[mcgsxr]

I am buying another pro audio amp for sub use in my HT.

I can, for the same price, buy either an older Yamaha Pro or QSC amp.

P3500 Yamaha
QSC Series One 1700

Both push 350wpc into 8ohms, 500wpc into 4 ohms, or can be bridged to 1000w at 8ohms.  Both are roughly 50 lbs, and both are fan cooled.

Anyone have good or bad experiences? 

I have owned Yamaha consumer goods in the past, and have always been happy, but understand that the QSC line is well respected in Pro circles.

Thoughts?

Thanks in advance,

[macrojack]

This has to be determined by condition/history/age of units under consideration. Both would do what you need done if they haven't been abused. Might be important to ask about service of either one in your area. Quieter fan might give an edge to one of them.

[mcgsxr]

Good points, I will have the opportunity to demo both in my system on Thursday, so I will add those questions to the list.

Just looking for data points around history for both - ie one has a bad rap or not - cannot find anything bad about either on the Net.

The QSC is older, looks to be early 80's.  The Yamaha is roughly mid 90's.  Leaning towards the Yamaha, based on personal experience and age.  It is reputed to use a 3 stage fan, vs the 2 stage for the QSC too.

[TheChairGuy]

Hey Mark....I think you inadvertently placed this post in Vinyl Circle.

What circle do/did you want me to move it to? Vintage, General Audio, ??

Far be it of me to give anyone the boot for posting here - but I think you'll get more varied responses elsewhere.

Thx, John (Facilitator / Vinyl Circle)

[mcgsxr]

Crap - meant to be in Vintage - help!

[TheChairGuy]

Ha - vintage, vinyl...you know, they look similar

Aren't you younger than me?  You're too young to have a brain fart like that

Your wish is my command...it's off to the Vintage Circle then

John

[Pez]

I own a newer version QSC for the bass section in my setup and it is pretty good. For what the amp is doing, pushing lots of watts for viseral bass, you don't need a lot more than an amp with excellent control and lots of overhead and the QSC fits the bill.

[fredgarvin]

We used QSC amps in our PA and monitor system for five years without a hint of trouble. Previously we used Crown's and the QSC was much better sounding. That was five years of tearing down and setting up.

[mcgsxr]

Thanks Chairguy - younger eyes are no guarantee of not making mistakes!!!

I have spoken more with the seller, and the QSC unit is older, has lived a harder life, and I am going to go with the Yamaha.  I have personally experienced the abuse a Yamaha retail unit can take (parties at university in the late 80's, running 2ohm loads for hours at max volume on a receiver...), so hopefully the 15 year old Yamaha pro unit will perform well.

Appreciate the insights, guys, one more excellent reason to love AC!

[Wayne1]

Mark,

For ANY power amp of that age, I would suggest you have the power supply checked out.

Electrolytic caps do age and wear out. They may even leak. Depending on the exact amp it may be a challenge to find a current cap that will physically fit into the same space.

[mcgsxr]

Thanks for the tip Wayne, I will have a local guy look it over (not shipping this 55lb beast anywhere!).  I saw it run, so I know it does.  Should be fun to move those OB woofers again!

[mcgsxr]

Got the amp all connected and running, but the low output from the modded SB3 (as fed through my active Xover) is too small to really get the Yamaha singing.

Much research on HomeTheaterShack isolated this beast as the best option - http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=110501277866&ssPageName=STRK:MEWAX:IT - should be here next week, and looking forward to it!

[Wayne1]

Mark,

The max output level of the analog modded SB3 is 1 volt. The standard output level for consumer electronics is 2 volts. The Yamaha wants even more voltage. The Samson will raise the voltage level, but how does it do it and how much noise does it add? It looks like you will be adding another switching power supply into the mix.

I would suggest something like a Burson Buffer with increased gain before your active crossover to start with. Even after the Samson you may not have enough gain to get the Yamaha going without a lot of added noise.

[mcgsxr]

Not sure about the noise it will add Wayne, though I did consider it - sub use only after all.

Lots of data here, where Google led me - http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/24476-line-level-problem-yamaha-pro-amp.html

Device appears to convert rca -10dBV to +4dBu.

If that combo does not do it, I will have to look for another gain device, as you state.

Agree that the added wall wart does not thrill me, but I have a pony panel next to the crazy basement audio setup, so I can actually put this gear on different AC lines, and am feeding the modded SB3 with a Felicia anyway.

[mcgsxr]

Just a heads up to any considering this as a solution - received the Samson box yesterday, very tiny thing, and it does a fine job of boosting the output of the modded SB3 to a closer match to what the Yamaha wants as an input.

More tuning time with the gain needed to match the OB mains, but happy with the direction it is heading in.

Truthfully though, and it hurts to admit (!), I think I would have had a much easier time just buying a new BASH woofer amp, as they are easier to blend into the system.

May have to give that some thought.

For HT passive sub use though, this device mated to a pro amp, would be a great way to get 1-2K WPC going for sub use.

[mcgsxr]

To formally close the loop on this - could not fight the hum in the system using the big old Yamaha.

Broke my heart to sell it, but had to, as it would not do what I needed.

Picked up a new BASH300 sub amp, works perfectly with my setup.

Sometimes, you just have to go with the right idea - should have done so from the beginning!