The HH amps 8/12 for the Rogers 3/5

[Arpangel]

The AM8/12 was specifically designed to drive the LS3/5A.

The LS3/5A was designed specifically for use in small OB vans, edit suites and control rooms where it would typically be within 1.5 to 2 metres of the listening position, and SPLs wouldn't be much above normal speech levels.

The AM8/12 delivered that adequately for both nominal 15 and 11 ohm versions of the LS3/5A, but it did provide more headroom with the later models, of course.

Hi-fi nuts use all sorts of amps with the LS3/5A, to extract their supposed magical properties.

In reality the LS3/5A is a good sealed box two-way from 50 years ago with a perceived quality that outstrips the truth. The job can be done better today...

But if you're building a BBC mausoleum, the AM8/12 is the correct amp to partner the LS3/5A.

Was the 3/5 primarily deigned for speech? with the bigger specified speakers for music monitoring?
I had a pair of Rogers 3/5’s for about a month, but sold them, I couldn’t monitor on them, they got too congested too quickly, but for hi-fi listening, on vocal stuff, light opera, piano, folk etc, they were really good, but not so good that had to to keep them, not as good as my Acoustic Research speakers at the time, but unfortunately, they turned to dust!

[CeruttiA]

This is the question, isn’t? It was surely designed for both speech and music , at least i remember seeing them at the world service, where both speech and music were broadcast

[Hugh Robjohns]

It was designed to provide the most accurate and consistent sound monitoring possible in the early 1970s, within the constraints of the small cabinet size made necessary by the OB applications it was intended to serve.

Inevitably (for the time) the physical design imposes a curtailed bass response and a restricted peak SPL capability. However, neither are a significant problem for the production of speech-based programmes which forms the majority of the BBC output.

So while it wasn't designed solely for speech, voice quality assessment was clearly a key goal and application, and something it excels at.

When it comes to music recording /mixing /production those same inherent performance limitations make it a non-ideal monitor, and more appropriate alternatives were always used in the BBC where possible and practical.

That said, the LS3/5A was the most affordable high-quality speaker available from the BBC's Equipment dept, and so it found homes all over the place, including in local radio studios where I'm quite sure a lot of music was recorded and mixed on them.

I've recorded and mixed music on LS3/5As countless times in all sorts of different studios, trucks, and on-site rig-ins, and while definitely not ideal, it is doable with care.

When it comes to replaying finished, mastered music at moderate levels, the LS3/5A was exceptionally good in its day (bottom 2.5 octaves excepted) and is still quite competent today for its size (assuming in good condition).

[MarkOne]

It's alright Kwackers... facts and realism hold no sway at all in hi-fi land. Your pension fund is secure!

Sad, but true. These days. It wasn't always so though. When I worked in the industry we were always striving for good solid engineering, backed up by measurement and critical listening (including blind testing) we used interconnects made from off the shelf reels and hardware bought at Farnell or the like.

You only have to open the pages of HFNRR from the 70s to see lab reports as an essential component to a review

I really don't know exactly how the loonies started to take over. I do remember at a bar during a big HiFi show arguing with a certain Russ Andrews about the physical properties of wire and how you can't apply what's happening at RF frequencies to the audio world.

It was shortly after that I moved into Avionics and next time I picked up a HiFi magazine I didn't really understand what had happened.

There are still companies out there doing solid engineering though. ATC make some cracking domestic kit with the same sort of rigour as they apply to their monitors. Similarly PMC. I still think companies like B&W, Arcam and Meridian have engineering excellence at their heart and they tend not to pander to the palladium interconnect crowd. (though I guess they know what their market consists of so have to make the right noises)

[ef37a]

Not so sure about B&W MarkOne? I recall seeing an advert (prob' HFNRR!) a cutaway of a speaker and the blurb went to great lengths to bang the drum about the PTFE insulated wiring.

The only 'advantage' I can see is that in the event of a fire all that will be left is the metal and the wire!

I too was a regular buyer of HFN, never missed a copy but as the beardy,tweaky rot set in I gave it up. I still bought Studio Sound with Hugh Ford bless'im but no other mags for ages until wife brought me SoS Feb 2005 in hospital. Took me fekking ages to find out what a blasted "DAW" was!

Dave.

[Folderol]

PTFE is sometimes specified for use in tropical environments and for vermin resistance
... just sayin'

[ef37a]

PTFE is sometimes specified for use in tropical environments and for vermin resistance
... just sayin'

Heh! Yonks ago we had a 'console' radio in with "very weak sound". All that was left of the 10" speaker was the magnet and the voice coil on its phenolic former!

Cone was a neat ball in the corner.

Dave.

[CeruttiA]

Can I simply use the HHs 8/12 mono blocks or would i need a separate volume attenuator to operate the LS 3/5 speakers ?

[Hugh Robjohns]

The BBC intention was that the separate HH amps be fed from a mixing console's monitor section outputs -- so the console provided the stereo volume control.

The input sensitivity controls on the amps themselves were just there for the initial system alignment to set the appropriate acoustic reference level.

You can use those sensitivity controls as volume controls, but you're going to need long arms and even then it's going to be very fiddly in a stereo system trying to adjust them together and maintain an accurate balance.

I'd use an external stereo volume control of some sort, personally... ideally within a monitor controller or system preamp so that you have practical and convenient source selection as well as stereo volume and mute facilities

[CeruttiA]

thanks so much, Hugh !

Are there any simple ballanced passive attenuators you can recommend for that purpose ?

[Hugh Robjohns]

https://www.thomann.de/gb/studio_monito ... ilter=true

I use a JBL Nanopatch Plus when I need a simple passive stereo volume control, but Thomann appear not to stock it. I quite like the simplicity of the TC Electronics Level Pilot X (there's a more basic Level pilot without the X which isn't balanced)

[ef37a]

thanks so much, Hugh !

Are there any simple ballanced passive attenuators you can recommend for that purpose ?

Someone mentioned the Behringer Monitor 1 here the other day. No idea how good it is. Do not get a Mackie Passive BK they are NOT balanced!

Dave.

[Hugh Robjohns]

I guess it's also worth saying that there are some inherent quality compromises with passive volume controls and often a decent active monitor controller is a better bet...

But it really all depends on what you play to do with these LS3/5As. What sources you're going to use? How far the controller/source will be from the amps?

Normally, the amps sit beside or directly on top of (sometimes below!) the speaker, with a short (300mm or less) speaker cable.

[CeruttiA]

Hello Hugh,
thanks very much indeed !
the source will be either a CD player (XLR) or the EMT 948 turntable (also XLR)

[CeruttiA]

Can I use a microphone pre-amp as a pre-amp for the rogers 3/5 set up ?

[James Perrett]

A mic preamp wouldn't make much sense in your setup. You would be adding extra unnecessary stages in the signal chain and I'm not sure why you would need that.

[Hugh Robjohns]

Can I use a microphone pre-amp as a pre-amp for the rogers 3/5 set up ?

You could if the source was a microphone....

But as your sources are a CD player and professional turntable with a line level outputs, I'd say there are probably better options...

Personally, I'd go for a decent active monitor controller since that will (a) control the volume), (b) select different inputs and (c) provide other useful functions like mono, dim, mute etc.

[CeruttiA]

I saw this preamp that a friend has created, based on the legendary MBL6010 preamp

Image download:
https://we.tl/t-Wl1JAixZf0

[CeruttiA]

sorry , do not know how to post images here , but I have the link.

[Hugh Robjohns]

The image needs to be publicly visible on some host site, and its direct web address placed in the post here between img tags.

I've downloaded and inserted your preamp image in your post above for you

[CeruttiA]

You are most kind, Hugh. What do you think about it ?
I hear some experts say that the less electronic there is in the signal path the better, others sau that a decent preamp is much better than a passive attenuator. What do you think ?

[Hugh Robjohns]

You are most kind, Hugh. What do you think about it ?

I don't know anything about it I'm afraid. From a quick scan around the web it appears to be a professionally-designed line-level preamp, but I've not seen any specs.

I hear some experts say that the less electronic there is in the signal path the better, others sau that a decent preamp is much better than a passive attenuator. What do you think ?

I think the 'experts' probably aren't!

It might seem self-evident that "the less electronic there is in the signal path the better", since all electronics introduce some level of noise and distortion.

However, that view is very naive and simplistic, and doesn't recognise the practical issues of real-world signal interfacing.

Moreover, entirely passive electronics can easily introduce noise and distortion too!

And in the real world, the benefits of active electronics in terms of driving cables and interfaces correctly and buffering signals with the correct input and output impedances usually far outweighs the entirely negligible noise/distortion artefacts associated with a good preamp design.

When you think of all the active circuitry involved in the recording studio console (several tens of op-amps through the signal path), the DAW and its interfaces (another handful of op-amps), and the mastering room (a shed-load more interfacing and signal processing)... do we really think a couple of (well implemented) op-amps in a domestic replay system will make or break the whole listening experience?

It's bonkers! Although obviously a cheap, nasty, rubbish active design won't sound good...

Personally, I'm in the group that argues a decent preamp is much better than a passive attenuator! Yes, I do use passive attenuators occasionally, when it is convenient or expedient to do so, but all my serious listening systems have active controllers/preamps of one form or another.

[Arpangel]

Just mentioning, to save on a separate preamp, my Quad 405 has been modified, with two potentiometers on the back, controlling the outputs, these have come in very handy, at times.

[CeruttiA]

Can sb tell me please whether the input and output plessey connectors on the amplifiers 8/12 are symmetrical?
Thank you !