WATTS do I need (to do)?

[DavidR]

Please bear with me on this as I try to determine which way to go on the evolution of my HT system.

Background Info: I had been using just Bose 901 series 6 for my HT system mostly because that’s all the room dimensions will allow. I never liked the series 6 that Bose gave me for cost when my series 2 foams surrounds rotted (not many of the series 2 had foam surrounds. Only late model when they fitted them with series 3 drivers). The series 6 were more efficient but didn’t sound as good. I recently acquired a pair of series 2 acoustic suspension with the CT cloth surround drivers and rebuilt the EQ with high end caps. Better sound but now I’m back to very inefficient speakers that need lots of watts. They aren’t a difficult load in terms of impedance as they stay fairly flat in the 8 ohm range. The EQ can demand 8 times the amp power (watts) at any time to accommodate the dB gain required. I am currently driving them with a modded Carver M500t (395 watts RMS/520 watts dynamic headroom). I’m getting tired of the 500t sound – very low damping factor at 30 and Bose recommends more than twice that. I have an XPA-2 G2 that’s too heavy and big to put on top of my TV cabinet. I have a pair of AR91 (3-way) 4 ohm speakers that will be my fronts. The M500t sucks on this load – poor bass performance). So I think the M500t amp’s days are numbered.

We plan on moving in 2 years so room accommodations will change and I will have room to do more with gear arrangement. I’d love to get another SA-250 to drive the AR91s

Question: I need to know what will drive my Bose 901_II speakers appropriately.
- If I get an SA250 will that drive my Bose adequately (not run out of power and clip) until such time they will do duty for the AR91s ?
- Will the XPA-2 G2 drive my Bose adequately (not run out of power and clip)?

I’m not talking driving them hard to high SPLs; just sound and music dynamics in movies and some 2-channel listening.

Just trying to figure out what gear to keep, buy and dump.

[garbulky]

A better plan would be to sell the Bose...than throwing super expensive amplification toward it. (imo)

[DavidR]

That's not going to happen.
I didn't start the thread to invite Bose bashing.

I happen to think they make very good rear speakers. No need for a sub with them and AR speakers.

[Gary Cook]

I understand the problem with the M500t and as you noted it's not watts, it's damping factor and resulting poor driver control. As a result I wouldn't be overly concerned with watts. My suggestion, just temporarily, would be to test your XPA-2 and your SA-250 and see exactly in your environment what the differences are. My guess, and it's only a guess, is that the SA-250 will be a dramatic improvement over the M500t.

Cheers
Gary

[mfeust]

Since you already have a XPA-2 I would move that amp into that room put it on the floor since it is to heavy for the TV stand and see how it works with those speakers.

Mark

[DavidR]

Gary Cook and mfeust Thanks for the input. I did hook up the series 6 with my Rotel pre and the XPA-2. All the muffled sound was gone. Dramatic control and difference. I kind of want another SA-250 for the AR91s which I have played on my 2-channel system with the SA-250 and an XSP-1 G2. I could do what you suggest but OMG what a PITA lugging that 73 lb. beast around.

I wish I knew the real wattage output that Lonnie eluded to that the SA-250 produces. He stated it was very under-rated at 250 watts RMS into 8 ohms.

[Gary Cook]

After having an XPA-2 I've gone done the monoblock route for my stereo listening so the SA-250 has never really hit my radar. From memory the SA-250 test data showed 252 watts @ 8 ohms and 510 watts @ 4 ohms;

emotiva.com/resources/media/SA-250_4ohm.pdf
emotiva.com/resources/media/SA-250_8ohm.pdf

Again I wouldn't be too concerned with watts, it's the damping factor of >500 that will make all the difference compared to the M500t.


Cheers
Gary

[Jim]

I've always used this website when I'm playing around with speaker sensitivities and amps:

myhometheater.homestead.com/splcalculator.html

It might leave you with more questions than answers - but definitely helps when you're trying to see what output you can expect with different combinations of amps and speakers.

[DavidR]

Just got off the phone with the Emo Sales person. I am the proud owner of a 2nd SA-250.

[DavidR]

So I informed the wife that the M500t Carver amp was to be replaced with a sleek modern A/B (over her head with the A/B) power amp............................................................................................................................................................. She's not happy. She likes the look of the stack



I said looks doesn't cut it. I do admit I will miss those big, blue VU meters. C'est la vie!

I'm keeping the BillD modded C-1 preamp for the time being and will probably keep the TX-11a tuner. My Rotel RC-1082 makes things a tad bright and I'm gonna try and sell it with the matching tuner.

[guitarforlife]

Mar 24, 2016 18:33:42 GMT -5 DavidR said:

So I informed the wife that the M500t Carver amp was to be replaced with a sleek modern A/B (over her head with the A/B) power amp............................................................................................................................................................. She's not happy. She likes the look of the stack

View Attachment

I said looks doesn't cut it. I do admit I will miss those big, blue VU meters. C'est la vie!

I'm keeping the BillD modded C-1 preamp for the time being and will probably keep the TX-11a tuner. My Rotel RC-1082 makes things a tad bright and I'm gonna try and sell it with the matching tuner.
View Attachment

I LOVE the big beautiful VU meters. I wish more amps had them.

[guitarforlife]

I run my 901's with a old Adcom GFA-5400 at 125 watts. with a Sherbourn pre-1 and it Is plenty to drive them. Keep in mind on this system I use 90% for Netflix and DVD's and I run them stereo only. I do run a 15" sub as well but I keep it turned down pretty low volume wise. For this situation they do a great job.

[DavidR]

Mar 24, 2016 19:22:33 GMT -5 guitarforlife said:

I run my 901's with a old Adcom GFA-5400 at 125 watts. with a Sherbourn pre-1 and it Is plenty to drive them. Keep in mind on this system I use 90% for Netflix and DVD's and I run them stereo only. I do run a 15" sub as well but I keep it turned down pretty low volume wise. For this situation they do a great job.

Those look like series 6 ported. I have a pair for sale. I went back to the acoustic suspension series II (below)



 
Going thru clean up and restain


new Mellotone grill cloth


Original EQ and (2nd pic) recapped EQ

[DavidR]

Mar 24, 2016 19:22:33 GMT -5 guitarforlife said:

I run my 901's with a old Adcom GFA-5400 at 125 watts. with a Sherbourn pre-1 and it Is plenty to drive them. Keep in mind on this system I use 90% for Netflix and DVD's and I run them stereo only. I do run a 15" sub as well but I keep it turned down pretty low volume wise. For this situation they do a great job.

I love that room!

Especially the Fragile Lamp

The old Adcoms are good amps. Was that model designed by Nelson Pass?

The 901_VI can handle more watts than the original or series II but the latter two require more power for the EQ curves.

[guitarforlife]

I read that he said he had a hand in redesign I think the 5400 is one of them. He talks a little about it on DYI audio.

[guitarforlife]

Yes you are correct I just look at the EQ and they are series 6. I just set it and forget it so I did not think of it.

[DavidR]

Mar 24, 2016 20:54:31 GMT -5 guitarforlife said:

Yes you are correct I just look at the EQ and they are series 6. I just set it and forget it so I did not think of it.

It's hard to kill them. I had a modded Carver M1.0t and one of the added transistors blew (it was a counterfeit Sanken) and sent 70VDC thru them. No issues.

I had the EQ for the ser6 recapped as well with Panasonic FM series in the power supply and Elna Simlic II with silk fiber electrolyte in the audio signal path. It made a nice difference.
 

[garbulky]

David. I apologise for coming across as putting down your setup. However that is my honest response. It's simply too much money for those speakers (for me). Now obviously you feel difference, and don't let anybody tell you different. Audio is about enjoyment. And if oyu feel this is the way, then you must go about it that way! I jsust offer my advice the best way I know. That's all. I'm not trying to bash anything.
Enjoy the music.

I would echo others to check out the XPA-2 first. You may be surprised at its amazingly beefy capabilities.

[DavidR]

Mar 24, 2016 22:00:28 GMT -5 garbulky said:

David. I apologise for coming across as putting down your setup. However that is my honest response. It's simply too much money for those speakers (for me). Now obviously you feel difference, and don't let anybody tell you different. Audio is about enjoyment. And if oyu feel this is the way, then you must go about it that way! I jsust offer my advice the best way I know. That's all. I'm not trying to bash anything.
Enjoy the music.

I would echo others to check out the XPA-2 first. You may be surprised at its amazingly beefy capabilities.

Thanks. No hard feelings. Sound is a matter of preference. I know the 901s have draw backs but they aren't the largest selling speaker for no reason. I got my first pair in college back in the 70s when the 901 was the new rage. They'll go down to 25Hz and the ARs are close with very nice midrange and a great wide dispersion tweeter. The polypro and silver mica caps in my EQ bring an amazing difference especially in the treble. They don't sparkle like my AR90s tweeters but fine detail and improved highs none the less. Once we move I will run the 901_II with my XPA-2 G2 and put the SA-250 on the AR91's. Just fronts and rears - not a surround system just a simple HT set up. I'm OK with that. I don't think the wife would go for a full blown surround system - complains about it being too loud as it is.

I restored the AR91s: veneer, surrounds and caps.

new surrounds



old crossover


new polypro caps

[garbulky]

very nice AR STUFF!