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March 2010 issue
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FINAL UPGRADE
I am about to embark on what could well be my final upgrade (musically that is ) and would very much appreciate your help. I have been an avid reader of your magazine for many years and I know that you have helped many Audiophiles through the upgrading minefield.

I have a pair of Klipschorn corner speakers that were born in 1972 and still with their original crossovers that must be feeling their age. My dilemma is, do I just replace the capacitors or would it be better to purchase new networks built by the likes of Bob Crites (www.critespeakers.com) which I am quite happy to do, as long as they will justify the extra cost. I believe other people in the States also build them?

My amplifiers comprise a Croft super micra preamp about 18 years old, a Croft Series V power amp, and a pair of Leak TL 10 Point Ones rebuilt by Glen Croft about 20 years ago.

Record deck is a Garrard 301 (Bastinised) with a Tom Fletcher arm and an ancient Decca London cartridge. I cannot afford to change the deck, neither can I afford to upgrade to a moving coil, plus phono amp with a budget of around £400 at the moment. That figure will be increased if I am lucky enough to find a good second hand S.E. amplifier. I would welcome your suggestions for a replacement M.M. cartridge please.

I still enjoy my Leak Troughline Stereo Tuner so I am not concerned about changing that. I sometimes play CDs and have a AH! Njoe Tjoeb 4000 player.

My speaker cables and interconnects are cheap and cheerful so I really must upgrade them and I am thinking of going the D.N.M. route. This is just a gut feeling plus financial consideration of course. The problem is that I won’t be able to audition them at home, so it’s pot luck.
Now for the big one. I have always wanted to try and hopefully buy a Single Ended Amp or amps which I understand could be a match made in heaven with Horns. Would you agree with that?

The Almarro 318B has had great reviews and must be high on my shopping list. This is at the top end of my budget and at least I can audition it at home. The amount of heat it produces may be a bit of a concern though, (35C?).

Something like a 2A3 based Yamamoto could be interesting, as could some of the many 300B designs, but I guess they will be too expensive for me.
We listen mostly to Jazz, Classical, Opera, Big Bands and also 50’s, 60’s and 70’s vocalists. Obviously I am looking for the most realistic reproduction possible.
very, many thanks in anticipation.
kindest regards,
Terry Mason

I have no experience of the Bob Crites crossovers so cannot comment. If funds are tight my tendency would be to remove the crossovers and rebuild them using quality Solen capacitors, or a brand you may prefer.  I also like the neutral sound of carbon film resistors, but you may like to experiment, as quality metal films can be good. Put the crossovers in Maplin plastic boxes, external to the loudspeakers so they are unaffected by vibration. Use good cable, again of your choice according to budget. You really should use at least budget loudspeaker cable from Chord or such like. I have tried Maplin Shark cable and found it sounds very vague.

Decca London? Ouch! Yes, I know its hair-trigger fast sound and great bass, but original London Blues mistracked terribly and left significant groove damage in their wake. This was inaudible with the Decca, but not with any cartridge that followed it. Later, improved Deccas overcame this to some extent, and hopefully this is what you have, or you are in for a shock. I suggest you buy a Goldring 1022GX  which does a fine job at a very reasonable price.

Single-ended amplifiers are a world of their own and the sweetest thing you'll ever hear. The models you mention are all worthy contenders and I loved the Almarro. Just don't expect to turn your house into a disco, but then I suspect those days are over! You may be interested in the next letter, where I seem (regrettably) to have upset a dedicated SE user. Such things raise passions. NK

DARK NIGHT
I was rather disappointed by Noel’s review of the Silver Night. I don’t think it gave a fair picture of using an SET amp and it could easily give the wrong impression.

Just as background, I have a WAD 300B Push-Pull (18W), Arcam power amps (solid state), Naim power amps, but my main system is the Audio Note Quest Silver SET (7W) and so I have a reasonable understanding and experience of the topic.
Noel gives the impression that the reason for choosing 2A3 valves is that they are cheaper than 300Bs. That’s really not true if you compare like-for-like quality, for example, good quality meshplates, where the 2A3s are slightly more expensive. It is true that the cheapest 2A3 is cheaper than the cheapest 300B but few people would choose to run the cheapest valves.

Noel mentions distortion levels and this shows up the problem of relying on objective measurements. Yes, valve designs do have higher levels of distortion than solid state. But the distortion from solid state tends to be high order harmonics which even at low levels makes the sound harsh and is intrusive. Distortion in valves is of low order harmonics and is much less apparent and can even enrich the sound. And so comparing the objective measurement of THD between valves and solid state can give a very misleading impression.

Noel mentions using a passive pre to allow switching, but here again it is misleading. I have used the MF Audio passive pre (both copper & silver versions) with Naim and the WAD 300Bs and Audio Note Quest Silvers and whilst it is a very transparent pre it does seem to bleed the life out of the music when used with valves -- it is very good with solid state. And so really the front end of a valve power amp should be a good valve pre-amp -- try it with the WAD Pre II or III (I’ve got both) and it brings the music to life. Move up to an Audio Note M3 and it will really sing -- but not a passive.
Noel mentions the lack of inputs well here again I think he’s missing the point and being misleading. The volume pot is simply there for convenience and acts as a simple passive control (not ideal) in a one source system. In reality the pot would be turned up full (i.e.bypassed) and a good valve pre would be the front end.

There is also a question of horses for courses in terms of music choice. An SET power amp driven by a good valve pre creates and incredible musical experience on acoustic music, especially vinyl jazz albums. But if you really want to rock then get a Naim which boogies better – I’ve got both.
But the strangest comment in Noel's review was the Verdict with three globes... “It’s inability to drive lower loads is unacceptable at this price.”  This is totally misleading and completely misunderstands SET amps. If you want more power then use a simple 300B Push-Pull (I have the WAD 300B PP) at 18W of valve-power it will drive all but the most insensitive speakers. BUT the sound does not have the delicacy of an SET. Noel seems to be looking at the Power Amp and Speakers as two separate and unrelated components and nothing could be further from the truth. You have to match speakers to power amp. Indeed Naim use their speakers to load the output stage of their power amps – including specifying a 3m long single run of speaker cable to ensure correct loading.

audion-silver-night-duo

Audion Silver Night single-ended amplifier. Just a two globe review from Noel, says Edward.

If you want to achieve the true beauty of sound and outright musicality that a SET power amp can give then you have to choose a speaker that has been designed with high sensitivity to work with SET amps. For example, a good quality single driver horn, or Audio Note AN/J or AN/E.
Therefore to really review an SET power amp you must review it in a system with a valve pre and high quality speakers designed to work with SET amps.

Therefore, sorry Noel, but this review is rather woolley and confused, written in a bit of a hurry perhaps? But only makes a two globe review.
regards,
Edward

Hi Edward. I designed early WAD amps so am well acquainted with the characteristics of thermionic v solid-state. 2A3s have a lovely sound but produce half the power of a 300B as I clearly stated, so little power the Silver Night amp was unusable on the 4 Ohm tap.

A valve amp is load matched by the output transformer and can supply the same power into 4 Ohms as 8 Ohms. If it doesn’t the output transformer hasn’t been designed or wound properly. Most loudspeakers nowadays are 4 Ohms and a real world amp needs to be able to handle them, as can WAD amps and Almarros etc. The Silver Night simply could not, hence 3 Globes.
best regards
NK

Dear Noel,
Many thanks for your reply, I do appreciate you taking the time to reply in person to me. I do understand the points you’ve made, and of course accept your judgement.

My main point, perhaps not well expressed, was that SET power amps are specialist and niche products therefore they should be evaluated using niche speakers designed to work with SET amps rather than the majority of speakers which are really aimed at high power solid state amps.
My main criticism of Audion power amps is that they have solid state power supplies. I think this gives them a very “clean” and precise sound but it doesn’t engage – I find my mind wanders during prolonged listening. If I compare them with the lower-end Audio Note amps which have valve power supplies (e.g. Quest or Quest Silver) then I find I stay up all night listening. Of course there are other differences as you mentioned in the wiring methodology and component quality of the Audio Notes.

Final point on speakers: among the pairs of speakers I own (approx: 24) I have a pair of Audio Note AN/J. They are rated at 93db sensitivity and designed and developed to work specifically with AN Quest Silver SET amps. And the sound when coupled with the AN amps really is, in my view, outstanding in all respects – very musical. They are reasonable but not great when driven by WAD 300B PP monoblocks. But sound quite thin and horrible almost lacking all musical qualities when driven by Naim (NAP200 or 250) or Arcam (Delta 290 + 290P). They are also OK when driven by Audion Silver Nights but nothing special. Indeed Mission 753s sound far superior with the Naim & Arcam amps but poor with the SET or PP monoblocks.

It was this experience which led me to argue that power amps and speakers should really be seen as a single component.
best regards, and thanks again for your response,
Edward

Edward - it's always nice to hear from a true enthusiast. You have 24 pairs of loudspeakers! Where do you keep them all? To be fair to me though (!) I did clearly say I liked the Silver Night driving 8 Ohms loudspeakers. Even by SE standards it was very sweet. But it fell flat on its face with 4 Ohm loudspeakers and as most are 4 Ohms nowadays that would have been the common experience, which I feel obliged to report upon. NK

DAB IS OFF
I’m sure Steven Green would be interested in seeing and commenting on this, if he hasn’t already.
http://www.telegraph.co.uk/technology/6616161/Digital-Economy-Bill-No-date-for-radio-digital-switchover.html
The article appeared today, and has attracted lots of user comments, mainly referring to many of DAB’s failings. But the main point is that Lord Carter is now contradicting his own report, saying there is no set date for FM switchoff.
Confused? I know I am.

But FM lives on, and I’m glad it does. (I still don’t think that the BBC should have a monopoly on drama etc, though.)
Best wishes,
Melvyn Dover.

FM does indeed live on - as this month's group test shows! Don't believe the government's hype about FM switch off; I'll believe it when I see it! DP

FIXING A LEAK

I am enquiring about info on the output transformer for this amp. I have a TL12 plus but there is no L/S impedance selector on the top of the o/p trans. It looks exactly as the ones with such a selector ...underneath there is a row of three soldering pins and a further two. In connecting these pins as in the diagram I have i.e. 4 8 and 16 ohm taps. Can you tell me the ohmic resistance of the windings on the normal output transformer. In talks with people there is the suggestion that it is a 100 volt line output. The number on the base is, the same white print as the mains transformer, is 8382. I would be a happy man if you can help or perhaps point me in the right direction. Thanking you in anticipation.
Edward Ashton


leak_tl12_plus

Leak TL12 Plus, a successor to the excellent TL12.

We do not have a TL12 Plus available for a measurement of D.C. resistance, but output transformer secondaries use few turns of heavy gauge wire and typically measure around 0.5 Ohms. As you can see from the circuit diagram reproduced here there is a basic 4 Ohm winding, and a tapped 16 Ohm section.

 

tl12-plus-final

Output stage of Leak TL12 Plus amplifier showing output taps.

You can identify the latter by the feedback line that comes off it. The 4 Ohm winding will have the lowest DCR. Only if windings all measure out at many ohms would I be suspicious about the nature of the output transformer. Leak did make special versions for the BBC and perhaps some line drive types, but if there are many terminals then the likelihood is that these are provided for loudspeaker matching purposes. NK



 
Comments (3)
Technics mods
3Wednesday, 25 May 2011 11:58
Dave Cawley
Hi Anton

We are SL-1200 modifiers and currently have a half page advert in Hi Fi World. I have tried very many combinations of arms and cartridges, both my own and customers. If the standard arm is new or not abused it can easily take an OC9 cartridge and you could live with that almost happily ever after. In my view, and we are all different, the Rega 300/301 is only marginally better than a perfect stock arm and as such we recommend going a bit further up market to the SME 309, which with an OC9 or AT33EV will give quite remarkable results.

The links Noel gives above are a good starting point.

Regards

Dave Cawley
Technics query
2Tuesday, 24 May 2011 11:55
NK
Hi Anton,
Our usual advice is to go to -
http://www.soundhifi.com/sl1200/SL1200%20PSU.htm
or look up the Timestep forum at -
http://www.time-step.net/
regards, Noel Keywood, publisher
Technics SL1200 arm?
1Tuesday, 24 May 2011 06:23
Anton
In Vinyl Quest DP says "There are a number of specialists who can do this (fit a Rega arm to a 1200) for you, and who advertise in HFW". I cannot see any ads on your site for this. Can you tell me these people?

thanks, Anton

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