... on your XLR connectors - >
pin 2: signal 'hot'
pin 3: signal 'cold'
pin 1: to chassis ground please
: )
pin 2: signal 'hot'
pin 3: signal 'cold'
pin 1: to chassis ground please
: )
Thanks for pointing that out Gordy, I just kinda threw that up there. lol
Well I got the amveco 62065 in today, I'm a bit confused though, it has 8 wires on it? one side has a purple, black, red and yellow wires. The other has blue red brown and green. the first sides wires have a yellow shell halfway up.
not sure how to wire this?
another thing, what is the ohm on the "Rdrop" on the power supply for the heaters? and what is the 25H coil on top of the power supply?
And another thing, I'm a bit new to AC driven circuit's, im not sure where the ground goes for the circuit, would that all link back to the chasis ground? (I've attached an image, grounds noted in red.)
And dont mind the 48v phantom power or the volt meter on there. I wont be adding those in now, just stuff maybe for in the future.
Thank you,
Weston
Well I got the amveco 62065 in today, I'm a bit confused though, it has 8 wires on it? one side has a purple, black, red and yellow wires. The other has blue red brown and green. the first sides wires have a yellow shell halfway up.
not sure how to wire this?
another thing, what is the ohm on the "Rdrop" on the power supply for the heaters? and what is the 25H coil on top of the power supply?
And another thing, I'm a bit new to AC driven circuit's, im not sure where the ground goes for the circuit, would that all link back to the chasis ground? (I've attached an image, grounds noted in red.)
And dont mind the 48v phantom power or the volt meter on there. I wont be adding those in now, just stuff maybe for in the future.
Thank you,
Weston
Attachments
This is how I have been wiring the Amveco toroid:
Be aware; dsavitsk (hope I spelled that right) has pointed out that in using one half the primary as a secondary we are violating the insulation rating of the winding varnish, so be advised. I don't do it this way any longer, since I am a commercial operator, sorta, and have Responsibilities. I now use the Antek AN-0232, with secondaries in series (yielding ~66V at derated service) and a fullwave voltage doubler. I'll post that schem if desired. I will say that I have had no trouble with the oddball connection of the Antek, but if you do use it that way, do not fail to have a 0.5A (0.25A if you're in a 230V country) slo-blo fuse in the hot wire to the transformer, in front of all switching.
Grounding, give it yer best shot. The open triangle symbol is circuit ground, and they are connected. The 'rake' symbol is earth ground, and is attached to the chassis. Connect this to your circuit ground at one point only, and I like to do it with a 1R 10W 'cement block' resistor. Lowers the hum.
Aloha,
Poinz
Be aware; dsavitsk (hope I spelled that right) has pointed out that in using one half the primary as a secondary we are violating the insulation rating of the winding varnish, so be advised. I don't do it this way any longer, since I am a commercial operator, sorta, and have Responsibilities. I now use the Antek AN-0232, with secondaries in series (yielding ~66V at derated service) and a fullwave voltage doubler. I'll post that schem if desired. I will say that I have had no trouble with the oddball connection of the Antek, but if you do use it that way, do not fail to have a 0.5A (0.25A if you're in a 230V country) slo-blo fuse in the hot wire to the transformer, in front of all switching.
Grounding, give it yer best shot. The open triangle symbol is circuit ground, and they are connected. The 'rake' symbol is earth ground, and is attached to the chassis. Connect this to your circuit ground at one point only, and I like to do it with a 1R 10W 'cement block' resistor. Lowers the hum.
Aloha,
Poinz
Hmm, well I already have the Amveco in my hand so I think i'll just use it.
Though, at the bottem of that image it says Amveco 62062? is that correct? I have a Amveco 62065 (what was specified in the schematic)
another thing about the UF1007s, cant I just use a 1000v bridge rectifier over wiring 4 diodes together to make a bridge rectifier?
I was thinking the KBP210 or GBPC1510.
And your saying, attach the circuit ground to chasis ground, through a 1R 10W resistor?
Though, at the bottem of that image it says Amveco 62062? is that correct? I have a Amveco 62065 (what was specified in the schematic)
another thing about the UF1007s, cant I just use a 1000v bridge rectifier over wiring 4 diodes together to make a bridge rectifier?
I was thinking the KBP210 or GBPC1510.
And your saying, attach the circuit ground to chasis ground, through a 1R 10W resistor?
The 62065 is the same trans with 2 × 22V (rather than 12V) secondaries. If you have the 62065, just use one secondary in series with the primary, rather than both. You need to keep the B+ voltage a few volts below 150V, in order to be able to find a reference voltage for the heaters that does not violate the Vh-k rating for either one (which is 25V up, 50V down). Again, make sure you fuse the circuit well and properly. You burn down your house, I gonna be sad.
Aloha,
Poinz
Aloha,
Poinz
Ok, Thanks. Its good that I wont have to get a different transformer. =)
And yes I will be using a fuse, you said 0.5 amp right? I havn't put anything together yet, infact I still dont have the resistor's or cap's yet. I'm wondering if I need any special resistors or cap's to take the 140vdc?
I'm also wondering if you have an instant messenger poindexter, it would be alot easier to talk on there becuase its instant. lol
Thanks,
Weston
And yes I will be using a fuse, you said 0.5 amp right? I havn't put anything together yet, infact I still dont have the resistor's or cap's yet. I'm wondering if I need any special resistors or cap's to take the 140vdc?
I'm also wondering if you have an instant messenger poindexter, it would be alot easier to talk on there becuase its instant. lol
Thanks,
Weston
Ok, Well I still need some more info. I just got the Hammond in today. now I got both transformers for the power supply, I still want to know if any of the resistor's cap's or diodes are anything special to handle the 140v? or just regular part's, I'm also wondering about what the coil in the top part of the power supply is? 25H? any part numbers for that?(or better yet, any digi-key part numbers for that coil?)
i'm also wondering about the 2 resistor's right before the heaters on the tubes, theres no impedance rating, it just says Rdrop? info please?
Thanks,
Weston
i'm also wondering about the 2 resistor's right before the heaters on the tubes, theres no impedance rating, it just says Rdrop? info please?
Thanks,
Weston
From memory these are simply whatever R is needed to bring the heater voltage down to 6.2V in your circuit. The V is just under 6.3 for longevity of the tube.
Rate the PSU caps for 250v or so and you should be good. That is for the main B+, the cap on the line biasing the heaters should be fine at 35v to 50v, 50v to be safe. Do the same with the film caps, just use common sense, caps suck when they pop so don't put a 140v cap where there will be 140v (voltage could go higher and you want some room for error and safety) and it should be smooth sailing. Resistors should be fine, most will say in the data sheet a voltage rating, but I wouldn't fret with 140v when using ½ watts or higher. Coil in the top part is a 25H (henry) power choke, anything in the 15H to 30H range should work as long as it is speced for 40mA or more. The diodes are rated for 1000v so those will be fine.
The resistors in the heater drop the voltage to about 6.2v so using 6T4's (4 of them at 225mA a pop) .... roughly 0.1 ohm 7.5 watt (maybe a tad high of a wattage ratting(?)) unless my math is off.
Cheers
James
Edit - for Poinz or anyone :
I am not doubting that you are right, you are a much better designer than I and this is YOUR circuit. However, I am still questioning if the 18k resistor on the output is needed when using a transformer output? Doesn't in this case the primary impedance of the output transformer provide the load for the gain stage that the 18k resistor normal would? I have attached a schematic showing this, more or less the same but with 12AU7's. The way I see it this is like a parafeed circuit and the resistor is no longer needed, or redundant. Like I said, I could be completely wrong, wouldn't be the first time 🙄 , but that is how we learn.
The resistors in the heater drop the voltage to about 6.2v so using 6T4's (4 of them at 225mA a pop) .... roughly 0.1 ohm 7.5 watt (maybe a tad high of a wattage ratting(?)) unless my math is off.
Cheers
James
Edit - for Poinz or anyone :
I am not doubting that you are right, you are a much better designer than I and this is YOUR circuit. However, I am still questioning if the 18k resistor on the output is needed when using a transformer output? Doesn't in this case the primary impedance of the output transformer provide the load for the gain stage that the 18k resistor normal would? I have attached a schematic showing this, more or less the same but with 12AU7's. The way I see it this is like a parafeed circuit and the resistor is no longer needed, or redundant. Like I said, I could be completely wrong, wouldn't be the first time 🙄 , but that is how we learn.
Attachments
Ok, I think I found a good choke for that, would the
Hammond 193C work well? its 20H 100ma. though its a bit expensive, does anyone have a better choke thats maybe cheaper?
So for the resistor there, would there only be 2 resistor's before all heaters, or 2 resistor's in between eatch heater?(total of 4 tubes=8 resistors) and the heaters are all in parallel of eatchother correct? and those should be 0.1ohm 7.5 watt eatch to drop it from 6.3 to 6.2v?
Thanks,
Weston
Hammond 193C work well? its 20H 100ma. though its a bit expensive, does anyone have a better choke thats maybe cheaper?
So for the resistor there, would there only be 2 resistor's before all heaters, or 2 resistor's in between eatch heater?(total of 4 tubes=8 resistors) and the heaters are all in parallel of eatchother correct? and those should be 0.1ohm 7.5 watt eatch to drop it from 6.3 to 6.2v?
Thanks,
Weston
The choke I use for this supply is the Tonyaba 010-25H50, which I get from Chung (VT4C Studio) for about seven clams, very reasonable. It is of high quality, has a grounding wire so I don't have to worry about the integrity of the chassis grounding through the screws, and is airgapped so it can be abused a bit (though I don't here) without dying onna groun'. If you're in the US, even in my western outpost, you want to build up a good order from him to offset the shipping cost, but fortunately he has lots of very kewl stuff. Browse around.
Aloha,
Poinz
AudioTropic
Aloha,
Poinz
AudioTropic
Poindexter said:
Ok I got the 6T4's in today, (there alot smaller then I thought...)
I was wondering about what you said, VT4C has some gold plated sockets for 6AQ5's which should fit the 6T4 tubes right? would those be good? or should I get the ones from Apex Jr for 0.35¢? or is there any other place I can get good qaulity sockets?(link please?) I would rather much spend a few more penny's for better qaulity sockets then have them break on me.
Thanks,
Weston
Oh I also found some sockets on ebay, at $1 a peice:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=300294303761
would these be good?
Those are PCB mount, theres also these for chassis mount:
http://cgi.ebay.com/Vacuum-Tube-Soc...ryZ73375QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Would any of those be good for the 6T4's?
Thanks,
Weston
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=300294303761
would these be good?
Those are PCB mount, theres also these for chassis mount:
http://cgi.ebay.com/Vacuum-Tube-Soc...ryZ73375QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Would any of those be good for the 6T4's?
Thanks,
Weston
The sockets in your second link are not miniature 7-pin - they would be TO big.
Get the 7-pin miniature sockets from Apex Jr they look great and you're not going to beat the price. For a wider variety, any of the 7-pin miniatures from SurplusSales will do, I just ordered 8 of the (TUA) TS102P03.
Max
Get the 7-pin miniature sockets from Apex Jr they look great and you're not going to beat the price. For a wider variety, any of the 7-pin miniatures from SurplusSales will do, I just ordered 8 of the (TUA) TS102P03.
Max
Just a few thoughts.
1. The SRPP design you are considering has only about 15dB of gain. Not enough for a mic pre
2. You do need an input transformer. It will provide gain and improve noise performance. I have never yet seen an SRPP with noise as low as 20uV, or indeed any pre with better than 40uV. If you achieve 100uV that will be OK, it's -80dBV. I would suggest a mic transformer ration of 10: giving an extra 20dB gain
3. The SRPP not only gives insufficient gain but its distortion characteristics are poor. You would get more gain and less distortion if you used a mu follower topology - it's much the same as an SRPP but with a few extra components and a higher supply voltage
4. You don't really need the output transformer - levels are high enough and unless you have very long cable runs it's pointless. Not only that you lose gain too.
5. A mu follower using say a 6SN7 or 6CG7 double triode will give you about 26dB of stage gain which with 20dB from the transformer gives a total of 46dB - probably enough for a basic mic pre.
Cheers
ian
1. The SRPP design you are considering has only about 15dB of gain. Not enough for a mic pre
2. You do need an input transformer. It will provide gain and improve noise performance. I have never yet seen an SRPP with noise as low as 20uV, or indeed any pre with better than 40uV. If you achieve 100uV that will be OK, it's -80dBV. I would suggest a mic transformer ration of 10: giving an extra 20dB gain
3. The SRPP not only gives insufficient gain but its distortion characteristics are poor. You would get more gain and less distortion if you used a mu follower topology - it's much the same as an SRPP but with a few extra components and a higher supply voltage
4. You don't really need the output transformer - levels are high enough and unless you have very long cable runs it's pointless. Not only that you lose gain too.
5. A mu follower using say a 6SN7 or 6CG7 double triode will give you about 26dB of stage gain which with 20dB from the transformer gives a total of 46dB - probably enough for a basic mic pre.
Cheers
ian
Lightning class
Hey Weston,
Maybe Victoria thought you were a sailor as well, your location is Michigan and they sail a lot of them up there. The lightning is a really nice little boat for day racing and your name looks like a boat id.
Hey Weston,
Maybe Victoria thought you were a sailor as well, your location is Michigan and they sail a lot of them up there. The lightning is a really nice little boat for day racing and your name looks like a boat id.
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