RB-1090 questions

**Aussie Geoff** · 21 January 2005, 06:10 Friday

Hired Goon,

The RB-1090 is a very high current device and benefits from a quality power cord (read heavy gauge with a nice tight fitting IEEE plug). I buy mine from the UK from http://www.audusa.com/ - the Eupen brand) but you can get your own even make your own.

Providing the RB-1090 is ventelated sch as an open rack with some space above (you can leave it on all the time - it barely gets warm and you would need to be seriously abusing it to get it hot...

How are you enjoying yours? Are you worrying that it is not right or are these just general - "lets get the best out of it" questions...

Geoff

**hired goon** · 21 January 2005, 07:56 Friday

G'day,

Originally posted by Aussie Geoff

How are you enjoying yours? Are you worrying that it is not right or are these just general - "lets get the best out of it" questions...

I haven't had a chance to really test it out yet. I'm still figuring out the best way to hook everything up. The RB-1090 has double binding posts, and the VAF I-93 allows tri-wiring, so it's a bit of an experiment at the moment.

I haven't powered the speakers with my old amp, so I haven't got any reference point for the RB-1090s. Apparently the speakers have only had a few hours use before I bought them, so there may be a bit of a break-in period before I can really comment.

I may still get the HTM1 I spoke of earlier, as well as a pair of N805s, and decide later on whether to go with VAF or B&W.

--Geoff

**Raphie** · 21 January 2005, 10:29 Friday

Owh Goon, that's on my wishlist as well, can you post a picture of the beasts?
How is the improvement in sound when going from 1095 to 1090? > Very curious

**Aussie Geoff** · 21 January 2005, 11:14 Friday

Hired Goon,

In terms of centres with the I-93 (off topic I know). I would seriously consider getting VAF to make you a special centre using matching midrange and treble drivers to the I93. for about $2700 Aussie you can get a redesigned full size I-66 with speakers centred etc. Contact there lead speaker designer Simon Wilde (I can give you his Email)... Perfect match to the I-93

Geoff

**hired goon** · 21 January 2005, 15:55 Friday

G'day,

Originally posted by Raphie

that's on my wishlist as well, can you post a picture of the beasts?

What's on your wishlist? The 1090, or the speakers?

Originally posted by Raphie

How is the improvement in sound when going from 1095 to 1090? > Very curious

As I said, I haven't driven the same speakers with both amps, so I can't get a reference point yet. In fact, the 1095 can't drive my new speakers.

Originally posted by Aussie Geoff

...I would seriously consider getting VAF to make you a special centre using matching midrange and treble drivers to the I93. for about $2700 Aussie you can get a redesigned full size I-66 with speakers centred etc...

I asked VAF about this earlier, and they can put an I-66 on its side for use as a centre speaker, though I'm not sure that an assymetrical driver arrangement (W MTM) is best for a centre speaker. Maybe it is -- I dunno. I'll have to ask VAF again, if I decide to keep the I-93s.

--Geoff

**Spearmint** · 21 January 2005, 16:56 Friday

HG

Here is a new product from Jaycar, which may help....

Remote mains outlet

The only downside is the current this unit can handle.

I use a similar unit by HPM, which is rated much higher just can't find it on their site anymore. With my unit I learnt the on/off into my programmable remote, so it works in a macro.

**hired goon** · 21 January 2005, 18:37 Friday

G'day,

Another question:

The back of the RB-1090 states "combined load 4 ohm minimum", and RB-1090 owner's manual states that "[the] nominal impedance of the loudspeaker(s) connected to the RB-1090 should be at least 4 ohms", but it also states that "[high] current capability allows the RB-1090 to drive difficult speaker loads with ease, including 2 ohm speakers".

So what's the official minimum? 4 ohms, or 2 ohms?

--Geoff

**MoonSpin** · 21 January 2005, 18:41 Friday

The RB-1090 has an even better build than the RMB-1095, so for 2-channel you will hear a very nice difference. It certainly was for me. I'm very pleased with my RB-1090, one of the best sounding amps I have right now, better than a couple of amps I have that cost much more than this one but still the RB-1090 even has a better build quality than those! Get that!

The RB-1090 comes with a standard power cord and I've found it does very well. I replaced it with an expensive one but didn't noticed any difference, so I borrowed a friends even more expensive power cord and still couldn't hear a difference. I put back the standard power cord and sold the expensive one to a guy on ebay.

I would not recommend leaving the RB-1090 on at all times, this means many power on hours that shorten the life of compoents as described in detail at many of the amp manufacturers website that you may want to read. Some people like to debate this, but I know I would not do so or want to buy a used amp from some one that left it powered-on at all times! No thanks!

The RB-1090 does very well with sounding good when you first turn it on, sounds great. It sounds it's best after about 20 to 30 minutes but the difference is so slight it will be hard for you to hear much of the difference unless you listen very very closely. It's a great amp, you will enjoy it indeed!

**hired goon** · 21 January 2005, 18:48 Friday

G'day,

Originally posted by Spearmint

The only downside is the current this unit can handle.

An interesting option -- the JayCar website mentions that this unit can handle 1000w, and the RB-1090 is rated at 800w (according to the back of my unit, and the owner's manual). I think the actual power consumption is 1200w, however (I recall a thread a while back on this issue). So I guess the JayCar unit isn't suitable :-(

... which leads me to another question: the RB-1090 owner's manual mentions that "the RB-1090 is capable of high power levels, in excess of 400 watts per channel into 8 ohms and 700 watts into 4 ohms". But just before this, the owner's manual states that "the RB-1090 [can] drive difficult speaker loads with ease, including 2 ohm speakers". So does anyone know how much current goes into a 3 ohm load? A 2 ohm load?

--Geoff

**Spearmint** · 21 January 2005, 19:12 Friday

Originally posted by hired goon

G'day,

An interesting option -- the JayCar website mentions that this unit can handle 1000w, and the RB-1090 is rated at 800w (according to the back of my unit, and the owner's manual). I think the actual power consumption is 1200w, however (I recall a thread a while back on this issue). So I guess the JayCar unit isn't suitable :-(

--Geoff

The power rating would be for both channels at full load, and for $40.00 why not give one a try, or if you can find a HPM one that would be better. If you know any guys with electrical experience you get a simple box made up with a plug & socket on either side with a 12v relay inside to do the switching, this relay could be controlled via a 12v trigger.

I also remember some years ago Electronics Australia produced a design for a 240v switch controlled via an audio signal i.e. similar to the auto switch on with sub plate amps. Now Dick Smith, Jaycar, and I think Altronics used to stock most of the EA kits and may still have these kits available.

All I am saying is there are ways around your little dilemma, in the US they have power boards with these smarts built in, here is OZ we need to be a little more creative.

Mate if things get too bad have the missus switch the amp on/off on one of her trips to the fridge to get you another beer. :T :B

**Cracking Oboe** · 21 January 2005, 19:32 Friday

Hired Goon,

Stereophile (Jan 2000) attempts to explain the inconsistency between the formal specs and what is stated in the manual (4ohms vrs. 2ohms). They have a quote from Rotel’s Mike Bartlett.

http://www.rotel.com/reviews/pdfs/poweramps/RB1090_Stereophile_Jan00.pdf

Because of the amps “rated 4 ohm load" they did not test power output at 2 ohms.

The Rotel site also has the report from inner ear magazine which stated that the RB 1090 is stable down to 2 ohms where it delivers peak power at over 1,000 watts. (Kinda like what Audio magazine said in the review of the 1095).

Cracking!

**Aussie Geoff** · 21 January 2005, 23:53 Friday

Hired Goon,

I asked VAF about this earlier, and they can put an I-66 on its side for use as a centre speaker, though I'm not sure that an assymetrical driver arrangement (W MTM) is best for a centre speaker.

They did a special design for me that they have since sold to several others that makes the speaker layout symetrical, tweeter centred etc... PM me if you want the full contact details etc of the guy there that did it..

Geoff

**JDH** · 22 January 2005, 03:49 Saturday

Originally posted by hired goon

G'day,

I bought a second-hand RB-1090 yesterday, and have a couple of questions:

The seller couldn't find the original power cord that came with the amp. I'm currently using a standard power cord. Is this adequate, or did the 1090 come with a higher quality power cord? Does it deserve a better power cord?
For WAF, I have my RSP-1068/RCD-1072/RMB-1095 connected via the 12-v trigger so that they can all be powered on/off via the remote. There's no 12v trigger with the RB-1090, and I'd prefer not to have others turning it on and off manually. Is it safe to leave this amp on continuously? My RMB-1095 can get very hot, and I'm wondering how the RB-1090 will fare over longer periods (especially during the hot Aussie summer).
Has anyone found that the RB-1090 needs a "warm-up" to sound its best ? I recall my Rotel dealer mentioning this in regard to the RB-1090, but I haven't noticed any change in sound.

--Geoff

Geoff,

In terms of having no 12V trigger on the RB-1090, this is not a problem if you have an hour or two to spare to build an external device to turn your amp on/off in the same way as what is built into the current power amps.

What I did was buy a small plastic box from Jaycar a 240V lead, 240V 10A relay, 12V socket etc. Basically within the black box is a 10A, 240V relay which is triggered from the 12V Rotel pre-amp, this in turn closes the relay to turn on any high current 240V device. I use this to turn on/off my RPTV, active subwoofer and and a few other hifi components. If you want, PM me with your email address and I can send you a photo of what I made and some tips on making one.

There is probably something similar comercially avalable you can buy, but it should be cheaper to make one yourself. I also think Jaycar sell a device in kit form which senses current flow and closes a 240V switch ie. in this case say when the device senses that the pre/pro is on it turns on the RB-1090.

You could also build the relay with switch into the RB-1090 but this would void your warranty if anything is still left on it.

jaycar.com.au

https://www.jaycar.com.au

Regards,

John.

**JDH** · 22 January 2005, 09:22 Saturday

This is the link to the kit that would help in automatically tuning on/off your RB-1090 + what ever else your want to automate with your RSP-1068. The one I made however is even simpler.

http://www1.jaycar.com.au/productView.asp?ID=KC5363&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=588

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