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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 289

post #4321 of 9784
Quote:
Originally Posted by mordy View Post
 

Hi Ctritical Bill,

 

Being unfamiliar with electronics, perhaps you could describe in more detail how to connect this regulated power supply? Could you take a wall wart of say 15V 1 A and connect it to the voltage regulator and then connect heater wires 3&4 (instead of putting these wires into the Vector adapter)?

 

Would the voltage regulator described here do the job? Looks like it has a built in voltage display. Also, would it be possible to use a driver tube that draws a higher current than the LD amp provides, as long as the external A/C adapter has enough capacity?

 

http://www.ebay.com/itm/New-LM317-Adjustable-Voltage-Regulator-Step-down-Power-Supply-Module-LED-Meter-/281168816716?pt=LH_DefaultDomain_0&hash=item4176f7aa4c

 

 

The answer to all your questions is ... Yes.

 

The wall adapter and voltage regulator are used instead of the LD transformer. So connect the heater wires directly to the output of the voltage regulator. This way, the suspected power limitations of the LD transformer are avoided and you can use tubes with a higher current demand. Also, as the name implies, this is a voltage regulator so you can adjust it to supply exactly 6.3v regardless of your supply voltage and current demands of different tubes.


Edited by Ctritical Bill - 12/11/13 at 12:01am
post #4322 of 9784

For those of us who decide to use one of these wall adapter/voltage regulator devices to provide heater voltage, something to keep in mind.... We will need to remember to turn this circuit on when we turn the amp on and turn it off when we turn the amp off. After all, we don't want to be running the tube's heater filaments all the time.

 

It might make sense to plug the wall wart into a power strip, or something similar, with an on/off switch, so we don't have to actually plug and unplug the adapter from the wall. And perhaps, we might want to consider plugging the amp and the heater circuit into the same power strip and and using the the power strip to turn both on and off at the same time....

post #4323 of 9784

Hi All,

 

"You can use tubes with a higher current demand."

 

Can anybody suggest inexpensive driver tubes that may work well with the higher current external power source for the heaters. The only thing that comes to mind is the 6SN7GT octal, but I remember seeing others being mentioned.

post #4324 of 9784

Here is an interesting liitle circuit for powering tubes from batteries, it monitors the battery voltage level till critical then a relay opens and the plate power is killed to the tubes.

 

http://www.klausmobile.narod.ru/projects/pr_10_batt_e.htm

:beerchug: 

post #4325 of 9784

If somebody is interested in a pair of Vector adaptors modified to accept 6DJ8 -6BQ7A tubes, adaptors will include a pair of Westinghouse 6BQ7A tubes already modified with about 40 hours on them .PM me If interested  $20.00+shipping  SOLD SOLD SOLD !!!!!!

  

 

                                                                                                                                                                                                                                                  


Edited by MIKELAP - 12/11/13 at 5:38pm
post #4326 of 9784

I received a Western Electric 396A/2C51 in the mail today, and I hope to get to it soon.... :)

 

 

FYI: There exists a 40 volt version of this tube, the 407A. Like the 12AX7, which can be configured to run on 6 volts, the 407A can be configured to run on 20 volts. As the only difference between the 407A and the 396A is the heater, I would expect them to sound very similar, if not identical, but unfortunately, I haven't been able to find much on Google about how they compare. Those who are running double triodes on their LD 1+ might want to try a 407A, as the LD1+ can be configured to drive 20 volt tubes. And those who are running double triodes on other LDs, a 24 volt wall adapter with a voltage regulator can be used to supply 20 volts to the heaters. Cheers. :)


Edited by gibosi - 12/13/13 at 7:30am
post #4327 of 9784
Quote:
Originally Posted by gibosi View Post
 

Amperex 6922 Face off

 

I have a 1961 US-Amperex 6922 (VL6 Asterisk1B) and a 1961 Holland-Amperex 6922 (VL6 Delta1K3), same year and change code.......

 

To summarize the Amperex faceoff, I found the Holland tube to be more forward and lush than the US tube, but the highs were softer and more gentle. Next up, a 1967 La Radiotechnique 6922 (VL8 F7B1) manufactured in the Philips-owned Mazda factory in Suresnes, France. The La Radiotechnique reportedly (Brent Jessee) has a sweet lush mid range like the Holland tube, but better detail and high end punch, so I wanted to see how it compared with the US and Holland made Amperex tubes.

 

La Radiotechnique vs Holland-Amperex

 

As expected, these tubes are very similar, both having a sweet, lush mid range. And indeed, as Brent Jessee notes, the French tube does have a bit more high frequency detail and punch. However, I found this difference to be rather subtle. To my (rather old) ears, the difference is small enough that if someone has one of these tubes, I would recommend against getting the other. But then, my ears are old... lol

 

So to be fair, it seemed reasonable that if someone (likely with younger ears than mine) found the high end of the Holland tube to be too soft, then perhaps the French tube might just be perfect. And with that in mind, I set up another face off to try to compare the high end detail of the French and US tubes.

 

La Radiotechnique vs US-Amperex

 

In listening to these two tubes, I felt that the treble was very comparable. However, I found that switching back and forth between the lush mid range of the French tube and the more laid-back and cooler mid range of the US tube to be rather jarring. But each time, after about 20 or 30 minutes, my brain settled down and both sounded great.

 

Again, I think I could be happy with any of these three, and at this point in time, I am unable to choose a favorite. Perhaps after some weeks, or months, one will eventually rise to the top, but for now, the best I can do is to recommend all of them. The transparency and dynamics, the imaging and spaciousness - the realism is just breathtaking.

 

Next, I will try to compare the 1961 Holland-Amperex 6922/E88CC to the 1960 Holland-Amperex 7308/E188CC. And then, finally, I hope to summarize my impressions of the 1975 Voskhod 6N23P....


Edited by gibosi - 12/12/13 at 8:46pm
post #4328 of 9784

Hi Gibosi,

 

Thank you very much for your in depth analysis of the various Amperex type tubes. I have the same experience as you, namely that I get used to listening to a certain great tube and then find it unsettling to get used to another great sounding tube. With the best sounding tubes, where nothing bothers you, it becomes a matter of taste or preference, but my brain still needs time to adapt.

 

That said, I have to get used to the Voskhod 1975 6N23P tubes I just got, in addition to Voskhod (Saratov) 6N9S octal tubes. The 6N23P tubes are detailed and punchy, and the Saratov tube has a very sweet spacious presentation that is very enjoyable.

 

I ordered a bunch of 6DJ8 variants (6BC8, 6BZ7, 6BZ8,X155) in the hope of finding an inexpensive alternative to the big A. Time will tell...

 

About getting higher current adapters: What is better to use for powering the heaters, a 15V 2A adapter, or an old laptop 20V 3.5A adapter? Will the laptop adapter fry a voltage regulator that is rated up to 40V and 2A?

post #4329 of 9784
Quote:
Originally Posted by mordy View Post
 

That said, I have to get used to the Voskhod 1975 6N23P tubes I just got, in addition to Voskhod (Saratov) 6N9S octal tubes. The 6N23P tubes are detailed and punchy, and the Saratov tube has a very sweet spacious presentation that is very enjoyable.

 

About getting higher current adapters: What is better to use for powering the heaters, a 15V 2A adapter, or an old laptop 20V 3.5A adapter? Will the laptop adapter fry a voltage regulator that is rated up to 40V and 2A?

 

What is the construction of your 1975 Voskhods? I have one with a wire getter post (left) and another with the getter supported by an extension of the shield (right). The first is a bit darker than the other, but both are fabulous. :)

 

 

Either of those adapters should be fine. It is my understanding that even though your laptop adapter can put out 3.5 amps. the tube will draw only what it needs, and therefore, for example, the voltage regulator should never see more than 600ma for a 6SN7

post #4330 of 9784

Heerlen VR2 E188CC vs New York 7L6 6922:

 

OK, so I finally found the courage to swap the tubes to give a lil' more feedback.

 

The US 6922 immediately sounds a little more extended; highs are more shimmering, bass has a kick/punch while extremely tactile. Mids used to sound close to perfect to me before trying the E188CC and still sound great to me even afterwards, just different I guess; mids on both tubes has body, but it is lusher on the E188CC and "just" musical on the 6922. Listening to the 6922 again, I think the soundstage is much larger, and probably deeper than with the E188CC; actually that might account, in part, for the impression of vocals being a bit more "forward" on the Heerlen tube.

 

Now, as far as details and realism go, it's really difficult to pick a winner here... Details seem more emphasized on the 6922: they come at you in a bigger, meaner, way from the angles, where I could swear I could hear a little more mids and high mids details closer to the center of the picture with the E188CC.

 

So, yeah, I guess the E188CC is more polite than the 6922: lusher but tamer mids, less glorious highs, less punchy bass, but probably a better sense of low level detail than with the 6922. You really get used to the bass impact and shimmering highs of the 6922, but at the same time, you immediately miss this sense of center imaging with more micro-detail and less extremes that the E188CC. The 6922 is macro-detail with body and impact, and the E188CC is micro-detail with intimacy and focus. I'm obviously overemphasizing the differences here though, as the tubes sound more similar than not, but you can definitely tell those are different in a few ways.

 

It's terrifying how quickly you can get used to something better than before... Comparing both tubes, I could almost swear something is missing now lol; a sense of absolute realism and detail in a way. Guess I just need to order more tubes now... It never ends I tell you.

 

Oh yeah, measurements: I measured voltages with the 6922. Wall was 228V.

 

Heater  -  5.89V


Plate (R) - 79.9V    Grid (R) - 2.04V
Plate (L)  - 79.8V    Grid (L)  - 2.05V

 

Where the last time I re-measured the E188CC (with 227V on the wall I think), I got:

 

Heater  -  5.84V


Plate (R) - 75.2V    Grid (R) - 2.06V
Plate (L)  - 75.2V    Grid (L)  - 2.08V

 

So, no huge difference here. The 35 mA lower current requirements of the 6922 might be responsible for the slightly higher heater voltage. The other values are pretty similar.

 

Edit: The E188CC is back in, yeah that was quick I know... I guess an even better way to describe both tubes in only one word is: the 6922 is punchy, whereas the E188CC is liquid - that's the word I was missing earlier. And listening again, the E188CC's highs are actually very detailed too, whereas the 6922's highs can almost sound a little sibilant on a bad day. Definitely a bit more microdetail in the midrange of the E188CC, but less bass too, which is a bit of a compromise (it's hard to forget to way the 6922 renders a bass kick, it's almost like air is actually blown towards you ear).


Edited by Audiofanboy - 12/13/13 at 8:32am
post #4331 of 9784

Hi Gibosi,

 

I got four used Voskhod 6N23P tubes from Aug 1974, all with the wire getter. In your opinion, how does this tube compare to the Amperex  6922/7308/6DJ8?

post #4332 of 9784
Quote:
Originally Posted by mordy View Post

 

I got four used Voskhod 6N23P tubes from Aug 1974, all with the wire getter. In your opinion, how does this tube compare to the Amperex  6922/7308/6DJ8?

 

I have not listened to a 1974 Voskhod, so I can't say.... However, I have listened to 1975 and 1978 Voskhods, and in my opinion, they are every bit as good as the Amperex 6922. And while I haven't yet had time, an Amperex vs Voskhod face-off is definitely on my To Do list. But first, I want to take some time to consider the Heerlen E188CC.

post #4333 of 9784
Quote:
Originally Posted by mordy View Post
 

Hi Gibosi,

 

I got four used Voskhod 6N23P tubes from Aug 1974, all with the wire getter. In your opinion, how does this tube compare to the Amperex  6922/7308/6DJ8?

 

 

Quote:
Originally Posted by gibosi View Post
 

 

I have not listened to a 1974 Voskhod, so I can't say.... However, I have listened to 1975 and 1978 Voskhods, and in my opinion, they are every bit as good as the Amperex 6922. And while I haven't yet had time, an Amperex vs Voskhod face-off is definitely on my To Do list. But first, I want to take some time to consider the Heerlen E188CC.


I own a paid of 74 and 75 Voskhod as well as the Amperex 6922 and I'd say they are about equal... the earlier Voskhods are more musical then the 75, which is tilted towards the drier more analytical side, but not what I'd call dry or analytical lol SO 74 slightly warmer then 75... this is with my Lyr obviously...

 

My parts for the single 6DJ8 to LD 1+ shipped today also... I should soon catch up to you guys!


Edited by kvtaco17 - 12/13/13 at 2:44pm
post #4334 of 9784
Quote:
Originally Posted by kvtaco17 View Post
 

 

 


I own a paid of 74 and 75 Voskhod as well as the Amperex 6922 and I'd say they are about equal... the earlier Voskhods are more musical then the 75, which is tilted towards the drier more analytical side, but not what I'd call dry or analytical lol SO 74 slightly warmer then 75... this is with my Lyr obviously...

 

Do your 1975s have a wire getter support like the 1974? Or do they have the getter supported by an extension of the shield? And gray plates?

post #4335 of 9784
Quote:
Originally Posted by gibosi View Post
 

 

Do your 1975s have a wire getter support like the 1974? Or do they have the getter supported by an extension of the shield? And gray plates?

Let me dig them out!

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