AMP (Fanless) Suggestions for Auratones AND Reftones?

[iasomph]

Hello to everyone!

I am buying a pair of passive vintage Auratones (5PSC) and a pair of Reftones LD-2.

I want to try both reference mixing cubes and see what it will work the best for me. At the moment I'm without my main monitors (I just have very good headphones), so I think it would be good having a pair of these for checking also panning decisions, and make a little more of traditional speakers mixing. Later I plan to probably use only one Auratone / Reftone cube in mono since it's better for balancing the mix levels and check mono compatibility... and use main monitors for the stereo information. I want to start to mix more in mono.... but who knows, maybe I'll love using these also in stereo, we will see!

These are my first passive speakers, so any recommendation about a good amp that may work for both of these?

- Vintage Auratones 5PSC speakers should take approx 30W of power if I remember correctly, while Reftones take up to 300W of power! So which wattage can you recommend for the amp? Better underpowering the Reftones or overpowering the Auratones? Or I'm forced to buy two different amps (I hope not!) Reftones recommended power, on their website is "15-300W".

- Also, since the amp will stay near my desk, another essential feature I want is to have the amp without fans (only convection), buzzes or hisses/noises.

- Another benefit would be to have it in a small form factor, since I don't have any other gear in racks! So I will place it on the desk, or under the desk. Smaller, the better. If possible, of course.

- Better Class AB or Class D for these kind of speakers?

- Budget: Anything from 100€ to 500€ (of course, lower the better, if not compromising the audio). I've never worked with passive monitors and also we are referring to small "one woofer" cubes with a sort of limited frequency range (Reftones are more extended in this regard).

On the internet some people says that the improvement in sound may be dramatic on these speakers with the good amp. And that actually, these speakers may transform themselves with a good amp (passing from "horror tones" to very revealing speakers). Is this real? I mean...passing from an amp of 150€ to an amp of 500€ can make a huge difference on these speakers?

Now, some models I've found (fanless), that I'm evaluating:

- Auratone A2-30: https://www.thomann.de/gb/auratone_a2_30.htm (seems great if used only with the Auratones...but I'm little worried that it could be not powerful enough for the Reftones which seems to be much more power hungry)

- PAS 2002 PCA: https://www.thomann.de/gb/pas_2002pca.htm (didn't know this brand before, but the reviews are amazing so it's a good sign. Little more expensive than I wanted, and also huge and with big weight. I can stretch and accept form factor if the quality justifies it)

- Amphion Mono 100 https://amphion.fi/create/products-pro- ... p100-mono/ seems very good, also in a great form factor... but only mono (for the price of approx 500€; stereo model double the price. 1000€ would be too much for Auratones I think!). The mono model could work good later on when (and if) I will be using only one cube.

- Dayton Audio DTA-120BT2 https://www.parts-express.com/dayton-au ... --300-3803 This is one of the recommended amps on Reftone's website. Anyway it's quite a cheap amp, and deisgned for hi-fi more than for the studio. I guess if such a cheap amp can be good enough for mixing on these speakers? Also, it seems not very powerful. Also, maybe the unbalanced inputs on the back are not great and practical for coming with the signal from the sound card (XLR)?

- Dayton Audio APA150: https://www.soundimports.eu/en/dayton-audio-apa150.html Another amp recommended on Reftone's website. Same considerations as above (except power, which is higher). Again, maybe the unbalanced inputs on the back are not great for coming with the signal from the soundcard (XLR)?

- Apart Champ Four: https://www.thomann.de/gb/apart_champ4.htm or some other Apart from the Champ series.

- Apart Revamp 2150 (or some other models of the Revamp or other series from Apart): http://www.apart-audio.com/press/Apart_ ... elease.pdf

- Drawmer CPA 50 https://www.kmraudio.com/drawmer-cpa-50.php same nice form factor as the Auratone A2-30, but even slightly less powerful (25 vs 30 w at 8 ohm), so maybe still better the Auratone one.

- Drawmer MPA 90 https://www.kmraudio.com/drawmer-mpa-90 ... lifier.php this seems a little more powerful in a nice form factor. It also seems discontinued, at least in Europe.

- Some of the T.Amp models (produced by Thomann), but I would prefer buying a more "traditional" amp brand if possible.

Any suggestion on these amps (or some other fanless models)? One side of me wants to try the Auratones / Reftones with a good amp, to be sure to experience and evaluate their utility at their best. Would be a shame to make them arrive from the US (so, not cheap!) and then try them with a very bad amp that can will them seem bad and not useful for mixing purposes. While instead, it will be just the bad amp.

The other side of me doesn't know if the difference in amps can bring out just different nuances in these speakers sound, or if they really can make a difference. I have to admit that I am completely ignorant on this topic.

Thank you all for your kind help

[cyrano.mac]

I'd already forgotten about Reftones...

They sell an 800$ kit with a Dayton Audio 40 W amp. I suppose that's sufficient? So I wouldn't worry about power. They spec 300W probably as the upper limit, to avoid some bloke testing his 2kW amp with Reftones.

The amps won't differ a lot. I happen to own an Apart Champ 4. It's fine, I might even buy a second one. I had a Dayton in the past.

Have you considered vintage power amps, like Quad 405, or Sugden? Or even a 70`s Pioneer? I know, some are expensive.

[resistorman]

I have the smaller Dayton amp (minus the Bluetooth) running some bookshelf speakers. It sounds surprisingly good and powerful. The power brick is almost as big as the amp!

[ef37a]

I would look at amplifiers of about 50W output.
That into the Auratones would deliver over 106dB SPL but that would be the absolute and very rare peak limit.
I cannot find a figure for the sensitivity of the Reftones but doubt it is much less than the 90dB/W/mtr of the Auratones?

As has been said, don't fuss the amp choice too much, almost any of the big name hi fi amps will serve you very well. It would be a very poor amplifier that produced one tenth the distortion of those 'grot boxes'!

Dave.

[bn1studio]

The traditional answer - at least in the UK - used to be a Quad 303 or 405. Always a good bet & they hold their value secondhand

I recapped a 303 recently and was struck by what a sweet-sounding amp it was

[iasomph]

I'd already forgotten about Reftones...

They sell an 800$ kit with a Dayton Audio 40 W amp. I suppose that's sufficient? So I wouldn't worry about power. They spec 300W probably as the upper limit, to avoid some bloke testing his 2kW amp with Reftones.

The amps won't differ a lot. I happen to own an Apart Champ 4. It's fine, I might even buy a second one. I had a Dayton in the past.

Have you considered vintage power amps, like Quad 405, or Sugden? Or even a 70`s Pioneer? I know, some are expensive.

Well, the Dayton Audio 40 W amp is included in their Reftone "travel pack kit", so it could be sufficient, but maybe it's thought more for a mobile use than for a home-studio use? At least, I guess.

Their support told me that, since the Reftones are professional grade and take up to 300 W of power, if I got the space and budget it would be better to go for a professional amp of at least 100 W.....

[iasomph]

I have the smaller Dayton amp (minus the Bluetooth) running some bookshelf speakers. It sounds surprisingly good and powerful. The power brick is almost as big as the amp!

This could be also a choice. Cheap, super compact....and it seems not bad (40 watt 8 ohm per channel). It lacks the balanced inputs (i would need another external box, a little pain...) and it cannot be bridged to give the speaker more power if I will end up using it in mono (the Drawmer MPA 90 allows this). I'm worried it could be just too chip/hi-fi, but it's still a good contender due to the super cheap price and small size.

[iasomph]

I would look at amplifiers of about 50W output.
That into the Auratones would deliver over 106dB SPL but that would be the absolute and very rare peak limit.
I cannot find a figure for the sensitivity of the Reftones but doubt it is much less than the 90dB/W/mtr of the Auratones?

As has been said, don't fuss the amp choice too much, almost any of the big name hi fi amps will serve you very well. It would be a very poor amplifier that produced one tenth the distortion of those 'grot boxes'!

Dave.

My Auratones will be the vintage ones from the eighties (Primo 5PSC): I don't know the exact wattage, but I guess less than the current Auratone model.

I'm not too worried about the Auratones, they don't seem very power hungry. I'm more worried about the Reftones, after the power recommendations I got from their support.

Actually the design/idea of the Reftones seems to be quite different from the Auratones (Reftones seems to be more full range and I expect them to be less middish). I expect them to be a sort of full range monitor with just one woofer (of course still quite limited in the frequency range, with just 70 hz as the lowest point). But they are sealed, so they should be able to tell something even also below this line. So I expect them to be less mid-range limited than the Auratones.

Anyway, 50 watt seems a balanced power also to me. I've read an article here on SOS about amps where it says that 50 watt 8 ohm should be considered an average good value. The Drawmer MPA90 doesn't seem bad to me. Its class D should also be a "good class D", since it should be based on Anaview modules which I've read are recognized for their quality (same brand used by Amphion amps).

But, producing and mixing bass heavy music, I'm still a little worried that 50 watt could be not enough.

[iasomph]

The traditional answer - at least in the UK - used to be a Quad 303 or 405. Always a good bet & they hold their value secondhand

I recapped a 303 recently and was struck by what a sweet-sounding amp it was

Thanks for the suggestion, but I don't live in the UK...and if possible I would prefer finding a new product....just to avoid nasty surprises. Of course if I can find an exceptional deal....

[ef37a]

I would have thought both of those speakers would run out of displacement steam, i.e. distort on even 50 watts with "bass heavy music"?

Not, I would aver what they are for?

Just a thought? Since the idea of these 'boxes' is to deliver a 'lo-fi, real world' sound maybe they SHOULD be paired with an amplifier of similar pedigree and not a 100W+ 'pro' quality unit?
That said, I am still of the opinion that, provided they are not driven into clipping, all competently designed and made power amps sound the same!

Dave.

[iasomph]

I would have thought both of those speakers would run out of displacement steam, i.e. distort on even 50 watts with "bass heavy music"?

Not, I would aver what they are for?

Just a thought? Since the idea of these 'boxes' is to deliver a 'lo-fi, real world' sound maybe they SHOULD be paired with an amplifier of similar pedigree and not a 100W+ 'pro' quality unit?
That said, I am still of the opinion that, provided they are not driven into clipping, all competently designed and made power amps sound the same!

Dave.

That's what I thought, initially. But, searching further, it seems that the Reftones are a different and in some way a more modern concept (better or worst I'll see when I'll try them, but I noticed that some well known mixers are using them, so this is reassuring) than the Auratones.

The idea is not to have "lo-fi" quality anymore, but obtain a higher quality, less distortion full range system (of course within the physical size limits) instead of just a "window" on the mid frequencies. But still with the benefits of the single woofer and the sealed design. Let's say a more modern Auratone concept with a wider frequency range, that take into accounts how music is made today. So I expect the two systems to be different. Maybe this is the reason why they suggest to have a more powerful amplifier? Is it possible that with a more powerful amplifier, the sound is "fuller" even at low volumes, or is it incorrect?

About amps: I ask because I don't really know a lot about amps: but if they sound the same, why an amp should cost 4.000£ and some other just 300£ if the difference is negligible and their output is similar? Who would buy the model that cost 4.000£? Anyway I know the law of diminishing returns, so my idea was to spend something between 200-500£ for small speakers like these. I don't need a Bryston, but I would like something that pairs well with these speakers.

[iasomph]

I want to add another topic/requirement. Since these small speakers will be near to me (on the desk), another important thing is that I don't want to hear "hisses" coming out from them when the amp is on and the speakers not in use.

I remember that on my KH-120A's, I had to lower the sensitivity on the back of the speakers, because on the highest sensitivity I could hear a quite noticeable hiss from such a short distance. So I decreased it with the switch on their back and the hiss became almost non-existant.

Now, how to be sure that this is the case with the amp I'm buying? I see that many amps don't even have a knob on the front for setting the gain....as it seems the case of the Drawmer MPA-90 or with the Amphion amp100 mono, or with the Rotel RB-1552MKII: basically on a lot of amps it seems to works this way!

So, are these models just set on "max gain/sensitivity" all the time and it's not possible to modify this? And so, with these amp models it's more possible to experience some hiss/noise when standing near the speakers? In this case, should I opt for a model with the gain knob on the front (or at least on its back) that will allow to reduce the speaker hiss, in case I will found it uncomfortable?

[Sam Spoons]

It's easy enough to put an attenuator or passive volume knob in front of the amp if it doesn't have one. The 'gain/sensitivity/attenuator' control on a power amp (or active speaker) acts on the input signal, the hiss you were hearing from your KH120* was almost certainly generated by the output from your audio interface or whatever was driving them, turning the input level control down simply allowed you to turn up the output from the AI to a higher level.

[James Perrett]

all competently designed and made power amps sound the same!

The problem is that there must be plenty of amps that aren't competently designed because certain amps DO sound different. I have a Teac AX75 (not a cheap amp) which makes NS10's unlistenable because it sounds sharper (or perhaps harsher) than a better amp. I also have a posh looking Tensai Hifi amp which doesn't give as much detail as I'd expect.

However, the differences between the standard Quad 405 and my custom Hypex powered 405 are much harder to hear.

[iasomph]

It's easy enough to put an attenuator or passive volume knob in front of the amp if it doesn't have one. The 'gain/sensitivity/attenuator' control on a power amp (or active speaker) acts on the input signal, the hiss you were hearing from your KH120* was almost certainly generated by the output from your audio interface or whatever was driving them, turning the input level control down simply allowed you to turn up the output from the AI to a higher level.

The KH-120A were connected directly to my sound card via balanced connection. So, I may be wrong, but shouldn't balanced inputs/outputs be immune from hisses?

Also, adding another device (like a volume pot) in the path it's something I want to avoid. I had a previous experience with a "cheap" volume pot and it screwed up stereo balance.

So I don't like, whenever possible, to add many devices in the audio path that goes from the sound card to the speakers. The less devices, the better. One of the nice thing of my sound card (currently is babyface pro) is that it has got some basic monitor controller functions. So, adding a passive volume pot just for adjusting the amp sensitivity and risking to make worst the stereo balance or degrading the sound would be a pity...

[ef37a]

I would have thought both of those speakers would run out of displacement steam, i.e. distort on even 50 watts with "bass heavy music"?

Not, I would aver what they are for?

Just a thought? Since the idea of these 'boxes' is to deliver a 'lo-fi, real world' sound maybe they SHOULD be paired with an amplifier of similar pedigree and not a 100W+ 'pro' quality unit?
That said, I am still of the opinion that, provided they are not driven into clipping, all competently designed and made power amps sound the same!

Dave.

That's what I thought, initially. But, searching further, it seems that the Reftones are a different and in some way a more modern concept (better or worst I'll see when I'll try them, but I noticed that some well known mixers are using them, so this is reassuring) than the Auratones.

The idea is not to have "lo-fi" quality anymore, but obtain a higher quality, less distortion full range system (of course within the physical size limits) instead of just a "window" on the mid frequencies. But still with the benefits of the single woofer and the sealed design. Let's say a more modern Auratone concept with a wider frequency range, that take into accounts how music is made today. So I expect the two systems to be different. Maybe this is the reason why they suggest to have a more powerful amplifier? Is it possible that with a more powerful amplifier, the sound is "fuller" even at low volumes, or is it incorrect?

About amps: I ask because I don't really know a lot about amps: but if they sound the same, why an amp should cost 4.000£ and some other just 300£ if the difference is negligible and their output is similar? Who would buy the model that cost 4.000£? Anyway I know the law of diminishing returns, so my idea was to spend something between 200-500£ for small speakers like these. I don't need a Bryston, but I would like something that pairs well with these speakers.

I have not of course have the speakers to test and I am NOT Phil Ward but I do not think a 4" speaker in a 5 inch per side box is going to reproduce "bass heavy" music at all well?
Cannot recall where I saw it but Dr Hugh mentioned the difficulty in finding sub woofers that did not distort and there we are talking big boxes, half kW amps and loadsamoney.

I am not going to get into a debate about power amplifiers! People draw their own conclusions. Yes, there are some very expensive amps but like interfaces and mic pres, there is a law of diminishing returns and a lot of "subjectivist twaddle' talked about them.

One thing I have noticed after 60years interest in audio? Put an amplifier in the box with the speaker and it becomes 'perfect'! At least in terms of comparison with other active speakers because I have never read a comment where crossover distortion was detected.

Of course, reviewers cannot get at the amps to test them (well, they can actually for a few designs) but it seems odd that we never get a bad report on one? The only exception to that is 'self noise' which is a totally unforgivable design cockup.

Dave (tin hat firmly seated!)

[Sam Spoons]

It's easy enough to put an attenuator or passive volume knob in front of the amp if it doesn't have one. The 'gain/sensitivity/attenuator' control on a power amp (or active speaker) acts on the input signal, the hiss you were hearing from your KH120* was almost certainly generated by the output from your audio interface or whatever was driving them, turning the input level control down simply allowed you to turn up the output from the AI to a higher level.

The KH-120A were connected directly to my sound card via balanced connection. So, I may be wrong, but shouldn't balanced inputs/outputs be immune from hisses?

Well designed 'balanced' connections are mostly immune to interference picked up by the cable (look up 'common mode rejection'). They can't eliminate noise generated by the source device. Good gain structure is how you address that.

Also, adding another device (like a volume pot) in the path it's something I want to avoid. I had a previous experience with a "cheap" volume pot and it screwed up stereo balance.

So I don't like, whenever possible, to add many devices in the audio path that goes from the sound card to the speakers. The less devices, the better. One of the nice thing of my sound card (currently is babyface pro) is that it has got some basic monitor controller functions. So, adding a passive volume pot just for adjusting the amp sensitivity and risking to make worst the stereo balance or degrading the sound would be a pity...

Yes, that makes sense, but the input level control on the power amp is just such an extra device?

[iasomph]

It's easy enough to put an attenuator or passive volume knob in front of the amp if it doesn't have one. The 'gain/sensitivity/attenuator' control on a power amp (or active speaker) acts on the input signal, the hiss you were hearing from your KH120* was almost certainly generated by the output from your audio interface or whatever was driving them, turning the input level control down simply allowed you to turn up the output from the AI to a higher level.

The KH-120A were connected directly to my sound card via balanced connection. So, I may be wrong, but shouldn't balanced inputs/outputs be immune from hisses?

Well designed 'balanced' connections are mostly immune to interference picked up by the cable (look up 'common mode rejection'). They can't eliminate noise generated by the source device. Good gain structure is how you address that.

Also, adding another device (like a volume pot) in the path it's something I want to avoid. I had a previous experience with a "cheap" volume pot and it screwed up stereo balance.

So I don't like, whenever possible, to add many devices in the audio path that goes from the sound card to the speakers. The less devices, the better. One of the nice thing of my sound card (currently is babyface pro) is that it has got some basic monitor controller functions. So, adding a passive volume pot just for adjusting the amp sensitivity and risking to make worst the stereo balance or degrading the sound would be a pity...

Yes, that makes sense, but the input level control on the power amp is just such an extra device?

Yes, but hopefully, being already integrated into the amp, it should be of a decent quality. Also, many active monitors don't have a rotary knob for this but a switch with 3-4 positions, that hopefully perfect match the stereo image. Any product like this, eventually (gain attenuator with switch at fixed levels that perfectly match the stereo information)?

Also...less devices, less cables = more tidy desk!

PS: the noise coming from the Neumann speakers was not an interference noise, it was just the self-noise of the amp (I suppose the tweeter amp) that was working at higher power. So, without music going on and with the speakers very near to you, you could really notice it. Lowering the sensitivity on the back of the speakers made this noise completely acceptable.

[Sam Spoons]

AFAICT both the input gain and output level controls are immediately after the input socket in the KH120 so will have no affect on the power amps. They will only affect noise generated by the source*. So if the hiss reduced when you turned them down it was coming from something connected to the KH120's input. You corrected this by improving the gain structure of your monitoring system.

"less devices = tidy desk"

* There is what I'm guessing is as input buffer shown between the XLR and gain/level section on the block diagram. I don't imagine this is introducing any noise.

[iasomph]

AFAICT both the input gain and output level controls are immediately after the input socket in the KH120 so will have no affect on the power amps. They will only affect noise generated by the source*. So if the hiss reduced when you turned them down it was coming from something connected to the KH120's input. You corrected this by improving the gain structure of your monitoring system.

"less devices = tidy desk"

* There is what I'm guessing is as input buffer shown between the XLR and gain/level section on the block diagram. I don't imagine this is introducing any noise.

Thanks. So which product (knob or attenuation switch) may I use in case I'd go for an amp that doesn't have any sensitivity control? Would the digital volume control of the Babyface Pro be enough, or I need to add another product in case I'll hear some self-noise hiss coming out from the passive speakers?

PS: I just checked, and the "switches" on the back of KH120A are for the output level: 114, 108, 100 or 94 db (db SPL at 1m). Near to these switches there is the input gain rotary knob....I guess for fine tuning left-right speakers small volume unbalances. So I acted on the output level in order to reduce the hiss.

[Sam Spoons]

The block diagram shows them as adjacent 'coarse' and 'fine' adjustments, the 'output level' cable is a tad misleading is it isn't controlling output level but input sensitivity.

You could buy a pair of reasonable quality attenuators if you need them, as you say, if you can find an amp with a gain control that would probably be favourite (and TBH, probably what I would in this case).

[iasomph]

The block diagram shows them as adjacent 'coarse' and 'fine' adjustments, the 'output level' cable is a tad misleading is it isn't controlling output level but input sensitivity.

You could buy a pair of reasonable quality attenuators if you need them, as you say, if you can find an amp with a gain control that would probably be favourite (and TBH, probably what I would in this case).

Sorry for all these questions: the attenuators you are speaking about are finished simple products that I can buy on Thomann, for example, or adding them to the setup would imply to open the amp case and modify its internal in some way?

Anyway I'm quite a bit shocked that not all the amps come with at least some kind of very simple attenuators (at least a switch with 3-4 sensitivity settings, like was the case of the Neumann's)!

[Sam Spoons]

Something like this https://www.canford.co.uk/Products/21254/20-912_CANFORD-IN-LINE-ATTENUATOR-With-phantom-pass-through-10dB-200-ohms

[Hugh Robjohns]

The KH-120A were connected directly to my sound card via balanced connection. So, I may be wrong, but shouldn't balanced inputs/outputs be immune from hisses?

You're quite right: you're absolutely wrong! Balanced connections are able to reject some forms of external interference, but they cant do a ything about signal noise. And the audible hiss you're complaining of comes from the inherent signal noise from electronic amplification. That noise might be generated within the power amp circuitry itself, or it might be coming from the circuitry in the preceding devices. If it reduces when you attenuate the amplifier input, then it's probably mostly noise from the preceding equipment.

Also, adding another device (like a volume pot) in the path it's something I want to avoid. I had a previous experience with a "cheap" volume pot and it screwed up stereo balance.

Yes, cheap ones will do that, especially if you haven't optimised the gain structure to ensure they operate in the most accurate part of their range. But there are more advantages than disadvantages to having an analogue volume control, and good quality ones aren't that expensive. Switched attenuator types are the best and readily available for DIY constructions.

So, adding a passive volume pot just for adjusting the amp sensitivity and risking to make worst the stereo balance or degrading the sound would be a pity...

In that situation, two mono trimmers (ideally added to the amplifiers themselves) would actually make a lot more sense, and could be calibrated accurately then left alone.

[Hugh Robjohns]

Lowering the sensitivity on the back of the speakers made this noise completely acceptable.

That's the wonder of correct gain structuring!