Valve amp integrated to power amp ratio

[RankStranger]

There appears to be a higher proportion of integrated amps - as compared to power amps - in the tube/valve category than there is in the solid state category. 
 

Have others noticed this or is it some variety of Baader-Meinhof situation and I’m imagining it?

 

If real, is there a technical reason for it? Like, something to do with impedance-matching preamps or something?

 

[georgehifi]

39 minutes ago, RankStranger said:

If real, is there a technical reason for it? Like, something to do with impedance-matching preamps or something?

 

"Gain"

With solid state power-amps you in many cases you can get away with using the source as the preamp also if it has a volume control, one less set of interconnects and no added preamp colouration/distortions. ("some" like those tube preamp colourations though)

 

Cheers George

Edited August 17 by georgehifi

[RankStranger]

18 minutes ago, georgehifi said:

 

"Gain"

With solid state power-amps you in many cases you can get away with using the source as the preamp also if it has a volume control, one less set of interconnects and no added preamp colouration/distortions. ("some" like those tube preamp colourations though)

 

Cheers George

thanks, George. That sounds like a good explanation. 

 

It follows that, in most cases you think the volume control on a valve integrated amp is an active circuit to add gain, rather than just a passive attenuator?

 

the reason I’m asking is that I’m planning to build a valve power amp at some point and my neuroticism doesn’t want an unnecessary volume control on the front but I don’t want to build myself into a corner either.
 

it’s just theory at the moment but it was nagging at me, as these things do

[georgehifi]

1 hour ago, RankStranger said:

It follows that, in most cases you think the volume control on a valve integrated amp is an active circuit to add gain, rather than just a passive attenuator?

Used to be, but these days many just build a poweramp and stick a passive alps pot at the front with a few switched inputs and call it an "Integrated", actually sounds better because there's less in the signal path.

 

Cheers George 

Edited August 17 by georgehifi

[THOMO]

In my experience valve amps can sound very good without a preamp or just a passive type of preamp.That is far less common with SS power amps.I have only owned one SS amplifier that sounded decent without an active preamp [a Bakoon].

[RankStranger]

28 minutes ago, THOMO said:

In my experience valve amps can sound very good without a preamp or just a passive type of preamp.That is far less common with SS power amps.I have only owned one SS amplifier that sounded decent without an active preamp [a Bakoon].

Thanks, Jon. I have a denafrips class AB power amp that I was initially running direct from a Auralic streaming dac and I thought it sounded great. I didn’t feel like I was missing anything. 

 

Then I built a diy pre mostly for fun and put it in between and the whole thing came to life in a way I never would have expected. It makes me wary of running passive options in general, although I haven’t tried any of those fancy transformer ones  

 

I’m still wondering if there is some technical reason this wouldn’t be the case with a valve amp. 

Edited August 17 by RankStranger

[aussievintage]

18 hours ago, RankStranger said:

It follows that, in most cases you think the volume control on a valve integrated amp is an active circuit to add gain, rather than just a passive attenuator?

 

It's just semantics.  Very few circuits actually have a control to alter the gain.  They nearly all use a passive control, and may or may not have a stage for added gain, but if not, that gain will/needs be somewhere else in the system, so it's all a wash.

[xlr8or]

From my understanding using valve amps it's to do with the gain/driver stage for the power tube in question being optimal. An integrated or power tube amp act the same with respect to their tube input, driver and power output stage circuitry delivering the same power output irrespective of the output transformer tap that is being used to match the nominal impedance of the speaker (4, 8 or 16 ohm). The only difference being an integrated tube amp, as George has mentioned, utilises a passive volume control in the circuit and the option of using a selector switch to accomodate different input sources.

 

One thing to be mindful of with valve amps is the driver stage and the necessary swing needed to maximise the output from the power tube. Some circuit design topologies just don't offer the best input and voltage swing circuitry combo and therefore using a tube preamp which step ups the line level signal and provides more gain entering into the input stage of the power amp may be a necessary addition to maximise the driver swing and power output stages. The only concern here is oversaturating the incoming signal and causing earlier break up and distortion of the power tube output section.

[sir sanders zingmore]

20 hours ago, RankStranger said:

There appears to be a higher proportion of integrated amps - as compared to power amps - in the tube/valve category than there is in the solid state category. 

Do you mean in the Classifieds? 
If so, I’m not sure that’s correct. 
Looking at the first 25 listings in the integrated section, only 3 are valve. 

In the power amp classifieds 6 are valves. 
 

[RankStranger]

18 minutes ago, sir sanders zingmore said:

Do you mean in the Classifieds? 
If so, I’m not sure that’s correct. 
Looking at the first 25 listings in the integrated section, only 3 are valve. 

In the power amp classifieds 6 are valves. 
 

Sorry. No, nothing to do with the classifieds. Just a general observation  

[RankStranger]

1 hour ago, aussievintage said:

 

It's just semantics.  Very few circuits actually have a control to alter the gain.  They nearly all use a passive control, and may or may not have a stage for added gain, but if not, that gain will/needs be somewhere else in the system, so it's all a wash.

Yeah, I worded that poorly. I was thinking of a gain stage in the context of my diyaudio BA2018 pre (which is I think +14dB), which of course is followed by a passive volume control, too. So maybe I just meant active gain stage vs none.

 

I’m still getting across some of the correct terminology  

[RankStranger]

2 hours ago, xlr8or said:

From my understanding using valve amps it's to do with the gain/driver stage for the power tube in question being optimal. An integrated or power tube amp act the same with respect to their tube input, driver and power output stage circuitry delivering the same power output irrespective of the output transformer tap that is being used to match the nominal impedance of the speaker (4, 8 or 16 ohm). The only difference being an integrated tube amp, as George has mentioned, utilises a passive volume control in the circuit and the option of using a selector switch to accomodate different input sources.

 

One thing to be mindful of with valve amps is the driver stage and the necessary swing needed to maximise the output from the power tube. Some circuit design topologies just don't offer the best input and voltage swing circuitry combo and therefore using a tube preamp which step ups the line level signal and provides more gain entering into the input stage of the power amp may be a necessary addition to maximise the driver swing and power output stages. The only concern here is oversaturating the incoming signal and causing earlier break up and distortion of the power tube output section.

I think I follow you. Is there a way to measure or calculate the input/swing-related characteristics or is it one of those "combination of arcane wisdom and trial and error" situations?

[xlr8or]

1 hour ago, RankStranger said:

I think I follow you. Is there a way to measure or calculate the input/swing-related characteristics or is it one of those "combination of arcane wisdom and trial and error" situations?

 

It's a combination of both. Here is a classic example taken from the Willsenton R8 and the input sensitivities that have been quoted.

 

Input sensitivity: 380mv (when Integrated amp input) 820mv (when pure power amp input)

 

Many users complain the integrated section has too high a sensitivity and the source signal saturates very easily. Nowhere near enough attenuation is available on the volume control circuitry to give some range to the volume control.  However, when bypassed and the integrated amp acts as a power amp a much lower sensitivity is apparent. Many users are finding using a preamp is a much better solution to crank up the preamp volume to give a wider range of volume control and not oversaturate the incoming signal. This can also happen the other way around for other tube amp configurations where the input sensitivity is too low requiring far more gain and even a step up from the input source. The use of a preamp here would benefit the incoming source signal going to the gain, driver and power output stages.

 

Edit: Just adding this is all independent of the tube amp's driver swing stage but at least ensures that you are feeding that stage as best you can. To work out the correct swing, etc, you would need to study the circuit and work out the optimal values and configured stage arrangements to use.

Edited August 18 by xlr8or

[aussievintage]

18 minutes ago, xlr8or said:

  However, when bypassed and the integrated amp acts as a power amp a much higher sensitivity is apparent.

 

Don't you mean lower sensitivity?  There is less gain without the preamp, so a larger input signal is required to drive it to full power, meaning it is less sensitive.    - or am I interpreting what you are trying to say incorrectly?

[xlr8or]

1 minute ago, aussievintage said:

 

Don't you mean lower sensitivity?  There is less gain without the preamp, so a larger input signal is required to drive it to full power, meaning it is less sensitive.    - or am I interpreting what you are trying to say incorrectly?

 

Yes, thanks. Will go back and fix it.