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efficient cabs for low power tube amps
- Thread starter zorf
- Start date
- May 9, 2008
- 4,081
- 1,236
- Disclosures
- Proprietor Springvale Studios
Due to the interest in specific historic guitar tones, the tooling for the Altec 417 12" musical instrument speaker was bought by Great Plains, and NEW production loudspeakers can be ordered.
The same magnet structure is used by the 418 series II And the oversized 16" white basket is still manufactured by Great Plains for the rest of there A7 driver manufacturing.
If you ask them they will build you a brand new 418 Series II from their extensive stock of both hard and soft parts.
http://www.ultimaterhoads.com/viewtopic.php?t=3410
- May 9, 2008
- 4,081
- 1,236
- Disclosures
- Proprietor Springvale Studios
In a fairly linear manner in a vintage JBL or Altec at least as far as >50watts per driver, which is what we are actually attempting to drown a drummer with in this case.
You will probably get as much as 6dB speaker compression before noticeable farting occurs at around 150 watts max per driver on low B with a K/E140.
Show me where I said it did. The greater cone travel of the 140 will, however, allow it to handle more power without farting out.
Sensitivity is essentially cone excursion per watt, measured at a distance of 1 meter, on axis. Sensitivity is not a well bounded spec. Some use the highest peak in response. A driver with a broad band sensitivity of say 95 db/w/m can be rated as 99 db/w/m based on an upper-mid/lower treble peak. Also note that some use a signal level of 2.83 volts (1 w into 8 ohms) on a driver with an impedance (through the midband) that is less than 8 ohms. This results in a higher drive level and a resulting higher (apparent) sensitivity. Even when measured at 1 w at the average midband impedance, the spec can be used as little more than a guide. Drivers within a few db (like 96 and 98 db/w/m) can sound essentially the same spl, or the lower one can actually sound a little louder. Check the sensitivity spec and compare it to the on-axis response level (db) - its measured at 1w. The two should be about equal through the midband, where the ear is most sensitive. You will find quite a few sensitivity figures based on peaks.
Honestly I think dB/1w/1m measurements are misleading. No one plays with only 1 watt. More telling would be a dB/10w/10m. The numbers would work out to be similar, but would line up more with what you experience on a gig.
Due to the interest in specific historic guitar tones, the tooling for the Altec 417 12" musical instrument speaker was bought by Great Plains, and NEW production loudspeakers can be ordered.
The same magnet structure is used by the 418 series II And the oversized 16" white basket is still manufactured by Great Plains for the rest of there A7 driver manufacturing.
If you ask them they will build you a brand new 418 Series II from their extensive stock of both hard and soft parts.
http://www.ultimaterhoads.com/viewtopic.php?t=3410
So they are a custom order? That isn't "in production". Who can have new drivers shipped out to me tomorrow?
so let me get this right: the vintage speakers need a big horn loaded box, are loud in the mids but roll off under 60 or 50 hz, are fragile, but people love them anyhow?
fair enough, but there are no improvements since then that don't involve standing up to a lot of power and at the same time needing a lot of power?
fair enough, but there are no improvements since then that don't involve standing up to a lot of power and at the same time needing a lot of power?
There are. The 15PR400 is a prime example. It and the Eminence 3015 match several of the vintage JBL drivers in sensitivity. They also go lower, handle more power, and are ultimately more robust as drivers.
Some people have rose colored glasses for yesteryear.
I've also heard that the 15PR400 in particular sounds somewhat like old JBLs.
Hence why ultimately I want a couple 2x15 cabs with those in them for gigging, and then a 1x15 loaded with a JBL K-140, powered by a small tube amp, for recording.
- May 9, 2008
- 4,081
- 1,236
- Disclosures
- Proprietor Springvale Studios
Well they don't need a large horn loaded box in order to make more than 106dB @ 1watt one metre for a 2x15, you might get another >2dB off a short horn like an a7 or a 4560.
These are genuine average SPL figures, I have an Eden 8x10LXT that's 8 ohms that claims some very impressive SPL figures but when I run it it parallel with one of the Altec SVT115a cabs, which are also a nominal 8 ohms.
The single Altec 418-II driver is apparently brighter and slightly louder at a volume I like to play at, than the coupling of the eight eden 10" drivers.
That should not be scientifically possible, but its certainly true.
PS I don't like a whole heap of boomy muddy resonant volume in my stage sound and I certainly don't want to be bassier in tone than a good clicky mic'd kick drum stage sound, thus I would far rather leave heavy sub bass to the PA Subs and associated high power amps in any boomy old venues I play.
It depends how you read your question. All the other answers you got are saying "yes". More cone excursion per watt makes more sensitivity.
But the other way of reading the question speaks to the nuts and bolts of speaker construction. Bassmec could write you a whole book on it. In short, build it tougher and it won't be as sensitive but it'll go further and get louder with all the extra power.
- May 9, 2008
- 4,081
- 1,236
- Disclosures
- Proprietor Springvale Studios
The 1501dt Used to be right about where a JBL a K140 SPL is, seemed more with tranny amps because it was half the impedance, the older 80's non increased power handling voice coil, non modern striated Kevlar impregnated cone, IE the old curvilinear cardboard black widow replacement basket was very efficient indeed but
Johnk10 has a demo in this thread of how much aparantly louder the D/k130 was, so let's just use the +3dB math here,
So for example a slightly clipped fender Bassman 50 is about the same apparent average volume with a JBL K130 or an altec 418-II as an old Electrovoice 200 watt rated EV15l or brand new Eminence 3015ho is with a slightly clipped Fender bassman 100. +3dB is equivalent to twice the loudspeaker coupling or twice the power in watts.
http://assets.peavey.com/literature/specs/116628_13614.pdf
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There is no conflict between the two answers. In their day, the JBL and Altec were both built 'tougher' than their contemporaries. The trend continues. While books could be written in answer, there is really no reason for it.
They are pretty good. The real winner in Peavey's line up is the 1505-8bw's. Really good balance of sensitivity, power handling, and response. Not going to out perform the neo drivers, but they are some of the best ceramic mag drivers out there.
I run an approx 6 cu ft ported box (2, 4 " flared about 4" deep) loaded with 2 3015's. I power it with an old Music Man 100 watt tube amp. The box was built of 12mm baltic birch, void free ply. Biscuit joinery and fEarful style bracing. It simply rocks. My cab was to a large extent inspired by the johnk_10 Starliner cab.
I am an old fan of the Sunn 2x15 loaded with JBL d140's. The 3015 is a very, very good approximation of that driver tonally. It is far more durable. Not to mention lighter and in production. No way I would bother with vintage drivers again. (Other than the old pair of Altec 417's in my low watt guitar rig... That thing near to never moves or get's pushed hard)
I am an old fan of the Sunn 2x15 loaded with JBL d140's. The 3015 is a very, very good approximation of that driver tonally. It is far more durable. Not to mention lighter and in production. No way I would bother with vintage drivers again. (Other than the old pair of Altec 417's in my low watt guitar rig... That thing near to never moves or get's pushed hard)
