Richard's Visit.

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Cressy Snr
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#1 Richard's Visit.

Post by Cressy Snr »

Richard Cooper came round yesterday afternoon for an evaluation session and a very interesting experience ensued.....very very interesting.
The idea was to play with three amplifiers, my Mazda 1watt single-ended British triode amp, my Rozenblit Son of Beast output transformer-less SEPP amplifier, and Richard's Naim clone, comprising power supply from an old Denon amplifier with a few extra reservoir caps and Avondale Audio boards.
He'd also brought his SABA green cone open baffles for a second opinion.

After barking dogs had been calmed and the dryer down the cellar had been silenced, we were able to get down to some listening and comparing.

First up was my OTL which to be honest was sounding bright, bleached and washed out. This was highly puzzling considering how awesome it had been at Steve's on Wednesday evening.

It took a while to realise what was happening, but looking over to the lights on the MF M1 DAC I noticed that the 24/96 lights were on. I had been, the previous night listening to some Linn ALAC high res downloads, which had sounded very well, and had set the Mac Mini to output a 24/96 stream.
Problem was, we were now listening to 16/44.1 standard Red Book stuff.

The Mac Mini was up-sampling the stream and the MF DAC was further up-sampling the up-sampled stream to 24/192, so the signal was suffering a lot of unnecessary processing.
Resetting the Mac to output a 16/44.1 stream, restored the body and heft to the sound.
This was a very clear difference. Panic over :)
Hopefully, the new version of iTunes out at the end of this month will do sample rate changing on the fly as the Squeezebox has done as a matter of course.

This is basic stuff Apple, for fscks sake! Come on, get with the times!

A bit of Beatles, here comes the sun, form Abbey Road, some Amy Winehouse later and we were both of the opinion that the OTL was a superb bit of kit, revealing clear differences between production styles. It was easy to discern how recording philosophies have changed over the years between the late 60s and the noughties. The Amy Winehouse Tears dry on their own, was unremittingly loud, zero dynamics, full of details but it was all in your face; a clear victim of the loudness wars. Yes it was listenable, but a shameful blight on the talents of a late lamented singer with such a wonderful voice.

The Beatles was an altogether different experience, brimming with subtlety, dynamic, shifts and little accents that enabled the listener to appreciate the consummate skills of the band, George Martin and engineer, Geoff Emerick.

We then decided to have a bit of fun with a dance track. Cueing up the Paul Oakenfold mix of "Rubberneckin' " by Elvis Presley was quite an eye-opener. This wholly artificial recording was a delight to hear through the OTL. Loads of stuff going on, little effects darting about the soundstage, like shoals of minnows, and all the time underpinned by a wickedly fast and deep bass synth that prowled about the lower spectrum, snapping up prey, taking no prisoners, shaking the floor. The bass just went on down and down. I didn't realise my Mets could go that low, with such control.

Next up was Richard's Naim clone with the same tracks as before. For me this was grin city. It was everything I remember about my old Naim setup, fast, rhythmic through the midrange. The sound was clearly band limited in comparison to the OTL. The highs seemed to go so far and then stop. Quite a definite effect, but part of the Naim way of doing things back in the day. The lows on the Elvis track were almost as good as the OTL, sounding a little more fruity, with a slight looseness in comparison, but again, it was Naim bass and none the worse for it. The surprise was that a valve amp could exert that kind of grip, in comparison to a solid state amp that is renowned for its control at the bottom end.

We discussed this apparrent contradiction at length, almost running out of time to play with the SET amp, but it was such an important finding to us that it seemed to merit a long discussion.

The conclusion we reached was that it was the power supply in the Naim clone that was letting the side down at the bass end, but Richard revealed has a cunning plan on that front, involving some new PSU boards developed by someone on Pink Fish Media.
The little test with Elvis appeared to confirm to Richard that he is on the right
lines with his Naim Clone developments.

It pains me to say this, but the much loved Mazda amp was I'm afraid, completely outclassed by both the OTL and the Naim clone. The Amy Winehouse was rendered nicer to listen to, with a fuller tonal quality than either the Naim, or the OTL, but it sounded coloured in comparison and lost most of the fine details that had been clearly there on both the other amps. It did the same with the Beatles track. The Elvis remix was a train wreck at the bottom end, the bass synth flailing about aimlessly, robbing the track of any sense of groove. As Craig Revell-Horwood would say, it was a dance disaster darling.

to give it a chance to redeem itself, we played Nils Lofgren, Keith Don't Go from his live acoustic set. It made a good fist of this track, plenty of lovely tone from his steel strung acoustic guitar, a pleasant listen. The SET did blunt the edges slightly, when Lofgren broke into his display of lightning fingerwork towards the end of the song, so it wasn't bad.

Trying Richard's baffles confirmed his suspicion that the bass driver was not sensitive enough to compete with the mid and treble drivers. Bass was all there but subdued in comparison to the rest of the frequency range. He therefore now has something to go at to improve them.

Sadly I have to report that I have moved away from low powered SE amplifiers, at least with the speakers I have. Nick's breadboarded pp EL34 amplifier set the alarm bells ringing at the last Owston and building the OTL and hearing Richard's Naim Clone has only gone on to confirm the suspicions that Nick's EL34 originally aroused

My speakers are not going to change so the amps that drive them have to, Thats all there is to it. But ironically I am happier than I have ever been with the sound of my system, so why worry?

Richard seems to now have somewhere to go with his system too, so all in all the little session was a success and is that not what these things are all about?
Last edited by Cressy Snr on Sun Oct 28, 2012 1:03 pm, edited 1 time in total.
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chris661
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#2

Post by chris661 »

Interesting read - thanks for reporting this.

A quick suggestion for Richard regarding the OB bass drivers - it might be worth adding stuffing in the rear side of the U frame (or is it a H-frame? - can't remember which you're running at the mo).

The idea behind it is that OB bass systems tend to be inefficient, as most of the sound cancels out - the front and rear waves are out of phase, and are allowed to meet up - so adding some stuffing to attenuate the rear wave a bit would improve bass output somewhat.

You could literally take a couple of pillows, and put one in the back of each cabinet - 2 minutes to try, and it might just give the speakers that bit more oomph.

Chris
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#3

Post by Neal »

An interesting write up Steve, thank you. I've more or less made my mind up to get the OTL kit, its a long term itch that I need to scratch as it where...
simon
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#4

Post by simon »

Sounds like another good session I missed, very interesting Steve. Bit of a surprise about your 1 watter though. I await Rosenblit's book eagerly.
Cressy Snr
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#5

Post by Cressy Snr »

simon wrote: Bit of a surprise about your 1 watter though. I await Rosenblit's book eagerly.
After having enjoyed the Naim clone and the OTL so much, I was half expecting it really. Though I was prepared for the 1watter to be not as good as the other two amps, I was gutted at the comprehensive thrashing it received. It had been my favourite amp of all the SE amps, but the results were conclusive, it got its backside handed to it big style.

Prior to hearing the OTL and Naim clone, I had been blissfully unaware of the shortcomings of the Mazda amp, and would have happily listened to it forever, had those two buggers not come along and upset the apple cart.

There is no way I am dismantling it but if anyone has super efficient (over 100dB) speakers I could be persuaded to part with it for a small fee :wink:
It is still by any standards a fab amp, just not with the Metronomes, not any more I'm sad to say.
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planet10
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#6 Re: Richard's Visit.

Post by planet10 »

SteveTheShadow wrote:
The Mac Mini was up-sampling the stream and the MF DAC was further up-sampling the up-sampled stream to 24/192, so the signal was suffering a lot of unnecessary processing.
Resetting the Mac to output a 16/44.1 stream, restored the body and heft to the sound.
This was a very clear difference. Panic over :)
Hopefully, the new version of iTunes out at the end of this month will do sample rate changing on the fly as the Squeezebox has done as a matter of course.

This is basic stuff Apple, for fscks sake! Come on, get with the times!
You are cheating yourself by using iTunes naked. Get thee a copy of PureMusic (or similar)... it makes quite the improvement, and it switches rez on the fly.

dave
Cressy Snr
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#7 Re: Richard's Visit.

Post by Cressy Snr »

planet10 wrote:[
You are cheating yourself by using iTunes naked. Get thee a copy of PureMusic (or similar)... it makes quite the improvement, and it switches rez on the fly.

dave
Hi Dave,

'Fraid it does not improve things on my Mac Mini.

I have tried all manner of so-called playback enhancement software including Pure Music, decibel, Fidelio, ad nauseum, and I have kept none of them on the computer after the demos had expired, returning to iTunes every time. They made the sound different yes, better not really.

Nevertheless I see channel d have a new version of pure music compatible with the iPad remote app and since I already have a license code I might try it out.

Watch this space

Cheers Dave
Sgt. Baker started talkin’ with a Bullhorn in his hand.
Cressy Snr
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#8

Post by Cressy Snr »

Well I installed a new version of Pure Music on the Mac Mini and was able to activate it using my old license code from 2010, so did not have to pay the $129 that new users would have to fork over.

First impressions are actually very good. The audio engine seems to be much improved over the older version I had. Integration with the iTunes database seems also much less flaky; in fact there have been no issues yet.

An experimental mixed res playlist played through no probs with the lights on the DAC responding appropriately, indicating that the software was functioning properly.

Sound quality is better this time rather than just different to standard iTunes so I'll accept that the new version has addressed the issues I had previously with it.

Pure Music can now be recommended without reservation I think, so thanks for the heads up Dave. I had been behind the curve with the development of the Pure Music software as I had not used it for almost three years.

The developer now appears to have a good piece of software on his hands.
I will refrain from upgrading iTunes to version 11 when it comes out, at least until I can be sure it will not break Pure Music.
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richardcooper2k
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#9

Post by richardcooper2k »

excuse the belated post
an excellent write up by Steve - i don't have much to add

The naim clone boards are not from Avondale but cheap ones off ebay. They are more like the Avondale circuit than the Naim circuit though. They also follow the Avondale choice of coupling/feedback capacitors rather than the naim choice of tantalums

Having heard the OTL amp at 2 venues in 2 different setups i am very intrigued by what it does at the top end. There seems to be a lot more there than the other amps heard on these occasions. So are the other amps lacking or is the OTL got a rising response at the top? Or is there something else going on? Maybe it's to do with typical valve amp output transformers and transistor amp feedback loops ?

To be fair to the Mazda amp if it had a regulated supply it made have stood more chance at keeping up with the pace of the others. And actually i preferred the sound of the mazda to the other 2 amps when the Nils Lofgren track was played. The tone of the intruments and voices was much more pleasing to my ear. Unfortunately even with the lofgren track when the crescendo was reached it didn't really do a crescendo so some of the expression of the musicians was not conveyed. For myself at home i switch between SET and the Naim clone as the mood takes me.
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Greg
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#10

Post by Greg »

richardcooper2k wrote:Having heard the OTL amp at 2 venues in 2 different setups i am very intrigued by what it does at the top end. There seems to be a lot more there than the other amps heard on these occasions. So are the other amps lacking or is the OTL got a rising response at the top? Or is there something else going on? Maybe it's to do with typical valve amp output transformers and transistor amp feedback loops ?
Hmmm, thank you. You've made a detailed response without making any performance observation other than that you are 'intrigued' by the OTL's top end.

Because I'm interested in this OTL, I really would appreciate a more critical observational report. How good is it? Does it out perform other stuff? Is Steve's belief that it is brilliant (my interpretation) insecure?

I read what you say but would much prefer an observational report. I just get the feeling that your post does not really represent what you actually think. Maybe you are holding back. I completely understand if you are concerned about offending someone, but actually, there is no room for that sentiment. We need to know what you honestly think, IE, What is your overall impression of this OTL?.

A critical review would be great :D
richardcooper2k
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#11

Post by richardcooper2k »

Hi Greg
I was able to note the OTL amp sounded different, seemingly at the higher frequency's.

For me to decide if i liked it i would have to live with it for a while and see over time if i continued wanting to use it in my system

I don't really listen to see if something sounds realistic as usually i get it wrong as i don't know what i'm trying to hear; or i find i don't enjoy the system that i think sounds most realistic

Putting it another way i find out if i like something by listening with my heart rather than analytically.

Which is of no use to you unfortunately

Fortunately you will be able to make your own mind up at Owston
Thoughts are just little stories that our brains tell us !
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