EEVblog #1162 - Little British Monitors

[b_force]

I can't believe how expensive these are. I got a very good pair of KEF 104/2s for about £350 recently!

Were your KEFs also made in a garage/home by a single person?

This is good why?

[AmmoJammo]

I can't believe how expensive these are. I got a very good pair of KEF 104/2s for about £350 recently!

Were your KEFs also made in a garage/home by a single person?

This is good why?

I wasn't sure if he was claiming this to be a good thing or a bad thing... I'd want to assume bad...

[The Soulman]

I don't wan't to write a long post about it, but in the discussion bass-reflex vs transmission line, those little boxes are bass-reflex.
Someone mentioned kef 104/2, those are band-pass (low-end).
All of the above are poor choices for faith full sound reproduction as they add smearing in the time domain.

Any serious studio monitor is sealed.

https://zstereo.co.uk/2015/06/24/bbc-ls35a/  (warning: 40% wank)
https://www.soundonsound.com/reviews/yamaha-ns10-story (actually mentions time domain  )

Tannoy and Genelec also had some (certainly not all  ) good boxes.

[David Hess]

In the end the best way to teil is to listen: TL has a tight and controlled bass whereas BR is loose and resonant.

Many bass-reflex designs are not tuned very well leading to poor impulse response and poor intermodulation distortion at low frequencies.  In production this is a problem because driver characteristics vary from unit to unit and nobody wants to individual tune enclosures.

And given that TL is hard to design, demands a lot from the woofer, have low efficiency, they are justifiably rare.

At least with low efficiency, the high noise from the power amplifier will not be noticed.  Is that a marketable feature?

He didn't even give any information about which IC's were being used.
For the record, TL074, or in other words; the cheapest of the cheapest.
I never use these things in any modern and new design anymore unless it needs to be cheap as chips.
They are even being sold as (quote) general purpose opamps.

Aww, TL074s are not all bad.  They have the increased bandwidth and slew rate needed for audio and their low input bias currents make design easier.  The circuit topology like avoiding common mode distortion by using inverting stages is more important and would ruin the performance of a better operational amplifier anyway.


Must ... look ... away ... from ... her ... speakers.  She needs to learn to solder properly; wipe the tip before soldering and not after to protect the surface from oxidation.

[Fungus]

Someone mentioned kef 104/2, those are band-pass (low-end).
All of the above are poor choices for faith full sound reproduction as they add smearing in the time domain.

I seem to remember Kef 104s were quite good. Back in the 1980s. They're ported but it's a big, front-facing port. Not as much of a band-aid as a typical 50Hz port on a tiny speaker.

Any serious studio monitor is sealed.

Yep. Or at least small, front-facing ports. Anything that blows air backwards at the walls is asking for trouble.

[mc172]

I can't believe how expensive these are. I got a very good pair of KEF 104/2s for about £350 recently!

Were your KEFs also made in a garage/home by a single person?

No, but they came fully assembled for that price!

OK, the KEFs weigh about 35 kg each and are huge floorstanding speakers, but for my money I'd rather have the best thing I can get for that amount of money than something brand new part built in someones shed somewhere in England.  The whole "built in England" thing is a load of wank anyway - most of the stuff will have come from China.

[Bassman59]

OK Im old, but what I see is one volume control for both speakers. So how would
one adjust the "balance" for proper separation which is  dependent on listener location and room response?

I would think adjusting balance is a job for the preamp that is feeding the speakers. Are you aware of powered speakers that have a balance control? I've never seen any with that feature.

My Genelec and KRK monitors have a volume control on each cabinet, so you could do balance there. The key to any successful monitoring room, of course, is to calibrate the whole system.

[Bassman59]

The low frequency response of those woofers doesn't look like anything to write home about - falls off abruptly below ~100Hz.  Do recording studios really rely on such as these?  Or do they add a big woofer third channel?

Recording and mastering studios have several sets of monitor speakers, ranging from soffit-mounted three-way boxes with large (15") woofers and two or three pairs of console-top mounted nearfield monitors, and a pair or two of some small "TV speaker" monitor. The nearfields are something like the Genelec 1031A with an 8" woofer and the Yamaha NS-10, and I see a lot of the ADAM monitors (very nice) too. Those "tv speaker" monitors are usually something like an Auratone cube, with a single driver, meant to sound like what one might hear in the car or through a television's built-in speaker.

Which speakers are being used depends on what the engineer wants to hear.

[IanMacdonald]

To bad that the amplifier  board  didn't  have discrete  transistor  driver  and   output power  stages  for each channel , instead of one of those Class A/B  modules  which  have a lot more T.H.D.  when driven hard

Agree. Chip power amps have two problems; crossover distortion at low levels because they have no standing current adjustment, and running out of power transistor drive at high levels because they typically use multi-NPN darlington arrangements with high burden volts.

Class D ICs using FET output stages tend to give better sound quality, only IME they are very blow-up prone. Even driving into distortion can cause some of them to pop.

For any critical application I'd go for a discrete complementary arrangement though.

Other point, that heatsink is the wrong way round and won't dissipate much. Plus, stainless may look nice but it's not a very good conductor of heat. (Ever watched a blacksmith hammering the red-hot end of a piece of steel whilst holding the other cold end in his hand? Try that with ally or copper and it will be ouch time.)