[ClementNerma]

As far as i know the TA-30 is also a hybrid. In fact it’s wise to be satisfied with the CTH as going OTL is an endless rabbit hole

The TA-10 and TA-20 are both hybrid, but the TA-30 is an OTL (you have that big ol' power tube in addition to the preamp tubes).
The main problem with OTL amps is that they tend to cost a lot more than hybrid ones or transistor-based amps, and they heat a lot which is not suitable for my use (I also hate the fact they they usually emit a lot of light). You also have to take care of replacing the power tube after a few years, etc. so that's really a lot more hassle, unless you go straight for a very clean and high-end amp with a four-digit price

In which case I'm a lot better off my $150 CTH

 

[Zachik]

The main problem with OTL amps is that they tend to cost a lot more than hybrid ones or transistor-based amps, and they heat a lot which is not suitable for my use (I also hate the fact they they usually emit a lot of light). You also have to take care of replacing the power tube after a few years, etc. so that's really a lot more hassle, unless you go straight for a very clean and high-end amp with a four-digit price

Actually, the #1 reason OTL amps are not more popular is their output impedance... OTL amps are ideal for 300 ohms headphones (ZMF headphones, HD600 and its siblings, HD800, etc). Not ideal match for low impedance headphones and for planars. That makes OTL amps more of a specialized product, whereas hybrids (like the CTH) are more of an all-arounder...

 

[ClementNerma]

Actually, the #1 reason OTL amps are not more popular is their output impedance... OTL amps are ideal for 300 ohms headphones (ZMF headphones, HD600 and its siblings, HD800, etc). Not ideal match for low impedance headphones and for planars. That makes OTL amps more of a specialized product, whereas hybrids (like the CTH) are more of an all-arounder...

I perfectly agree with this, but as I'm using an HD 58X (150 Ohms which is still quite high) the main problems for me are the heat, the light, and the lifetime of the power tubes (even though it's not like you have to replace it every month).

 

[Zachik]

I perfectly agree with this, but as I'm using an HD 58X (150 Ohms which is still quite high) the main problems for me are the heat, the light, and the lifetime of the power tubes (even though it's not like you have to replace it every month).

I may not be the average person to answer that, since I tube-roll often, but according to people that have been into tubes for longer (much longer) than I have - tubes need to be replaced, under heavy usage, every 2-3 years. Under light usage - easily 5-10 years... Just saying
Anyhow, the point I am trying to make here:
If OTL amp works for you, the fear of dealing with "consumable" tubes is a non-issue!
(please no examples of amps that use 4 super-rare-and-expensive tubes... )

 

[ClementNerma]

I may not be the average person to answer that, since I tube-roll often, but according to people that have been into tubes for longer (much longer) than I have - tubes need to be replaced, under heavy usage, every 2-3 years. Under light usage - easily 5-10 years... Just saying
Anyhow, the point I am trying to make here:
If OTL amp works for you, the fear of dealing with "consumable" tubes is a non-issue!
(please no examples of amps that use 4 super-rare-and-expensive tubes... )

Oh of course, like I said it's not like it's a huge issue, unless you indeed get rare and/or very expensive tubes. But these are mostly found in very high-end amps, which if you can afford them means you can also afford tube replacement

It's really the heat that bothers me the most, as well as the light. But I must admit OTL amps sound damn good, although they add a whole lot of distorsion in the sound (the reason are nearly "banned" from AudioScienceReview) the sound is really enjoyable and relaxing.

 

[HTSkywalker]

I may not be the average person to answer that, since I tube-roll often, but according to people that have been into tubes for longer (much longer) than I have - tubes need to be replaced, under heavy usage, every 2-3 years. Under light usage - easily 5-10 years... Just saying
Anyhow, the point I am trying to make here:
If OTL amp works for you, the fear of dealing with "consumable" tubes is a non-issue!
(please no examples of amps that use 4 super-rare-and-expensive tubes... )

In fact NOS tubes are listed to operate for 10K hours depending on manufacturer while the good old ones may die on you depending how much they were used before or due to corrosion etc.
As you said, the higher the impedance the Warner the sound and the more heat the OTL will radiate.
Planars only shine with SS amps or other few hybrids like the CTH.

 

[ClementNerma]

Btw, is is possible to plug a 12AU7 tube on a 6922 socket? I've seen adapters on the web but they seem to be fully passive, so I don't quite grasp whether there is a compatibility problem or not...

 

[jonathan c]

Btw, is is possible to plug a 12AU7 tube on a 6922 socket? I've seen adapters on the web but they seem to be fully passive, so I don't quite grasp whether there is a compatibility problem or not...

Not without an adapter. The adapter “rewires” the 12-volt based nine-pin 12AU7 to make it “look” like a 6-volt based nine-pin 6922. Direct insertion of a 12-volt tube in a 6-volt socket would “fry” the circuit.

 

[ClementNerma]

Not without an adapter. The adapter “rewires” the 12-volt based nine-pin 12AU7 to make it “look” like a 6-volt based nine-pin 6922. Direct insertion of a 12-volt tube in a 6-volt socket would “fry” the circuit.

Ok, I'll avoid putting my 12AU7 in my CTH then

 

[Guidostrunk]

Ta-30 is still a hybrid. Similar to the Woo audio Wa6. Transformer coupled. OTC instead of OTL.
Which is good because it leaves the door open for low impedance cans, and 3w(32ohms) is pretty powerful.

 

[ClementNerma]

Ta-30 is still a hybrid. Similar to the Woo audio Wa6. Transformer coupled. OTC instead of OTL.
Which is good because it leaves the door open for low impedance cans, and 3w(32ohms) is pretty powerful.

Never thought that, I thought that big power tube = OTL. How can I how if an amp is OTC/OTL without looking at the specs sheet?

 

[Guidostrunk]

That's just a rectifier tube. It converts ac to dc voltage. The transformer is performing the output. That's why the ta-30 can run 3w @ 32ohms.
If the amp was tranformerless it would have output tubes which provide a lot of voltage and less current.
If that were the case you wouldn't have that type of output power stated and would only be able to use high impedance cans ie... HD800, 650 , ZMF ....etc.

The 12au7 are input/preamp tubes.

 

[ClementNerma]

That's just a rectifier tube. It converts ac to dc voltage. The transformer is performing the output. That's why the ta-30 can run 3w @ 32ohms.
If the amp was tranformerless it would have output tubes which provide a lot of voltage and less current.
If that were the case you wouldn't have that type of output power stated and would only be able to use high impedance cans ie... HD800, 650 , ZMF ....etc.

The 12au7 are input/preamp tubes.

So if I understand there are three types of tubes: input/preamp tubes, power tubes, and output tubes?

 

[Guidostrunk]

There are variations of OTL amplification. Has to do with coupling the output without a transformer.
https://en.wikipedia.org/wiki/Output_transformerless

 

[ClementNerma]

I received my 6922 JJ tube this morning, so here we go! I guess the tube will need a bit of break-in, as it appears that even though most audio hardware doesn't need to, tubes really benefit for a bit of break-in.

For now, there is an undeniable details loss, but the sound is more engaging. It is less analytical and more 'relaxed', even though it's not the level of my Bravo Audio Ocean, which has a lot less details but has a warmer sound (probably due to the usage of a 12AU7 preamp tube). The bass is also -no surprise here- looser than with the EH tube.

Finally, using this tube doesn't give a very 'warm' sound like some hybrid amps are capable of ; it's still more on the neutral side than on the 'very warm' side.

I'll test the tube thouroughly in the next days and give my detailed impressions later on

On the other hand, when I rolled the EH tube, I saw that one of the pin was really torned, even though it was in the amp for something like 2 months. Can this be a problem for the amp even if the tube fits perfectly?