do i change the preamp or the speakers?

I recently acquired a set of Odyssey Stratos Monoblocs (w/ upgreaded cap) which i run through an Audible Illusions 2d with new tubes from AI. This set drives my Kef 104.2's. i use some streaming through an Adcom DAC but mostly i listen to vinyl on my Thorens TD 160 with Shure cart.

Before the Stratos arrived i was driving this Kef's with an older Bryston 3B and it was nice.

The Stratos betters the bryston in all ways but the Bryston was "brighter" and suited my listening tastes better when using the Kef's. This new combination is too warm for me. In fact i find the combo of the Stratos and AI sound better driving my IQ TED 400's which are a brighter speaker. I have also substituted my old NAD 1155 solid state preamp which is not the same class as the AI but the slighter brighter nature and the ability to adjust he tone and loudness for lower listening levels has me switching back and fort between the two preamps.

So the question i have is this. Do i change the speakers or do i shop for a replacement preamp.

if it matters, i am a fan of rock music.
The great thing about a tube preamp is that you can substitute the stock tubes with tubes of different sonic signatures. You can roll tubes to make your preamp have a different timbre, in your case you need tubes that would provide more air on top or a higher frequency extension.

Here is some good reading regarding the different manufacturers and the characteristics of their tubes. These are NOS tubes which would most definitely provide you with the sound you seek. One tube that comes to mind is a RCA Cleartop which has sounds open and airy on top.


BTW, while you are learning about NOS tubes, let your AI stock tubes burn-in for at least 60 hours before you judge them.
"So the question i have is this. Do i change the speakers or do i shop for a replacement preamp."

That's a difficult question to answer. I think you're right to be looking at those 2 components. The only problem is there are so many variables involved that the only way about it is to actually try different components in your system to see what works. I can't recommend speakers because its just too personal a choice and I don't know your current speakers well enough to know what direction to go. For a preamp, if you can find a VTL dealer, have a look at the 2.5 preamp. The dynamics are exceptional on that unit. You won't be giving up tubes either. That said, I would still try it first in your system, as there's no guarantee that it will fix your problem.
Good comments by the others. But before replacing anything I would first try increasing the capacitive loading of the phono cartridge. You didn't mention which Shure cartridge you are using, but some of them require significantly higher amounts of load capacitance than most cartridges do. In some cases as much as 400 or 500 pf, which is unlikely to be provided by a typical length of phono cable and the input capacitance of most preamps or phono stages. And even if you are conforming to the load capacitance recommendation for the particular cartridge, going higher than that will likely result in a brighter sound.

DB Systems sells a kit which can facilitate that, consisting of y-adapters and capacitors of various values built into RCA plugs.

Beyond that, and if the issue persists after the new tubes seem to have accumulated sufficient breakin hours, you may also want to consider replacing the cartridge with one known to be brighter, rather than replacing the preamp or speakers.

The first two graphs on this page, pertaining to the Shure M97xE, illustrate what I'm talking about quite dramatically.

As to why you may have found the tonal balance of the system to be acceptable with the added brightness of the Bryston 3B, while being disappointed with the excess warmth you are now getting, perhaps the 3B was excessively bright and was thereby compensating for a cartridge or cartridge loading issue.

Finally, if you do change preamps, in choosing the replacement be careful about its output impedance. Many tube preamps have output impedances which rise to much higher values at deep bass frequencies than what is specified (the specs usually being based on a mid-range frequency). With some tube preamps that will be a problem in combination with the 22K input impedance of your power amps.

-- Al
P.S. to my previous post: Here is a link for the DB Systems kit I mentioned.

-- Al
As usual Al has provided excellent advice especially changing the cartridge loading. I also believe that the Bryston has a brighter sonic signature than the Modulus.

I may have spoken too soon regarding the use of NOS tubes. AI states that the proper selection of tubes is critical and makes recommendations.

In any event, allow your stock tubes time to burn-in before making any decision on a new preamp.
Maybe its just me, but I am confused. You were enjoying the sound of your system, and then you inserted some new amps that sounded better than your old amp in every way, except for the fact that you no longer like the sound of your system, it is now too warm. And you want to know whether the preamp or speakers are too blame?

What am I missing here? It seems to me that you prefer the sound of the Bryston amp. I am not a fan of Bryston amps, as they are too bright sounding for me, but you claim that you enjoy that kind of sound. It seems to me that the simple fix is to sell the Odyssey Stratos monoblocks and going back to the Bryston amp.

Generally, when I insert a new component into my system, if I have a negative feeling over the overall performance of my system, I remove the new component. I don't start to guess what I should change next to help the new offending component fit in better.


the Bryston 3B is a power amp and a fine one at that. If you are looking for a new pre-amp then the Bryston Sp-1, Sp-2 or Sp-3 will make a nice match.
Remember, a pre-amp is the heart of any system, select it w/ care. Keep us posted. Happy Labor Day!
Lowrider - i totally agree about the ability to change tubes to accomodate. In fact thats why i bought the AI... however, i just want to get it dialed-in and sit and enjoy. Question. The AI has a built-in Stand-by mode. Does that count as burn in time?

Al - i have the Shure N91ED. it was delivered with a new Jico SAS stylus and another. Unfortunately i don't know which is the new Jico... and unfortunately i left my turntable on one Fri eve until Monday am such that the needle created a bunch of vinyl dust from going round and round for so long... and i think that was the new yellow body JICO... what a rookie i am
How do you tell when your stylus is done?
the Stratos is still better but i want it to provide the same brighter characteristics of the byrston as well.

also, is there such a thing as an "in line" loudness switch... i really miss that option which is offered on my lower fi NAD preamp.

i know its about musical purity, but it nice to be able to compensate for the equip and room with a dial.
Fivefasts, I don't believe there is any plate voltage in the tubes during standby, so the preamp must be powered-up for the tubes to generate current and burn-in. And, it doesn't need to be playing any music so the amps can be turned off.
Anybody feel free to correct me if I'm wrong.
This seems simple enough.
1-Re-read John Grogan's post.
2-And when selecting a new preamp follow Almarg's caution on preamp
output impedance to amps input impedance
Fivefasts, the recommended load capacitance for the M91ED ("N91ED" is its stylus assembly) is 400 to 500 pf. I would expect that under typical circumstances the total capacitance of the turntable wiring, the phono cable, and the input capacitance of a preamp or separate phono stage will be in the vicinity of perhaps 200 to 250 pf or so, and sometimes significantly less.

Some Googling will reveal numerous comments by users to the effect that loading the M91ED with too little capacitance will have adverse effects in the treble region, and specifically that it will weaken the brightness region.

Also, my perception has been that generally speaking Shure cartridges are not known for their brightness. And the graphs I linked to earlier, for the frequency response of the M97xE, are certainly consistent with that. It could be that the cartridge is just not to your liking, and your present system configuration is not compensating for that to the extent it was previously.

-- Al
Great help Al !!!!
First-experiment with ac power isolation and conditioning. You can't know the true sound available from what you have without it.
From what I saw when I looked under the hood of either Odyssey Stratos/Khartago Monoblocs, is that each monoblock was a stereo amp that was bridged to make mono.

Google disadvantages of bridging amplifers, it may send you in another direction.

Cheers George