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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 265

post #3961 of 10578
Quote:
Originally Posted by Artsi View Post
 

But there is a cure. Me and my octals like. 

 

These past few days I have found myself listening to Holly Cole's Night over and over. My Sylvania 5751 (1950's, 3 micas, D-getter and black plates) really like this album.

 

Maybe you and your octals will like this too? :)

 

Holly Cole Trio - You've Got a Secret (live version)

 

post #3962 of 10578
Quote:
Originally Posted by gibosi View Post
 

 

These past few days I have found myself listening to Holly Cole's Night over and over. My Sylvania 5751 (1950's, 3 micas, D-getter and black plates) really like this album.

 

Maybe you and your octals will like this too? :)

 

Holly Cole Trio - You've Got a Secret (live version)

Very good quality as a live performance. Me like! :dt880smile:

post #3963 of 10578

Now beat this!

 

 

post #3964 of 10578

Kick it up into 720p for the best sound!

Harvest - Opeth - Royal Albert Hall

\m/:D\m/

post #3965 of 10578
Quote:
Originally Posted by Oskari View Post
 

Now beat this!

 

 


wow, very, very nice !

post #3966 of 10578

how's this ??

 

post #3967 of 10578

Sadly, my religion forbids me from listening to music on youtube through my headphones... Yeah, tough hi-fi gods, I know; but my religion also has its perks, even though my wallet may disagree lol...

 

Meanwhile, a seemingly silly idea crossed my mind earlier, after reading up on the history of OTL tube amps since the 70s. Most of the "top tier" premium single ended triode OTL amps are "no feedback" amps, whereas even on the highest gain setting our MK III & IVs still have a 470k ohms resistor acting a negative feedback input. So here's the question: would it seem totally unreasonable to just remove that resistor? Bonus questions: would that screw up the circuitry somehow, would it actually sound better, and should ever so slighly higher "volume" be expected if that last bit of feedback were to be removed?

 

Just a thought; thinking and -very- light DIY work being pretty much my only purpose around here lol (don't expect crazy cargo ship sized adapters from me)!

 

As a side note, I wonder if I might not prefer (read "take more listening pleasure with") my Amperex OG tube than over my more premium Amperex US 6922 tube. The OG really has a special quality to its sound. Listening with the Heerlen-made 6DJ8 from the OG years, it's not hard to pinpoint what sounds great actually: it all boils down to lush -not warm- mids, sweet highs and chocolatey tight bass, all this over a dark, transparent et palpable background. I guess I may be more of a sucker for the tube sound and its richness than I thought huh (though I'm also a sucker for ultra detail and balanced FR)?

post #3968 of 10578
Quote:
Originally Posted by Audiofanboy View Post
 

 

Meanwhile, a seemingly silly idea crossed my mind earlier, after reading up on the history of OTL tube amps since the 70s. Most of the "top tier" premium single ended triode OTL amps are "no feedback" amps, whereas even on the highest gain setting our MK III & IVs still have a 470k ohms resistor acting a negative feedback input. So here's the question: would it seem totally unreasonable to just remove that resistor? Bonus questions: would that screw up the circuitry somehow, would it actually sound better, and should ever so slighly higher "volume" be expected if that last bit of feedback were to be removed?

 

Some of the guitar amps can have NFB bypass put in, it can increase distortion and give more volume. 

 

I'd put a 500K pot in place so you can adjust it and observe the effects.

post #3969 of 10578
Quote:
Originally Posted by TrollDragon View Post
 

Kick it up into 720p for the best sound!

Harvest - Opeth - Royal Albert Hall

\m/:D\m/

post #3970 of 10578
Quote:
Originally Posted by Audiofanboy View Post
 

Sadly, my religion forbids me from listening to music on youtube through my headphones... Yeah, tough hi-fi gods, I know; but my religion also has its perks, even though my wallet may disagree lol...

 

[snip]

 

As a side note, I wonder if I might not prefer (read "take more listening pleasure with") my Amperex OG tube than over my more premium Amperex US 6922 tube. The OG really has a special quality to its sound. Listening with the Heerlen-made 6DJ8 from the OG years, it's not hard to pinpoint what sounds great actually: it all boils down to lush -not warm- mids, sweet highs and chocolatey tight bass, all this over a dark, transparent et palpable background. I guess I may be more of a sucker for the tube sound and its richness than I thought huh (though I'm also a sucker for ultra detail and balanced FR)?

 

It's not as if I go out of my way to listen to youtube, but I find it to be a very good way to learn about new music. I first heard Holley Cole on a youtube video posted in another forum. And I was so impressed that I immediately grabbed one of her albums.

 

Listening to my Sylvania 5751 these past several days, I am not feeling any urge to get back to my US-Amperex 6922. However, I have a few more premium 6DJ8 (1975 Voskhod 6N23P, Heerlen, Holland E188CC and Suresnes, France E88CC) coming soon. And of course I am very curious to discover whether the Sylvania will stay on top?

post #3971 of 10578
Quote:
Originally Posted by TrollDragon View Post
 

Some of the guitar amps can have NFB bypass put in, it can increase distortion and give more volume. 

 

I'd put a 500K pot in place so you can adjust it and observe the effects.

 

Interesting. So you wouldn't so much remove all feedback but use less, or implement a versatile way to change the resistor value huh?

 

Well, if anyone with good DIY soldering skills is willing to try, I'd love to hear how it sounds! I could snap off a resistor or two in my amp if needed, but soldering a whole pot or a new resistor in there just involves to much handiwork for me lol... I'm pretty sure it would be worth trying though, as the general feedback setting really does have a strong influence on the sound (and all extra gain is good gain in my book; I've been trying to squeeze the last bit of power out of my amp for months now, with some success).

 

Quote:
Originally Posted by gibosi View Post
 

 

It's not as if I go out of my way to listen to youtube, but I find it to be a very good way to learn about new music. I first heard Holley Cole on a youtube video posted in another forum. And I was so impressed that I immediately grabbed one of her albums.

 

Listening to my Sylvania 5751 these past several days, I am not feeling any urge to get back to my US-Amperex 6922. However, I have a few more premium 6DJ8 (1975 Voskhod 6N23P, Heerlen, Holland E188CC and Suresnes, France E88CC) coming soon. And of course I am very curious to discover whether the Sylvania will stay on top?

 

Really? So right now, you don't find anything fundamentally "lacking" running a 5751? Interesting, especially compared to all those pretty premium 6DJ8 you've been using. I'm curious to know how you'll like the Heerlen E188CC though!

 

I'm waiting for my last two US Amperex 6922 tubes (and two new -smaller- 9 pin sockets, after my utter failure to make small adapters this weekend) to compare them both single and as a pair with my single OG tube. I'm hoping the two late 64 and early 65 US tubes will be decently matched (enough that I can't hear the difference, which is virtually always the case; they were only made 8 weeks apart too, so I wouldn't worry about sound), and I also have high hopes for the earlier 62 "USN" tube; they say the earlier the better for those tubes, so I wouldn't exactly be surprised to find large differences in sound for tubes of different years.

post #3972 of 10578
Quote:
Originally Posted by Audiofanboy View Post
 

 

Interesting. So you wouldn't so much remove all feedback but use less, or implement a versatile way to change the resistor value huh?

 

Hey AFB!
 

I don't know enough of the math behind the NFB resistor to say if just taking it out completely would have any dire effects or not, that is why I suggested a pot and the ability to change the value as quite a few amps have a variable NFB, but thinking about that now we want to open this circuit not reduce it to zero... Don't mind the barin fart.... :D

 

Or someone with a LD MKII can just unsolder one side of the resistor and see what happens since the MKII's board is so much easier to gain access to.

 

It's like they say "No pain, No Gain!" Here is a interesting little read about NFB...

http://www.hometheaterhifi.com/volume_5_4/essaynegativefeedbackoctober98.html

 

:beerchug: 


Edited by TrollDragon - 11/13/13 at 8:22am
post #3973 of 10578
Quote:
Originally Posted by TrollDragon View Post
 

Hey AFB!
 

I don't know enough of the math behind the NFB resistor to say if just taking it out completely would have any dire effects or not, that is why I suggested a pot and the ability to change the value as quite a few amps have a variable NFB, but thinking about that now we want to open this circuit not reduce it to zero... Don't mind the barin fart.... :D

 

Or someone with a LD MKII can just unsolder one side of the resistor and see what happens since the MKII's board is so much easier to gain access to.

 

It's like they say "No pain, No Gain!" Here is a interesting little read about NFB...

http://www.hometheaterhifi.com/volume_5_4/essaynegativefeedbackoctober98.html

 

:beerchug: 

 

Hmm... Again, interesting. And also incredibly confusing lol!

 

I've had a chance to try the different gain / feedback settings on my MK IV SE a few times already, and despite what I've read, I've always found that the higher gain setting (lowest feedback, just one 470k resistor controlling global feedback per channel, if I understand correctly) sounded the best. The lower settings had "richer harmonics" and a very musical sound, but ultimately more feedback seemed to "dull" the amplifier a bit, whereas the lowest feedback setting (gain x10) had the most "air" and hi-fi sound -hence my wondering if no feedback at a all would yield even better sound.

 

I also never noticed any kind of roll-off with the higher gain setting; if anything I noticed the opposite phenomenon...

 

Come on, someone try it! I won't be able to sleep anymore until I know what it does lol!

post #3974 of 10578
Quote:
Originally Posted by Audiofanboy View Post
 

Really? So right now, you don't find anything fundamentally "lacking" running a 5751? Interesting, especially compared to all those pretty premium 6DJ8 you've been using. I'm curious to know how you'll like the Heerlen E188CC though!

 

The Sylvania 5751 TMBP (Three Micas Black Plates) is a complete package. It lacks nothing. To my ears, it is equal, and perhaps better than my US-Amperex 6922, and it is certainly better than my Hamburg Valvo. If you can find one of these at a good price I encourage you to grab one. Compared to the other 12AX7s you have trialed, I think you will be very pleasantly surprised. But of course, I am hoping that the Heerlen E188CC and the others on their way to me will offer some formidable competition. :)

post #3975 of 10578

Can somebody explain what the purpose of this adapter is? Could it be used for any application re the Little Dot?

 

 

 

Here is the link to this supplier:

 

http://www.ebay.com/itm/1pc-EC90-6C4-CV133-EC90-6C4-CV133-ECC82-12AU7-Tube-adapter-6-3v-version-/190905983642?pt=US_Home_Audio_Amplifiers_Preamps&hash=item2c72e2229a

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