tube rolling

Berndt · « **on:** 17 Oct 2006, 03:53 pm »

I just went crazy on ebay and my wife put me on time out.

Tubes will start showing up soon, I hope some of them work

Is there a lubricant you use for the pins and sockets?
Is there a suggested damper?
Thanks, Bill

ZLS · « **Reply #1 on:** 17 Oct 2006, 04:04 pm »

Herbie's Audio Labs have excellent tube dampers.

Soundbitten · « **Reply #2 on:** 17 Oct 2006, 04:13 pm »

Quote from: Berndt on 17 Oct 2006, 03:53 pm

Is there a lubricant you use for the pins and sockets?

Quicksilver , a contact enhancer , I'm gonna try some on my tubes . It worked well on my cables ... made a significant audio improvement .

Berndt · « **Reply #3 on:** 17 Oct 2006, 04:28 pm »

I have some automotive connector lube made by Wurth, from my BMW mechanic days, but was thinking there was something audio specific. I'll look into the quicksilver. The Herbies dots made a large change when I placed them under my xo boxes. Those little mapletree boxes need something better than felt for the feet, they are sliding all over. Just wait til I get a power cord in there.

Berndt · « **Reply #4 on:** 26 Oct 2006, 03:07 am »

Ok, I've come to the end of my tube rolling for now.
The Tung Sol rectifier and the RCA 12sx7gts.
I keep coming back to this combination and am thinking it is time to tweak other areas of my system. Most all of the substitutions are dry and bright. This is the only combination that really works for me, so far I have not been able to error on the side of too tubey.
I received two new rectifier tubes today, a Los Gatos 6x5wgt, and a Sylvania 6x5wgt. They both never really warmed up for me. Interesting to wait for a tube to sweeten up and it never does. Both of them have pretty mica bases. I am surprised that all of my ebay purchases actually work. I am still into building a travelling set, BTW.
I still love listening to this thing, the U4. My music has never sounded so good. The tapping on the guitar body in some Joe Pass tunes is right there.

hartwerger · « **Reply #5 on:** 15 Nov 2006, 03:41 pm »

Hey Berndt. Bad news. My Bendix 6x5 tube is dead. Was up at P. Gunn's place and before putting it in the Ultra we put it in his tube tester. Looked like its life support was disconnected some time ago. Maybe that's why that tube sounded thick and syrupy as it was on its last breath, and not a very strong breath at that. What a shame. If I ever see another one in my travels, I'll pick it up and let you know how it sounds.

What's your favorite 6x5 tube so far?

Berndt · « **Reply #6 on:** 15 Nov 2006, 03:57 pm »

I am using a tung sol 6x5gt and rca 12sx7gt's.
I try to change the sx7's because they are a touch bright in my system but they have a wonderful growling bass that no other driver tube has produced. I haven't been seeing any bendix rectifiers lately on ebay, just got a mullard to try though.

dpump · « **Reply #7 on:** 16 Nov 2006, 04:17 am »

As far as I know, Bendix never made a true 6X5. Bendix did make a tube labeled JAN-CEA-5852. This tube can be used in place of a 6x5, but it is not a true 6X5. The Bendix 5852 draws 1.2Amps. A regular 6X5 draws about half that current.
You cannot just plug a 5852 in place of a 6X5. If you do, you may overload the filament transformer and burn it out. The filament transformer that is used in the current Mapletree PS2 is not rated to handle the current draw of the 5852. In some equipment you may be able to use a 5852 if you modify it to get at least 6-volts to the heater and you have a filament transformer that can handle the 1.2Amp current draw. I'm not an tube expert, but I know this from talking to Dr. Peppard.
Let me also say that you haven't heard the full potential of your Mapletree preamps if you haven't used a Bendix 5852 instead of a 6X5. Let me explain. The first Mapletree power supply was the PS1. This was a solid state power supply-no tubes. The second power supply was a PS1T. This was a 6x5 rectified power supply. However, the filament section of the power transformer was rated at 2.5Amps. By changing one resistor to get 6-volts to the heater of the 5852, you can then use a 5852. The 5852 makes a large improvement in the sound of the Mapletree preamps. My preamp is a Line 2 SE but the same power supply works on all Mapletree preamps.
The current PS2 uses two separate transformers-one for the high voltage and one for the filament voltage. The filament transformer is not rated high enough to handle a 5852. So do not plug a Bendix 5852 into your PS2. You won't get the proper heater voltage and you will overload the heater transformer. You may eventually burn out the filament transformer.
You may have a 6X5 that is labeled Bendix, but it would have to be a regular 6X5 that someone labeled Bendix. It is not a true Bendix tube.
I was able to modify my PS1T to use the Bendix 5852 by talking to Dr. Peppard. You might be able to modify your PS2 to use the 5852 if you could replace the filament transformer with one that is rated at 2Amps or more. You would need to ask the Dr. about this.
I think this information is accurate. If not, please correct me. If Dr. Peppard reads this, please add any corrections or other information you feel is necessary.

audioferret · « **Reply #8 on:** 16 Nov 2006, 04:21 am »

Any recommendations on a good source to find replacement 6R7G/GT tubes? These seem relatively rare and I am having trouble finding spare tubes - much less ones that could be used to do tube rolling with...

steve k · « **Reply #9 on:** 16 Nov 2006, 04:26 am »

I bought some National Unions and some Sylvanias from Antique Electronic Supply. I also picked up some French Visseaux and Neotron metal over glass tubes from Pacific TV. There's a link to them on Doc Leppard's website. Pacific is a great source for the more obscure tube types.
steve

londonbarn · « **Reply #10 on:** 16 Nov 2006, 05:41 am »

Steve , are you talking about Def Leppard?, or Doc Peppard?

steve k · « **Reply #11 on:** 16 Nov 2006, 12:07 pm »

The Doc rocks!!

londonbarn · « **Reply #12 on:** 16 Nov 2006, 10:02 pm »

LOL, yeah!, if he did guitar amps.... wouldnt "Def Peppard" be a cool name..... the word play on "deaf" is hilarious... He might not like that , though LOL

Berndt · « **Reply #13 on:** 17 Nov 2006, 11:28 pm »

Quote from: audioferret on 16 Nov 2006, 04:21 am

Any recommendations on a good source to find replacement 6R7G/GT tubes? These seem relatively rare and I am having trouble finding spare tubes - much less ones that could be used to do tube rolling with...

the 6r7g is used in the phono circuit, yes?

Berndt · « **Reply #14 on:** 17 Nov 2006, 11:29 pm »

Quote from: dpump on 16 Nov 2006, 04:17 am

As far as I know, Bendix never made a true 6X5. Bendix did make a tube labeled JAN-CEA-5852. This tube can be used in place of a 6x5, but it is not a true 6X5. The Bendix 5852 draws 1.2Amps. A regular 6X5 draws about half that current.
You cannot just plug a 5852 in place of a 6X5. If you do, you may overload the filament transformer and burn it out. The filament transformer that is used in the current Mapletree PS2 is not rated to handle the current draw of the 5852. In some equipment you may be able to use a 5852 if you modify it to get at least 6-volts to the heater and you have a filament transformer that can handle the 1.2Amp current draw. I'm not an tube expert, but I know this from talking to Dr. Peppard.
Let me also say that you haven't heard the full potential of your Mapletree preamps if you haven't used a Bendix 5852 instead of a 6X5. Let me explain. The first Mapletree power supply was the PS1. This was a solid state power supply-no tubes. The second power supply was a PS1T. This was a 6x5 rectified power supply. However, the filament section of the power transformer was rated at 2.5Amps. By changing one resistor to get 6-volts to the heater of the 5852, you can then use a 5852. The 5852 makes a large improvement in the sound of the Mapletree preamps. My preamp is a Line 2 SE but the same power supply works on all Mapletree preamps.
The current PS2 uses two separate transformers-one for the high voltage and one for the filament voltage. The filament transformer is not rated high enough to handle a 5852. So do not plug a Bendix 5852 into your PS2. You won't get the proper heater voltage and you will overload the heater transformer. You may eventually burn out the filament transformer.
You may have a 6X5 that is labeled Bendix, but it would have to be a regular 6X5 that someone labeled Bendix. It is not a true Bendix tube.
I was able to modify my PS1T to use the Bendix 5852 by talking to Dr. Peppard. You might be able to modify your PS2 to use the 5852 if you could replace the filament transformer with one that is rated at 2Amps or more. You would need to ask the Dr. about this.
I think this information is accurate. If not, please correct me. If Dr. Peppard reads this, please add any corrections or other information you feel is necessary.

Thanks for this info.
More soldering in the works.

steve k · « **Reply #15 on:** 18 Nov 2006, 12:46 am »

Quote

the 6r7g is used in the phono circuit, yes?

No, the 6R7G is used as the output tube on each channel of the cathode follower circuit in the Magic 5B. The single 12SN7 input tube uses each side of the triode for each channel input.

The other two 12SN7's are use for the SRPP circuit, each acting as input and output on one channel.
steve

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