, prevstate = 0;
int nextEncoderState[4] = { 2, 0, 3, 1 }; int prevEncoderState[4] = { 1, 3, 0, 2 };
const byte attSetAddr = 0x38;
const byte attResetAddr = 0x3E;
const int offVolume = 100;
const int relayLatchTime = 3; // time in milliseconds
int newVol = offVolume ;
void setup() {
delay(1000);
Wire.beginTransmission(attResetAddr);
Wire.send(0);
Wire.send(0xFF);
Wire.endTransmission();
delay(relayLatchTime);
Wire.beginTransmission(attResetAddr);
Wire.send(0);
Wire.send(0x00);
Wire.endTransmission();
delay(relayLatchTime);
// Set up for the encoder
pinMode(5, INPUT);
pinMode(6, OUTPUT);
pinMode(7, INPUT);
digitalWrite(5, HIGH);
digitalWrite(6, LOW);
digitalWrite(7, HIGH);
}
void SetVolume(int newVol)
{
int sendVal;
// now set
sendVal = (byte)newVol ;
Wire.begin();
Wire.beginTransmission(attSetAddr);
Wire.send(0);
Wire.send(sendVal);
Wire.endTransmission();
delay(relayLatchTime) ;
Wire.begin();
Wire.beginTransmission(attSetAddr);
Wire.send(0);
Wire.send(0x00);
Wire.endTransmission();
delay(relayLatchTime);
// now reset
sendVal = 0xFF ^ (byte)newVol;
Wire.beginTransmission(attResetAddr);
Wire.send(0);
Wire.send(sendVal);
Wire.endTransmission();
delay(relayLatchTime);
Wire.beginTransmission(attResetAddr);
Wire.send(0);
Wire.send(0x00);
Wire.endTransmission();
delay(relayLatchTime);
}
void loop() {
state = (digitalRead(7) << 1) | digitalRead(5);
if (state != prevstate) {
if (state == nextEncoderState[prevstate]) {
newVol = newVol + 1;
if (newVol > 255)
newVol = 255;
SetVolume(255-newVol);
} else if (state == prevEncoderState[prevstate]) {
newVol = newVol - 1;
if (newVol < offVolume)
newVol = offVolume;
SetVolume(255-newVol);
}
prevstate = state;
}
}
EDIT:
Quick thanks to Max and the Arduino site where I got some of the code segments
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I've developed some software to use with the Arduino Uno board. I can post that in the next day or so with some simple instructions.
Kevin is working on an all-in-one device (display, process, interface) separately.
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I just looked at the circuit and it looks like it will draw around 52mA or so (Kevin - please chime in if I'm wrong here) for both channels. Doubling is not a bad rule of thumb, so 100mA should be OK, but 150mA would give a bit more headroom.
The power supply is pretty efficient. It consumes about 5mA for the pre-reg stuff, about 1.2mA for the bleed-off resistors around the caps, and an additional 3mA on the positve rail for the bias.
Edit:
Doesn't the KGSSHV have a variable output stage bias design?
I was looking at the current sinks on the output stage to guess the current draw.
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Turning that into a transformer that works can be more problematic than
you might think.
I've tried to cut things too tight on my first couple of transformers and ended up under voltage when the full load was applied. You also have to consider that there could be as much as a 10% variance in what's coming out of the wall.
If you're looking to save on heat, then you're better off using the doubler circuit for the bias. Because of the current regulator and two RC filters, it is incredibly clean.
If you want simpler, then don't use use the doubler, but make sure you've got enough volts under load.
Richard at SumR is pretty good if you tell him what the load is (I usually multiply by 2.5 of the actual required current) and what your required AC voltage is under load.
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This should be fixed now.
Thanks. That really helps
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I've got all of the board only orders shipped now
I've got a lot of testing to go still, so the assembly orders will take a bit longer.
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I was just looking at the BOM for the KGSSHV power supply. The bridge diodes you have listed in the BOM (511-STTH1512W) look like they are too big. I looked up the part number on Mouser. I think you need TO-220, not TO-247.
I haven't gone in great detail yet, but I just happened to notice this.
Thanks for pulling this all together.
The ultimate DIY? A Stax SRM-T2!
in Do It Yourself
Posted · Edited by Kerry
Same here... but I am very happy about it
Already got it for my daughter
I also go her the 10th doctors along with a TARDIS