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Using my Previous Marantz THX Receiver Amp Sections as Dedicated Amps

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#1 of 5 OFFLINE   bronsontheman



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Posted August 25 2013 - 02:38 AM

POSTING AGAIN! (Some glitch :/)


I am new to the forums here and thought I would ask what everyones thoughts are in using a new setup of mine (Also looking for data to back up your input if talking about nitty gritty specs) . I am using (2) of my fully functional Marantz SR7500 THX Receivers amp sections (7.1 Channel Input/Direct Input, not using the sub in) in combination with my new Marantz SR6008's Pre-out's. I am a sound engineer and love to play with electronics, I know these Marantz SR7500 units had the following specifications: CLASS A/B Current Feedback, 105 dB S/N, 105 Watts x 7, large transformer and filter capacitors (18,000uf x2), discrete regulation sections and a Power consumption of 650 watts. Yet, I know for the "NEW" Marantz SR6008 (aside from hdmi switching, hdam, and great connectivity for me) Still Class A/B Current Feedback the power supply is much smaller, (filter capacitors (only 10,000uf x2) AND transformer reduced in size, regulation components are cheap, no THX certification, amplifier section has changed, smaller heatsinks, roughly 10 lbs. lighter, and the S/N ratio is below 100 dB.


With my testing I have concluded this:


1) 6008 Pre-out's -> First 7500: 7 ch. Input (L/R/C) , Second 7500 7 ch. Input (RS,LS,RR,LR)

2) Set 7500 gain to 0dB Fixed, Use 6008 as the processor/pre-amp

3) Each 7500 has a power consumption around 650W, minus other internal components parasitic loads and non-perfect efficiency I would estimate 600W is reserved for the amplifier section in combination with the massive filter capacitors. This means 600W/7 Ch. gives aprox. <85W per ch. all channels driven. BUT this leaves no head room, I want to harness peak power capabilities and lower distortion, NOT be limited to 85W per ch. and risk distortion. I realize this mentality only comes into play when sheer power is required, but I like the fact that I can obtain high quality amplification, low distortion, good S/N and have power on reserve when needed. Thus, I shall only use 3-4 channels on each amplifier: 600/3 = 200W/ Ch. (available) or 600/4 = 150W/ Ch. (available).

4) I Tested this layout with multiple films with very quiet to very loud passages. When comparing to the 6008: I heard less noise (quiet passages), no clipping, more impact, the amps "sounded warmer", and measured roughly a 2 dB increase in loud passages. (NOTE: ALL AUDYSSEY BYPASSED / DIRECT, same room, and same speakers/placement)


Utilizing two of these 7500's, I still have better specifications then the New Marantz 5 ch. amps. It is only until you get into the New Marantz 8000 line of power amplifiers do you see the larger power supplies, 105dB S/N etc. Why would I spend thousands of dollars on a dedicated amp that has worse specifications and lower power capability? The ONLY REASON I could see degradation in signal flow would be the Marantz 6008's hdam preamp out going into the 7500's 7ch pre-in. Since the 7500's gain is fixed at 0dB Reference level (and noise with no material present is really at a minimum placing your ear about 2 inches away from the speaker) and the 6008 is being used as the processor / preamp, I feel within the MARANTZ PRODUCT LINE (I prefer Marantz) this is a great choice to utilize my higher quality amp sections in my pre-hdmi receivers.


OPTION 2: Build more of my own gear! Pull Amp sections and power supply only (or upgrade to larger transformer), bypass all preamp circuitry, put into a nice enclosure, add rca's and binding posts, then it really would be a dedicated 14Ch. Amplifier ready for all the future surround formats


Thank you all!



Edited by bronsontheman, August 25 2013 - 01:55 PM.

#2 of 5 OFFLINE   schan1269


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Posted August 25 2013 - 07:41 AM

I've advocated the use of the pre-ins on many AVR to use them as amplifiers, once their days were "up" being current.


#3 of 5 OFFLINE   Type A

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Posted August 25 2013 - 12:42 PM

This thread isnt loading right both in Chrome and IE

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#4 of 5 OFFLINE   bronsontheman



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Posted August 25 2013 - 01:49 PM

I'm not sure why it's not loading right...? Maybe I should post again?

#5 of 5 OFFLINE   bronsontheman



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Posted August 25 2013 - 02:00 PM

Reposted, hope you all can read it now!  :D

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