Your Joule from what I found only has 11db of gain. The AR is still only 12.5db, your problem is the speakers, but if your attached to them then.
You have 108db efficient speakers and an amp that has 100kohm input impedance and 29db gain, "which is perfect recipe for a 20kohm passive preamp", your line source/s should be fine into a 20k passive preamp.
And if you use phono, use a phono stage with gain of 50-60db that has low output impedance say <300ohms.
Cheers George |
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The attenuators mentioned by others here such as the Schiit won't work for you - they're unbalanced and you're using your Ref 6 in balanced mode. Talk to your dealer - he can install resistors on the Ref 6 input.
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Parts express has balanced attenuators, but if the dealer can install resistors to attenuate I think that would be a better solution. |
The only problem with in line fixed attenuators, is you don’t know what resistors they have used in series and to ground to get the attenuation.
This can ruin the minimum 1:10 input to output impedance ratio, could end up 1:2 or something, won’t hurt anything but may screw with the sound. |
This is my biggest fear when purchasing a new preamp. If you love those amps, which are special, I’d sell the arc and research a good match for the pass amps. Good luck. |
op
iirc audio research can take the ref line stages and alter the gain profile at user request for situations such as this
contact greg c their service manager |
What jjss49 said. If you are dead set on the Ref 6, let ARC modify it and do it right. They did my LS17SE. Took a bit, but it was done right and wasn’t a hinky “fix”.
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Don't see Miller replying to this one:
'Dimwit, your speakers are way too sensitive, concentrate on getting speakers with less than 87dB efficiency'. :-))
Crazy to ask AR to modify the piece. They would need to work out what to do and charge you $000s. And the amp would be unresellable after.
In any case, the big matching problem is not with the Ref 6.
You need to change the power amp or the speakers.
Changing the Ref 6 for a pre-amp that's flat with no gain will only partially solve the problem. Losing 12dB of gain will mean your volume tops out at position #(7 + 12/0.3), as each step is about 0.3db. That's #47 which is still less than halfway up to #103.
Having said that, I run a Ref 6 too. With Krell Reference 200s upgraded to 400w per side and Martin Logan CLX Anniversary specced at 90dB sensitivity but probably a bit less, the volume is certainly very full on at around #40-45 and I get enough differentiation from those 40 steps.
It wasn't so long ago when I upgraded to Ref 6 and vdH The Grail SB.
I calculated the system gain very carefully before diving in. I recommend others do the same. |
By using xlr interconnects your db output is 2 x as much ,the volume pot on the Joule also seems to be much less ,
with speakers this efficient did the dealer give you a 30day audition for comparability ? You should try a pr of rca interconnects , just to see how much gain and if thisis then suitable , if not the preamp is not a good match and needs to go
back ,or sell it , Don Sachs would build your custom preamp
to have ample gain , for I doubt the AR volume control is a shunt, resistive ladder type, Aron Sachs uses a A Khozmo which I have used several times , if you want a true top of the Line RaduTarta
builds DHT custom preamps using all top transformers and
can build to your amplifiers output for $5k you can have a preamp
with far superior parts quality.I know for not only do I know about
modding or upgrades for years ,but he is a 40 year expert in vacuum tube equipment SET amplifiers , and DHT preamps are by far the purest but. Incredible build quality and musicality ,even the exterior can be custom wood or metal and he uses several excellent brand volume attenuators , which can make or break
your preamp , for your speakers you have Waay too much gain
in all honesty you-should have agreat 8 watt set amp , your speakers use only 3-4 watts ,the gain is high ,any speaker with over 100 db efficiency , made for a high quality low power amp .
SSamps typically have too much gain send Nelson Pass a Email
See what he would do , his great 20 watt amps for around $4k
woould be ideal ,not 60wpc . Send Nelson an email he will help you things out . If you want a great vacuum tube preamp,or SET
tube amp Radu Tarta without any hesitation ,and per $dollar spent
by far the best parts quality ,for he builds each one by hand
and no dealer markup . You discuss what your budget max is
and then take it from there , do a search ,build quality for a life time at very fair prices.
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I had a similar problem. BHK Sig. pre > Jeff Rowland Monos > Spatial X-5's (97dB, 8ohms). The volume level was low but manageable, but I was having a lot of trouble with tube noise due to the gain of the preamp. Someone on the PS Audio forum suggested Rothwell balanced -10 dB attenuators and it worked like a champ. These go in the amps with the IC's into them. Very little noise and the volume level is now around 30 for casual listening, 50-60 for blowing the doors off. Rothwell also make -20dB attenuators as well if you need to go that far. Well made, reasonably priced, and no issues for me. |
FWIW I agree with markmuse. They are cheap and effective. Obviously they require another set of cables and you (as some others) might find them less than transparent). If you can they would be great in a tape loop. If you found you really liked them you could consider moving on to a mod in your pre-amp to do the same thing. I'm not familiar with the ARC 6 but in other ARC products it has been a simple and reversible change. You can always call and ask. |
You need to throw some gain away, obvious is to dump the preamp/s. And use a 10kohm passive pre so anything can drive it. (save for some silly high output impedance sources) (usually tube).
Forget inline attenuators, too much of a gamble, you never know if you have an impedance match or not, (unless you know how to measure them) because from what I was told they don’t state what series/shunt resistances they have used inside them
Cheers George
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You do have a gain problem because of the having to use balanced interconnects it gives you 12 decibels more gain than what you think 6 db from the pre amp and amp each that would give you 32 plus 18 which is 50 db of gain way too much on an avantgarde if you could hook it up single ended you would have 38 db of gain ant that would be ok on the avangardes i would think but maybe still a little too much but nothing like the 50 db you have now.
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Gain spec of Joule preamps in product lit are not accurate. I have actually measured many different Joule preamps.... in default shunt to ground volume control configuration, a Joule LA-150 has little bit more than unity (i.e a few tenth more than 0db IIRC) gain at max volume. Switching the preamp volume control jumpers to voltage divider got you around 6dB.
CheersRich
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Thanks all for the advice. As a first step, I am going to try the Rothwell Attenuators. If they work that’s great, if not then I am not out that much $. I looked into having AR modify the preamp but they say this can only be done on older models. If the attenuators don’t work then it’s going to need something more drastic ... preamp or speaker change. Unbalance interconnects are a non starter for me as I have a very long lead between amp and preamp ... and for reasons I won’t go into I can’t change this. I also discovered that my Lumin X1 DAC/streamer has an analogue volume setting of normal or low. The low completely takes care of the matching problem but there is a big change in bass volume ... which I can’t explain. Again, thanks to everyone who responded!
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