Yes grannyring your output impedance of your pre at up to 1kohm, (which by the way is not far off a 10kohm passive for drivability) should be fine for any poweramp with say 33kohm or higher input impedance. But you probably have gain in it also, it would be nice if you could configure it to have unity gain, if it stays stable, some opamps can be used as output buffers and are unity gain stable as well as being very low output impedance like 10-20ohms. eg OPA627. Cheers George |
Lightspeed is around 10kohm Grannyring, it mimics similar parameters as a 10kohm logarithmic potentiometer. So sources feeding it should be less than <1kohm, as I believe in the >10-1 ratio rule. And as for a tube amp and the Job not liking each other, it's not that they don't like each other it's the fact that there is too much gain, massive in fact, as Devilboy said way back about the Job "IMO, the 225's specs SCREAM passive" You be nutz to put a preamp with it that has gain. Remember what Nelson Pass said, (and he designs and sells active
Cheers George |
I’m sure if you used two of my or any passive pre’s in series the sound would be crap as well without using the Rothwell’s. I'm sure the Rothwell will be fine on the input of a high input impedance (>47kohm?) poweramp, if the pre before it had a low output impedance of below say <50 or a 100ohms. Cheers George |
It’s not that the Rothwell’s themselves can "change the sound in not such a great way" But what the Rothwell’s can do is change the perceived impedance as seen by the previous stage, as then not to have a good impedance match. This can mainly happen with a tube or passive preamps, most solid state preamps should not have this problem Cheers George
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0.75V sensitivity for full output! With all this gain and 94dB speaker why use a active preamp with gain?? Most sources give out more than 2v these days, even phono stages, and the Job I believe is 100kohm input impedance, all this is a perfect match for a passive pre such as the $49 Schitt Sys http://schiit.com/products/sys Then you will not have any hum or noise problems and as a bonus zero colourations that all actives have. Cheers George
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Grk: "Hi,I'm using the JOB to power Devore Nines and it is the most dynamic and best bass that I have heard from these speakers!" Hardly supprising, as most of the Devor range are very easy loads, that remains at or above 8ohms, and don't tax the amps at all, easily driven by 9 watts so Jazz Times say From Stereo living: "The Nines are among our best selling products. Needless to say they sound great but beyond that they are easily driven by any tube amplifier in our store. They will sound wonderful with an entry level tube integrated" From Jazz Times: "I had to call DeVore to tell him that these were the most outstanding speakers I’d ever heard in my home, a judgment made while listening with a modest nine-watt amplifier." Cheers George |
04-09-14: Klh007 The JOB 225 had sound stage and transparency/detail, at the expense of tone sounding leaner than the Veritas. This tonal balance has been stated by more than just by you Klh007, it was a trait that devilboy also heard when he used the Lightspeed Attenuator passive pre with it. As the Lightspeed is like a direct connection from source to poweramp, he preferred a preamp that made up for the Jobs lean character with something that augmented the lower registers or bought the tops down. Cheers George |
Quote from the Jazz Times review:Speakers can take up to several hundred hours of playing time to begin sounding their best. However, as soon as I had the Nines up and running, I had to call DeVore to tell him that these were the most outstanding speakers I’d ever heard in my home, a judgment made while listening with a modest nine-watt amplifier.Quote: From this review: http://jazztimes.com/articles/18496-devore-fidelity-the-nines-loudspeaker Cheers George |
No I have not heard them, and agree they may sound great on the Devore speakers as they are reviewed as being a very easy load and can be driven by a "quoted" 9 watt amp. On another forum a member measured the heat sink temp at 60c on a 23c day driving a pair Lennahan Audio ML-1 book shelf speakers at moderate level. http://www.lenehanaudio.com.au/index.php/products/ml1-loudspeakers/ml1-measurements.html They have an impedance curve and phase plot that is quite easy to drive, they are a little low in efficiency, but not abnormal for a book shelf. Recommended amps are from 20-300w for this speaker, not as easy as the Devores but not very difficult either. This kind of tested heatsink temp on a coolish day is too high, and the chassis forms part of the heatsink, which means the internal temp will be high also. Any increase in the ambient temp will increase the heatsink/chassis by the same amount. Electronics specifically capacitors won't like this kind of temp, and the junction of the output transistors will be even higher. Cheers George |
Sorry to come back again Genjamon, but you don't get it. With your very easy to drive speakers, this amp may I admit sound very good. I'm referring to those here and on other forums that spruik that this amp can do wonders on speakers that are harder to drive than yours, which is simply not the case. And potential customers need to know this and take it into consideration before buying one. Cheers George |
"Genjamon: Also, it's true the Maggie's would be a hard load." The Magie 3.7 is from what I have found out is very similar to the impedance of the 3.6. That is it's a benign 4ohm load, that even a good reciever will drive. From Absolute Sounds: "The speaker’s impedance is 4 ohms. Its load is essentially a resistive one; therefore, driving it doesn’t pose the loading problems" From Stereophile: http://www.stereophile.com/content/magnepan-magneplanar-mg36r-loudspeaker-measurements Cheers George |
