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Supertweeters
Hi Arvind,
I've heard back from someone who also has Quad 989's and has tried adding Air Motion tweeters, and a subwoofer. His email reply is below. I'd be interested in your views, especially around his observation that he couldn't tell any difference.
Regards,
Trevor - E-mail: trevor_loveday (at) hotmail.com

AK
Hello Trevor,
I am surprised he did not hear a difference. An easy test is to put the tweeter right up to your ear, once setup and music on, to verify all connections are good. After that I'd look into the capacitor value to start here, maybe it rolled off at too high and inaudible a frequency.
Regards,
Arvind Kohli

LC
Dear Duc,
the cabinet displayed in that article is not our own design, it comes directly from Wilmslow Audio, see for example their large collection of cabinets for full-range drivers here. I'm afraid they do not supply schemes for their cabinets, as this stuff is for sale on their website. Try contacting them directly and ask for a price quote for the building plans, perhaps they'd be happy to sell these. Eventually cite our article, so that they can quickly understand which cabinet are you referring to.
Hope this helped somehow,
Lucio Cadeddu

Arcam rdac or rdacII versus Rega dacr
Hello Andy,
I've read your reviews. I am setting up my system from scratch and It's difficult to decide on a DAC. I just bought a LFD LE5 with Harbeth P3esr speakers and I'll be using a recently purchased MacBook Pro. I will download my 1300 CDs, mostly jazz to the MacBook but would also like to stream from Tidal and other services of this caliber.
I would appreciate your suggestions.
Thank you,
Larry - E-mail: larryinbeijing (at) gmail.com

AN
Hi Larry. Thanks for getting in touch.
A tricky choice – and you’re spoiled for choice at that price level. I think you’ll find a computer based system a revelation after listening to CDs. It’s just so convenient. The big danger is that it’s too easy to switch between tracks and end up “surfing” your collection rather than listening to it (I am often guilty of this).
As to the two DACs you mention, I suspect there’s not much to choose between them. The ARCAM will be a very good performer – I have listened to the irDAC extensively and always found it very businesslike - clear and transparent. I’m waiting for a sample of the new ARCAM DAC but don’t know when we’ll get it for review. I have only heard REGA DACs at shows where they sound good in REGA systems.
Reviews suggest a warmer sound than the ARCAM but I suspect the differences will be small in practice. I’d suggest trying to get hold of both and returning the one you least enjoy. It’s also worth thinking about facilities as these may differ more than ultimate sound quality at this level (do you want Bluetooth for example?).
Regards,
Andy Norman

GH
Sadly no I can't - sometimes I wish I could.
Yours is the first email (and I've had probably a 100 from high-end manufacturers, designers of arms and cartridges and enthusiasts) that backs up the VTA claims.
However as I keep saying throughout the article that doesn't mean that some people/systems aren't sensitive. However as there is no scientific evidence or even credible theory as the why I am inclined to be skeptical until someone puts forward empirical evidence to the contrary.
The answer is obvious and you have the tools to perform it and at least add meaningfully to the knowledge pool on the subject. Simply do the experiment as described in the second part of the article - 100% as described and no cheating - and then post me your results.
I'll be more than happy to publish them. If you can persuade another company with similar views to repeat the experiment so much the better. If you wish you could supply the equipment and I'd conduct the experiment myself. I'd be very happy to be the first person to publish empirical evidence for the importance of 0.001 degree of VTA change...
Then there's the practical side of things...
Looking at your arm design the changing of VTA will have a major effect on VTF at the same time - so for every record you play you need to alter VTA and VTF (to correct). You need to do this before every play - no good writing down favourite settings unless your room is air-conditioned to exact temperature and the system fully up to working temp - i.e. cartridge - this heats considerably during use.
So, for all but a few obsessives the VTA question - even if audible - quickly becomes irrelevant.
And lastly - if you take a fine arm design and strip off all the bells-and-whistles - arm-lift and especially VTA tower then you will hear the difference - all the time - with every record - without having to spend 10 minutes faffing about before you put a disc on...
Cheers,
Geoff Husband

Dayton Audio AMTPRO 4
Hi Arvind,
I found an article online from November 2014 in which you tested three tweeters with your Quad ESLs and achieved a beneficial result. I have a pair of 989s and am inspired to try this from your article. I just have a few questions that I hope you can help with:

• Did you introduce any crossover or are the tweeters just taking a parallel feed from the normal connectors?
• Would you still recommend these tweeters or are there better alternatives available?
• Is the increased sensitivity of the AMTPRO 4's an issue with matching? If so, how can this be attenuated?
• Is there a need for any special mounting considerations, e.g. in the way that a subwoofer typically needs a big vented cabinet - I assume not.

AK
Hello Trevor,
Let me respond in the same order as your questions.

• The tweeter needs a crossover, since it cannot handle frequencies below 800hz. This was done by using a 1.0pF capacitor on a line feed from the speaker inputs on the Quads. The signal to the Quads were unfiltered...I feel put any kind of filter on the signal coming into the Quad would defeat the purpose of having a full range ESL.
• Of my survey these were the best tweeters, but I have not looked around since I wrote the article. I definitely prized that the design allows for dipole use. I wouldn't mind if the range was a bit more extended, since the tweeter is only rated to 18khz, but I am not sure if higher FR would be audible or not.
• In the article I mention I also used an L-pad at the setting of 8, this provided the needed level matching. You could also use a resistor in-line, but you'd have to play around with finding the right value.
• There is no frame needed, but for aesthetics I built an open back frame of wood. I'll write a followup on that. It is imperative that the back is open, for the dipole effect.

• Output voltage at 1 kHz 5 cm/sec - 0.3 mV
• Internal impedance, DC resistance - 5 Ohm
• Recommended load impedance - >20 Ohm

LC
Dear Tony,
quoting directly from the Quintet Mono manual:

Quintet Mono uses a strapped output to deliver the same output signal from both sets of pole pins. This effectively eliminates the need for mono-specific equipment, making it possible to enjoy true mono reproduction on any stereo playback system.

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