Follow up on Primaluna HP Int amp

[slipperybidness]

No. KT88 upgrade... Thought I was getting the KT120 when I did the upgrade.

I'm intrigued by the auto-biasing circuitry on this amp.

I did not do a thorough read, but it seems to say that the amp will auto-bias. It will maintain the proper bias even as the tubes age? And how about when you swap from EL34 to KT88? Is there some selector switch or some dip switches? Or do you just plop in a tube and it auto-biases?

Wheels are turning. I'm curious if there are any open-source auto-bias schematics online.

 

[ematthews]

I'm intrigued by the auto-biasing circuitry on this amp.

I did not do a thorough read, but it seems to say that the amp will auto-bias. It will maintain the proper bias even as the tubes age? And how about when you swap from EL34 to KT88? Is there some selector switch or some dip switches? Or do you just plop in a tube and it auto-biases?

Wheels are turning. I'm curious if there are any open-source auto-bias schematics online.

There is a rocker switch on the side that says EL34/KT88-120... Switch to select what tubes you are running.

 

[slipperybidness]

There is a rocker switch on the side that says EL34/KT88-120... Switch to select what tubes you are running.

OK, that makes sense. I couldn't see a simple solution to auto-biasing both styles of tubes without some type of selector.

Now, I'm wondering if it's just a simple diode voltage regulation (extremely inefficient, but heck it's already inefficient due to the tubes), or if it's a voltage regulator IC. Either way, with auto-bias, this is really almost a SS/Tube hybrid design.

 

[JonnyFive23517]

Either way, with auto-bias, this is really almost a SS/Tube hybrid design.

I'm not sure that's accurate? Autobias is a great feature, and they don't run the tubes anywhere near their limit so they last longer. My biggest concern moving to a tube power amp is the output impedance/damping factor, and what that's going to sound like in the bass section of my 87 dB efficient towers. I may not really notice it though, so I plan to audition.

You should be able to see the auto-biasing boards here: HP Integrated Amplifier

 

[ematthews]

I'm not sure that's accurate? Autobias is a great feature, and they don't run the tubes anywhere near their limit so they last longer. My biggest concern moving to a tube power amp is the output impedance/damping factor, and what that's going to sound like in the bass section of my 87 dB efficient towers. I may not really notice it though, so I plan to audition.

You should be able to see the auto-biasing boards here: HP Integrated Amplifier

Hey
Are we looking from the bottom up on the picture in the link? Was wondering since the volume pot is on the upper left of the pic....

 

[GranteedEV]

Hey, I recommend this amp:

Kaluga

I don't think my RBH will be the last. I still think the bass sounds a little loose and the treble doesn't match what I was getting out of the RAAL ribbon on the Ascends. I'm not complaining. The RBH are fantastic.. I just still should get a separate amp to drive the bass. This was I could turn it down a touch.

No comment on the treble, but you can probably tighten up the bass with EQ:

Kill that that ~7db peak centered at 140hz with a q = ~0.9 (?) -6db PEQ

 

[slipperybidness]

I'm not sure that's accurate? Autobias is a great feature, and they don't run the tubes anywhere near their limit so they last longer. My biggest concern moving to a tube power amp is the output impedance/damping factor, and what that's going to sound like in the bass section of my 87 dB efficient towers. I may not really notice it though, so I plan to audition.

You should be able to see the auto-biasing boards here: HP Integrated Amplifier

Thanks for the link. I read through the info that they provided.

So, yeah, the autobiasing circuit uses some ICs and looks to operate in the digital domain. This does look like a good idea and should be awesome assuming that it is implemented correctly.

Now, a LOT of what they have on that web-page is marketing mumbo-jumbo. Let's not kid ourselves here.

They talk about how they bias and why they bias and etc, etc.

BUT, and this is a big BUT, I don't see anywhere that they say this is a class A amp or a Class B (AB) amp. When you read between the lines of all the marketing hype, this looks like a class AB design to me.

I'm not saying that class AB is an inherently inferior design by any means. It does have some advantages. What I'm saying is that they try to hide the facts with marketing to make you think they are doing something double-secret-special, and that just doesn't look to be true to me.

Class A, B, C, AB, these all depend on the bias quiescent point. Class A is mid-point bias and will take more power than class B that is "biased near cutoff". To me, they are just trying to disguise this with mumbo jumbo.

I'm sure this is fine amp! There's no need for any hand-waving, but they did it anyway.

Edit: Their "contact us" link was very painless, so I sent a quick question to see if my hunch is correct.

 

[ski2xblack]

I'm sure this is fine amp! There's no need for any hand-waving, but they did it anyway.

They know their audience, that's for sure. At least they did a clean job inside. Thanks for the link to under the hood pic, JF.

Autobias is a compelling feature. It's completely outside the signal path, so it's still a tube amp...well, it uses ss rectification, but that is just another example of Primaluna surrounding their old school tube circuit with some more modern touches that actually make sense.

 

[JonnyFive23517]

I like the autobiasing, I also like that the tubes don't push into a printed circuit board which will become brittle over time. Other brands have those tube sockets right in the PCB.

I assumed it was all class A power. Is that not right?

That Kaluga mono looks amazing, and I'm sure it's great. At $16k/pr though, not something I'll ever afford.

 

[AcuDefTechGuy]

No, the OP should just stick to the fine ATI AT2000 amp he already owns. $16K Class-D amps or Tube amps won't sound any better IMO.

 

[ematthews]

No, the OP should just stick to the fine ATI AT2000 amp he already owns. $16K Class-D amps or Tube amps won't sound any better IMO.

I agree but also disagree a bit. I think this Primaluna would sound fantastic with the right speakers. They would have to be leaning toward the brighter side IMO since the tubes are on the smooth and warm side. The RBH speakers are very smooth across the board and sound fantastic with the P5/ATI combo.

 

[ski2xblack]

No, the OP should just stick to the fine ATI AT2000 amp he already owns. $16K Class-D amps or Tube amps won't sound any better IMO.

C'mon, Mr. Moderator, don't be a party pooper, get in the spirit of the discussion!

I agree to the point that the OP's ATI will provide benchmark performance, but that "better" is in the ear of the listener, and this is a hobby after all. At least he has the ATI as a baseline to compare such alternative approaches to.

FWIW, after my forays into tubes, I ended up with ATI and single ended pentodes.

I think this Primaluna would sound fantastic with the right speakers.

Have you tried it with your RF-82s? Assuming you still have them (listed in your sig).

 

[AcuDefTechGuy]

The RBH speakers are very smooth across the board and sound fantastic with the P5/ATI combo.

Exactly. I think the only other thing that could improve the sound is active bi-amp of the RBH so you could fine - tune the bass, which could be adversely affecting the treble and midrange in your room.

 

[AcuDefTechGuy]

C'mon, Mr. Moderator, don't be a party pooper, get in the spirit of the discussion!

I agree to the point that the OP's ATI will provide benchmark performance, but that "better" is in the ear of the listener, and this is a hobby after all. At least he has the ATI as a baseline to compare such alternative approaches to.

FWIW, after my forays into tubes, I ended up with ATI and single ended pentodes.

Didn't think he should be spending thousands $$ jumping amp to amp.

 

[ski2xblack]

Um, he already bought it, per the first post in the thread. (And this from the guy whose bought and sold how many amps and sets of speakers over the years? What's that saying about people in glass houses?)

 

[crossedover]

Exactly. I think the only other thing that could improve the sound is active bi-amp of the RBH so you could fine - tune the bass, which could be adversely affecting the treble and midrange in your room.

Just so we are clear, your plan is to active bi/tri amp your RBHs? Is this going to include a crossover and amp for each divide or are you just going to do the sub modules with your prepro and a seperate amp?

 

[AcuDefTechGuy]

Um, he already bought it, per the first post in the thread. (And this from the guy whose bought and sold how many amps and sets of speakers over the years? What's that saying about people in glass houses?)

I was talking about the $16K class D amp recommendation.

 

[crossedover]

Exactly. I think the only other thing that could improve the sound is active bi-amp of the RBH so you could fine - tune the bass, which could be adversely affecting the treble and midrange in your room.

I was talking about the $16K class D amp recommendation.

Sorry was referring to yours

 

[AcuDefTechGuy]

Just so we are clear, your plan is to active bi/tri amp your RBHs? Is this going to include a crossover and amp for each divide or are you just going to do the sub modules with your prepro and a seperate amp?

I was referring to the OP's RBH SX-6300/R. The treble and midrange would be passive amp. Only the woofers would be active amp via the preamp's XO (Parasound Halo P5) & external amp (like a $300 HSU subwoofer amp).

 

[AcuDefTechGuy]

Sorry was referring to yours

It would be similar with my system.

For my system, the treble & midrange would be passive amp (RBH internal XO + ATI amp). The woofers would be active amp (Denon AVP-A1HDCI's XO + ATI amp). Thus I would be using a total of 10 channels of ATI amps for the five SX-T2/R towers.