Amplifier and preamp matching

saabracer23

saabracer23

Super Member
So I know that there is a certain way to find a preamp that will work well with an amplifier by looking at certain specs like impedances. I'm a bit clueless on the process and thought maybe you guys could let me know if my setup is okay or if I should look for a different pre maybe?

I have a Classé CA-400 amplifier and a Counterpoint SA-3000 preamp that is a tube hybrid or something like that.

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Here is the setup for now. I'm still getting it setup as I just moved into this are in our basement. Trying to spruce up the room for my work space. Sorry for the mess. Got some new records from GW.

Dan
 
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Looks like a nice match. Even if the pre wasn't giving enough voltage, I'm sure that amp has more than enough ooomph to keep you happy!
 
A good rule of thumb is for the power amp to have an input impedance of =/>10x a preamps output impedance.
 
Pre amp output voltage and power amp input sensitivity are rarely a concern/issue.

But, a general rule of thumb is that power amp input impedance should be 10x, or more, than pre amp output impedance.

The power amp input impedance is given at 75,000 ohms. Pre amp output impedance is not listed in the posted info (I did not follow link).

Considering the rule of thumb, pre out impedance could be up to 7,500 ohms and still qualify as acceptible "match".

Since pre out impedance is typically ~1,000 ohms or lower, many way lower, the odds are that it's OK from that angle.

For example, the pre amps I have are output impedances of 300 ohms, 100 ohms, 47 ohms, and "less than 20 ohms".
 
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Agree with above. I'm pretty sure your combo will work correctly. What I'm not so sure about is that 120 pound amplifier sitting atop that Home Depot style storage rack.

What are the white speakers?
Happy and satisfied Counterpoint owner.
Jimmy
 
The real issue is how the amp gets along with the speakers. No specifications will ever help in this regard.
 
WaynerN said:
The real issue is how the amp gets along with the speakers. No specifications will ever help in this regard.
Click to expand...

There is never a guarantee, but knowing the speakers and the amp one can generalize if they should play nice.

If the amp is designed to do something other than provide a larger version of what went in that's another matter.
 
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The speakers are Pinnacle Arctic 2s. I have the arctic 1s as well which are the same drivers, just a single 5-1/4". They're okay, I'll be using much nicer speakers once I get everything setup.

The amplifier is great, easily handles 1 ohm loads in stereo (2 ohms when bridged). Crazy amounts of current and can drive anything I hook up to it. My fathers infinity kappa 9 mark1 were a breeze for it and I know those can be difficult to drive. I took it to my fathers ad we had a throw down with several larger Mac amps and some others and it came out on top.

I was running it upstairs using a maverick tube Dac and it sounded great. Then I moved it all downstairs and started using this pre and it sounds a lot thinner. I have to turn the treble pot on the Dynaco A50s down as they were too bright at the setting I had upstairs.

I just wanted to make sure that the pre was okay with the amp. I really think it's the room, it's lively. All hard surfaces and no carpet. I should put a rug down and see what happens.

Dan
 
I haven't heard anyone talk about buying a preamp from the same company that made your amplifier. Most companies design components to compliment each other.
 
Mamrak1 said:
I haven't heard anyone talk about buying a preamp from the same company that made your amplifier. Most companies design components to compliment each other.
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I took the question to be more a point if there was anything suggesting this would be a bad pairing.

The OP mentions brightness but concedes here have been several changes all at once; preamp, speakers, and room.

There is nothing that suggests to me it's the pre amp, and I tend to agree it could be the room as it is lively based on the OP's description.

I say all this only to suggest there is an opportunity to narrow down variables, before deciding a different pre is in order.
 
I really do think it's the room. I'd really like it to to take everything upstairs and take a listen, but hauling a 120 pound amp up a staircase is not fun. The toroidal transformer in this thing is the size of nice birthday cake. I've thought about going with a Classé preamp, but I'd have to sell my current one first. If I can get the sound I want from this preamp I'll just stick with it. I'm not sure I'd gain anything by switching. How often should I change the tubes in the preamp??? Will certain tubes change the sound of the pre? I'm confused by it being a hybrid.

The stand the amp is on is very sturdy and I think rated to hold 400 pounds or so. As you can see in the photo that things are in a bit of disorder. I'm sure things will be moved around.

Dan
 
A big problem that I see is your whole set up is crammed together in a small space and against a back wall. That can't be good.
 
From the hifiengine manual, the output impedance of both main and tape outs on the Counterpoint preamp is 760 ohms, which should be fine.

However, the line-stage sensitivity is listed as 24mV, and the stated maximum output is 24V. If these numbers are correct, that makes it a very, very high gain preamp. Do you find yourself running the volume knob way low, like 8 o'clock or 9 o'clock, with the system plenty loud?

With so many of your changes going on at once, I wouldn't want to be hasty to blame the preamp. But with the amp sensitivity at 1.9 volts, and the preamp rated to put out 24 volts with only 24 millivolts input, it may indeed be a poor match. A typical CD player outputs around 2 volts at maximum encoded samples. This means that a typical CD player could fully drive your amp to its rated output with no added preamp gain at all. It is enough to make me wonder whether there are adjustments inside the preamp to dial down the gain (the manual is long, and I didn't read the whole thing, just found the specs...), otherwise there is enough gain to potentially drive your amp to clipping a thousand times over, so to speak.

Maybe someone with more electronics experience than I have can either correct me, or confirm what I am suspecting. If what I suspect is true, you may be able to use the preamp as a phono stage, taking its output from tape-out, and use a passive preamp for a volume control, skipping the Countepoint's line stage.
 
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The snippet posted says the preamp has 24dB gain (line).

24dB is fairly high gain but not nearly as high as the implication of 24mV producing 24V out (60dB gain). I suspect 24V is max, as stated, not the nominal output at the stated input sensitivity (or there is a typo somewhere).

At the stated 24dB gain it would take roughly 125mV input to put out 2V.
 
Yes, the line stage gain is stated as 24 dB in the manual.

I did not find a "rated output" spec, just one labeled Line Stage Maximum Output Level, stated as: 24V p-p @ 1% thd, 20-20kHz

Oddly, the section labeled Maximum Input Levels (1% thd, 1kHz) has:
Line Inputs: 100 Vrms
MC Phono Input: 20mV rms (32dB headroom)
MM Phono Input: 150mV rms (30dB headroom)

So, you can put in 100 volts, but only get 24 volts out.

Weird. :dunno:
 
I do find that running at 9 o'clock it's pretty loud. It's weird though, it has two outputs and they drive the Classé great but don't seem to have enough oomph for the Dayton 230 watt sub amp. It seems I need way more gain for the sub amp. Maybe you can adjust each output.

It looks crammed now but I'll be spreading it out. Maybe I should just get a Classé?

Dan
 
sqlsavior said:
Yes, the line stage gain is stated as 24 dB in the manual.

I did not find a "rated output" spec, just one labeled Line Stage Maximum Output Level, stated as: 24V p-p @ 1% thd, 20-20kHz

Oddly, the section labeled Maximum Input Levels (1% thd, 1kHz) has:
Line Inputs: 100 Vrms
MC Phono Input: 20mV rms (32dB headroom)
MM Phono Input: 150mV rms (30dB headroom)

So, you can put in 100 volts, but only get 24 volts out.

Weird. :dunno:
Click to expand...

It looks like a mix-match of units in the specs which confounds the situation.

24Vp-p is 8.5Vrms so it seems the max output isn't way higher than I've seen elsewhere. That's about the same as the max output from my Yamaha C-80 pre amp.
 
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saabracer23 said:
... It's weird though, it has two outputs and they drive the Classé great but don't seem to have enough oomph for the Dayton 230 watt sub amp. It seems I need way more gain for the sub amp. Maybe you can adjust each output.
Click to expand...

One has to consider all the downstream components in the big picture. The Counterpoint pre amp has plenty of "oomph", but the downstream signal is taking two different paths.

There are two different amps so the relative gains of those must be considered. And, the two different amps have each have different speakers/sub connected. So, in addition to the possible difference in gain between the two amps there is the possibility of difference of sensitivity of the different speakers/sub.

That the sub doesn't seem to have enough "oomph" is unlikely to be a factor of the pre amp output - that has quite high output capability. The issue with relative levels (the sub seeming weaker) is attributable to the different downstream net gains of the two different paths the signal is taking.

The SA230 amp has a gain/level control. Where is that set?
 
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