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doody
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Monoblocks tweaks

Hi there,

I am new to this forum and also new to this high end stuff, got a question and hope one of the experts can answer, I have 2x Roksan monoblocks and Roksan pre amp, I am not sure where to position the monoblocks in relation with the speakers, shall i just leave them on the equipment rack together with the cd player and the preamp, or get a long interconnect and have each monoblock by the loudspeaker?

regards

Kal Rubinson
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Re: Monoblocks tweaks


Quote:
Hi there,

I am new to this forum and also new to this high end stuff, got a question and hope one of the experts can answer, I have 2x Roksan monoblocks and Roksan pre amp, I am not sure where to position the monoblocks in relation with the speakers, shall i just leave them on the equipment rack together with the cd player and the preamp, or get a long interconnect and have each monoblock by the loudspeaker?

regards

I vote for the latter. IMHO, one of the advantages of using monoblocs is that you can minimize your speaker cable runs.

Kal

mmole
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Re: Monoblocks tweaks

Kal: That's interesting but then you're maximizing your interconnect run. Why is that a better solution?

Kal Rubinson
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Re: Monoblocks tweaks


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Kal: That's interesting but then you're maximizing your interconnect run. Why is that a better solution?

It is the well-defined (and linear) impedances and the irrelevance of power losses in the interconnects that make them more like transmission lines and more tolerant of extended lengths.

That also fits with my subjective experience (although there have been exceptions).

Kal

Jan Vigne
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Re: Monoblocks tweaks

I agree that long interconnects are typically the best way around the situation. However, not knowing the output impedance of the pre amplifier, there might be a problem running long interconnects. I am guessing Kal knows whether the Roksan is suitable to driving long interconnects. An output impedance above 500-600 Ohms would make me reconsider the options. If the pre amp doesn't employ output buffers I would also tend toward long speaker cables since the output impedance will not be consistent at all volume levels. And, of course, what interconnect is chosen would have to be taken into consideration. Cables with high capacitance wouldn't be advisable.

doody
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Re: Monoblocks tweaks

Thanks for the replies, I checked the preamp specs, and impedence not shown, i coopied them below

Line Inputs 5 plus Tape
Input Impedance 47 kΩ
Line Outputs Tape, Preamplifier (x3)
Power Supply 350VA Ultra Low Noise Toroidal Transformer
10 Regulated Supply Rails
Frequency response -3dB, <0.5Hz

Kal Rubinson
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Re: Monoblocks tweaks


Quote:
I agree that long interconnects are typically the best way around the situation. However, not knowing the output impedance of the pre amplifier, there might be a problem running long interconnects. I am guessing Kal knows whether the Roksan is suitable to driving long interconnects. An output impedance above 500-600 Ohms would make me reconsider the options. If the pre amp doesn't employ output buffers I would also tend toward long speaker cables since the output impedance will not be consistent at all volume levels. And, of course, what interconnect is chosen would have to be taken into consideration. Cables with high capacitance wouldn't be advisable.

Certainly. Since I have no knowledge of the Roksan's output stage/capabilities, my comments were generic and assumed a competent, low-impedance output with sufficient drive.

Kal

Jim Tavegia
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Re: Monoblocks tweaks

Are the Roksan's outputs balanced? If they are then a longer run would probably be OK. If single ended then as others have mentioned care might be in order.

If you do not have to buy new cables, experiment and see if you can hear differences that matter to you. Tiime to put on your "Dexter's Laboratory" white coat and do your scientist stuff.

Appears you have some very nice gear to enjoy.

doody
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Re: Monoblocks tweaks

Jim, thanx for the reply, the roksan is not balanced, actually when i bought this system, it was all based on reviews, never had the chance to audition it. somehow it is a disappointement, but i think it is a bit early to judge i am trying to figure out how to tweak it and run in the speakers

regards

Monty
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Re: Monoblocks tweaks

Since you are using both the Roksan pre and the Roksan amps, I would be very surprised if they weren't complimentary in being able to run some interconnects of at least 3 or 4 meters if needed.

If your electronics and cables are new, it's not unusual for them to need a couple hundred hours of run time to open up and show you what they can do. I wouldn't hesitate to leave them powered on and playing music for a week solid before I became critical of the sound.

Apart from that, there is no substitution for proper speaker placement within your room and in relation to your listening position. I mention that only because you mentioned being somewhat new to serious sound. That's a really big deal in getting the sound you heard at the dealer to also arrive in your room.

Jan Vigne
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Re: Monoblocks tweaks


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Since you are using both the Roksan pre and the Roksan amps, I would be very surprised if they weren't complimentary in being able to run some interconnects of at least 3 or 4 meters if needed.

You would think it might be set up to run long interconnects but that might be an assumption that isn't worth chancing. The dealer where the equipment was purchased should have this sort of information. If not, then I would call Roksan (or their district rep) and ask for specifics. You'd kind of hate to invest in long interconnects of any quality only to find out Roksan never intended the cables to be more than 2 meters long. I would apply the same sort of fact checking to whatever cables I decided to buy. Make certain the manufacturer states the cables do well with long runs. High capacitance cables run over a long length can not only give poor sound quality but they can cause the amplifier to oscillate which could result in damage to the system. The cost of a phone call is cheap compared to the cost of repairs.

Monty
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Re: Monoblocks tweaks

Very true, yes. If the user could post which models he has, we could probably look-up the specs and determine if the pre and amp can handle long ICs and/or long cables.

lightspeed
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Re: Monoblocks tweaks

Hello,

I'm new to this audio forum although I participate in a local one in Canada, where I live. I've not long ago posted an answer to the question, "which is the lesser evil, long IC's or long speaker cables?" and I thought it might be helpful to offer that same answer here -- although I can tell from previous posts that many here are way ahead of me (so no offense, I don't mean to imply that I know more than anyone else).

Anyway, as stated already, the answer depends on one's components and cables.

For the preamp, it depends on the output impedance. For the IC's, it depends on their capacitance.

My Transparent IC's have a capacitance around 350 pf per meter and my Purist IC's are around 400. These are in the range of standard capacitance values for most interconnects. So a long run of say, 8 meters of Purist interconnects (~25 feet) could introduce up to 3200 pf of capacitance.

If the preamp's output impedance is on the high side, say, over 600 ohms (like many tube pre's), and if the interconnects have very high capacitance (or are very long), the frequency response on the top end will be attenuated a little.

Hence the claim that some high-capacitance interconnects are merely tone controls. That said, in my example with the 25 feet of Purist interconnect driven by the average high output impedance tubed preamp, we are only talking about perhaps 3dB down far above 20 kHz, so my neighbours dogs might hear the rolled of highs but I wouldn't -- although it could be measured. In the real world, chances are some other component in the system will roll off earlier anyways.

Rule of thumb with long interconnects: To preserve the high frequency response, choose an interconnect with low capacitance if the preamp's output impedance is high.

Unlike the case with interconnects, capacitance is less a problem with speaker cables because they are (generally) dealing with far lower impedances -- but here resistance can have an effect.

Whereas interconnects aren't affected much by resistance (e.g. if the preamp has 1k ohm output resistance, adding a few ohms with the interconnects won't matter) -- speaker cables with high resistance (say, over 5 ohms) will audibly lower the amp's damping factor, given your average 8 ohm speaker.

In general, the longer the speaker cable and the smaller the gauge of the wire, the higher the resistance of the cable (and thus the lower the damping factor of the amp).

One point about a high output impedance preamp: the preamp circuit might get around the problem by using a buffer amplifier which has a lower output impedance to drive the interconnects. Some preamps might use a transformer to do the same thing -- but then you are trading off the advantages of impedance conversion with the signal degradation that a transformer might cause (and possibly same with a buffer amp).

There is also the issue of input impedances, but this post is too long already to get into that.

Summary:

In general, go long interconnects/ short speaker wire if you have:

- high resistance speaker cables (light gauge),
- or an amp with a low damping factor,
- a preamp with a low output impedance,
- and interconnects with low capacitance.

In general, go long speaker cable/ short interconnects if you have:

- low resistance speaker cables (heavy gauge),
- or an amp with a high damping factor,
- a preamp with high output impedance,
- and interconnects with high capacitance.

I hope that helps someone. I've had great pleasure reading Stereophile for many years (and had the pleasure of meeting JA once at a show), and I look forward to participating in these forums.

Jeff Wong
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Re: Monoblocks tweaks

lightspeed - What a great 1st post! Welcome to the forums.

lightspeed
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Re: Monoblocks tweaks

Thanks for the kind words and warm welcome, Jeff!
It's a pleasure to be here.

cyclebrain
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Re: Monoblocks tweaks


Quote:
It is the well-defined (and linear) impedances and the irrelevance of power losses in the interconnects that make them more like transmission lines and more tolerant of extended lengths.
I would think that at the lower signal levels and lower loads (higher impedences) in line level signals, noise would be a bigger concern with long lengths than with the high level, high load signals at the speaker connection.
As for the transmission line analogy, at audio frequencies I don't think that it would apply.
That also fits with my subjective experience (although there have been exceptions).

Kal

hermanvis
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Re: Monoblocks tweaks

For listening tests I have performed it seemed there was no such thing as too large a speaker cable gauge, conversely there shoud be no such thing as too short a length. So I favor moving the amps close to the speakers.

Cardas makes a low capacitance cable that virtually all pre-amps should be able to drive, additionally he claims there is no change in the sound of this cable at different lengths. I think he calls it his neutral reference, there's also a golden reference at 12pF/foot. These cables are described as less warm than the higher capacitance cables he also makes. None of them are cheap and he has a good reputation for high quality.

Cables are worth a high investment in time because they will make that last bit of differnce in a truly enjoyable system vs. a so so sound. My experience indicates that in spite of insane prices, this is money well spent if the rest of your gear is good.

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