[yyz]

I have recently undertaken the task of shopping for my next set of speakers. Before I get to my question, here is the list of speakers I was able to audition in the past 12 months. I am including this info because I find it fun to read about it when others post such info. I had the chance to listen to the speakers listed below for ½ hour to 3 hours.

** Coincident driver design (my favourite) **

Thiel CS 3.7 + Classe amps
Vienna Accoutics Kiss with Audio Research digital amps
Vienna Accoutics The Music with 6 subs (forgot the amps)
TAD Evolution One with Audio Research digital amps
KEF Blade with Chord SPM 14000MkII Reference mono power amplifier

** Other Non-coincident speakers **

Wilson Alexia with D’Agostino Momemtum monoblocks
Wilson Alexandira XLF with D’Agostino Momemtum monoblocks
Magico Q7 with Bryston 28B-SST2
Bryston Model T with Bryston 28B-SST2

I have decided that the KEF Blade will work best for my ears, wallet, and wife. So now I need to choose an amp. The KEF dealer was pushing the 1000 watt Chord mono amps but I think the Bryston 7B-SST2 or Bryston 28B-SST2 will work just as well. The dealer almost laughed at me on that one. I laughed to myself when I heard the price of the Chords ($40K each).

So finally my question,

If you have owned both the 7B-SST2 and 28B-SST2, can you tell me if there is a huge difference in sound between the amps? What am I giving up if I do not go with the 28B-SST2?  Would it be that the 28B-SST2 sounds better at low sound levels? Or are there other audible differences that jump out at you? Is one more tubey than the other? I listen to a lot of different types of music but I like to listen to rock the most.

My preamp is a solid state BAT VK-42SE which I know works great with Bryston amps.

I spoke with a Bryston sales representative at the demo of the 28B-SST2 and he said that a small group of customers actually preferred the 7B-SST2 sound over the 28B-SST2. So I do not want to dismiss the 7B-SST2 because it is cheaper and lower powered over the 28B-SST2.

A couple of Blade reviews for background:
http://www.theaudiobeat.com/equipment/kef_blade.htm
http://www.tonepublications.com/MAGPDF/TA_058.pdf   (large PDF download)

Thanks in advance.

[Laundrew]

Perhaps I am somewhat biased here - purchase the 28's if you have the option and be done with it once and for all and you will never have to deal with the "what if" syndrome.

I also liked the 7's and they are certainly an outstanding amplifier, but for me the 28's offered just a little more performance - personally I would rate the 28's 4-5 percent better in performance than the 7's so we are not looking at a huge difference. Diminishing returns re-visited 

Does vanity also come into consideration? I would say this was also true in my purchasing considerations - hangs head in shame over his shallowness.  Also keep in mind that many 28's have more than 1 kilowatt of power, if I remember correctly, mine are around 1200 watts and I believe that some members here are over 1250 watts. I imagine the 7's may also put out more than their advertised power.

If I am correct, the 28's put out the first 100 watts or so in Class A operation so this is great for low volume listening - James if this is incorrect please let me know 

Anyway, you can't go wrong with either amplifier.

Be well...

[PRELUDE]

Hi,
I know a guy who is my friend's friend and I did not even know him and at the first and only time when I met him he asked me what amp should drive his Kef blade at the best? I told him the 7BSST2 would be a great partner.
He has the white one(Great speakers and personally I would take them over the Wilson and Magico )and he married them with 7BSST2 and he is very happy.

[Elizabeth]

If you can afford the 28B-SST² then BUY them. No question they are the best amp.

[Rod_S]

In looking at the Kef Blade's specs I see the amplifier requirements are 50-400 watts so with that in mind one would think the 7's would be more than enough given they they will put out over 600 watts at 8 Ohms. I also see that the Blade is rated as a 4 Ohm speaker so you would be getting 900 watts with the 7's at 4 Ohms.

I guess one reason for going with say the 28's with these speakers might be if what Laundrew says is true, that the 28's stay class A all the way up to 100 watts. If that's the case then I suspect most of your listening would be in class A with the 28's whereas if the 7's switch to A/B at a lower rating then you would be in A/B more so there may be a slight difference in sound if true.

I have a pair of 28's and love them but I also have a 6B-SST and 4B-SST which I have used for many years (the 28's were just recently purchased last fall) and they sound very close for most listening. There is no mistaking that they are all cut from the same cloth so to speak and I love that the sound is so consistent across the amps, even amps from different generations as my 4B and 6B are pre-squared amps.

Laundrew is also correct about the actual ratings being above the advertised 1000 watts. My 28's are 1245 and 1246 watts respectively. Even my 6B and 4B's were a little above their 300 watt advertised rating falling at 330 watts for the 6 and just shy of 340 for the 4's.

Thanks,

Rod

[srb]

According to James Tanner via Bryston engineering department, the Bryston amps are Class A for ~ 1% of their output.  A 100W/channel Class A amplifier is and would be a small space heater.

Steve

[95Dyna]

According to James Tanner via Bryston engineering department, the Bryston amps are Class A for ~ 1% of their output.  A 100W/channel Class A amplifier is and would be a small space heater.

Steve

That's my impression as well, Steve.  I remember being told at one point that the my 7BSST2's run in class A up to about 6W.  The 28's then would be 10W or 1% of whatever your factory test sheet indicates.

[yyz]

Reading the posts here makes me think the 7B-SST2 is the way to go. I don't have that much cash to buy the top of the line, but I could make it work with a second job (that's how the Blades came into the picture). The fact that people are stating that the sound of the SST and SST2 are close and that the 7B-SST2 and 28B-SST2 are even closer tells me the sweet spot for me would be the 7B-SST2.

Once I buy something that sounds decent I don't have a desire to upgrade. So if the 7B-SST2 works like people are stating I won't be thinking "what if".

Thanks again for the feedback.

[PRELUDE]

Reading the posts here makes me think the 7B-SST2 is the way to go. I don't have that much cash to buy the top of the line, but I could make it work with a second job (that's how the Blades came into the picture). The fact that people are stating that the sound of the SST and SST2 are close and that the 7B-SST2 and 28B-SST2 are even closer tells me the sweet spot for me would be the 7B-SST2.

Once I buy something that sounds decent I don't have a desire to upgrade. So if the 7B-SST2 works like people are stating I won't be thinking "what if".

Thanks again for the feedback.

Please, do not forget to share your impression with us when your system is complete and good luck.

[Diamond Dog]

According to James Tanner via Bryston engineering department, the Bryston amps are Class A for ~ 1% of their output. 

Steve

In a thread on this topic, James Tanner said it was approx 5%. A 7B-SST2 tested at 660 watts into 8 ohms would be running in Class A for approx. the first 30 watts or so using this statement as a guide.

http://www.audiocircle.com/index.php?topic=96377.msg964159#msg964159

D.D.

[srb]

Here Chris Russell said that the Class A output of a 3B SST is about 1.5W (1%) and a 4B SST about 2.5 to 3W (1%).  http://www.audiocircle.com/index.php?topic=5750.msg50792#msg50792

Here James says that engineering tells him that the amplifiers run Class A for about the first 1% of their power rating so a 14B would be about 6 watts.  http://www.audiocircle.com/index.php?topic=65491.msg605149#msg605149

Steve

[Diamond Dog]

Apparently some clarification would be in order. Paging Mr. Tanner...

D.D.

[Elizabeth]

Yes some clarification By James would be nice.
I remember the 5% comment just last year. The 1% comment is 5 years old.

The main thing anyone can tell is just plain old heat. Class a is HOT. so the more "class A" at idle the hotter the whole amplifier will be.
My small Forte'4 at 50 watts per channel would be hot at idle. I could just hold on to the fins at idle, and the amp actually got COOLER if it was playing music.

My Bryston 4B-SST² is much cooler, but is also much more massive.. So I would say from guessing that my Bryston 4B-SST² is putting out almost as much heat BTUs total at idle as my Forte did. The Bryston has six times the power output of the Forte. (and way more parts in it)
Anyway the Bryston must be idling at more than a few watts class A IMO. If it is 5% the Bryston 4B-SST5 would be about 15 watts per channel class A at idle. And for the heat put out, I would 'seat of the pants' say yeah that is what it is doing.
If it was 1% (3 watts per channel) then my amp runs pretty warm for only dumping 3 watts per channel (or 4 times that AC wasted 12 watts)  as heat, at idle.

This is all crazy theory, so if you want to chop giant holes in my ideas.. feel free to do so.

Another point is the Bryston 4B-SST² uses 170 watts at idle.(as in the stats for the amp from Bryston)
Class B is about 75% efficient. Class A is only about 25% efficient. (at idle class B is off, Class A is full on 100%)
1/4 of 170 is 'near enough' to the total 30 watts/both channels, 30 watts times 4 is 120 watts just for idling at 5% class A) at idle Considering the extra bits of electronics wasting some power (especially the transformer), So the amp parasitic waste is only about 50 watts to power itself, sans output. which IMO makes sense).

If the amp was class A at only 1% ( 3 watts per channel at idle, times 4 for the AC power used to make 3 watts class A per channel) then the Class A power use is about 24 watts total, and the parasitic waste (at idle) is way bigger and is over 146 watts parasitic waste.
This alone makes me additionally say it is 5% class A
Thank you for reading all this.

[James Tanner]

Hi Folks,

I will bow to Chris when it comes to specs on the amplifiers.

james

[mclsound]

In this case for the OP
specs dont matter. ..7 or 28..either will work
What matters is...........
How loud will your lovely wife allow you to listen!!!!!!!!!!!
Truely..how loud do you go on those one off listening sessions..
Because either amp will work but if you like that 148db moment......well maybe 108 or 118db..
That is the answer to your delema ..

[Elizabeth]

Hi Folks,
I will bow to Chris when it comes to specs on the amplifiers.
james

Yeah.. but that was ELEVEN years ago.. Things change.. Even at Bryston.. ??

[Diamond Dog]

Hi Folks,

I will bow to Chris when it comes to specs on the amplifiers.

james

That's it ! Goin' to tubes!

D.D.

[Laundrew]

According to James Tanner via Bryston engineering department, the Bryston amps are Class A for ~ 1% of their output.  A 100W/channel Class A amplifier is and would be a small space heater.

Steve

Thanks Steve 

I stand corrected  For some reason I thought it was closer to 10 percent. Oh well, I think that I will still keep the beasties on the shelf 

Be well...

[David C]

I'm still confused ..... the 5% mentioned by James is from 2011, the 1% link from SRB that is from James is from 2009????????

Whatever it is I love my 14Bsst2

[95Dyna]

I'm still confused ..... the 5% mentioned by James is from 2011, the 1% link from SRB that is from James is from 2009????????
 
Whatever it is I love my 14Bsst2

My bet is that 1% is the correct figure.  One of the 7B's chief competitors, the Parasound Halo JC-1, switches from pure A to AB at 30W and has a 10W cutoff switch for those who don't have the environment to mitigate the "too hot to touch" heat generated at the 30W setting.  I've managed to make my 7's clip but they were never anywhere near too hot to touch under any circumstances.  Also one of the criticisms of the JC-1 is the harm it does to the sound when switching from pure A to AB.  the 7BSST2 has no such problem.