[Docere]

Hi all

I am currently looking for a small, easily positioned, hi-eff ‘speaker design to match with a SET amp – (undecided as to which, as I would like to factor in ‘speaker choice first).

1) It seems that although the Hemps have been suggested for SETs in the past, I am thinking the aperiodic loading of the A8 may be a better match for SETs, which may struggle below the port tuning of a vented cabinet. Also, I seem to prefer the sound of sealed cabinets… Others seem to have had success with A8s and SET – so this OK?

2) I have searched, but can find only vague discussions in relation to A8 driver beaming. I often share music with friends and have been known to get up shake it, so to speak. I know I can not expect a wide dispersion presentation from an 8” full range driver, but the other extreme of carefully aligned sweet spots are not for me. Is anyone able to share in some detail how the A8s perform in this regard? Hmmmm, some attractive-looking turned wood diffusers might be a nice option for larger diameter drivers.…

Thanx in advance, Raymond.

[JLM]

Raymond,


I'm sure Louis, as a tube lover, can provide the straight scoop on aperiodic versus open baffle.  A few folks (check the Red Wine Audio circle) have been using the B200's in open baffles, perhaps they can help too.  I agree, aperiodic or sealed designs has got to address tube damping concerns better than ported or open baffle.  


Regarding beaming, I own 8 inch full range drivers that don't have a whizzer cone either.  The laws of physics would suggest that the beaming phenomenon would be the same for both drivers and would kick in around 4,000 Hz.  I'd recommend buying or borrowing a test tone CD and find out what 4,000 Hz sounds like because most folks, even around here, don't know.  It's pretty high (I can still hear 16,000 Hz), but there just isn't much music above 4,000 Hz.

I do my "intense" listening from a single chair with the drivers aimed to cross at my knees (for better imaging) and don't miss any of the highs, but if I lean waay over to one side I would.  Most of my listening (like right now) is casual and is done from about 30 degrees off the centerline of drivers.  From here imaging suffers much, much more than loss of high frequencies.  So personally I wouldn't be concerned with party use.  IMO anything that gets between me and that simple cone would be evil.

[Hank Murrow]

Docere;

You will find that aperiodic loading flattens the impedaance curve just like but not as well as transmission line loading. This should help your SET amp deliver the goods down low. Another help would be a properly designed and implemented parallel feed tube SET. I used a highly modded Dyna Stereo 70 amp for a long while, and when I heard the Bottlehead and the John Tucker amps at VSAC in Silverdale I could barely believe my ears. Their implementations of the parallel feed topology really delivered the bass realm with authority and clarity.....not often found together, BTW. I am building my 300B amps with that topology using Magnequest iron throughout, and expect great tuneful bass from them. My experience only, but Louis will no doubt concur.

Cheers, Hank

[Docere]

Thanx heaps for the info guys!

JLM – I am more a physical / palpable rather than a pinpoint / cardboard cut-out kind of imaging person. I any case, I am more interested in the high frequency extension; seems the A8s may be OK in this regard. I do enjoy a sense of space / place,  especially depth, but unfortunately can not fit bipoles. Grrr!

Hank – Thanx for the parafeed reminder; it seems the benefits of ridding the OPT of DC outweighs the disadvantages of that hefty parafeed signal cap. A8s with a nice parafeed set-up should give that nice agile and resolved (some would say overdamped) bass that I like.

Thanx again, Raymond

[Louis O]

Hi Docere,

Many thanks for your post and welcome to our forum.

There is a lot to be said about sealed box design and it was my first thought with the B200. The aperiodic design just made so much sense with the B200. I like a speaker to be very fast and articulate and the A8s have this quality. JLM points out the lack of wizzer cone with the B200 and it really is amazing in it’s ability to extend in the treble they way it does. The lack of the wizzer will give you a bit better dispersion. It is an 8” diameter cone and it will beam a little, but I think it’s treble extension it’s not a big issue at all.

Hi Hank,

Agree 100% regarding the parallel feed SETs. I had one for a while and a big fan of Bottlehead and John Tucker. All the best with your amp and please post pictures when it’s done.

Thanks again,
Louis

[Docere]

Thanx Loius. That eases my concerns a little.

Kind regards, Raymond.

[Louis O]

Hi Docere,

My pleasure and thanks again,
Louis