System matching advice

If you can get the Classe monoblocks for a good price, they will definitely fit the bill.

Classé CAM 350 monoblock power amplifier

I've been using a pair for 20 years! Only reason I bought Classe instead of Pass Labs at the time: HEAT! I was using Pass X.600 monoblocks for my work, but those idled at 700 W per chassis! With no airco at my home here in California, it would not have been pleasant. I think the Classes use something like Krell's plateau-biasing, as they only get seriously warm if you turn the wick up! Nearly 800 W into 4 ohms should be enough to light up the Avalons.

 

I think thats sensible.
Its a good idea to buy speakers and amp
Same time.
Cost being problem for many.
Some speakers need welly!
Or oodles of power. If you knew what amp Avalon used to design their loudspeaker.
The LS3 5A was such a design in that it needed power, but had a max of 25 watts.
So a tube was not ideal.
Robin Marshall of Epos ES14 fame
Used a Naim NAP 250 when testing the ES14. At the time i used a NAP 140
And it was a marriage made in heaven.
If it were me, and i liked the sound of my tube amp, i would find a speaker thst suited it.
Mind, you could do the opposite and find an amp to suit.
Speakers fall into different categories
Some are well damped meaning the cone is well controlled ,
Others need a big amp to control the cones to prevent the speaker from running out of control.
Damping factor is another.
An amp with a low damping factor exerting little control over the speajer.
But ultimately, commecting amp and speakers is most reliable test

 

Aside from the cartridge being worn out, which is a possible culprit, I am nearly willing to bet it's a amp/speaker mismatch.

So, after you try your speakers with a high-powered SS amp, do yourself a favor - also try your amp with high-sensitivity (preferably) and definitely high-impedance (at least 8 Ohm, more is better) speakers, especially since most of your listening is Jazz. Omega, Zu Audio, the aforementioned AN UK speakers should give you a taste of it. Also, the LS 3/5A (the 15 Ohm version) is famously well-suited to tube amps, despite its low sensitivity - your amp certainly has enough power to drive them.

I am speaking from personal experience: I am driving Zu Omen Dirty Weekend II (97 dB sensitive, 12 Ohm) with a SET tube amp of a whopping 8 WPC. I also have a 275 WPC SS power amp driving 90 dB speakers, and I wouldn't ever trade the former pairing for the latter when Jazz is concerned. I'd also run the Zu with PrimaLuna EL34-based amp, with similarly good results.

 

They do make high powered tube amps if you care to go that route.
Maybe keep your eyes open for what turns up on the used market.
Here's one of my VTLs being menaced by a frog.

 

I have tried a couple of the manufacturers you mentioned. I loved the Classé CA-2300 when tried a few years ago, as I thought it was absolutely superb with orchestral music and had wonderful timbre reproduction. However, I could hear its fan running in some quiet passages, which rather spoiled the effect. All new Classé amps have fans. If your room is quiet, you may hear it, too, though Classé owners tend to chime in and say they don't hear it in their rooms.

I also tried the Pass X250.8, a powerful Class AB amp. I liked it a lot, though I suspected it was more beautiful than life (as, say, ECM recordings can be). Definitely liquid, non-fatiguing, and powerful! The killer for me was that it throws off 400 watts of heat at idle. I had no way to get rid of that much heat from my room, and I did find myself sweating during the audition.

Having heard those (and others, among them the Bryston 4B3 and Sanders Magtech), I wound up with the cheapest option -- monoblocks made with PuriFi modules -- and to my ears, it was not a compromise. If there is any flaw I can hear, it's a slight dryness -- but the clarity and lack of harshness are outstanding. They might not be best for anyone else -- everyone has different tastes and hearing, which makes this hobby interesting.

 

There are no fans in the CAM-350 amps.

 

I installed yesterday, a Russ Andrews
6 way extension with silencer
Plus 2 power chords.
The effect was dramatic.
I suddenly thought of your problem.
Maybe you have already done something

Similiar its just thst you have outstanding
Components and i wondered if such an addition would do same for you.

 

I have MA Gold 200 speakers that are 4 ohm 88db. I was using a parasound A23+ amp and had the same sound experience. I just didn't think I was getting everything out of the speakers and the high tones often sounded very bright. I upgraded to a parasound A21+ amp and could not be happier. The full sound range of the speakers is now apparent, everything is tighter and more dynamic.

 

That's not going to change the fact that the OP's VTL amp is not designed to drive the low impedance load of his Avalons.

 

Yes, i m sure thst you are right.
Personally i like to research Amplifier/Speaker interface.
Its only way to get the 'Magic' our friend is after

 

Hi team.

Thanks again for these insights. I’ve decided to keep pursuing a solution that keeps the speakers and gives them a chance. It’s boiled down to a trial between Pass labs INT-25 (plus possibly INT-60) and the VTL St-150 added to my existing IT-85 (used just as a pre).

The INT-25 is an intriguing option as many claim its current belies its power rating. Despite the 25watts it’s capable of driving difficult speakers (even less than my 88db) with ease (apparently). With its all class A operation and a consistently described sound signature that fits my needs like a glove, I’d be mad not to try it.

All this said, I have to wait for used examples to come up. If anyone hears of something I’d be very grateful…

I will update with any trials as soon as I can. Will also look at other suggestions re VTA, cartridge and room acoustics.

Cheers for now!

 

I think you're trying to jam a square peg into a round hole here with a tube amp with what I think is a 1 ohm or more output impedance, or a with low power solid state amp. You have nice, and expensive, low impedance, current hungry speakers. I think you owe it to yourself and to your speakers to try 'em with high powered solid state amps with beefy power supplies and low output impedance that can really deliver current into low impedance loads and see how they sound. I think that's really the sort of amplification it sounds like these speakers were designed to be driven by. Forget the sonic signature of the amp. The sound you'll hear is the sound of the interaction between the speaker load and the amp's ability to deliver what the speaker is demanding. The sound of the amp is the sound that the speaker load causes it to deliver. That's what's going to define the sound signature of the system.

 

I couldn't agree more with @chervokas about this. I urge you to try a high-powered, high-quality, solid-state amp with your Avalons before narrowing the field. Then, whatever you buy will be based on having heard more options. (As a personal experience, I used to own Revel Studios -- large, power-hungry speakers -- and when I first tried a Bryston 14B SST in place of my conrad-johnson amp, my jaw dropped at how effortless and sweet the sound became.)

You have a really nice setup now. If you sense a mismatch, it can be worth working with sellers that will let you audition several types of amp. Yes, it may cost more, but the chance to try before buying is ofen worth the money, as it can increase your satisfaction and cut down on turnover.

Do dealers in the UK not offer home auditions to serious buyers?

I don't want to be a pest, so I'll stop here. Whatever you get, I hope you enjoy it.

 

I have to ask, what caused the about face? You were on the right track with amps like the Classe CAM-350, but are now back where you started?

Let me start with saying that I agree with the comments of @chervokas and @Mike-48. While it is your money, and you have to be happy with the result, I fear you risk wasting both time and money.

Maybe some numbers will help?

Firstly, as I stated earlier in the thread, your speaker, being a nominal 4 ohm model, requires 2.83 V to produce 88 dB at 1m. In other words, it is 88 dB per 2 W @ 1m, or 85 dB per 1W @ 1m. (V^2 / Z, or volts-squared divided by impedance equals power, and 2.83 = sqrt 8, so you have 8 / Z, and, in your case, Z is nominally 4, hence 2W.)

The next thing to ask is how loud (peak) you will want to play? This is one of the most frustrating things on this forum as people spout numbers (usually in the 75dB to 85 dB range) without any qualifiers. Peak? Mean? Fast/slow response? A-weighted? C-weighted? Other?

I don't know what sort of music you like, nor how loudly you like to listen, but it is not uncommon to hit PEAKS in excess of 100 dB, especially if you want a sense of realism. So, you need a minimum of 15 dBW to hit that level from one speaker at 1m. Let's make things simple and assume that the gain from having two speakers in your room equals the loss from having the speakers more than 1m from you plus absorption, etc. To ensure the peak level is clean, you would want some degree of headroom. Let's assume 3 dB, which is quite common, and you need 18 dBW minimum (or 63 W). This is only slightly more than the MINIMUM amplifier power recommended by Avalon for your speakers.

Because our hearing is logarithmic, I always prefer to deal in dBW because it makes it easy to determine peak volume level. I grew up in the UK and remember all the letters to Hi-Fi Answers, HFN&RR, etc. where readers were agonizing over 25 W vs 35 W amplifiers, not realizing that there is virtually no difference between them (all other things being equal).

The specs for the ST-150 show that it has twice the power output of the IT-85 with the same (high) 3% THD specification. So, you will just be gaining 3 dB in volume level, whereas you need 10 dB for a perceived doubling in volume level (each 10 dB increase = 10 times the power!). Even if the ST-150 had a sufficiently high power rating, it still suffers from the same issue as the IT-85: it is NOT made to drive low impedance speakers. Indeed, in triode mode VTL state that the amp should be used with speakers having an efficiency of 92 dB/W/m or higher. Since the power doubles in tetrode mode, we could assume that the minimum efficiency would be 89 dB/W/m, and these amps like HIGHER speaker impedances. So, I think you will quickly be back to square one in this case.

I'm a huge fan of Pass amps, as I wrote before, but the INT-25 is under-powered for your speakers, IMO. Stereophile defines clipping as the point where the THD reaches 1 %. For the INT-25 driving a 4 ohm load that occurs at 98 W or 19.9 dBW. Keep in mind that the 1% distortion figure is a bone of contention. Many think that that level is too high, especially for some solid-state amps. In any case, you would just be able to comfortably reach a 100 dB peak. If you need more, then you need a more powerful amplifier. Moreover, Stereophile's measurements at 1/4 power into varying impedances showed rising distortion into 4 and 2 ohms, causing John Atkinson to conclude: its intolerance in the treble for loads of 4 ohms and below means it will work best with loudspeakers whose impedance doesn't drop below 8 ohms at high frequencies.

I have no idea whether you would have the same problem with the more powerful Pass INT-250. I have used the far more powerful X-series amps with a number of low impedance speakers, and they have no trouble driving them to very high levels! If you fancy Pass, maybe you should consider the X-350 stereo power amplifier instead?

 

Sorry, me too
Your speakers sure aren't cheap, all the stuff looks good. Before equipment, we'd love to see PICTURES of the room because I really wonder if physical setup is causing some problems. That's the first place to start. And yes I would certainly *try* a solid state amp, since your tube's output impedance may just be an unhappy match to the Avalon's impedance. Definitely tube amps affect the response, measurably, solid state far less so.

 

Wow - thanks guys. I hear you and appreciate the advice and the figures too. I thought the Pass Labs INT 25 qualified for me as my room is relatively small and for the most part volume levels will be a little below the full wack. That said I now understand that this could still be borderline or underpowered for best results. I can't send pics of the room set up right now as it's being decorated next week (after a few electrical changes) and all the kit is dismantled. Once reinstated I will gladly send.

So will now definitely look at more options along the lines of the suggestions above. The thing with the Classe monoblocks is just space - but where there's a will...

Thanks again and will update you on trials (when the old ears have a go) when I can get back in the room. Cheers and again, much appreciated!

 

If space is an issue, you could consider something like the Bel Canto REF series. They made very high power stereo and mono amps in small chassis (they are digital amps, but were very well reviewed, and can drive anything).

Alternatively, since you are in the UK, ditch the speakers and amp and buy some ATC active speakers -- something like the active 40 towers would tick all the boxes for you.

SCM40A Active Loudspeake | ATC Loudspeakers

You may be able to get away with the larger ATC 50 active towers at a push. I have used active 50s and (especially) 150s a lot, and they are excellent, and represent excellent value, and you don't need to worry about amplifier synergy.