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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 249

post #3721 of 10509
Quote:
Originally Posted by mordy View Post
 

I have to apologize to AFB for asking what the advantage is of the the 12A7 tubes over the 6AV6 tubes which are supposed to be one half of a 12A7 tube.

 

Now to the nitty gritty: If I understand correctly I could connect a 6 Volt tube such as the 6BQ7 without any changes to the wiring except connecting pins 8 and 9 on the tube itself to eliminate ground hum. Is this correct?

 

Next question: Post #3645 by Gibosi and AFB is a wiring instruction table for using 12A7 tubes. (Many thanks!) Looking at Gibosi's amp on post #3625 it seems to me that right and left is the opposite of post #3545. In post #3545 the left channel has five connections to the the adapter, and the right adapter has three connections.

It seems to me that the picture on Post #3525 has the opposite; the left channel has three connections, and the right channel 5 connections.

 

I think the 12Ax7 types are just made "better" (i.e., better construction, alloys used, design...) than their single triode "equivalents" -which are only that on paper really- designed for different applications like a three-in-one tube for car radios (detector, auto-volume control (or something...?) and amplification). The 12AX7 is basically just a high gain double triode, designed to do just that (voltage gain), and do it at least decently.

 

Yeah, different people have been wiring their adapters one way or another. My 12Ax7 adapter has the -three- heater pins wired to the left socket, while my -to be soon put to use- 6DJ8 adapter has the -two- heater pins and the shield wired to the right channel like all the cool kids (just because no one has managed to get rid of that ground through the left socket yet, and I'd rather be on the winning team lol).

 

Quote:
Originally Posted by gibosi View Post
 

 

For your 12AX7, both tube pins 4 and 5 are connected to socket 3. To use your 6BQ7, the lead for tube pin 5 must be disconnected from socket 3 and connected to socket 4. And tube pin 9 must be disconnected from socket 4 and connected to tube pin 8.

 

These connections do not have to be soldered as long as you have a very tight mechanical connection.

 

I agree that a tight mechanical connection is more than enough (wire leads squeezed tightly between the adapter shell and metal taps. I've had solder points burst or wires break (my wiring was way too tight on my 12Ax7 adapter) on my DIY adapters, but even when I manhandled the device back into submission and resoldered wires without taking anything apart, the wires on the Vector adapter side didn't even budge. Basically, the connection is more solid on the adapter side than on the socket side in my case... My second adapter is better though.

post #3722 of 10509
Quote:
Originally Posted by Audiofanboy View Post
 

Yeah, different people have been wiring their adapters one way or another. My 12Ax7 adapter has the -three- heater pins wired to the left socket, while my -to be soon put to use- 6DJ8 adapter has the -two- heater pins and the shield wired to the right channel like all the cool kids (just because no one has managed to get rid of that ground through the left socket yet, and I'd rather be on the winning team lol).

 

I am pretty sure that the shield and the heaters need to be connected to the same adapter. But I am not sure about the two triodes....

 

I have tried only one configuration and it works! :)

 

Pins 1, 2, and 3 (triode #1) to one adapter (the left one) and pins 6, 7, and 8 (triode #2) to the other adapter (the right one). And then the heaters and shield to the same adapter as triode #2.

 

So if the heaters and the shield need to be on the same adapter, does it matter if it is triode #1 or triode #2? I do not know....

post #3723 of 10509
Quote:
Originally Posted by Edgard Varese View Post
 

Texas Instruments shipped me a pair of OPA2107 op amps - for free - and I'm in Christchurch.  All you need to do is register on their site and request a sample.

Thanks for that i went to there site & i filled out all of there form's. It's in the post as you said for free that has made my day. I  wonder how long it takes to get to New Zealand. In my boring life ( recovering from spine surgery) this is a little bit of excitement i feel like a big kid again. I'l let you know when it arrives. Thanks again very much

post #3724 of 10509

In today's mail came 4 Voskhod 6N2P-EV, manufactured in 1973. These are sturdy tubes with rhodium pins and they exude quality. The 6N2P is purported to be a 6-volt version of the 12AX7, but we need to configure our adapters for 6DJ8 tubes. And these were relatively cheap. I paid $23.00 for four of them shipped. That is, $9.00 for four tubes plus $14.00 / shipping from Tbilisi, Georgia, to the US.

 

Artsi reports that these are excellent tubes, so I am anxious to get mine burned in....

 

post #3725 of 10509
Quote:
Originally Posted by bundy View Post
 

Thanks for that i went to there site & i filled out all of there form's. It's in the post as you said for free that has made my day. I  wonder how long it takes to get to New Zealand. In my boring life ( recovering from spine surgery) this is a little bit of excitement i feel like a big kid again. I'l let you know when it arrives. Thanks again very much

 

It takes about a week or so, quite prompt service.  Good luck with your recovery!

post #3726 of 10509
Quote:
Originally Posted by gibosi View Post
 

In today's mail came 4 Voskhod 6N2P-EV, manufactured in 1973. These are sturdy tubes with rhodium pins and they exude quality. The 6N2P is purported to be a 6-volt version of the 12AX7, but we need to configure our adapters for 6DJ8 tubes. And these were relatively cheap. I paid $23.00 for four of them shipped. That is, $9.00 for four tubes plus $14.00 / shipping from Tbilisi, Georgia, to the US.

 

Artsi reports that these are excellent tubes, so I am anxious to get mine burned in....

 

I compared photo of your 6N2P-EV tube, and i see little differences with metal plates to my -76. There could be some differences in sound too.

 

Got today GE 6BZ7/6BQ7A, RCA 12AZ7A, RCA 12BH7A, RCA 12AU7A, RCA 12AV7, Tung-Sol 12AV7 and GE 12AZ7A.

 

6BZ7/6BQ7A needs 8-9 pins connected to get rid of hum. Tung-Sol 12AV7, RCA 12AV7 and GE 12AZ7A works in EF92 mode without hum. Weird that RCA 12AZ7A works perfectly with EF95 mode. 12BH7A is even bigger than 6N6P-IR and it draws 0.6A heater current.

post #3727 of 10509
Quote:
Originally Posted by gibosi View Post
 

In today's mail came 4 Voskhod 6N2P-EV, manufactured in 1973.

 

 

I have about 20 hours on these and feel that I know their sound well enough to comment. However, as I have recently changed my DAC and the op amp in my LD 1+, I can't really compare these to other tubes at this time -- I am still trying to recalibrate my ears. However, I am very comfortable in saying that these tubes are excellent. They have great bass, nice mids, clean and detailed highs, a nice 3-D stage plus they are very quiet.

 

Even better, these can be purchased quite inexpensively. Again, 4 premium Voskhod 6N2P-EV for $23.00 shipped, whereas, premium 12AX7 / E83CC typically go for upwards of $50 for only one tube! So if you are interested in rolling double triodes, you can't miss with these. Highly recommended!

 

~~~~~~~~

 

For those of you with the LD 1+, I have rolled in a MUSES02, replacing the LME49990, and I am not going to take it out! :) The LME49990 is a great op amp, very neutral, but as others have noted, it can be rather cold and clinical when paired with some tubes. The MUSES02 adds a bit of mid-range presence, bringing vocals slightly more forward. As a result, instruments have more impact and presence and the overall presentation is more musical and toe tapping than the LME49990.

 

So for a more analytical sound, go with the  LME49990. For a more lively and musical sound, go with the MUSES02.


Edited by gibosi - 10/29/13 at 6:51pm
post #3728 of 10509

700

Something like this is coming soon. Still waiting for many critical components, hope i get them this week. Better leave these 9pin usual double triodes as a driver, i have them so many, better for tube rolling.

 

If this is not killing my little dot, then it survives everything...:beerchug:

post #3729 of 10509
Quote:
Originally Posted by gibosi View Post
 

In today's mail came 4 Voskhod 6N2P-EV, manufactured in 1973. These are sturdy tubes with rhodium pins and they exude quality. The 6N2P is purported to be a 6-volt version of the 12AX7, but we need to configure our adapters for 6DJ8 tubes. And these were relatively cheap. I paid $23.00 for four of them shipped. That is, $9.00 for four tubes plus $14.00 / shipping from Tbilisi, Georgia, to the US.

 

Artsi reports that these are excellent tubes, so I am anxious to get mine burned in....

 

Today i also received in the post a matched pair 6J1P-EV Voshkod the ones with the grooves in the glass, which the guy i brought them from seemed to think that made them special so. At only NZ $22.50 including postage im happy with the price. As for the sound after only 4 hrs burn i like it, not too bright warm bass, vocals ???. But there's plenty of burn time left. I think it is very promercing 

post #3730 of 10509

Hi Bundy.

 

Glad you are recovering nicely from your op - I am sure following the guys on this forum is proving wonderful convalescent therapy! I personally have gained much in the relatively short time since I found this thread - AND it's been great fun...keep up with it...

 

May I just encourage you to make quantum leaps in this rolling game by taking advantage of the immense time, dedication and effort (not to mention money!) the guys have invested over the past months - tubes have been discovered that will leave the 6J1P way behind, e.g. my personal favourite (as a straight substitute in EF95 setting, with no need for any modification) the Ei 6HM5, which is listed with a link by Gibosi in post #3366, and has had offer of $5 a tube accepted with FREE delivery! Unless you fancy entering the world of double triodes and adapters, that is - which I am only just in the process of sorting out...

 

Whatever, I wish you all the best in this fascinating, if sometimes frustrating(!) rolling game...

post #3731 of 10509

Hi Gibosi,

 

Reading about your positive impressions of the 6N2P-EV tubes.

 

Is 6N3P (9pin, 0.35A) also a tube that is compatible with the LD amps?

post #3732 of 10509
Quote:
Originally Posted by Artsi View Post
 

700

Something like this is coming soon. Still waiting for many critical components, hope i get them this week. Better leave these 9pin usual double triodes as a driver, i have them so many, better for tube rolling.

 

If this is not killing my little dot, then it survives everything...:beerchug:

Wow a whole hog conversion!

 

I'd look into an aluminium enclosure for the top of your LD in the same size, http://www.ebay.com/bhp/aluminum-enclosure to keep the hum and interference down.

Pick up some chassis mount Octal's and a B9A socket, unsolder the LD's tubes sockets, run wires up to your new sockets from the board holes below and enjoy the conversion!

Goning to be a sweet mod!

:beerchug:

post #3733 of 10509
Quote:
Originally Posted by mordy View Post

Hi Gibosi,



 



Reading about your positive impressions of the 6N2P-EV tubes.



 



Is 6N3P (9pin, 0.35A) also a tube that is compatible with the LD amps?


 



6N3P is not easily compatible. Pin order is different. 6N23P is compatible with 6DJ8.

http://www.qsl.net/d/dl7avf/roehren/trioden2.html
Edited by Artsi - 10/30/13 at 9:13am
post #3734 of 10509
Quote:
Originally Posted by gibosi View Post
 

 

I have about 20 hours on these and feel that I know their sound well enough to comment. However, as I have recently changed my DAC and the op amp in my LD 1+, I can't really compare these to other tubes at this time -- I am still trying to recalibrate my ears. However, I am very comfortable in saying that these tubes are excellent. They have great bass, nice mids, clean and detailed highs, a nice 3-D stage plus they are very quiet.

 

Rolled my US Amperex 6922 back in and can now provide a quick comparative observation. The Voskhod 6N2P-EV has a good bit more bass than the Amperex and the mids are not as forward. Again, nice tubes, but In my system, the Amperex is still number one. However, I can imagine that the V 6N2P-EV might complement bass-shy headphones very well.

post #3735 of 10509

I waited two whole days to give my impressions about my Amperex Orange Globe -thereafter OG like the Lyrists call these- 6DJ8 tube; imagine how hard it was for me to wait that long to post about these!

 

First, I've got to say that the ebay seller who sold me this tube, mercedesman something, does not muck around, seriously. This tube was in perfect shape! Not even a small fingerprint, perfect silkwriting (and therefore resell value), and obviously strong; so strong in fact, I actually think it was pretty much NOS, as it improved after 10+ hours. People, you're only $37 away from glory! Get to it and contact this guy to get your very own OG (sounds like a cheap TV ad lol: "get hooked on OGs").

 

'Nyway, this is my best tube. Period (until the next one). This truly could be an "end game" tube, and it turns out to be for many people. The differences between good tubes used to be subtle or marked at best, but here the difference with anything else I've tried is obvious and dramatic. Joe's tube lore describes this tube very well on his eponymous webpage, but the one word -OK, two words- that comes to me is immediate, and also transparent. I've never heard music sound so immediate and surrounding. You can't test or spend an hour comparing this tube to other tubes, it just draws you in and you just have to listen to the music. Now, that's a head-fi experience for you!

 

It should be an end game tube, it very well could be as far as my ears are concerned, but just can't stop now that I've seen what a good 6DJ8 can do! So, expect more -albeit less frequent for obvious price concerns- 6DJ8 testing in the following weeks!

 

Side note: I'm really going back to thinking that it would be a lot easier to just bite the bullet and use pairs of 6DJ8 in our LDs (once one finds his "graal" tube). Small footprint, basic, DIY adapters or Vector-type socket testers for an easier and (for us less handy folks or the less arts & crafty types like me) prettier result (non-destructive two-socket solutions wouldn't be difficult to create, the ram-6DJ8-in-B7G-socket is no longer an acceptable option). On the MK IV SE, it really kind of pains me to ruin the overall esthetics of the amp with any kind of single tube adapter...

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