[PatOMalley]

The little red rings you usually see in use are made of silicone which has not yet melted on any of my tubes.

Just a word about the dampers. They are said to draw heat from the tubes increasing their already 10,000 hour life span for small small small signal tubes.

There is my 2cents of audio-nervosa.

 

[gknix]

Hi guys,

I've read a lot about this amp, and I am finally going to purchase them! It seems like 408A seems to be a quite popular change, but I still am not sure what tubes to roll to fit my particular headphones.

I'm using HF-2s, and I feel that the mid-bass/ and mids are a little muddled, and clarity/details/instrument separation/soundstage needs to be amended. What tubes and opamps would be recommended?
I'm also new to all this tube rolling fun, but is it hard to change the opamps?

Cheers!

 

[gknix]

Just a question, is this the GE408A that people previously purchased?
408A Tube [408A] - $5.49 : Piexx Company, Computers & Electronics

 

[gknix]

Answered my own question*

 

[schwallman]

is this what i would need for the lme49720? the adapter its fitted onto would work correct?

LM4562 LME49720 LME49710 NA MA HA

 

[Rotomoto]

or this doesn't need an adapter

Digi-Key - LME49720NA-ND (Manufacturer - LME49720NA/NOPB)

 

[schwallman]

Any real difference since one is round and the other is flat?

 

[Rotomoto]

Same circuit, different package. But you could buy both and tell us if you can hear a difference

 

[schwallman]

Quote:

Originally Posted by Rotomoto /img/forum/go_quote.gif Same circuit, different package. But you could buy both and tell us if you can hear a difference

I'll save $30 and just get the flat one. I hope there kidding about $10 for shipping. It weighs nothing.

 

[Rotomoto]

Quote:

Originally Posted by schwallman /img/forum/go_quote.gif I'll save $30 and just get the flat one. I hope there kidding about $10 for shipping. It weighs nothing.

Nope, sound about right. It's still cheaper than ebay and you know for sure you're getting what you order.

 

[gknix]

6028 JAN SYLVANIA 1975 VAC.TUBE 408A SUB EMISSIONS 96 - eBay (item 120497973029 end time Mar-25-10 10:29:34 PDT)

Anyone tried these? How different are they from the sylvania gold pins 408A?

 

[john57]

Quote:

Originally Posted by gknix /img/forum/go_quote.gif 6028 JAN SYLVANIA 1975 VAC.TUBE 408A SUB EMISSIONS 96 - eBay (item 120497973029 end time Mar-25-10 10:29:34 PDT) Anyone tried these? How different are they from the sylvania gold pins 408A?

I can not say anything about the sylvania gold pins 408A but I have the GE408A with golden pins and plain pins that works well as well as the RCA 408A I just recently aquired. Western Electric is my third choice and it is the most common 408A tube. The sylvania plain pins are my last choice.

 

[Aynjell]

Quote:

Originally Posted by john57 /img/forum/go_quote.gif I can not say anything about the sylvania gold pins 408A but I have the GE408A with golden pins and plain pins that works well as well as the RCA 408A I just recently aquired. Western Electric is my third choice and it is the most common 408A tube. The sylvania plain pins are my last choice.

Hrm, I have gold brand but not gold pin. I wonder if it's really worth my going and getting the other gold brand.

 

[john57]

Right now there is a sale of the 408A golden pins on Ebay labeled Westinghouse that might suit you. Right now I am using the 408A RCA plain pins on my Little Dot. I did had a problem with a Ebay seller that mix up the tubes that I requested and he send me more of the RCA 408A tubes that are working especially well and my total cost was $1.66 per tube. It was a very good bargain. The 408A tubes were originally made for high frequency telephone switching devices and there is not many amps today that can use the 408A tubes. You just have to be sure to move the heater voltage jumper pins back to normal if you are using a different family of tubes on the Little Dot. I have noticed that the 408A tubes that I have are very low in Microphonics, far better that the 12AX7 and the 6DJ8 tubes types that I am using in other equipment.

 

[Aynjell]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif You may need em and will have them when you do. I am not sure which tubes they may make a difference with - I just put them on as standard and never think about it after. and for the 91's what other revealing opamp is there but the LM4562? They combine to make a solid tone/timbre with extension and lots of inner detail.

Yeah, but mine doesn't sound right with teh LM4562, and using the goo stuff isn't on the top of my list of things I want to do to my amp. I'm okay with soldering a cap to the op amp. If I could get that damned thing to work right, I probably WOULD go for LM4562. It sounds good, but doesn't work in my setup.

If there was a more forgiving op-amp with the same sound signature, I'd buy it, but right now I don't trust putting something that has static in one channel in my amp.