Alexander -

(1) Please explain the connection between your question about pre-amps and your headline about the BBC Rogers speakers. I have those speakers as one of the sets in my hi-fi system, and, although I check supposedly finished mixes on them, I don't use them as studio monitors.

(2) You need to tell us what type of material you intend to use the pre-amp for, the microphone(s) you will be using with it, the A-D converter that you have and also some information about the acoustics of the room you will be recording in.

(3) It's not possible to comment usefully on the Glensound mixer until we know the answers to (2).

(4) You are new to RO, so you probably don't know that it's not necessary to post the same question in more than one forum. I have deleted the post from the "Monitoring and headphones" forum, where it does not belong.

Thank you very much for the comments. Actually my question is about the use of the Rogers LS 5/8 ( Quad driven). The question is what would be a nice pre-amp to use. I do not like to use common HiFi components, which I find coloured and imprecise. Hence the question to have an alternative route: for example , would an old analog console be a possibility ? What else do you recommend ? Since the configuration imposes the use of Quads , I have to find a pre amplifier that has depth, precision , nice gain and warmth.
All ideas are welcome.

Thank you very much !

OK, thanks for explaining a bit more. Perhaps I should have started by asking what it is you have in mind when you say "pre-amplifier"?

Thank you -
What is your advice then about a suitable pre amplifier or alternative combination ?

Thank you

Alexander

Alexander -

Boswell has asked you some pertinent questions so that we can help you more... but you haven't answered his questions yet. It's very difficult for us to give you answers or advice until you do that.

Boswell, post: 434032, member: 29034 wrote:

(1) Please explain the connection between your question about pre-amps and your headline about the BBC Rogers speakers. I have those speakers as one of the sets in my hi-fi system, and, although I check supposedly finished mixes on them, I don't use them as studio monitors.

(2) You need to tell us what type of material you intend to use the pre-amp for, the microphone(s) you will be using with it, the A-D converter that you have and also some information about the acoustics of the room you will be recording in.

(3) It's not possible to comment usefully on the Glensound mixer until we know the answers to (2).

I'll add this... What is your idea of a preamp? From what you've mentioned, it sounds as if you might be confusing a preamp with a power amp. If you were to explain to us what it is that you want to do, and hope to accomplish, we could help you a lot easier than this back and forth dialogue where you just repeat the same questions without answering those that were presented to you.

If this is perhaps due to a language barrier ? we do have a core member here at RO who speaks and writes French.... let us know if this is part of the difficulty in understanding you.

Welcome to RO.

Dear Sir,

i am perfectly fluenty in English, having grown, up there. Thank you very much.

My purpose was stated in my previous email. I am using Rogers LS 5/8 with quads 405 and looking to find the right pre-amp that would drive them in the best way.
My question is are there any alternatives to the typical consumer market hi-fi, where you end up paying for the name and not for the quality of the sound. As I am not an engeneer I need your help. For example it uccured to me that I could use an old analog Mixing desk, but this seems not to be useful to bring out beautiful sound. So what professional pre-amp or pre-amp alternatives would the panel recommend.

Many thanks in advance

Kind Regards

Alexander

Am I right in saying you want a pre-amplifer to feed the inputs of your Quad 405 hi-fi amplifier? If so, this is all about a hi-fi stereo pre-amp with selectable inputs, tone controls, RIAA equalisation etc, and I'm sorry to say we don't deal much with that sort of equipment in these forums.

In terms of specification, the Quad 405 needs a signal level of only about 500mV unbalanced for full ouput, so practically any hi-fi pre-amp would drive it, and may even have to be attenuated so as not to overdrive with clicks and pops that could damage your Rogers loudspeakers.

We would be happy to help you at the technical level, but you may have to ask elsewhere for subjective opinions on what the best makes and models of hi-fi pre-amp are for your application. One thing that I can say, however, is that your Glensound mixer is not suitable for this task.

Thank you very much, Boswell !
My cd player has balanced outputs and I am looking for preamps with balanced outputs as well. This limits the choice of pre a!o gear to McIntosh pre amps which have such outputs. Were I to use a non balanced pre amp do you think a unbalanced to balanced transformer would be good or is the adding of more extra gear not the best solution ?

What you say about the Quads is worrying, how can I prevent the damage ? Do you think there is any way of modifying the Quads or getting the Quads 520 to drive the Rogers ( the 520 has 100 w per channel ).

Any ideas welcome !

Thank you very much

Alexander

I don't understand why you would need a pre-amp with balanced outputs to drive the Quad 405, as that has unbalanced inputs. The need for signal balancing in domestic use is pretty much restricted to low-level signals (from microphones), long distances (from house to a shed at the bottom of the garden) or electrically noisy environments (other half's manicure set).

When you have settled on a pre-amp to drive the Qaud 405, the best way of reducing the risk of damage to the loudspeakers is to put simple attenuators between the pre-amp output and the amplifier input. These are not expensive to buy, or are even cheaper to make. It's not possible to give the details of the attenuators until you know exactly the model of pre-amp you would like to use.

do you know if the Rogers can be driven with the 502 quads, which I find are much superior ?

vonrozen, post: 434083, member: 49120 wrote: do you know if the Rogers can be driven with the 502 quads, which I find are much superior ?

I'm not trying to step on Bos's toes here... he's been more helpful than anyone else here on this topic, and if he has more advice for you, or can answer more of your questions, then that would be great...

But... RO is primarily an audio recording/studio forum; mics, digital recording, studio monitors, mic pre's, room acoustics, mixing consoles, etc..

I'm certainly not kicking you out, or even suggesting that you leave, either. We welcome all new members, and you're welcome to stay for just as long as you like. :)

But, you might end up getting more responses, and more answers to your questions, if you considered visiting a forum where home hi-fi is the focus and specialty.

http://vintagehifi.audio/index.php

http://www.whathifi.com/forum/hi-fi/vintage-hifi

link removed

FWIW
-d.

vonrozen, post: 434083, member: 49120 wrote: do you know if the Rogers can be driven with the 502 quads, which I find are much superior ?

The Quad 405 is a 100W/channel power amp designed for the domestic market. It has an input sensitivity of 500mV rms for rated output. The Quad 520 (not 502) is a rack-mount 100-150W/channel amplifier aimed at the professional market. It also has an input sensitivity of 500mV rms for rated output, but was available with balanced inputs as an option. It's not clear from your posts whether you have both of these amplifiers, and if you have the 520, whether it has the balanced input option.

There should be no difference between the two different amplifiers when it comes to driving the Rogers loudspeakers. Your difficulties seem to lie in choosing a suitable hi-fi pre-amplifier.

Sure, but as you know the line between a professional approach to HiFi and studio gear can be blurred.
The Rogers come from an engener of the BBc and were chosen for their precision and for being monitor speakers.

As you know, normal HiFi gear is often badly constructed, GH e sound is sweetened and devoid of its reality. Therefore my interest is more in the technical side and in having the best possible reproduction of the sound. Hence my questions. I think, if I do not get lucky here I will simply ask aa sound engineer friend of mine to build me 2 amplifiers for the Rogers with enough power and the sort of sonority you would get in aprofessional ampkification.

HiFi forums are often populated by bored who spend hours comparing subjective opinion on sound with little or no idea about how to change or later things on the electronic or acoustic level.

Question: what do you think about the effectiveness of the ballanced in - line attenuators ?

Kind Regards
Alexander

Thank you Boswell,

Great answe and thanks for the advice on the 520 amps ! The problem would be in how to connect them as , I think the Quads 405 are specifically modified for this purpose. I will investigate this .

Thanks again

vonrozen, post: 434101, member: 49120 wrote: Question: what do you think about the effectiveness of the ballanced in - line attenuators ?

They attenuate, so I'm not sure what you mean by "effectiveness".

Don't get hung up on signal balancing in this situation. You can buy or make a suitable attenuator to sit at the input of whichever Quad amplifier you have or you intend to acquire, and for your usage it will make no difference to the sound quality whether the attenuator is balanced or unbalanced and how it is constructed.

My offer of designing you an attenuator that you can build yourself or have built is still open. However, no designer can work without a specification, which in this case is still missing the output details of the driving equipment and the input details of the driven equipment.

vonrozen, post: 434101, member: 49120 wrote: HiFi forums are often populated by bored who spend hours comparing subjective opinion on sound with little or no idea about how to change or later things on the electronic or acoustic level.

I wasn't aware of that, thanks for shedding light; but I suppose it only makes sense; there's quite a bit of subjective opinion in studio engineering and gear, too.

As mentioned, You're welcome here for as long as you like, I hope you decide to stick around, and I hope you can benefit from the brain trust here - although it appears as though you would be a valuable addition yourself to that knowledge base, for others to benefit from your knowledge, too. ;)

-d.

I've just read through this and I have to assume that the intended use for your system is domestic Hi-Fi and not really anything to do with recording per se.

If I understand this correctly you have Quad amplifiers (405 or 520 etc.) and as Boswell says these are quite adequately driven by an unbalanced input and there would be no sonic benefit to using balanced inputs. You do however say you have a CD player with balanced outputs so I have to presume your comments regarding balanced signals relate to this and therefore it is not balanced outputs from a pre-amp that you are looking for but balanced inputs.

Is this correct? Either way, in the domestic environment, there is nothing to gain sonically by using balanced outputs from the CD player and unbalanced inputs could easily be used.

If all this is correct, your question seems to boil down to asking us for a recommendation for a pre-amp to use in your Hi-Fi. Before I say more, can you please confirm that this is a reasonable interpretation of your requirements?

Alexander - I've done a bit more digging on the original BBC LS5/8, so I have to ask: do you have the AM8/16 crossover networks for your speakers? These speakers were designed to be driven bi-amped, so you would use one Quad 405 (or maybe the 520) to drive each speaker with the pre-amp driving the crossover and the inputs of the two amplifers driven from the two crossover outputs.

Hello guys,

how would you rate the Rogers 5/9 then, in comparison with the 5/8 as far as music reproduction goes, color and precision ?
I know that it is hard to compare thel since the 5/9 is passive, but would be keen to hear your opinions

Alexander

You are encroaching a rather esoteric corner, and questions like that, although perfectly valid, are getting into the realms inhabited by other forums and away from the core expertise of Recording.Org.

In my domestic hi-fi system I have the next size down BBC monitors, but in my dealings with the BBC I have heard many types of material on the original (non-Rogers) versions of their large monitor speakers. This means I can't really comment usefully in answer to your question, but there's a chance that others here may be able to offer some opinions.

Almost a lifetime ago I was trying to decide which speakers to construct for the new Hi-Fi I was building (on a student budget hence mainly self built). This was around the time the initial LS5/8 design was published. They were (and still are) excellent speakers but I finally decided to go with the Bailey designed transmission line design (the second design he published). I still have them and they were recently pushed into service for a garden party and even nowadays there were comments about the "excellent sound quality"! They are more limited than the BBC design as the driver units I chose limit the power handling to around 50 watts. In terms of volume, that's not a lot of difference to 100 watts though. One day I'll get round to putting the veneer on them - honest!

As with all things Hi-Fi, you pay your money and make your choice. Unusually with the Hi-Fi fraternity, many then seem to spend most of their time trying to convince everyone how their particular choice is simply the best! I've never had any time for such debates, I prefer to listen to the music...

Hello guys,

finally I have acquired the Rogers Ls 5/8. The Quads 405 and 405-2 ( both BBC modified version ) are indeed XLR ballanced outputs.
The speakers are great, but the humm and hiss are considerable. What do you do ? Is it a amplifier problem ? What can be effectively done to combat it ?

Any info appreciated.

greetings from Paris.

Alexander

You presumably have the AM8/16 crossover network at the inputs of the power amplifiers, but is it fitted internally in the amplifier chassis or is it an external unit? If external and you replaced it with short-circuited XLR plugs (pins 1,2,3 all connected together), does this make any difference to the hum and (separately) the hiss?

A small level of hiss on these older Quad amps is normal, but excessive hum can indicate that the large electrolytic capacitors in the power supply section need replacement.

i hops this explains it better !
the configuration is inside

Would an in -line attenuator / tranformer help to ged rid o the noise ? for example :

http://www.ekmpowershop16.com/ekmps/shops/rothwellaudio/balanced-in-line-attenuators-3-p.asp

or

http://www.jensen-transformers.com/product/pi-xx/

Possibly, but that's a bit further on yet.

Your photos show you have the production versions of the amplifiers with the AM8/16 cards mounted internally and with inputs on standard XLR 3-pin sockets. That means you should be in a position to try shorting plugs in these sockets to see what effect that has on hum and noise. The result I would expect is that the hiss drops to a low level but the hum stays much the same.

Dear Boswell -

I am sorry that being stupid I do not understand what do you mean by : "to try shorting plugs in these sockets" - could you explain better, please ?

Thank you very much

Alexander

It's what I was describing in post #24 above: an XLR plug that has all 3 of its pins connected together so that the two signal lines are connected to ground.

if you have a photo or a link to a photo /website showing what it is it would help... sorry to be so slow

you mean this ?
http://www.neutrik.com/en/xlr/xlr-cable-connectors/fxs-series/

vonrozen, post: 435321, member: 49120 wrote: you mean this ?
http://www.neutrik.com/en/xlr/xlr-cable-connectors/fxs-series/

Not quite, no. That one has only pins 2 and 3 shortable via a switch, not pin 1 in order to preserve phantom power. I was trying to find a photo of an XLR plug wired with all three of its pins connected together, but it's been very difficult.

thanks so much for trying, if you do find it I would be grateful - and will implement your adbvice with great audio-joy !

Dear Boswell -

I am sorry to trouble you, I have been somewhat deceived by my seller and have paid 2 900 € for 2 Rogers that are full of problems. Therefore, I would appreciate any help and advice you could give me . I have attached some photos to illustrate my points:

LEFT ROGER
1. crossover is new
2. tweeter is the old Audax 1003 tweeter
3. Sound is dull, high instruments are hardly audible
4. Tweeter 's hum can be heard at 1m
5. big loudspeaker has been replaced (?) , the plastic is "even", without any porous structure inside,
6 the distance between the membrane glued to the support is not always regular ( sometimes 1cm, sometimes 2 cm) / there is a slightly "yellow-ish" trace as if it has been glued.
7. the loudspeaker has connection contacts facing the bottom of the speaker

RIGHT ROGER
crossover is od and leaking
2. tweeter is more recent : Audax TW034X0
3 sound is sharp and crisp
4. Tweeter's hum can not be heard at 1m
5. big loudspeaker seems to be of origin, the plastic a little porous ( tiny bubbles inside) ,
6. the distances are even everywhere / no traces of any "glue"
7. loudspeaker has connection contacts facing top of the speaker

Questions:
- where to buy the tweeter and cross-overs ?
- could you send me a picture of how a good membrane and crossover driver should look like ?

Thank you very much ,

and again, my sincere apologies for disturbing you.

Attached files

Sorry, I simply panicked ! Apologies. I will replace the tweeter and see what I can do to recap and tune the filters !

OK, and good luck!

I would not replace the capacitors in the two crossovers unless you have specific evidence that they need replacement. The ones shown in your photos are not the electrolytic type used for power supply rail decoupling that are known to leak electrolyte, lose their capacitance value and increase their ESR (equivalent series resistance) with age.

Thank you, Boswell !
I owe you at least one good bottle of Bordeaux vine !

vonrozen, post: 435434, member: 49120 wrote: Thank you, Boswell !
I owe you at least one good bottle of Bordeaux vine !

Nice, thanks! Let me know when, then you start pouring it into the internet router at your end and I'll hold a capture glass under the internet router at my end.

I am serious, your help is very much appreciated ! You are welcome to tell me more about what you do in a private message and if I know of any potential clients for you I would be happy to direct them to you.

After analysing the sound of the speaker I think i should replace the capacitatrs and transformer with new ones - do you happened to know, by any chance, what these capacitators are and what the transformer is called - so that I can obtain identical or better ones ?

Kind Regards
Alexander

( now its 2 bottles , at least. )

Dear Boswell –

Do not worry about it – I will simply buy the same components.

Do you think on the side of the high frequency speaker I could anything better than the recommended Audax TWO 34x0 ?

There must be more precise sounding tweeters that coul be used ?

here are the original BBC specs:
Nominal Power RMS
70W

Nominal Free Air Resonance Fs
800 Hz

Sensitivity (2.83V/1m)
93.0 dB

Nominal Rdc 5.3 Ohm

Total increase in acoustic output 6dB

Crossover frequency 1-2 KHz

Ideas welcome !

Thank you very much indeed

Alexander

Well, as I mentioned, I would be reluctant to replace anything until I had evidence that it needed replacing. Physical damage to a loudspeaker cone is sufficient evidence to re-cone or replace the actual loudspeaker, but, even then, it may not get the units sounding as good as a pair as they once did.

I speak from experience here. Some years back, the bass unit in one of my BBC monitors (Spendor BC1s) started to crackle on large excursions. I found that the cone surround had weakened, causing the voice coil under gravity to scrape against the magnet at higher drive levels. Rather than have the unit re-coned, I bought a new bass driver of the same colour code. That speaker is now fine, but it does sound very slightly different from the other unit.

If you are thinking of replacing any of the drive units, I personally would not buy anything different from the original types, although a pair of modern versions of the type would probably work OK.

I fear that the internet forums are filled with people saying they re-wired their BBC monitors with silver wire or they have installed crossover capacitors immersed in oil, but I'm rather more of a pragmatist. I've heard very many examples of BBC monitors and they are all different, although the differences can be very subtle.