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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 385

post #5761 of 10502

Hi Rossliew,,

 

 

The 6AS7 tube draws 2.5A with an amplification factor of 2. It seems that it is possible that you could use this tube as a driver tube, but only with an external power supply since the LD MKIII cannot handle such high current with it's built in power supply. The socket adapter for octal tubes should work for the 6AS7 tube.

 

I am not sure if anybody has used the 6AS7 as a power tube in the LD MKIII. This setup would require external power supplies for both tubes. Then it seems to be a question if the internal electronics match this tube - could be that the amp would be damaged.

 

A low amplification factor means that you have to turn the volume up higher than what you normally do. I am running a 6BX7 octal tube as driver with an amplification factor of 10 (draws1.5 amps) without any problems.

 

I cannot say that I understand well the relationship between all these factors. In the past I tried to use 6FQ7/6CG7 tubes as power tubes but that did not work well. However, using the adapters and 6SN7 tubes works beautifully, and they sound better than the 6N6P-IR tubes that were my previous best power tubes.

post #5762 of 10502
Quote:
Originally Posted by Rossliew View Post
 

Thanks for the advice! LOL thankfully I didn't go crazy and start buying all types of tubes...what about those unique tubes which Gibosi uses in his amps? Where can one find an adaptor to match them to the LD mk III?

 

First, I am using these tubes as drivers. and not power tubes. In order to do so, I have an external breadboard 9-pin socket, Vector test sockets and an external power supply. Once that is set up, you can buy very specific adapters to run ECC40, 2C51 and 6SN7s. If you still want to do this, I suggest you search this forum looking for "Vector", "breadboard socket", "ECC40 adapter" and "2C51 adapter".

 

I know... I should probably put all this in one place, but...........

 

And if you take no extra steps to make it pretty, you will have something like this:

 

post #5763 of 10502

Or this:

 

 

As you can see from sophisticated colorful spider web inspired set up, there are two breadboards connected for a quick change from octal/12AX7  to 6DJ8 pinout tubes. Please note the advanced Sears multitester for voltage readings ($10 on sale) and the switched off LED on the voltage regulator which cannot decide if it is 6.7 or 6.8V -make that 6.3V at the tube pins for this 1.5A tube.

 

Thanks Gibosi for all the inspiration and cheerful advice.

 

But folks, this works! Beautifully.....


Edited by mordy - 4/6/14 at 12:34pm
post #5764 of 10502
Quote:
Originally Posted by mordy View Post
 

Or this:

 

 

As you can see from sophisticated colorful spider web inspired set up, there are two breadboards connected for a quick change from octal/12AX7  to 6DJ8 pinout tubes. Please note the advanced Sears multitester for voltage readings ($10 on sale) and the switched off LED on the voltage regulator which cannot decide if it is 6.7 or 6.8V -make that 6.3V at the tube pins for this 1.5A tube.

 

Thanks Gibosi for all the inspiration and cheerful advice.

 

But folks, this works! Beautifully.....

Hi mordy,

     Have you ever try stacking the 2 vector does it hum when you stack them on top of each other?I would like to know if you done that because my new adapter i'am planning to solder all the wires together for the adapter socket and separate all the Heater wires in that way i can just plug-in all the tubes that i need and turn them on one at a time via heater switch.Connetions would be 6 wires from LD driver sockets to 6SN7 socket 6AS7 socket 6DJ8 socket 12AU7 socket but all the heaters are in thier own power switch.They  would all be plug-in all together then just turn on the switch that you need.

post #5765 of 10502

Hi 2,

 

I have thought of it, but I am afraid to try it because even though the heater wires can be switched off, it seems to me that the wiring from one Vector set up could interfere with a different wiring configuration with another Vector as far as the amp is concerned.

 

For me it is not very difficult to pull out the Vectors from one breadboard and plug in another set from another breadboard. The heater wires are always connected to both bread boards, but I make sure that only one tube is plugged in. The other thing to remember is to check the voltage - I briefly ran a 6V tube on 8V because I forgot to check.

 

As pointed out previously, the voltage at the tube pins seems to change depending on the tube, and that setting has to be checked as well when switching tubes.

 

I am the first one to admit that I do not know much about electronics, and there may very well be a way to stack the Vectors without any problems, but I defer to others to try it.

post #5766 of 10502

Thanks, Mordy and Gibosi for the advice. Looking at the pictures above and my very limited understanding of electronics and wiring, I think I will stick to the 6SN7 adaptors and enjoy that for awhile. Unless either of you chaps can prep one of those breadboards and external PSU ready for plug and play use, then I will gladly pay for a set to try out myself  :)

post #5767 of 10502
Quote:
Originally Posted by Rossliew View Post
 

Thanks, Mordy and Gibosi for the advice. Looking at the pictures above and my very limited understanding of electronics and wiring, I think I will stick to the 6SN7 adaptors and enjoy that for awhile. Unless either of you chaps can prep one of those breadboards and external PSU ready for plug and play use, then I will gladly pay for a set to try out myself  :)

 

Unfortunately, my setup is too messy to lend itself to a nice and neat system that is plug and play. That said, all the information you need is contained in this forum. And if you do decide to give it a try, all you need are these items and some wire:

 

1) One 9-pin breadboard socket. Search eBay for "9-pin breadboard socket" and "9-pin experiment socket"

 
I purchased this one:
 

http://www.ebay.com/itm/9-pin-breadboard-prototype-tube-socket-for-DIY-experimenting-/161388726782?

 

2) Two 7-pin Vector test sockets:
 
http://www.radiodaze.com/product/15450.aspx

 

And if Radiodaze is out of stock, you can make some test sockets using a 7-pin socket and some 16 gauge wire:

 

https://www.youtube.com/watch?v=MxLckWT-fvg

 

3) A step down voltage regulator. This allows you to roll 6SN7 and ECC40 at 6 volts as well as 12 volt tubes like E80CC and 13D3.

 

I purchased this one:

 
http://www.ebay.com/itm/LM2596-Digit-Display-4-40V-DC-DC-Converter-Module-Step-Down-Regulator-Voltmeter-/360685295663?pt=LH_DefaultDomain_0&hash=item53fa84d82f

 

And this one can handle more current:

 

http://www.ebay.com/itm/1pcs-DC-DC-Step-Down-Power-Module-4V-38V-to-1-25V-36V-5A-Voltmeter-Adjustable/351197902632?

 

4) An AC to DC power supply. You might have one of these already, an extra laptop power supply. Make sure it is rated for at least 1.5A. And if you anticipate running 12.6V tubes, at least 15V.

 

For example:

 

http://www.ebay.com/itm/19V-3-42A-Laptop-Power-Supply-AC-Adapter-Charger-Cord-for-Acer-Toshiba-Gateway-/121387965243?

 

~~~~~~~~~~

 

If you decide to give this a try, come back here once you have all the parts and we will walk you through the connections.

 

Cheers

 

Edit: Clarified AC to DC power supply requirement.

Edit2: Updated AC to DC PS to accommodate 5687/7044

Edit2: Updated links


Edited by gibosi - 3/23/15 at 11:38am
post #5768 of 10502

Wow!! This is what I call a real committed and very helpful community! Many thanks, G, for the kind advice and offer. I shall find time to read up more on this thread and google to learn a bit more basics before i attempt anything. Don't want to blow the amp (or possible myself!) up in the process...

post #5769 of 10502
Quote:
Originally Posted by Rossliew View Post
 

Wow!! This is what I call a real committed and very helpful community! Many thanks, G, for the kind advice and offer. I shall find time to read up more on this thread and google to learn a bit more basics before i attempt anything. Don't want to blow the amp (or possible myself!) up in the process...

 

You are very welcome. It is fun and very easy, and I believe you will be very pleased with how much better your LD sounds with double triodes.

 

A good place to begin to follow our double triode journey starts with Audiofanboy's post on page 204. And you will see that our first steps were even cruder and more primitive than what you have seen here recently. lol :)

 

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/3045#post_9830528

post #5770 of 10502

Hi Rossliew,

 

On page 301 post #4507 there is a step-by-step pictorial guide how to build a breadboard adapter. It does not require any technical knowledge and is easy to do with the right parts.

post #5771 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi 2,

 

I have thought of it, but I am afraid to try it because even though the heater wires can be switched off, it seems to me that the wiring from one Vector set up could interfere with a different wiring configuration with another Vector as far as the amp is concerned.

 

For me it is not very difficult to pull out the Vectors from one breadboard and plug in another set from another breadboard. The heater wires are always connected to both bread boards, but I make sure that only one tube is plugged in. The other thing to remember is to check the voltage - I briefly ran a 6V tube on 8V because I forgot to check.

 

As pointed out previously, the voltage at the tube pins seems to change depending on the tube, and that setting has to be checked as well when switching tubes.

 

I am the first one to admit that I do not know much about electronics, and there may very well be a way to stack the Vectors without any problems, but I defer to others to try it.

Hi Mordy,

         Thanks for the Info and about pluging tubes   to the proper voltage regulator/socket is very important to remember which tube you have on the socket.I did plug-in 6SN7 to 12V thinking that that was the Marconi 12SN7 but it was the marconi 6SN7 so when i look at it told my self that tube is glowing really bright and i leaved it there untill  the sound started to distort then i unplug it when it cools down i checked that tube and it was 6SN7 luckily it did not burn to this day that tube  still working and from that i always double checked what tube i have and which plug it's in(6V or 12V Socket).

post #5772 of 10502

Thanks, Mordy and G for the links...need to read and absorb the info there!

post #5773 of 10502
Btw, anyone have pictures on how to change the jumpers from ef95 to ef92 on the LD Mk 3?
post #5774 of 10502
Its in the user manual... If you don't have the one that came with your amp, it is available on the little dot site...

http://dl.dropboxusercontent.com/u/6037680/Little%20Dot%20MK%20III%20Reference%20Guide.pdf
Edited by kvtaco17 - 4/8/14 at 9:20am
post #5775 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi Rossliew,,

 

 

The 6AS7 tube draws 2.5A with an amplification factor of 2. It seems that it is possible that you could use this tube as a driver tube, but only with an external power supply since the LD MKIII cannot handle such high current with it's built in power supply. The socket adapter for octal tubes should work for the 6AS7 tube.

 

I am not sure if anybody has used the 6AS7 as a power tube in the LD MKIII. This setup would require external power supplies for both tubes. Then it seems to be a question if the internal electronics match this tube - could be that the amp would be damaged.

 

A low amplification factor means that you have to turn the volume up higher than what you normally do. I am running a 6BX7 octal tube as driver with an amplification factor of 10 (draws1.5 amps) without any problems.

 

I cannot say that I understand well the relationship between all these factors. In the past I tried to use 6FQ7/6CG7 tubes as power tubes but that did not work well. However, using the adapters and 6SN7 tubes works beautifully, and they sound better than the 6N6P-IR tubes that were my previous best power tubes.

 

Hi mordy.

 

First off I heartily agree with you re 6SN7 tubes as powers...the more I listen to my Sylvania VT231s (with the C3GSs as drivers) the more I am liking them - they are absurdly good for the money. They really are giving my MUCH more expensive Psvane CV181-T IIs a run for their money (and that's before I make my own silver wire adapters!).

 

Secondly, just for interest's sake, I am awaiting a Tung Sol 7N7 - the loctal version of the 6SN7GT...more adapter-making!! Looking forward to seeing how they compare to the Sylvanias...

 

And thirdly - don't ask me why (perhaps iluvmusic's pioneering spirit with 6AS7s has lit a fuse in me!) - but I have just bought some very nice-looking RCA "coke bottle" 6AS7Gs...wait for it...to try as power tubes. I know, I know...I am putting it down to early onset dementia! Whatever, I am determined to at least see if it is a complete no-no.

As for heater power, I am wondering if it is possible to have one tube fed by the LD, with the other fed externally...suppose a peek inside would show if each is fed separately or not...

And I would need to take off the front panel and stick my finger inside to test for excessive heat...NO, ONLY KIDDING!! - the dementia isn't that far advanced?? A thermometer - carefully positioned! - should do the trick.

 

You could try to dissuade me, mordy, but I am all fired up at the moment!...Still, I have probably a fortnight to reflect on my madness...This rolling game has become too addictive, lol...:eek:

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