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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 466

post #6976 of 8065
Quote:
Originally Posted by gibosi View Post
 

 

From this discussion:

 

http://www.head-fi.org/t/600110/2359glenn-studio/735#post_8661420

 

The cathode resister needs to be one-half the value of that used for a 6AS7. The objective is to run the plates at a higher current. However, I do not know what the proper value is for a 6AS7, nor do I know the value of the LD's stock cathode resister. Assuming that the LD's resister is about right for the 6AS7 (a rather risky assumption I think) and you decide to reduce that resistance by one half, then you have to determine if the transformer can supply the necessary extra current, and if so, can the LD circuitry handle the extra current.....

 

Thanks gibosi...looks like a LOT more research is needed!...Will have to be later, though.

 

Cheers!

post #6977 of 8065

Hi Gibosi,

 

Here is a spec sheet for the TS 5687.

 

5687 - Jogis Roehrenbude

 

By connecting pins 4 and 5 (skipping pin 8 and not tying together 4&5) to an external heater PS I could run this tube at 12.6V. Would there be any advantage in doing this?

 

(I am still trying to correct the hum, mainly in the R channel - got a little bit better but not gone)

post #6978 of 8065
Quote:
Originally Posted by mordy View Post
 

By connecting pins 4 and 5 (skipping pin 8 and not tying together 4&5) to an external heater PS I could run this tube at 12.6V. Would there be any advantage in doing this?

 

(I am still trying to correct the hum, mainly in the R channel - got a little bit better but not gone)

 

Yeah, these tubes can be run at 12.6 volts just like a 12AX7. And just like 12AX7's, it doesn't make any difference - 6 of one, half-a-dozen of the other. :)

 

As the hum is getting better, it just may be that you have a NOS tube, and the hum will go away after burning in for a few hours.

 

Cheers

post #6979 of 8065

I'll let the tube burn in and will recheck the humming - thanks.

 

Something else that I don't understand: The 6080 power tubes have an amplification factor of 2, which means that I can turn up the volume on the LD amp all the way without any distortion.

 

Normally, with my headphones, I leave the volume at 9 o'clock. With the 6080s, I need to run it a 12 o'clock. As mentioned, with speakers, I keep it all the way up.

 

Now, when listening to the hum in the left channel, it keeps increasing with increasing volume levels, but at full volume the hum decreases - why?

post #6980 of 8065

I'm trying to remember....  It's been a while since I had to deal with "new tube hum"....  But as best I can remember, with new tube hum, the level of the hum doesn't change with the volume setting. Further, checking the tube every couple hours during the burning-in process, the tube becomes noticeably quieter. So.... if the hum does't get better with time, you may well have a defective tube.... :(

post #6981 of 8065
Quote:
Originally Posted by gibosi View Post
 

 

It is my understanding that a 5998 requires a different cathode resistance than the 6AS7 in order to really shine. That said, lots of folks have put 5998's into amps designed for the 6AS7 and believe they are an improvement. As the LD was not designed to run 6AS7's, it is just really, really tough to predict how they will sound.....

 

But "Then again, nothing ventured....!! ...And if nothing is lost, better still."

 

And for sure, if they are not a significant improvement, you could likely resell them for what you paid... so nothing lost....

 

So I say, 'Go for it!" lol :)

 

SAVINGS RAIDED!! (Have I finally lost the plot?).

 

Hey, gibosi, methinks you just might have something to answer for, lol...especially if "She who must be obeyed" finds out how much I paid! :blink:

 

Well, I took your advice (sic) AND the plunge. But given the question mark over the 5998's requirements, I treated myself to an early Christmas present (or rather another one!)...a pair of NOS British made CV2523s (6AS7G equivalent, as you know) which should be OK and which would appear to be at least as good as, if not better than, the 5998 (depending on ears, of course).

 

The heart attack, thankfully, has been mediated by several factors :

 

1. The 5998s, with customs and VAT, now come up to their price level (when they used to be MUCH cheaper).

2. As you said, if not much different, I could always resell...hmmm...any real chance of that happening?!

3.Cheaper than a MK9/La Figaro/Glenn etc etc.

4. If my poor LD does finally succumb to the torture, I could get yet another Christmas present - a La Figaro 339, which I am sure would say "thank you"!

 

So, as you can see mon ami, I've done a fairly good job of convincing myself of my folly...and of absolving you of all blame (well, nearly all!! :wink_face: ). Now I just can't wait to get my sticky hands on 'em, and see if they really do better the Chathams...:D

post #6982 of 8065
Quote:
Originally Posted by hypnos1 View Post
 

 

SAVINGS RAIDED!! (Have I finally lost the plot?).

 

Hey, gibosi, methinks you just might have something to answer for, lol...especially if "She who must be obeyed" finds out how much I paid! :blink:

 

Well, I took your advice (sic) AND the plunge. But given the question mark over the 5998's requirements, I treated myself to an early Christmas present (or rather another one!)...a pair of NOS British made CV2523s (6AS7G equivalent, as you know) which should be OK and which would appear to be at least as good as, if not better than, the 5998 (depending on ears, of course).

 

The heart attack, thankfully, has been mediated by several factors :

 

1. The 5998s, with customs and VAT, now come up to their price level (when they used to be MUCH cheaper).

2. As you said, if not much different, I could always resell...hmmm...any real chance of that happening?!

3.Cheaper than a MK9/La Figaro/Glenn etc etc.

4. If my poor LD does finally succumb to the torture, I could get yet another Christmas present - a La Figaro 339, which I am sure would say "thank you"!

 

So, as you can see mon ami, I've done a fairly good job of convincing myself of my folly...and of absolving you of all blame (well, nearly all!! :wink_face: ). Now I just can't wait to get my sticky hands on 'em, and see if they really do better the Chathams...:D

I guess youll hold on just a bit tighter to them when removing .the horror 

post #6983 of 8065

I hope the CV2523s are GECs. I have original military CV2523s labelled as Valve Electronic but are russian made but very similar boxes to the GEC also labelled by  Valves Electronic (and I broke the original seals) so are not later repacks.

post #6984 of 8065

Today I received a pair of Chatham JAN CAHG 6080WA tubes for $10 incl shipping.  This tube was manufactured in Sept 1960 - is this after Tung Sol took over Chatham? These used tubes light up and sound OK.

 

 

 

 

 

 

After I bought them, the seller, a woman, asked me: "I am really curious why these tubes were viewed by shoppers over 896 times during the week they were listed. If you don't mind, please tell me a little more about them. I do hope you find them useful! Thank you again"

 

What should I tell her? How come I was the single bidder?

post #6985 of 8065
Quote:
Originally Posted by mordy View Post
 

After I bought them, the seller, a woman, asked me: "I am really curious why these tubes were viewed by shoppers over 896 times during the week they were listed. If you don't mind, please tell me a little more about them. I do hope you find them useful! Thank you again"

 

What should I tell her? How come I was the single bidder?

 

Tell here those tubes are closely watched by Homeland Security and you are using them to build a small geothermal nuclear device, ask if she has any lithium-6 deuteride (6Li2H) for sale... :L3000:

post #6986 of 8065
Quote:
Originally Posted by MIKELAP View Post
 

I guess youll hold on just a bit tighter to them when removing .the horror 

 

You bet ya, M!

 

Quote:
Originally Posted by Nic Rhodes View Post
 

I hope the CV2523s are GECs. I have original military CV2523s labelled as Valve Electronic but are russian made but very similar boxes to the GEC also labelled by  Valves Electronic (and I broke the original seals) so are not later repacks.

 

Hi Nic...you tryin' to give me another heart attack lol?! They were listed as Mullards, and I know 'their' 6AS7Gs were in fact Russians...but hopefully these are the real deal - they certainly look it, from the photos...any comments? :

 

 

 

They look pretty Kosher to me...fingers crossed (listed as made in UK so if not, they go straight back!). :redface:

post #6987 of 8065

Hi TD,

 

Did u know that Chatham Electronics started out building Geiger counters in the late 40's - early 50's? I have tried to find information on this company, but there are so far very few references that I have found.

Does anybody have a reference to the history of Chatham?

post #6988 of 8065
Quote:
Originally Posted by mordy View Post
 

Today I received a pair of Chatham JAN CAHG 6080WA tubes for $10 incl shipping.  This tube was manufactured in Sept 1960 - is this after Tung Sol took over Chatham? These used tubes light up and sound OK.

 

 

 

 

 

 

After I bought them, the seller, a woman, asked me: "I am really curious why these tubes were viewed by shoppers over 896 times during the week they were listed. If you don't mind, please tell me a little more about them. I do hope you find them useful! Thank you again"

 

What should I tell her? How come I was the single bidder?

Because i was too busy checking my BH CRACK Kit parts  don't have time to do some ebay shopping :biggrin:BTW i purchased two of that and one of them does not work i punch a hole insert a LED and sold it for $15 to my Boss son.

post #6989 of 8065
Quote:
Originally Posted by hypnos1 View Post

 

Hey, gibosi, methinks you just might have something to answer for, lol...especially if "She who must be obeyed" finds out how much I paid! :blink:

 

Well, I took your advice (sic) AND the plunge. But given the question mark over the 5998's requirements, I treated myself to an early Christmas present (or rather another one!)...a pair of NOS British made CV2523s (6AS7G equivalent, as you know) which should be OK and which would appear to be at least as good as, if not better than, the 5998 (depending on ears, of course).

 

 

Wow! A pair of NOS CV2523! Wow! But yes, I agree, for the same cost there is significantly less risk in going with these versus 5998. But wow! :)

post #6990 of 8065
Quote:
Originally Posted by mordy View Post
 

After I bought them, the seller, a woman, asked me: "I am really curious why these tubes were viewed by shoppers over 896 times during the week they were listed. If you don't mind, please tell me a little more about them. I do hope you find them useful! Thank you again"

 

What should I tell her? How come I was the single bidder?

 

Well, this is just a WAG on my part, but perhaps "Chatham" is the reason. Given that Chatham 6AS7G and Chatham 5598 are much sought after, people saw "Chatham" in the listing title and decided to check to verify what they were. But again, just a WAG on my part. :)

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