Rather than bump an old thread (2005) I thought it better to start a fresh one.
I've just won a pair of what I think are Scandyna A30 speakers complete with what look like the original stands (all for £17 / $25 or thereabouts). The cabinets look to be in remarkably good shape as do the drivers. My hesitation about the model is that the dimesions are the same as the Dynaco A35, but mine have an externally facing aperiodic port above the tweeter. There's no fancy variable tweeter output thingy and the captive speaker cables have old style DIN plugs but are only about 30cm long. To test them out, I'll have to snip off the DIN connectors and use some cheapo cable connectors to attach some longer cables. They will be driven by an Icon Audio Stereo 40i valve amp (EL34 push pull, 38wpc in ultralinear mode, 19wpc in triode mode).
After testing and running for a while, I'm minded to do some or all of the following mods:
1. Addition of binding posts to the rear & sealing the captive speaker wire hole
2. Internal rewiring to the new binding posts
3. Addition of damping material to the walls (dynamat type)
4. Addition of a couple of braces between the side walls
5. Repacement of the tweeter capacitor (single 5uf Clarity Cap ESA perhaps)
6. Addition of tweeter Lpad if the new cap makes things too bright
7. Removal of tweeter protective mesh
8. Possible replacement of the H087 tweeters with SEAS 27TFFC if I want more/better/airer treble.
I'm reluctant to scrap the boxes as some have suggested or the stands as they really look the period part, but it does mean that the tweeters are firing a bit low rather than ear level. I'm not quite sure how to address the tweeter height issue.
I understand that these Scandyna/Dynaco speakers work well close to a rear wall - at least this is what I'm hoping, as I've been struggling to find something suitable to date.
Observations and recommendations will be most gratefully received.
I've just won a pair of what I think are Scandyna A30 speakers complete with what look like the original stands (all for £17 / $25 or thereabouts). The cabinets look to be in remarkably good shape as do the drivers. My hesitation about the model is that the dimesions are the same as the Dynaco A35, but mine have an externally facing aperiodic port above the tweeter. There's no fancy variable tweeter output thingy and the captive speaker cables have old style DIN plugs but are only about 30cm long. To test them out, I'll have to snip off the DIN connectors and use some cheapo cable connectors to attach some longer cables. They will be driven by an Icon Audio Stereo 40i valve amp (EL34 push pull, 38wpc in ultralinear mode, 19wpc in triode mode).
After testing and running for a while, I'm minded to do some or all of the following mods:
1. Addition of binding posts to the rear & sealing the captive speaker wire hole
2. Internal rewiring to the new binding posts
3. Addition of damping material to the walls (dynamat type)
4. Addition of a couple of braces between the side walls
5. Repacement of the tweeter capacitor (single 5uf Clarity Cap ESA perhaps)
6. Addition of tweeter Lpad if the new cap makes things too bright
7. Removal of tweeter protective mesh
8. Possible replacement of the H087 tweeters with SEAS 27TFFC if I want more/better/airer treble.
I'm reluctant to scrap the boxes as some have suggested or the stands as they really look the period part, but it does mean that the tweeters are firing a bit low rather than ear level. I'm not quite sure how to address the tweeter height issue.
I understand that these Scandyna/Dynaco speakers work well close to a rear wall - at least this is what I'm hoping, as I've been struggling to find something suitable to date.
Observations and recommendations will be most gratefully received.
I would be reluctant to remove the tweeter mesh. It could be part of the design of the tweeter. You might have to redesign the crossover if you remove it. If you want more air, you could bypass the series resistor of the L-pad with a small (~1µF) capacitor.
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Hi,
Aperoidic loading is pretty redundant. Its controlled leakage
to reduce one note bass and very hit and miss. In the 70's
they found a much better method - capacitive loading.
Big series capacitor on the bass unit, model it in free Basta!.
(Driver specs on on the Seas website.)
http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Black Box_copy.pdf
Lots of speakers used it in the seventies.
That is what I'd do, with extra front baffles and better driver layout.
rgds, sreten.
Aperoidic loading is pretty redundant. Its controlled leakage
to reduce one note bass and very hit and miss. In the 70's
they found a much better method - capacitive loading.
Big series capacitor on the bass unit, model it in free Basta!.
(Driver specs on on the Seas website.)
http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Black Box_copy.pdf
Lots of speakers used it in the seventies.
That is what I'd do, with extra front baffles and better driver layout.
rgds, sreten.
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Thanks for the link Sreten. I'll have a play tomorrow with the stock speakers and see what I think. The World Designs dynaco based WD25 variants were well regarded by HiFi World, hence my interest in the design and a cheap Ebay win offering the chance to have a play at little expense.
Speakers often don't work well against or close to a wall unless the baffle coincides with the wall, ie the wall is an extension of the baffle. Otherwise you can have troublesome reflection issues.
What issue do you have that you're hoping to deal with?
The technique is old (Thiele claims it was originated by Benson), but is described in quite some detail by Thiele himself about 2 years before his death.
AES E-Library Closed-Box Loudspeaker with a Series Capacitor
Of course the technique is useful (except in some special cases) for a sealed box only.
AES E-Library Closed-Box Loudspeaker with a Series Capacitor
Of course the technique is useful (except in some special cases) for a sealed box only.
Hi AllenB. The issue is one of WAF, primarily! I really need to get speakers as close to a rear wall as is feasible but with something that has sufficient weight for full orchestral music AND without sounding boomy. I fear there may be some mutually exclusive elements here!
Not necessarily. Walls might either be joined, or avoided. It's when you go close to walls without fully making the connection that they can be problematic. It's also fairly speaker dependent.
You could try putting your speakers into your corners facing out at 45 degrees and crossing over in front of your listening position. Then adding some wings, or absorption if wings would be difficult.
You could try putting your speakers into your corners facing out at 45 degrees and crossing over in front of your listening position. Then adding some wings, or absorption if wings would be difficult.
One solution to WAF and decent sound is where I went. Small speakers mounted on the walls and good subs...
I've tried the 'small plus sub' approach and although bass extension is fine, overall 'weight' is still lacking.
I've now opened up one of the boxes as I have a blown tweeter. I'll be replacing them with SEAS recommended 27TFFC H0881-06 units. Interestingly, the "crossover" has a single 12uF capacitor and 10 ohm resistor for the tweeter. These are different values than the usual ones I see related to the A25.
The original bass drivers are pretty flat to 2khz and the 27TFFC start their low end fall-off also at around 2khz. Impedance at this point is about 6.8 ohms. This tweeter is 1db less efficient (91db) than the original, so I'd expect the original resistor value to be OK for starters.
The original bass drivers are pretty flat to 2khz and the 27TFFC start their low end fall-off also at around 2khz. Impedance at this point is about 6.8 ohms. This tweeter is 1db less efficient (91db) than the original, so I'd expect the original resistor value to be OK for starters.
Any further info on the A30's?
I noticed you were working on the A30's last year.
How did you progress with any mods?
I have the exact same speakers with the same crossover components.
I've just fitted binding posts and replaced the old Jensen cap with a 12 microfarad polypropylene Mundorf. Also removed the tweeter grill.
Not bad sounding speakers.
The drivers seem quite high quality and the cabinets are also quite nice.
Was wondering if anyone had come up with any upgrades to the crossover circuit to get them sparkling?
I noticed you were working on the A30's last year.
How did you progress with any mods?
I have the exact same speakers with the same crossover components.
I've just fitted binding posts and replaced the old Jensen cap with a 12 microfarad polypropylene Mundorf. Also removed the tweeter grill.
Not bad sounding speakers.
The drivers seem quite high quality and the cabinets are also quite nice.
Was wondering if anyone had come up with any upgrades to the crossover circuit to get them sparkling?
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