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Rogers BBC monitoring speakers LS 5/8 bi amplified with Quads 405

Discussion in 'Preamps / Channel Strips' started by vonrozen, Nov 26, 2015.

  1. vonrozen

    vonrozen Active Member

    Hello everyone -

    2 easy questions :
    1. Which pre-amp would you recommend that has balanced inputs and a nice warm sound

    2. Would there be any point in using a nice old Glensound mixing console as a pre-amp or would i get nothing out of it soundwise ?

    Thank you so much, dear friends

    Kind Regards

  2. Boswell

    Boswell Moderator Distinguished Member

    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.
  3. vonrozen

    vonrozen Active Member

    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 !
  4. Boswell

    Boswell Moderator Distinguished Member

    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"?
  5. vonrozen

    vonrozen Active Member

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

    Thank you

  6. DonnyThompson

    DonnyThompson Distinguished Member

    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.

    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.
  7. vonrozen

    vonrozen Active Member

    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

  8. Boswell

    Boswell Moderator Distinguished Member

    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.
  9. vonrozen

    vonrozen Active Member

    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

  10. Boswell

    Boswell Moderator Distinguished Member

    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.
    kmetal likes this.
  11. vonrozen

    vonrozen Active Member

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

    DonnyThompson Distinguished Member

    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.



    link removed

  13. Boswell

    Boswell Moderator Distinguished Member

    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.
  14. vonrozen

    vonrozen Active Member

    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
  15. vonrozen

    vonrozen Active Member

    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
  16. Boswell

    Boswell Moderator Distinguished Member

    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.
  17. DonnyThompson

    DonnyThompson Distinguished Member

    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. ;)

  18. MrEase

    MrEase Active Member

    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?
  19. Boswell

    Boswell Moderator Distinguished Member

    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.
  20. vonrozen

    vonrozen Active Member

    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


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