Linus
Well-known member
I'm in the US but was able to order a TBone SCT700 from the provided link. The price was pretty cheap ( 30 euro shipping but no VAT so 155 euro total) and the simplicity of using the same stuff is great.
MK7 - tube mic project
- Thread starter ioaudio
- Start date
Help Support GroupDIY Audio Forum:
ioaudio
Well-known member
yes, switchable primaries on the psu.
JW
Well-known member
How much was shipping to the U.S. for the T-Bone 700?
Got 2 of these from nashkato: http://www.groupdiy.com/index.php?topic=29710.0
They're beautiful by the way, and very well built, but the advantage of having a power supply that's mostly there, as well as having three layers of mesh almost has me re-thinking what I want to use for the housing.
Got 2 of these from nashkato: http://www.groupdiy.com/index.php?topic=29710.0
They're beautiful by the way, and very well built, but the advantage of having a power supply that's mostly there, as well as having three layers of mesh almost has me re-thinking what I want to use for the housing.
imo
Well-known member
OK, here is a pretty comprehensive US parts list. There are a few items that could be doublechecked. For instance, on the .047 film cap, i didn't know the spacing sp went with the 13mm WIMA. The polystyrene 1n cap i found is a bit off (940p) and i couldn't find any 50k resistors at either Mouser of Digikey. Other than that i think its pretty close.
Also remember that there are the 3 output values to try(.33, .47, and .68)
Here is what i have. Hope its helpful, and again thanks to Max for putting this together!!
1 x pf86 (siemens, valvo) ebay?
1 x noval tube socket chassis mount tube depot SK-9PINB
2 x M3 screws/nuts to mount tube socket ---- i think 4-40 would work here
1 x 1µF 250V filmcap tubular mouser 75-MKT1813510255
1 x 0,33µF 250V filmcap tubular - mouser 146-MEA2E334K (also try .47 and .68)
1 x 47nF 160V film mouser 505-MKP4.047/400/10 (10mm spacing confirmed)
1 x 10nF 160V styroflex surplus sales CPF) 010000R0AECK
1 x 1nF 160V styroflex surplus sales CPF) 000940R0AECK (940p)
2 x goldcap 0,22F 5,5V - digikey PART# P10792-ND
2 x 100 Megaohm 0,25W -- digikey MOX200J-100ME-ND ($3.00 a piece!)
1 x 68 Megaohm 0,25W-- mouser 660-GS1/4LC686J
1 x 33 Megaohm 0,25W mouser 660-GS1/4LC336J
1 x 1,4 Megaohm 0,25W mouser 660-MF1/4DC1404F
1 x 1,2 Megaohm 0,25W mouser 660-MF1/4DCT52R1204
1 x 100 Kiloohm - plate resistor mouser 660-MFS1/4DCT52R1003
1 x 20 Kilohm 1W mouser 594-5073NW20K00J
1 x 2,2 Kiloohm 0,25W mouser 660-MF1/4DCT52R2201F
1 x 3,9 - 9,1 Ohm 1W *(for pf86 @3.9) mouser 594-5073NW3R900J
1 x 2,2 Ohm 1W (for pf86) mouser 594-5073NW2R200J
3 x glass tubes, diameter 2mm, length 6mm, superglue--with kit
Pattern selector :
1 x rotary switch 3x1 (lorlin or similar) mouser: 105-13571
1 x 4,7µF 250V electrolyte mouser 647-UVZ2E4R7MPD
3 x 100 Kiloohm 0,5W mouser 660-MF1/2DCT52R1003F
1 x 50 Kiloohm 0,5W(used 51k) mouser 273-51K-RC
psu upgrade
3 x 10.000µF/16V mouser 647-UFW1C103MHD
1 x 22µF/16V mouser 647-UKL1C220KDDANA
1 x LM317 mouser 863-LM317LZG
1 x trim pot 500 Ohm mouser 652-3299W-1-501LF
3 x 2,2 Ohm 1W mouser 594-5073NW2R200J
1 x 240 Ohm 0,25W mouser 271-240-RC
1 x 910 Ohm 0,25W mouser 271-910-RC
2 x 1N4002 mouser 863-1N4002G
Also remember that there are the 3 output values to try(.33, .47, and .68)
Here is what i have. Hope its helpful, and again thanks to Max for putting this together!!
1 x pf86 (siemens, valvo) ebay?
1 x noval tube socket chassis mount tube depot SK-9PINB
2 x M3 screws/nuts to mount tube socket ---- i think 4-40 would work here
1 x 1µF 250V filmcap tubular mouser 75-MKT1813510255
1 x 0,33µF 250V filmcap tubular - mouser 146-MEA2E334K (also try .47 and .68)
1 x 47nF 160V film mouser 505-MKP4.047/400/10 (10mm spacing confirmed)
1 x 10nF 160V styroflex surplus sales CPF) 010000R0AECK
1 x 1nF 160V styroflex surplus sales CPF) 000940R0AECK (940p)
2 x goldcap 0,22F 5,5V - digikey PART# P10792-ND
2 x 100 Megaohm 0,25W -- digikey MOX200J-100ME-ND ($3.00 a piece!)
1 x 68 Megaohm 0,25W-- mouser 660-GS1/4LC686J
1 x 33 Megaohm 0,25W mouser 660-GS1/4LC336J
1 x 1,4 Megaohm 0,25W mouser 660-MF1/4DC1404F
1 x 1,2 Megaohm 0,25W mouser 660-MF1/4DCT52R1204
1 x 100 Kiloohm - plate resistor mouser 660-MFS1/4DCT52R1003
1 x 20 Kilohm 1W mouser 594-5073NW20K00J
1 x 2,2 Kiloohm 0,25W mouser 660-MF1/4DCT52R2201F
1 x 3,9 - 9,1 Ohm 1W *(for pf86 @3.9) mouser 594-5073NW3R900J
1 x 2,2 Ohm 1W (for pf86) mouser 594-5073NW2R200J
3 x glass tubes, diameter 2mm, length 6mm, superglue--with kit
Pattern selector :
1 x rotary switch 3x1 (lorlin or similar) mouser: 105-13571
1 x 4,7µF 250V electrolyte mouser 647-UVZ2E4R7MPD
3 x 100 Kiloohm 0,5W mouser 660-MF1/2DCT52R1003F
1 x 50 Kiloohm 0,5W(used 51k) mouser 273-51K-RC
psu upgrade
3 x 10.000µF/16V mouser 647-UFW1C103MHD
1 x 22µF/16V mouser 647-UKL1C220KDDANA
1 x LM317 mouser 863-LM317LZG
1 x trim pot 500 Ohm mouser 652-3299W-1-501LF
3 x 2,2 Ohm 1W mouser 594-5073NW2R200J
1 x 240 Ohm 0,25W mouser 271-240-RC
1 x 910 Ohm 0,25W mouser 271-910-RC
2 x 1N4002 mouser 863-1N4002G
plumsolly
Well-known member
wow imo! I have one going as well. for the styroflex/polystyrene caps, PartsConnexion, Michael Percy Audio, Justradios all have them, but i think mostly in 630v. I got some from justradios and they aren't to big.
just to add for the .33uf(/.47uf/.68uf) if anyone wants to go with polypropylene or film and foil instead of polyester, here are some options from mouser:
.33uf Cornell Dubilier 930C6P33K-F (polypro)
.47uf Vishay/Roederstein MKP1845447255 (polypro) Vishay/Sprague 710P474X9400 or 730P474X9250(film and foil)
.68uf Cornell Dubilier 935C6P68-2K-F (polypro)
alos for this: 1 x 3,9 - 9,1 Ohm 1W *(for pf86 @3.9) I wonder if we could use a 10 ohm trimpot? they are pretty expensive in that voltage rating, however.
-Ben
just to add for the .33uf(/.47uf/.68uf) if anyone wants to go with polypropylene or film and foil instead of polyester, here are some options from mouser:
.33uf Cornell Dubilier 930C6P33K-F (polypro)
.47uf Vishay/Roederstein MKP1845447255 (polypro) Vishay/Sprague 710P474X9400 or 730P474X9250(film and foil)
.68uf Cornell Dubilier 935C6P68-2K-F (polypro)
alos for this: 1 x 3,9 - 9,1 Ohm 1W *(for pf86 @3.9) I wonder if we could use a 10 ohm trimpot? they are pretty expensive in that voltage rating, however.
-Ben
imo
Well-known member
The surplus sales site is pretty nice for stuff like this. Definitely worth a look.
I have a question then about using an Ef86 and the consequential changes.
If we are bringing in around 7.5 volts to the mic, the Ef86 sources 200mA heater current, dropping about .45v. If the tube is running at its standard heater voltage it sources an additional 6.3v and we are left with around .75v on the cathode. Do we need to provide more voltage than this at the power supply to get the cathode to the 1.3v on the schematic? Around 8-8.1 volts? Or can we pull the heaters down to 5.7v (the lower accepted voltage) and keep the supply the same?
Thanks
ian
I have a question then about using an Ef86 and the consequential changes.
If we are bringing in around 7.5 volts to the mic, the Ef86 sources 200mA heater current, dropping about .45v. If the tube is running at its standard heater voltage it sources an additional 6.3v and we are left with around .75v on the cathode. Do we need to provide more voltage than this at the power supply to get the cathode to the 1.3v on the schematic? Around 8-8.1 volts? Or can we pull the heaters down to 5.7v (the lower accepted voltage) and keep the supply the same?
Thanks
ian
ioaudio
Well-known member
i run the pf86 @ about 4,2v and the ef86 @ 5,7v for lower noise - current is than a bit lower than the specified 300 and 200 mA.
a 10ohm pot is a very good idea, especially since you can bias the tubes individually. 1 watt is a very conservative rating, if you plan to replace it with a fixed resistor after the measurement you can take any standard pot.
the 0,047 film´s footprint is 10-11mm
take 51 or 47Kohm for the 50kOhm
you can measure spacings from this picture, it should be 46 x 124 mm for the original size
http://www.twin-x.com/groupdiy/albums/userpics/pcb_front_silkscreen.JPG
-max
a 10ohm pot is a very good idea, especially since you can bias the tubes individually. 1 watt is a very conservative rating, if you plan to replace it with a fixed resistor after the measurement you can take any standard pot.
the 0,047 film´s footprint is 10-11mm
take 51 or 47Kohm for the 50kOhm
you can measure spacings from this picture, it should be 46 x 124 mm for the original size
http://www.twin-x.com/groupdiy/albums/userpics/pcb_front_silkscreen.JPG
-max
stitch-o
Well-known member
JW said:
I'm curious as to the grill-layer-mojo-situation:
Why would 3 layers of mesh be bad for the MK7 design, If you don't mind me asking?
Cheers!
Linus
Well-known member
JW said:
They charged me 30 euro but you don't have to pay VAT.
JW
Well-known member
No, I meant that the 3 layers may be more desirable since it's closer the U47 head basket, right?
plumsolly
Well-known member
called mxl today and no luck getting a schematic for the 960 power supply. The person I talked to said they didn't even have one. Nor did he know the b+ or heater voltages.
It looks like, with shipping to u.s. the T Bone will cost $240. Not too bad. Im still deliberating. I'd like to use the mxl because it's cheaper and has the mogami cable, but it may be too much of a headache. Also the fact that max approves of the grill design of the T Bone is something to consider...
-Ben
It looks like, with shipping to u.s. the T Bone will cost $240. Not too bad. Im still deliberating. I'd like to use the mxl because it's cheaper and has the mogami cable, but it may be too much of a headache. Also the fact that max approves of the grill design of the T Bone is something to consider...
-Ben
djn111
Well-known member
Servus,
Vienna, I am just back from Austria, Zell
, but depending on the price, I will take 2.
Gruss Dirk Jan.
Vienna, I am just back from Austria, Zell
, but depending on the price, I will take 2.Gruss Dirk Jan.
R3
Member
Waitin on this and the dale m7 Let me know! Excited.....
-R
-R
seavote
Well-known member
just watching the thread (as im hoping to get a kit in the next, (??or future??) group buy.) but for you members in n. america ,$240 for a mic to use only the body is more than you should pay. there are many chinese import mics that are exactly the same as european counterparts. i'm not certain but i think with a little more digging you could find a cheap tube mic (assuming you are looking to modify a stock power supply) that will fit the mk7 pcb and have a head basket that approximates the U47 . if you plan on making your own PSU for the mic you have even more options. look around the mic meta or maybe a forum member already knows a good candidate and can make a suggestion (ask in a new thread?) used on ebay will be even cheaper
$240 for a body and power supply is not that bad plus you get some parts like high value resistors.
If you have the mxl 960 measure the voltages in the power supply.
Adjusting the china power supplies is easy. Ohms law is you friend and NS app notes are your friend.
Sometimes you need to do what I do buy the stuff and measure, test it yourself. Or go to the microphone web sites and read the dimension specs.
If you have the mxl 960 measure the voltages in the power supply.
Adjusting the china power supplies is easy. Ohms law is you friend and NS app notes are your friend.
Sometimes you need to do what I do buy the stuff and measure, test it yourself. Or go to the microphone web sites and read the dimension specs.
ioaudio
Well-known member
always depending on how easy it is to replace the 3-pin XLR with a 7-pin version, dont forget the possibility to use a non tube mic housing as a alternative. building your own PSU is a good thing, especially for this project where we need very low ripple for the heater/bias. it would frustrate me to see someone expecting the stock psu to give the best results and it does not.
for example low mains voltage could be a problem, since the overhead for the heater rail is rather small.
since the stock psu is quite small modifications are limited.
why not use the small gold/super caps in the psu?
the internal impedance of goldcaps is too high. true electrolytics 10000µF/16v are needed for the rough job, the goldcaps quiten the last bit insided the microphone.
i build a supply with a choke for the heater/bias, but the stock psu housing would not be big enough for a transformer+choke and big capacitor arrays.
as already noted, a different approach changes the bias method , adding a cathode resistor for self bias and disconnecting the heater rail completely from the audio path - this is the easy way and works with the unmodded stock psu, except for the pattern switch assembly.
for self bias the gold/super caps can be ommited, for a ef86 additionally the 2,2R and the 3,9 resistor should be left out:
which bias method is better
try, find out and report back!
-max
for example low mains voltage could be a problem, since the overhead for the heater rail is rather small.
since the stock psu is quite small modifications are limited.
why not use the small gold/super caps in the psu?
the internal impedance of goldcaps is too high. true electrolytics 10000µF/16v are needed for the rough job, the goldcaps quiten the last bit insided the microphone.
i build a supply with a choke for the heater/bias, but the stock psu housing would not be big enough for a transformer+choke and big capacitor arrays.
as already noted, a different approach changes the bias method , adding a cathode resistor for self bias and disconnecting the heater rail completely from the audio path - this is the easy way and works with the unmodded stock psu, except for the pattern switch assembly.
for self bias the gold/super caps can be ommited, for a ef86 additionally the 2,2R and the 3,9 resistor should be left out:
which bias method is better
try, find out and report back!
-max
ioaudio
Well-known member
this one is too high for some housings - find the 250V version. think 3d.
when i have time i check the other entries.
Building a power supply tailored for this project would seem smart.
I'm more concerned with getting a donor mic with a GREAT sounding grill, than just buying one cause it has a psu.
Any suggestions?
Also maybe this seems silly and very basic to some but how do the laminations effect the transformers?
[edit: http://www.circuit-innovations.co.uk/transformers.html lol]
I'm asking because of the limited number of these kits available and the high demand, and yes I'm well aware 'ioaudio' is working on a sub.
But I'm still curious, as well as eagerly watching the BM.
Thanks!
I'm more concerned with getting a donor mic with a GREAT sounding grill, than just buying one cause it has a psu.
Any suggestions?
Also maybe this seems silly and very basic to some but how do the laminations effect the transformers?
[edit: http://www.circuit-innovations.co.uk/transformers.html lol]
I'm asking because of the limited number of these kits available and the high demand, and yes I'm well aware 'ioaudio' is working on a sub.
But I'm still curious, as well as eagerly watching the BM.
Thanks!
