[mordy]

It's more to do with the headphones you're using. With a warmer sounding headphone like Atrium, you'll want more energy from your tubes, hence higher gain. With a very inefficient headphone like Susvara you definitely want higher gain tube.

With my very efficient Grado GH1, a 20 mu is more than sufficient. The less the better with Grados.

I think it's common sense to match bright drivers with warm power tubes to balance it out and vice versa. However sometimes uncommon sense prevails when you specifically choose a bright setup or a very warm setup.

For example I am usually someone who prefers transparency and neutrality but when I listen with Audeze LCD4 and Auris Nirvana, the chocolate syrupy sound taste good in mouth literally.

So no formula. On Monday, you like bright sound. On Tuesday, a bit more moderate. On Wednesday you're almost over the hill, so you start to gravitate towards warmth. Come Friday, you're all blues and smokey. On the weekend, you pass out and just sleep in.

My main headphones are 80 ohm. Most of the time I use the Ultimate as a preamp and listen through speakers. Sometimes it occurs to me that certain tube combinations work better with the speakers compared to the headphones.
Does using the Ultimate as a preamp change the mu matching of input to output tubes?
I have another amp that has two headphone jacks - one for low ohm and one for high ohm headphones. When I asked the designer which jack to use for preamp out, he said to use the low ohm jack.

 

[Deleeh]

My main headphones are 80 ohm. Most of the time I use the Ultimate as a preamp and listen through speakers. Sometimes it occurs to me that certain tube combinations work better with the speakers compared to the headphones.
Does using the Ultimate as a preamp change the mu matching of input to output tubes?
I have another amp that has two headphone jacks - one for low ohm and one for high ohm headphones. When I asked the designer which jack to use for preamp out, he said to use the low ohm jack.

Yes, a little, depending on what's in it.
I guess you will have to open the potentiometer on the Ultimate a little further for the sweet spot with less mu and vice versa with high mu gain, but it doesn't really matter because you can also control this on the main amplifier.
Low mid would also be right because of the clipping it could cause on high mid.

 

[UntilThen]

My main headphones are 80 ohm. Most of the time I use the Ultimate as a preamp and listen through speakers. Sometimes it occurs to me that certain tube combinations work better with the speakers compared to the headphones.
Does using the Ultimate as a preamp change the mu matching of input to output tubes?
I have another amp that has two headphone jacks - one for low ohm and one for high ohm headphones. When I asked the designer which jack to use for preamp out, he said to use the low ohm jack.

Thank you very much. You just solve my problem of providing source to 4 amps from Yggdrasil.
Yggdrasil's xlr out to Ultimate's xlr in. Yggy's rca 1 out to Odyssey and Yggy's rca 2 to Oblivion.
Then Ultimate preamp out to Redgum Rgi125enr integrated amp driving my Axis Voicebox S speakers. Brilliant !

I don't think it's that restrictive on mu matching between drivers and power tubes using Ultimate as preamp. My Redgum is 264 watt into 4 ohms. That literally drives any speakers including B&W 801s.

Here I am using the same c3gs into 5b/254m in Ultimate as preamp and feeding Redgum and I am listening to my speakers now. Just such a great tone on the speakers as well as on headphones.

Btw I can use headphones through Ultimate's headphone output while all this connection is on between Ultimate and Redgum.

 

[UntilThen]

Yes, a little, depending on what's in it.
I guess you will have to open the potentiometer on the Ultimate a little further for the sweet spot with less mu and vice versa with high mu gain, but it doesn't really matter because you can also control this on the main amplifier.
Low mid would also be right because of the clipping it could cause on high mid.

Because my Redgum is so powerful, I set the volume on it to 9am only and then I vary the volume on Ultimate. If I want it louder I just turn up the volume on the Redgum or the Ultimate. Probably on the Redgum because it has a remote.

 

[mordy]

Because my Redgum is so powerful, I set the volume on it to 9am only and then I vary the volume on Ultimate. If I want it louder I just turn up the volume on the Redgum or the Ultimate. Probably on the Redgum because it has a remote.

I find that I have to balance the two volume controls on the Ultimate and the power amp for the best sound. And yes, you can use the headphones at the same time as the preamp out. And the XLR headphone jack can be converted to a 6.3mm headphone jack with an adapter if needed - the Ultimate can drive two sets of headphones at the same time.
Glenn used to listen with headphones and speakers - said that it gave him better bass.

 

[UntilThen]

the Ultimate can drive two sets of headphones at the same time.
Glenn used to listen with headphones and speakers - said that it gave him better bass.

You're not supposed to drive 2 sets of headphones at the same time. Eric caution about that sometime ago. ALO Audio Studio Six is different. It can drive 4 headphones at the same time. The power supply is good for 20 watts.

You can though listen with headphones and speakers at the same time. There is the speaker on/off switch. When you listen with headphone and speakers at the same time, there is some kind of back filling, like a backing orchestra and added bass but for pureness of sound I don't do that.

 

[UntilThen]

I find that I have to balance the two volume controls on the Ultimate and the power amp for the best sound.

Yes of course. You do this by ear.

 

[UntilThen]

Back in the days when there were WA22, Studio Six and Glenn OTL amp. This is already a very good trio but it is much better now.

 

[crakers7]

These just arrived ,looking forward to hearing them and see how they compare to my 807’s

 

[mordy]

You're not supposed to drive 2 sets of headphones at the same time. Eric caution about that sometime ago. ALO Audio Studio Six is different. It can drive 4 headphones at the same time. The power supply is good for 20 watts.

You can though listen with headphones and speakers at the same time. There is the speaker on/off switch. When you listen with headphone and speakers at the same time, there is some kind of back filling, like a backing orchestra and added bass but for pureness of sound I don't do that.

Is there a problem using line out as a preamp and having the headphones connected at the same time?

 

[UntilThen]

Is there a problem using line out as a preamp and having the headphones connected at the same time?

No.

 

[UntilThen]

These just arrived ,looking forward to hearing them and see how they compare to my 807’s

Beautiful new Mullard EL38. Such a joy to see new tubes. Literally new old stocks.

 

[Deleeh]

You're not supposed to drive 2 sets of headphones at the same time. Eric caution about that sometime ago. ALO Audio Studio Six is different. It can drive 4 headphones at the same time. The power supply is good for 20 watts.

You can though listen with headphones and speakers at the same time. There is the speaker on/off switch. When you listen with headphone and speakers at the same time, there is some kind of back filling, like a backing orchestra and added bass but for pureness of sound I don't do that.

Why shouldn't you drive 2 headphones at the same time?
Is impedance related to the headphones?
If so, I would agree.
I've had both Zmf on at the same time several times and everything was fine, both are 300 ohms and was no problem.
The Auteur could have been a bit louder for the sweet spot while the Atrium had already reached it.

edit: Ultimate is a Tank,

 

[UntilThen]

These just arrived ,looking forward to hearing them and see how they compare to my 807’s

Which is your favourite 807?

 

[UntilThen]

Why shouldn't you drive 2 headphones at the same time?
Is impedance related to the headphones?
If so, I would agree.
I've had both Zmf on at the same time several times and everything was fine, both are 300 ohms and was no problem.
The Auteur could have been a bit louder for the sweet spot while the Atrium had already reached it.

edit:%20Ultimate%20is%20also%20a%20tank,%F0%9F%98%81%F0%9F%98%81%F0%9F%98%81%F0%9F%98%81%F0%9F%98%81

I can't remember what Eric said about not using both xlr and 1/4 out at the same time but he did say that.