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View Full Version : A visit to RJS, aka mixing it with the big boys.



Firebottle
30-05-2015, 14:05
Rob is a member on here but not very active. He is quite local and Lee suggested we get together, this is the second visit.

Without beating around the bush Rob has the best system I have heard to date. Scale, clarity, slam, imaging, you name it there is bucket loads on offer.
A quick run down of the system and you should see why.

Speakers - hORNS FP-15. Polish origin, new to me, STUNNING :eek: A horn loaded compression driver for the treble end of things and a whopper 15 inch for bass duties, all in a 90 litre cabinet.

Rob tells me that whatever improvements he makes downstream the hORNS just lap it up and spit it out even better than before.

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/P1040834.jpg

Amplifiers - These are a loan pair of humongous Ming Da class A monoblocks, and I mean humoungous, each psu case is 50Kg.
Model MC998A and needless to say I think they could drive anything. With the sensitivity of the hORNS the Ming Da's are just about ticking over :mental:

Preamp - now this gets interesting as you might be able to tell from the photographs. Usually a Townshend Allegri passive autoformer fulfils this role but a different pre was in circuit.

DAC - This could probably be described as the beating heart of the system, a fabulous LampizatOr Golden Gate.

Never heard of it? It's the ultimate LampizatOr, it's the Big 7 on steroids, everything but everything taken to the ultimate. Boy what a performer, hi-res, direct DSD, the lot.


How does it sound you ask. Insert superlatives here: .................................................. ................................
It's got expression, it's got soul, it's got grab you by the goolies and make you listen presence.

Everything that was played sounded sublime. Quite a few different jazz tracks, including a favourite test track of Rob's by Fink.
Elvis Presley from DSD, never heard so good, no, magically good!

Tears for Fears featuring (don't you hate the 'feat' abbreviation) Oleta Adams: effortless effortless voice.

Dave Brubeck Take five, when it started the realism just overtook me.

A couple of tracks from a recent S/H CD purchase 'Two Rooms - Celebrating the Songs of Elton John and Bernie Taupin'.
Kate Bush - Rocket Man, with a reggae beat, fabulous, Rob rather liked this one.
Joe Cocker - Sorry Seems To Be The Hardest Word. What can you say about Joe's voice, an absolute favourite, and the sax on this track is sublime.

A different perspective:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/P1040835.jpg


Now to the preamp. Rob has had the Firebottle KIN on loan and has requested to keep it. Giving more detail and a better balanced presentation was the report.
To say I was aiming high with the new design and now achieving it has rather put a spring in my step :)

We didn't finish there, I had also taken the 'ugly duckling' around (thanks for the description Gordon), my SE EL84 jobbie just for an experiment.
It was hooked in and didn't disgrace itself:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/P1040837.jpg

It turned out that Rob is a fan of the humble EL84. With the FP-15's as a load it was fairly rocking along. Oodles of clarity in the mids and the treble but just a smidgen lacking at the bottom, no surprise given the (relatively) small output tranformers. All in all class A just works, big or small :thumbsup:

So a fabulous mornings listening, I'm already looking forward to the next time.
Thanks for the invite Rob.

:cool: Alan

CageyH
30-05-2015, 14:45
Sounds like the new pre amp is something special Alan.
It certainly look's like Rob has an interesting system. I am not sure Mrs H would let me have amps like that in the house!

awkwardbydesign
30-05-2015, 15:16
Now that looks interesting! I used to have a pair of "little" Ming Da 845 monoblocks. I say little, as they were the same size as the pair hiding on the left! And my wife WOULD let me have a pair of the big 'uns in the house; she just wouldn't let me BUY them. I saw them (I think) at the Bristol show, but the sound in the Ming Da room wasn't good, so I couldn't tell what they were really like.
I like the idea of horns with 15" bass drivers, but is there no discontinuity where they cross over? The few I have heard had that problem, but I would love them to work. If these do, then that's a result! The big Consonance speakers look good to me, but I've never heard them, there is only one pair in the country, as far as the importers know.
http://blog.stereophile.com/china2006/m15.jpg
And what's the story on the pre? The rest of his gear is out of my reach, but that interests me.

Gordon Steadman
30-05-2015, 15:58
Take 5 is a well known test track and my standard for any new gear that crosses the threshold. The Kate Bush track is terrific, I discovered it on YouTube and play it regularly. Good music choices there. The gear looks a bit intimidating, the speakers very black and menacing. Still, it's the sound that matters.

Not thinking about abandoning the Quads then Alan?

Firebottle
30-05-2015, 16:08
Richard the hORNS cross over at 1kHz, about the sensible upper limit for a 15 inch woofer I would have thought.
I was sceptical about 1kHz for xover to the tweeter, but I'm told as it's a compression driver it copes to below this frequency.

Didn't sound in any way compromised, believe me.

The Firebottle KIN preamp is my swansong of design, a giant killer at rather less than a giant price. So far proven as a line preamp, following up shortly with the phono section as well. A sample will be at NEBO6, unfortunately that's not a lot of use to you where you are presumably.

:)

Firebottle
30-05-2015, 16:14
Gordon, I won't be giving up on the Quads, I'm quite happy with them plus the sub.

A bit more tinkering with the 6W OTL power amp, plus a KIN preamp should then do me for amplification.

We'll have to get together for a bake off with the KIN :)

Gordon Steadman
30-05-2015, 16:38
Gordon, I won't be giving up on the Quads, I'm quite happy with them plus the sub.

A bit more tinkering with the 6W OTL power amp, plus a KIN preamp should then do me for amplification.

We'll have to get together for a bake off with the KIN :)
Excellent, when are you back??

I'm sure I can find a few things to keep you occupied:eyebrows:

awkwardbydesign
30-05-2015, 16:43
AFAIK, a major LF limit for a horn is the mouth size, and that is hard to cheat. But if it works, it works!
And what do you mean "swansong"?

Firebottle
30-05-2015, 16:54
Richard, the 15 inch woofer is bass reflex loaded with two ports at the rear.

I did wonder about using that term, swansong.
I'm using it in the guise of I don't think I will design anything better, as in 'the pinnacle of ones career' meaning.

:cool:

Gordon Steadman
30-05-2015, 17:28
I did wonder about using that term, swansong.

I'm using it in the guise of I don't think I will design anything better, as in 'the pinnacle of ones career' meaning.

:cool:

Ah well, you never know for sure do you?

RichB
30-05-2015, 18:38
The Firebottle KIN preamp is my swansong of design, a giant killer at rather less than a giant price. So far proven as a line preamp, following up shortly with the phono section as well. A sample will be at NEBO6, unfortunately that's not a lot of use to you where you are presumably.

:)

Treats in store!!! I'll look forward to hearing that.

Great thread and pics guys.

Qwin
31-05-2015, 19:01
That looks a meaty set up, I can imagine it would sound VERY good!

Also looking forward to hearing the phono stage at NEBO6.

awkwardbydesign
31-05-2015, 20:48
That looks a meaty set up, I can imagine it would sound VERY good!

Also looking forward to hearing the phono stage at NEBO6.

Can I have video link? :scratch:

Firebottle
10-06-2015, 21:17
To achieve better you sometimes have to take the left field approach. Everyone must know I am a big fan of OTL power amps :eyebrows:

So when the opportunity arose to hear a new model around at Rob's it would have been churlish of me not to take advantage.
This is the beast, from Absolutor, still in its pre-production guise:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/SAM_0930_1200x.jpg

A very well constructed unit with some quality components inside, rear view here:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/SAM_0934_1200x.jpg

It's a single ended 4W class A with paralleled output tubes.

:wow: Having said the sound was excellent previously it was now sublime. Difficult to come up with the superlatives, a real clarity and extension to the soundstage. One of Rob's test tracks from Bjork with 'lethal' bass on it was so coherent at the bottom end it makes you realise what limitations there are with output transformers, however massive/expensive.

Equipment line up was Lampizator transport, Lampizator Golden Gate DAC, Firebottle KIN preamp, Absolutor OTL, hORNS FP-15 speakers.

Heavenly. The tracks played were mixed up a bit, one of the better known being Hotel California from the Eagles, very well known by me.

Just the best ever, ever. I need a lie down just thinking about it :D

walpurgis
10-06-2015, 21:24
That certainly looks the part!

Ali Tait
11-06-2015, 07:01
How much is the amp going to be?

Firebottle
11-06-2015, 07:31
I'm told about £2.5K

:)

hifinutt
14-07-2015, 18:39
good to see RJS on here . I rather miss robs input on a certain other forum . having heard those lampizators here I am rather taken with them

rjs
16-07-2015, 22:01
good to see RJS on here . I rather miss robs input on a certain other forum . having heard those lampizators here I am rather taken with them

Hi Phil,

Yes it's been a while, and thanks for the warm welcome. Alans Firebottle Kin pre is an outstanding piece of work by the way - well worth a listen.

Do feel free to PM me if you fancy catching up offline/in the actual, genuine, real world :eek: .

Robert

Barry
16-07-2015, 23:50
To achieve better you sometimes have to take the left field approach. Everyone must know I am a big fan of OTL power amps :eyebrows:

So when the opportunity arose to hear a new model around at Rob's it would have been churlish of me not to take advantage.
This is the beast, from Absolutor, still in its pre-production guise:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/SAM_0930_1200x.jpg

A very well constructed unit with some quality components inside, rear view here:

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Visit%20to%20Robs/SAM_0934_1200x.jpg

It's a single ended 4W class A with paralleled output tubes.

:wow: Having said the sound was excellent previously it was now sublime. Difficult to come up with the superlatives, a real clarity and extension to the soundstage. One of Rob's test tracks from Bjork with 'lethal' bass on it was so coherent at the bottom end it makes you realise what limitations there are with output transformers, however massive/expensive.

Equipment line up was Lampizator transport, Lampizator Golden Gate DAC, Firebottle KIN preamp, Absolutor OTL, hORNS FP-15 speakers.

Heavenly. The tracks played were mixed up a bit, one of the better known being Hotel California from the Eagles, very well known by me.

Just the best ever, ever. I need a lie down just thinking about it :D

I'm not too familiar with OTL circuitry, so I hope you won't mind me asking a few, possibly, naive questions. To obviate the need for an output (anode) impedance matching transformer, I assume the (single ended?) output valves are wired in parallel. Do they act as cathode followers? How is the inevitable DC offset blocked - do you use an output capacitor?

I have heard that under fault conditions, things can go wrong - disasterously wrong! Can you elucidate what can happen?

Thanks

Firebottle
17-07-2015, 07:32
Hi Barry, fire away with the questions my good man.

I'll answer your last one first, yes things can go horribly wrong :eek: There are instances of speakers being blown when catastrophic faults occur, including with the old Croft OTL before Glen changed to regulated HT.
I believe there is a member on here who has experienced a Croft OTL self destructing.

With push pull OTL circuitry the HT is in the region of + and - 120 to 180V so the energy available under fault conditions is considerable. Most (some?) circuits have HT fuses which go some way to limit any fault current, but a better approach is to include a gas discharge tube across the output as well. This clamps almost instantaneously when the voltage exceeds the breakdown so offers a much quicker protection than just a fuse.

http://i601.photobucket.com/albums/tt97/Paramotorpilot/Valve%20amp/Outlawcircuit.jpg

This is the circuit of my low power OTL, 6W per channel into 8 ohms, the HT is actually a little lower than 145V.
You can see that the output valve grid resistors are quite large, this is done to limit the fault current if one output valve fails.

The overriding consideration is not to over stress the output valves, a good contender for output valves is the 6KG6 or EL509 as they have a large Va rating.

With SE OTL circuitry there is an output capacitor, frowned on by the OTL purists, but as I have heard with the above ABSOLUTOR amplifier it doesn't seem to detract from the sound. The 6KG6 valves are all in a parallel cathode follower configuration, 3 per channel, with a choke load to ground and two 3300uF parallel output capacitors.

The low dc resistance of the choke load would be beneficial under fault conditions, the HT fuse in this amp is 1.5A.

Cheers,
Alan

PS The Absolutor amp/design isn't one of mine.

Jimbo
24-07-2015, 12:10
WHO builds the Absolutor?!

Firebottle
24-07-2015, 19:32
It's of Polish origin, see http://www.blog.absolutor.pl/absolutor/idealna-koncowka-mocy-do-absolutora-2015-03

Available in the UK through G Point Audio.

:cool: (I've run out of beer, oh no :doh:)

Jimbo
24-07-2015, 20:04
It's of Polish origin, see http://www.blog.absolutor.pl/absolutor/idealna-koncowka-mocy-do-absolutora-2015-03

Available in the UK through G Point Audio.

:cool: (I've run out of beer, oh no :doh:)

Cheers Alan:cool:

pgarrish
10-11-2015, 20:12
Rob's system is cracking. I heard a previous incarnation with the DAC Level 4 (I think) and the 'baby' 845 amps. Very good. I'm struggling to guess how it sounds better with those massive amps and the KIN pre etc.... There was nothing wrong as it was.