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I'm looking to possibly add a 2nd power amp to a 2 channel system

EJC1

EJC1

Active Member
I'm putting together a new stereo system in a new home. As things progress, I look to modify.
I may have hit a snag with my next idea and would appreciate opinions.

The system is pretty much dedicated to LPs.
Starting with:
McIntosh MA352 Integrated Hybrid amp - Tube front end, SS Power amp
Klipsch Forte II speakers
2 Subwoofers - currently connected to the pre-out on the MA352
VPI Prime turntable w/ Ortofon Orange
Thorens TD-160C w/ Shure V15III

I'm now thinking of expanding the system. Not sure why, but the word insanity comes to mind.
The MA352 has a switchable PRE-OUT and I'm thinking of adding a 2nd Power amp for the option/addition of full tube amplification.
I'm thinking of adding an MC-275 and a 2nd set of speakers.
The Klipsch would move to the MC-275
and I'm thinking of a pair of JBL L100s on the MA352

The question: if I want to run both power amps at the same time will I need an attenuator to be able to balance the power amp output levels?
 
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EJC1 said:
I'm putting together a new stereo system in a new home. As things progress, I look to modify.
I may have hit a snag with my next idea and would appreciate opinions.

The system is pretty much dedicated to LPs.
Starting with:
McIntosh MA352 Integrated Hybrid amp - Tube front end, SS Power amp
Klipsch Forte II speakers
2 Subwoofers - currently connected to the pre-out on the MA352
VPI Prime turntable w/ Ortofon Orange
Thorens TD-160C w/ Shure V15III

I'm now thinking of expanding the system. Not sure why, but the word insanity comes to mind.
The MA352 has a switchable PRE-OUT and I'm thinking of adding a 2nd Power amp for the option/addition of full tube amplification.
I'm thinking of adding an MC-275 and a 2nd set of speakers.
The Klipsch would move to the MC-275
and I'm thinking of a pair of JBL L100s on the MA352

The question: if I want to run both power amps at the same time will I need an attenuator to be able to balance the power amp output levels?
Click to expand...

yes

And why many use amps with gain controls for the second pair.

Kenwood had a nice feature on some of their older integrated amps around during quads hey day. The main in leaves the volume control inline to allow balancing the output of the additional pair of speakers.

I'm currently using a Kenwood KA-4006 attached to the tape output on a Kenwood KA-7300 to drive my rear lanai speakers. no matter what level the inside speaks the lanai are totally independent to crank or not.
 
if you like the sound of the fortes, I would ditch the sand power (SS) and go with tubes.
sounds like you have a pretty nice system. You have two powered subs, continue to use them.
Fortes and tubes are like ice cream and cake.....they go together very well.
You have to good MM carts, consider upgrading the phono stage to a Marantz 7 clone from China. Should outperform the MAC phono stage.

Hi end 12AX7 Tube MM RIAA Turntables Phono amplifier base on Marantz 7 L7-44 | eBay
 
No problem as long as the outboard amplifier has gain controls. I would also suggest the speakers with the lower sensitivity be driven by the more powerful amplifier in order to maximize the amount of headroom available for the entire system while remaining "in balance".
 
62caddy said:
No problem as long as the outboard amplifier has gain controls. I would also suggest the speakers with the lower sensitivity be driven by the more powerful amplifier in order to maximize the amount of headroom available for the entire system while remaining "in balance".
Click to expand...


Thanks.
By switching the Klipsch to the lower power amp (the MC275) I think this would be accomplished. But the MC275 has no gain control and that is the problem I'm looking into now.
 
mcgjohn said:
if you like the sound of the fortes, I would ditch the sand power (SS) and go with tubes.
sounds like you have a pretty nice system. You have two powered subs, continue to use them.
Fortes and tubes are like ice cream and cake.....they go together very well.
You have to good MM carts, consider upgrading the phono stage to a Marantz 7 clone from China. Should outperform the MAC phono stage.

Hi end 12AX7 Tube MM RIAA Turntables Phono amplifier base on Marantz 7 L7-44 | eBay
Click to expand...

I'm using a Project Tube Box S2 with the Thorens and the Mac phono with the VPI. Both sound sweet.
May consider your phono suggestion after getting it all together
 
@EJC1 , with the Project Box S2, a simple upgrade is to replace the wall wart with a real linear supply, either build one or buy one....18VDC with several amps of current. will be quieter phono stage with greater dynamics.
 
The Schitt unit is a passive attenuator which means it can only reduce the signal to the secondary amplifier, not increase it as gain controls can. Would only be useful if the speakers connected to the secondary amplifier happen to be playing louder than those connected to the MA252 (without the SYS inserted) The ability to bring both pairs of speakers into balance would therefore be limited.
 
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62caddy said:
The Schitt unit is a passive attenuator which means it can only reduce the signal to the secondary amplifier, not increase it as gain controls can. Would only be useful if the speakers connected to the secondary amplifier happen to be playing louder than those connected to the MC252 (without the SYS inserted) The ability to bring both pairs of speakers into balance would therefore be limited.
Click to expand...

Thanks
 
Why not just pick up the Gordon Gow Commemorative? It suits your criteria perfectly and the downside will be minimal if/when you go to sell it. It's a lot less expensive than a new MC275 MkVI which will drop in value $1,500 as soon as you break the seal on the box. Only 400 GG CE were made. Pretty much a no brainer as far as I can see.
 
62caddy said:
Why not just pick up the Gordon Gow Commemorative? It suits your criteria perfectly and the downside will be minimal if/when you go to sell it. It's a lot less expensive than a new MC275 MkVI which will drop in value $1,500 as soon as you break the seal on the box. Only 400 GG CE were made. Pretty much a no brainer as far as I can see.
Click to expand...

The posting I saw for the Gordon Gow unit was $6995, for a 25yr old unit. Then I'd have my tech go through it to make sure it was ok and spec'd out

I just went back the price appears to have dropped
 
EJC1 said:
The posting I saw for the Gordon Gow unit was $6995, for a 25yr old unit. Then I'd have my tech go through it to make sure it was ok and spec'd out
Click to expand...

It's $3,999 on this end. No need to have tech touch it - this has already been done and brought to spec.. That's the advantage of buying from Audio Classics and it is warranted for 90 days.

Whatever they list as "B1" condition is usually near mint. B=cosmetic condition (all used equipment gets this rating no matter how perfect) 1=perfect operational condition.

*It was $3,999 at the time I posted the link. Strange...:confused:
 
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It looks like I am now shifting directions, slightly.
I ran the idea by my McIntosh dealer and he came up with this.
The McIntosh C7 preamp (from the late '80s) which plugs in between the MA352 out 2 and the power amp.

My other concern is that since the MA352 is 200W/ch that the MA275 would not have enough power at 75W/ch, and would be difficult to pair the two and I'd probably need to bridge them requiring 2 MA275s.

Instead, the MA1502 with 150W/ch is probably a better match for the output of the MA352 and use the C7 adjust the gain and pair them up.
 
The sensitivity of the JBL L100 is 90 dB for the Forte it is 96 dB.

This means the JBL will require 4 times as much power as the Klipsch speakers to produce the same theoretical loudness. If a 75 wpc amplifier was used with the Fortes, a 300 wpc model would be needed with the JBLs to produce the same theoretical maximum SPL output.

That said, don't even worry about it. Chances are you'll never run either amplifier anywhere near full output - and even if they were, the difference in loudness wouldn't be worth talking about.
 
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62caddy said:
The sensitivity of the JBL L100 is 90 dB for the Forte it is 96 dB.

This means the JBL will require 4 times as much power as the Klipsch speakers to produce the same theoretical loudness. If a 75 wpc amplifier was used with the Fortes, a 300 wpc model would be needed with the JBLs to produce the same theoretical maximum SPL output.

That said, don't even worry about it. Chances are you'll never run either amplifier anywhere near full output - and even if they were, the difference in loudness wouldn't be worth talking about.
Click to expand...

I've been playing with numbers.
The JBL L100 is a 4ohm speaker, 90dB sens - the MA352 is 300w/ch driving 4ohms - this gives a max gain 115.1dB
the Klipsch Forte II is an 8ohm, 99dB sens - The MC275 is 75w driving 8ohms - this gives a max gain of 117.8dB

I agree with you that the amps will never be run at max output and the difference will probably not be noticed.
Perhaps I'll check in on that Gow amp tomorrow.
 
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EJC1 said:
I've been playing with numbers.
The JBL L100 is a 4ohm speaker, 90dB sens - the MA352 is 300w/ch driving 4ohms - this gives a max gain 115.1dB
the Klipsch Forte II is an 8ohm, 99dB sens - The MC275 is 75w driving 8ohms - this gives a max gain of 117.8dB

I agree with you that the amps will never be run at max output and the difference will probably not be noticed.
Perhaps I'll check in on that Gow amp tomorrow.
Click to expand...

Can't find fault with that analysis. :thumbsup:
 
62caddy said:
Can't find fault with that analysis. :thumbsup:
Click to expand...

The c1 Gow amp was gone. But as I researched over the weekend it appears that the new Mk VI sounds better.
So I guess it will be the new amp that I'll order tomorrow
I ordered the speakers today.
 
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