Preamp compatability and math
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VSAT88
Posts: 1,227
I am terrible with math and lack enough understanding of ohms law to figure this out so I would like some help please. As some of you know I acquired a B&K EX-442 amp the other day as well as a Pro 5 B&K preamp. Even though these two are obviously match I do not like the sound of the Pro 5. I have a C2 Kenwood preamp as well and the sound is much better. I have restored the Kenwood with all new capacitors and Op amps, changed out the diodes to relieve the Op amps of excess voltage as well. That being said according to the information I have this is the way it all lays out.
The C2 Specs at 1000 mV (1 volt) at 100 Ohms.
The B&K EX 442 Specs at 1.6V 24.3 K input impedance.
I guess you know where I am going with this.
Are the two compatible (B&K EX 442 and the Kenwood C2) as it seems the C2 has to be turned up on the volume knob much more that the B&K Pro 5 to get the same output thru the speakers.
The B&K Pro 5 seems to produce much more bass output.
The C2 walks all over the Pro 5 as far as sound clarity.
So, what do you guys think of this. Any help or opinions will be appreciated.
The C2 Specs at 1000 mV (1 volt) at 100 Ohms.
The B&K EX 442 Specs at 1.6V 24.3 K input impedance.
I guess you know where I am going with this.
Are the two compatible (B&K EX 442 and the Kenwood C2) as it seems the C2 has to be turned up on the volume knob much more that the B&K Pro 5 to get the same output thru the speakers.
The B&K Pro 5 seems to produce much more bass output.
The C2 walks all over the Pro 5 as far as sound clarity.
So, what do you guys think of this. Any help or opinions will be appreciated.
Comments
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How does it sound is all that matters. I have run preamps that don't match optimal amp impedance input recommendations and loved the sound.Basis 2200 Signature, Vector 4, Transfiguration Proteus, Allnic H3000, Meridian 200/563, CJ ET5, McIntosh 501's, Thiel CS6, 3.6, Polk SDA SRS 2.3tl, MIT EVO, KS/Wywires PC's
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How does it sound is all that matters. I have run preamps that don't match optimal amp impedance input recommendations and loved the sound.
Thanks and I agree. I have ran equipment (different brands that is) that sounded great together however I would still like to know a bit more about the math or to put it another way about what should be a good match by using the numbers. -
The math says the input impedance of the amp should measure at least 20 times higher the amount of output impedance of the preamp.
If the output impedance of your Kenwood is 100 ohms, that is very low and can easily drive your B&K amp.Basis 2200 Signature, Vector 4, Transfiguration Proteus, Allnic H3000, Meridian 200/563, CJ ET5, McIntosh 501's, Thiel CS6, 3.6, Polk SDA SRS 2.3tl, MIT EVO, KS/Wywires PC's -
The math says the input impedance of the amp should measure at least 20 times higher the amount of output impedance of the preamp.
If the output impedance of your Kenwood is 100 ohms, that is very low and can easily drive your B&K amp.
That's what I am talking about. I will keep that for future reference. I have a few different preamp and amps, some of them tube type so I am happy to have that information. -
As mentioned impedance won't be an issue. The 1.6 volts is the input level required to drive the amp to full rated power. The 1 volt stated by Kenwood is likely the level at which THD levels were measured and spec'd at, not its full output potential.
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As mentioned impedance won't be an issue. The 1.6 volts is the input level required to drive the amp to full rated power. The 1 volt stated by Kenwood is likely the level at which THD levels were measured and spec'd at, not its full output potential.
So, it is possible that the C2 may not be as capable of driving the EX 442 to it's full rated power as the Pro 5 therefore the need to turn up the volume control higher than would be expected to get the volume level up. That is what I am reading here, right ? -
As I mentioned Kenwood likely used the 1 volt as the reference level to measure and spec the distortion(THD) at. That does not mean it is the maximum output level.It should be able to drive the amp to full level just fine.Volume control setting may well be considerably different from the Pro5 since the internal circuit gain levels may differ by several db.
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As I mentioned Kenwood likely used the 1 volt as the reference level to measure and spec the distortion(THD) at. That does not mean it is the maximum output level.It should be able to drive the amp to full level just fine.Volume control setting may well be considerably different from the Pro5 since the internal circuit gain levels may differ by several db.As mentioned impedance won't be an issue. The 1.6 volts is the input level required to drive the amp to full rated power. The 1 volt stated by Kenwood is likely the level at which THD levels were measured and spec'd at, not its full output potential.
So, it is possible that the C2 may not be as capable of driving the EX 442 to it's full rated power as the Pro 5 therefore the need to turn up the volume control higher than would be expected to get the volume level up. That is what I am reading here, right ?
Yep, but as another possibility, as stated, the internal circuitry on the gain levels could also be different. Usually it's an impedance mismatch that might dictate variations in the volume dial. The "20 times" rule of thumb is just that, a rule of thumb, not written in stone. It's very possible to have one 10 times, and sound just fine.
Not so uncommon when mixing and matching brands, just gets a tad tricky because specs aren't always quoted in the same manner. Which I believe is simply a way of hiding negative aspects of a piece.
HT SYSTEM-
Sony 850c 4k
Pioneer elite vhx 21
Sony 4k BRP
SVS SB-2000
Polk Sig. 20's
Polk FX500 surrounds
Cables-
Acoustic zen Satori speaker cables
Acoustic zen Matrix 2 IC's
Wireworld eclipse 7 ic's
Audio metallurgy ga-o digital cable
Kitchen
Sonos zp90
Grant Fidelity tube dac
B&k 1420
lsi 9's -
If I may, as a nearly pointless aside: the real purpose of add-on, standalone buffers (be they vacuum tube or soiled state) is to buffer impedance mismatches between components.
In other words, a good buffer* might rescue the audio performance of a poor preamp/power amp combination.
* As opposed to the cheap little harmonic distortion boxes sold as "tube buffers" to add "that warm tube sound" to sterile digital recordings and clinical sounding soiled state components.
