TOPIC:

I'm hoping to organize my audio setup as SHD into Tube Preamp into Solid State Power Amp. I'm currently using SHD as a preamp into SS Power Amp. SHD also outputs to a powered subwoofer. I want to add the tube preamp to add that tube warmth sound into the mix. It would be easier to go with a tube power amp and keep SHD as the preamp but the speakers i'm looking at are inefficient and need the SS watts.

Would this setup work? Essentially it uses the SHD as streamer, sub crossover, Dirac room correction, and input selector (for analogue phono). But I would make the volume on it fixed and use tube preamp for volume.

I think this would work but i'm a little new to minidsp usage so want to make sure i'm not missing anything. For example, I realized this scenario wouldn't work to keep using SHD to control volume because then the subwoofer volume is controlled separately from the preamp volume which puts it out of balance.

Thanks.

Hi,

I think it doesn't work. If you put the tube preamp in front of the shd, eg. feed the output of the preamp into the shd, you don't have the tube preamp in the chain for measurements with Dirac. If you connect the preamp behind the shd, eg feed the analog out of the shd to the preamp, it would only act as tube buffer. What a waste for a fully featured preamp. There could be the danger of removing the tube characteristics by Dirac filtering.

You will always have to control the volume by shd since the tube preamp is probably two channel.

I retired my tube preamp because of theses thoughts.
I tried it once, when I got my shd and the result was quite disappointing ( only tried preamp in front). The shd as standalone preamp gave me better results. Its quite an excellent preamp. Modify the sound by working with the target curves, if you feel the need to do so.

Greets
Christian

Thanks. You're right, I essentially just want to use it as a tube buffer to add that tube sound. Am I misguided in doing that? I've just always loved the sound of tubes in other systems I've heard and wanted to add that to my system. As long as I'm using volume control on the SHD, is this idea not possible.

Appreciate the feedback.

Only realistic way it could work is to use a separate streamer feeding the tube preamp, and feed the preamp output to the SHD.. You would be using the SHD for Dirac and Bass management only with fixed volume. While volume control and input selection would be handled by the tube preamp.

elikirschner wrote:

Thanks. You're right, I essentially just want to use it as a tube buffer to add that tube sound. Am I misguided in doing that? I've just always loved the sound of tubes in other systems I've heard and wanted to add that to my system. As long as I'm using volume control on the SHD, is this idea not possible.

Appreciate the feedback.

Yes you can do this, so long as you can keep the tube pre-amp gain fixed. Only you can decide whether you'd like the result though.

If it's just 'warmth' that you want I'd have thought you could achieve this with DSP applied by the SHD. If on the other hand what you want is the euphonic harmonic distortion that valve amps typically introduce then you won't be able to achieve this with the SHD.

murtazao wrote:

Only realistic way it could work is to use a separate streamer feeding the tube preamp, and feed the preamp output to the SHD.. You would be using the SHD for Dirac and Bass management only with fixed volume. While volume control and input selection would be handled by the tube preamp.

Hi,

As I wrote before, I wouldn't put a tubeamp in front of shd, because dirac will try to "correct" it. I tried both, in front and as tube buffer behind shd and then retired the tube preamp
Greets
Christian

Ultrasonic Wrote:

"If it's just 'warmth' that you want I'd have thought you could achieve this with DSP applied by the SHD."

Ultrasonic, can you recommend how this would be achieved? To my (limited) understanding, tube sound has a slightly elevated mid-range frequency boost - are you suggesting doing that with the Dirac curve?

murtazao wrote:

Only realistic way it could work is to use a separate streamer feeding the tube preamp, and feed the preamp output to the SHD.. You would be using the SHD for Dirac and Bass management only with fixed volume. While volume control and input selection would be handled by the tube preamp.

Could you explain "only realistic way?" I don't understand why the SHD has to be after the preamp (preamp out to SHD). If the preamp volume is fixed, why can't the SHD come before it, to be used as streamer, input, and volume control?

elikirschner wrote:

"If it's just 'warmth' that you want I'd have thought you could achieve this with DSP applied by the SHD."

Ultrasonic, can you recommend how this would be achieved? To my (limited) understanding, tube sound has a slightly elevated mid-range frequency boost - are you suggesting doing that with the Dirac curve?

If you're already applying Dirac in the relevant frequency range, yes. If you're only applying Dirac at bass frequencies (as I do) then you could apply a filter to add a boost using the PEQ section in the plugin.

Your setup will work but the quality of the sound will likely be worse with the tube preamp inserted between the miniDSP and the amp than without the preamp, at least at low volumes, and here is why.
The problem is that you will be controlling the overall sound volume through the DSP and not the preamp, meaning that the input signal received by the preamp will vary depending on the volume. This is NOT what a preamp expects : it is designed to receive input signals with a predefined voltage (typically a few hundreds of mV) and control the OUTPUT signal to the power amplifier by adjusting the gain of the preamplifier stages. With your setup, the signal fed by the miniDSP to the preamplifier at low volume will be too weak and you will degrade signal-to-noise / distorsion performance in your preamp. Should you nevertheless proceed with your setup, make sure that the volume control of the miniDSP is below or equal -12dB since DIRAC correction sometimes add quite significant peaks of volume at certain frequency, which means that, if the volume of the miniDSP is set above that level, the signal fed to the preamp could saturate its input stages, leading to sound distorsion...
Hope this helps.

Out of interest, how sensitive are your speakers? I’ve been where you are worrying about tubes not having enough power but I got over it! I’ve got the SHD feeding some valve monoblocks and it’s surprising how few watts you actually need!

I’ve only just seen this post and having a skim read I think I might have read someone saying the SHD/Dirac messes up the valve sound. In my experience it doesn’t. The sound comes from the type of harmonics (even order) produced and how they increase with volume mimicking real life. The SHD will not be correcting this so the valve sound (which I would describe as making everything sound more natural) will be/is maintained. If you have a sub then you have solid state for the really low stuff so you’ll have the best of both worlds.

Hello asx77, 
I like your approach and have thought that since my low end is covered by my subs that I might be able to use tube amp's for mids and highs.  My speaker sensitivity is 88 (B & W's 706 S2) , which is average sensitive as I understand. . Do you think I could  use tube amps to get that holographic 3-d sound while using the SHD as my preamp?  I have heard if you go for a Class D amp to get a tube preamp to help smooth out the sound. What the noise floor like with tubes? Any hum?  Thank you. 

Hi,

I’d describe my sound as fast, natural and never fatiguing…

My speakers are 88db sensitivity too and my power amps are “only” 28W but the system goes plenty loud enough. The max I've turned the SHD up to has been about -16db but normally I listen between -35 and -25db. This doesn’t mean you will be the same max as it depends (I think) on things like the amp gain and input sensitivity for max output. But interesting fact told to me by a valve amp OEM, is valve amps power rating is based on the point at which they produce 1% distortion so actually I could push my amps past 28w if I ever needed to but just have more distortion. Do they all follow that rule though?… I don’t know. Anyway point is I think unless you have a large room, 88db and a reasonably powerful valve amp will be fine. 

However, I matched mine with speakers that have a relatively flat impedance (valve amps like that) also the phase angle remains positive for most of the speakers frequency range and where it goes negative (below 100hz) the impedance rises to compensate and a little below that, the subs cut in.

Hum? What hum?! The subs hum more than the valve amps. If anything they’re deathly silent which is most noticeable when there are gaps in the music. 

Last thing… I know a lot of people mix valve pre with SS power. Personally I don’t get this. Valves and SS are opposites when it comes to distortion and harmonics… SS: higher distortion at low power levels and odd order harmonics; Valves: even order harmonics and increasing THD with power draw - this incidentally mimics the real world. Even order harmonics and more distortion as (instruments) are played louder! Now I wouldn’t mix valves and SS because although many argue you get the best of both, they’re could be a point where you’ll get the worst of both. For me it’s one or the other however if you did want more efficient power (SS A/B or class D) choose a power amp that has no distortion! Getting one type of component in a system to help correct another also doesn’t sit right with me. 

Make sure you go with an established valve amp manufacturer. Although it’s a given with valves that you’ll have a certain level of distortion, it still should be relatively low even order that’s present. There are loads of companies that have jumped on the bandwagon and whose amps may have more distortion (of all orders) than they should and who hope their customers won’t notice as they’ll be distracted by glowing valves. 

Hi asx77, 
I have to ask what type of tube amp are you using with your 88db sensitive speakers ? I have been using ss all my listening life and I would like to begin my knowledge base with a tube amp manufacturer that would potential work equally well or me. Can you recommend a short list of manufacturer's as a starting point?  Thank you. 

I’m using Art Audio Tempo monoblocks built in the 90s. I don’t have much experience with valve amps as I’ve only ever owned ss before these. Art Audio are a small manufacturer, with exceptional amps but I think generally made to order these days.The obvious well known brands that I’d imagine can be trusted to ‘do it right’ would be PrimaLuna, Icon Audio, Unison Research, Quad, Conrad Johnson, Pathos…If you buy second hand I would avoid vintage amps - they seem very popular but probably not as good as people remember them to be. From the 90s or later and you should be in safer territory. Other small OEMs maybe to look out for are Croft, Beard, Scott - I think these were low volume niche amps, not sure the oems are even still in business but well regarded none the less. I’m sure a few brands in the Far East will have copied some good amp designs by now so no doubt there could be some reasonable and generally more cost effective brands coming from that area but I wouldn’t know who to recommend or avoid. Where are you from? Get yourself to a few shows and have a listen / ask how different amps would suit your speakers. Do B&W recommend valves or SS?