[attmci]

I tried to buy 2 into 1 adapter for my darkvoice amp from eBay Hong Kong the seller let me know that it won't work, this are his words "because darkvoice amp different design Elise amp.darkvoice amp one channel using half 6AS7 tube,but Elise amp one channel using one tube,if insert adapter and tube,amp have hum noise." Does anyone have experience with darkvoice? Thanks

Is that true? Just curious.

 

[adeadcrab]

As a lafigaro 339 (similar to darkvoice) owner the only adapters recommended are for driver tubes, power tubes can't be swapped

 

[maheeinfy]

In my experience, 6ASGA sounded laid back. Mine were GE branded though...

I switched back to RCA 6ASG and didn't bother upgrading. They sound just right - nice smooth tube sound

 

[adeadcrab]

6AS7G is exactly the same as the 6AS7 except with a straight envelope instead of the coke bottle style

edit: 6AS7G*A* is the same as 6AS7G.. the rest still stands

 

[gug42]

Hello,

I'im looking for informations about the sound differences between Chatham and RCA 6AS7G ? Can you help me please ?

 

[thecrow]

Hello,

I'im looking for informations about the sound differences between Chatham and RCA 6AS7G ? Can you help me please ?

If you're talking about chatham 2399 tubes (or tung sol) I would describe them as definitely punchy and lively and somewhat dynamic. Definitely a solid level of detail. I sometimes use them in my wa2.

My main tubes are the gec 6as7g which are up another level

 

[gibosi]

The Chatham/Tung-Sol 2399 is actually a 5998. Chatham/Tung-Sol also manufactured the 6AS7G, 6080 and 7236.

It has been a very long time since I have listened to either the RCA or Chatham 6AS7G, but the one impression that sticks in my mind is the RCA is a good bit warmer than the Chatham.

 

[gug42]

Hum it's for a little dot mkVI+, so 6AS7G (for 5998 a bias tunning is better from what I read, and well 5998 are really expensive)
Ok thank you. I need a quad, so I will test RCA and maybe Chatham if I can get at a good price.
Others options are really costly (because of quad needed)

 

[gibosi]

The 5998 and 6AS7G are not electrically identical. And therefore, a circuit designed to run 6AS7G is not optimal for the 5998. At the very least, I seem to remember that the recommended cathode resistance for a 6AS7G is about twice as high as that for the 5998. Even so, it is perfectly safe to run the 5998, and in fact, many people believe it to be among the very best tubes available.

But for sure, as you need a quad, a complement of 5998 is likely going to be expensive. But I would remind you that all four tubes do not have to be identical as long as you keep both sides identical. Running one Chatham and one RCA per side just might be a very nice combination. And another combination that I have wanted to try for a long time is one GEC 6080 and one Bendix 6080 per side. Maybe someday I will get around to it....

 

[Dogmatrix]

My take . Looking for Ts / Chatham 6as7g I would go for the 6520 as they seem to be better quality . Concerning Rca I have found the 6as7g to be inconsistent and unreliable with even the Russian version superior in these terms . In my experience best sound on a budget is the early RCA 6080 , although they lack the aesthetic appeal of the 6as7g .

 

[gibosi]

My experience is different it seems. I was not able to distinguish any difference tween 6520 and 6AS7G manufactured by Chatham. And the several pairs of RCA I own are all fine. That said, my ears are pretty old, so you should probably take this with a grain of salt.

But I would generally agree that most 6080 are quieter than 6AS7G.

 

[100VoltTube]

The 6AS7G is very different from the 5998 electrically. They are similar enough that they can often be substituted without modification to the gear, but if the gear is not designed for the 5998, it might not work properly.
A run down on the differences:

• The μ (mu: amplification factor) of the 5998 is 5.4, compared to the 2 of the 6AS7G, meaning that the same bias will result in different plate voltages. In a cap-coupled amp, this is not a big deal, but whenever there's DC coupling, this could be a problem, causing distortion or clipping, or even a release of the magic smoke if the amp is designed in such a way that it would be damaged by a change like that. I wouldn't worry too much about tube gear being damaged, but a hybrid might not like it. It depends on the amp.
• The Rp (plate resistance) of the 5998 is 350 ohms, vs the 6AS7G at 280. Not a huge difference.for the most part, it won't matter.
• The Gm (transconductance) of the 5998 is 15.5mS, vs 7mS. This is the most important difference for a cathode follower, which is the output stage topology of most headphone amps, like the Crack. The output impedance of a basic cathode follower is approximately the reciprocal of the transconductance. The output impedance of a 6AS7G-based cathode follower is 1/0.007=142.9 ohms, give or take. A 5998 cathode follower is approximately 1/0.0155=64.5 ohms. This is why 5998's in an OTL amp sound much better than 6AS7G's with lower impedance headphones; a better damping factor.
• The plate curves of the 5998 are mugc better (more linear) than the 6AS7G, so there is slightly less distortion.

An A2293 would be an interesting option to try, but it'd need an adapter. Same for the 7233. Both are obscure, cheap, single triodes in a 9-pin miniature package with very good performance. Based on specs alone, I would recommend a pair of 7233's over all of the other options, 5998 included.

 

[gug42]

The 5998 and 6AS7G are not electrically identical. And therefore, a circuit designed to run 6AS7G is not optimal for the 5998. At the very least, I seem to remember that the recommended cathode resistance for a 6AS7G is about twice as high as that for the 5998. Even so, it is perfectly safe to run the 5998, and in fact, many people believe it to be among the very best tubes available.

But for sure, as you need a quad, a complement of 5998 is likely going to be expensive. But I would remind you that all four tubes do not have to be identical as long as you keep both sides identical. Running one Chatham and one RCA per side just might be a very nice combination. And another combination that I have wanted to try for a long time is one GEC 6080 and one Bendix 6080 per side. Maybe someday I will get around to it....

Well I try RCA 6AS7G, will see
Can you explain a little more about mixing tubes please ? A pair of tubes is for right channel and a pair for the left ? How did they work well ?

Any good "mix" for a little dot mkVI+ ?

The 6AS7G is very different from the 5998 electrically. They are similar enough that they can often be substituted without modification to the gear, but if the gear is not designed for the 5998, it might not work properly.
A run down on the differences:

• The μ (mu: amplification factor) of the 5998 is 5.4, compared to the 2 of the 6AS7G, meaning that the same bias will result in different plate voltages. In a cap-coupled amp, this is not a big deal, but whenever there's DC coupling, this could be a problem, causing distortion or clipping, or even a release of the magic smoke if the amp is designed in such a way that it would be damaged by a change like that. I wouldn't worry too much about tube gear being damaged, but a hybrid might not like it. It depends on the amp.
• The Rp (plate resistance) of the 5998 is 350 ohms, vs the 6AS7G at 280. Not a huge difference.for the most part, it won't matter.
• The Gm (transconductance) of the 5998 is 15.5mS, vs 7mS. This is the most important difference for a cathode follower, which is the output stage topology of most headphone amps, like the Crack. The output impedance of a basic cathode follower is approximately the reciprocal of the transconductance. The output impedance of a 6AS7G-based cathode follower is 1/0.007=142.9 ohms, give or take. A 5998 cathode follower is approximately 1/0.0155=64.5 ohms. This is why 5998's in an OTL amp sound much better than 6AS7G's with lower impedance headphones; a better damping factor.
• The plate curves of the 5998 are mugc better (more linear) than the 6AS7G, so there is slightly less distortion.

An A2293 would be an interesting option to try, but it'd need an adapter. Same for the 7233. Both are obscure, cheap, single triodes in a 9-pin miniature package with very good performance. Based on specs alone, I would recommend a pair of 7233's over all of the other options, 5998 included.

Thank you for this clear explanation Some people use 5998 with a little dot mkVI+ without trouble, but the vu metter goes down to 40 .... I don't know if it's can damage or not the amp ...
Perhaps it could be a must have to modify the Little dot to use full potentiel of 5998 ... but i don't know how to do it ...

At least People who use 5998 with this amp report a "good sound" ... but well they cost half the price of the amp so ...

I did'nt find any russian equivalent for 5998 ?

 

[gibosi]

Well I try RCA 6AS7G, will see
Can you explain a little more about mixing tubes please ? A pair of tubes is for right channel and a pair for the left ? How did they work well ?

Any good "mix" for a little dot mkVI+ ?

Your LD is shipped with four RCA 6080, two for the left channel and two for right channel. I am suggesting that you can mix brands as long as both channels are the same. For example, the right channel pair is one RCA and one Chatham and the left channel pair is also one RCA and one Chatham.

I don't know if you will like the sound, but it is worth trying.

Thank you for this clear explanation Some people use 5998 with a little dot mkVI+ without trouble, but the vu metter goes down to 40 .... I don't know if it's can damage or not the amp ...
Perhaps it could be a must have to modify the Little dot to use full potentiel of 5998 ...

I suggest that you send an email to David at Little Dot and ask him if it is safe to run 5998 in your amp.

 

[gug42]

Ok thank you. I will ask
Can i try to mix 6as7g and 6080 too ?

Thx