What should I be looking for in a pre??

sts9fan · « **on:** 15 Jun 2006, 12:43 pm »

So right now I am running my SB3 right into my Khartago extreme which is feeding my Studio 60v3s. the woman is pissed because she cannot listen to the radio or pop a cd into the dvd player if someone brings one over. Poor me she wants me to get more gear

Anyway I am still new at this and with what I have what should I be looking for in a pre? I want to try tubes so tubes it will be. Here are the mesurments from the amp in case that helps.
thanks in advance

http://www.soundstagemagazine.com/measurements/odyssey_khartago/

rosconey · « **Reply #1 on:** 15 Jun 2006, 04:35 pm »

talk with klaus about the new candela-should be shipping soon-
nuff said-

sts9fan · « **Reply #2 on:** 15 Jun 2006, 04:50 pm »

that in no way answered any of my questions. I am wondering about with the attributes of my amp what I should be looking for in a pre. I know Odyssey has a tubed pre coming out but which I may try but there is no chance I am not going to buy it new.

PhilNYC · « **Reply #3 on:** 15 Jun 2006, 05:09 pm »

The main thing you should look for is a pre whose output impedence is a good match with your amp's input impedence. The general opinion is for the amp's input impedence to be about 100x the preamp's output impedence.

Beyond that, look for features (eg. remote, number of inputs needed, etc)...

WEEZ · « **Reply #4 on:** 15 Jun 2006, 05:29 pm »

I would agree with Phil as far as looking out for impedence matching. I'm not sure of the input impedence of the Khartago, but I think I read somewhere that it's around 10k. If that is the case, make sure that the output impedence of your pre-amp is no more than 1k. (Less would be better.)

This will likely mean that if you're looking at using tubes; the design should be one that uses a cathode follower (or similar) topology and/or a hefty output drive. And keep the cables short.

WEEZ

avahifi · « **Reply #5 on:** 15 Jun 2006, 05:33 pm »

What should a preamp do?

First, it should have pure resistive 47K ohm input impedanced on all line level inputs independent of the active stage feedback to provide an easy load for all sources.

Second, it should have a low output impedance, high slew rate, and high output drive current capability to allow driving any load or cables downstream without stressing the preamp line circuits, or making the sources have to attempt driving those loads directly.

Third, it should intercept and not pass on out of band garbage (digital switching sidebands, cartridge mistracking shatter, out of band resonances, etc) because your amplifier and speakers will not like that garbage.

Fourth, it should have ultra transparent and dynamic internal active circuits (don't screw up the source material). It should present you with sonic quality that exceeds your expectations and have long term durability.

Fifth, it should have the all of the control flexabily that you need, executed well (precision tracking controls, trouble-free switches, etc.).

Sixth, it should protect your amplifier and speakers from on or off transients from the preamp and from any equipment switched on or off by the preamp.

Seven, if you use the preamplifier for making recordings, the preamp should have buffered tape driver circuits available to isolate your sources from the really nasty loads recording devices often present, especially when they are connected to the tape outputs and turned off.

Note that none of these requirements require really expensive prices, just good careful engineering done by a company that actually knows what is needed to do right to make a useful product.

Frank Van Alstine

R_burke · « **Reply #6 on:** 15 Jun 2006, 05:43 pm »

Quote from: PhilNYC

The main thing you should look for is a pre whose output impedence is a good match with your amp's input impedence. The general opinion is for the amp's input impedence to be about 100x the preamp's output impedence.

Beyond that, look for features (eg. remote, number of inputs needed, etc)...

I too am looking for a pre-amp for almost the same reasons as STS9fan and had pretty much decided on the ACA 2b. At least until this post, my amp is a Sonic Fronitiers Power 2 and it's rated at 100K input impedance and the ACA 2b is 10,000 output impedance = 10X

Not being technical, can anyone tell me what the affect of only being 10x instead of 100x is

mcgsxr · « **Reply #7 on:** 15 Jun 2006, 06:00 pm »

Looks like you are getting some great advice here.

Having heard the SB direct to an amp in the past, and presently using an integrated, I would say that in my estimation, the modded SB3 benefits are more fully felt, with only 1 volume control in the signal path.

To that end, I would add an HT bypass to your list of wants, so that when you use the SB3 through that input, the pre steps completely out of the way...

Just my opinion, as a modded SB3 user, who loves music, and has tried tube pre's in the past.

sts9fan · « **Reply #8 on:** 15 Jun 2006, 08:18 pm »

Thanks for all the help!!
Does anyone have any suggestions on pres with the proper impedence? It seems like all the ones I was looking at do not match up well.

avahifi · « **Reply #9 on:** 15 Jun 2006, 09:53 pm »

If the preamp you are considering has a 10K ohm output impedance, it should work well with any amplifier with a 20K input impedance or higher. A lower amplifier input impedance will just cause a bit of a wide band gain reduction, easy to make up for with a step or two up further on the volume control, assuming that the preamp has adequate current drive for the load.

A 100X ratio is certainly not necessary or a factor of merit.

Frank Van Alstine

sts9fan · « **Reply #10 on:** 16 Jun 2006, 12:33 pm »

Thnaks for te info everyone this was very helpful for me

JLM · « **Reply #11 on:** 17 Jun 2006, 10:20 am »

Another option would be to replace the SB with an Olive. It works the same way as a SB but doesn't need a PC and includes a CDP. Can you live with internet only "radio"?

sts9fan · « **Reply #12 on:** 17 Jun 2006, 01:20 pm »

The SB does internet radio but I need regular radio. Why would I ever get rid of my SB3? The thing is wonderful and gives me no problems. I have a dedicated server and all. Nope no chance at a OLIVE here.