Milestone 604 Sorta-Clone

[Skywave-Rider]

Recently heard Milestone 604s -- pleasing sound! The box was surprisingly trim, relative to big 604/605 boxes, and look great to my eye. I did a bit of digging around and they may be 6 cubic ft (?).. The Manta Ray horn sounded good, despite design issues. Unfortunately my listening session was limited to relatively low to moderate levels, and the speakers were spread out too far in a crowded retail space; not ideal.

But it was good enough to get me interested and looking at some coaxial driver systems, namely the GPA 604HIII and the Beyma 15CXA400Fe.

If I could make the GPAs work in a box the size of the Milestones, or smaller, I would seriously consider making a set. Was this box a simple ported design, or an MLTL?

I would go active crossover and have no aversion to a little active assist for lows, as it's easy to do. I'd like to hear opinions about this.

My digging around the net turned up remarks that the HIII horn is a clone of the later Urei 813/815 unit, minus the foam. I used to use and remember liking those. However, the missing blue foam had to solve some problems which are not being addressed in the GPA units -- so is wrapping felt around the mouth sufficient, or necessary? This assumes it actually is a clone of the Urei horn.

I wanted to make these preliminary inquiries because I'm a little weary combing forums and hope to be pointed in the right direction and or slapped upside my head. Those are expensive units to get into without hearing them.

[Altec Best]

Hey Skywave ! The 604's IMO will benefit from a cabinet a little larger than 6 cu.ft.If you can stand the larger footprint.9 cu.ft seems to be optimum for the 604 like a 620 cabinet.I never heard of the Milestone.It looks like it may have been geared for the Japanese market.That cab looks like a simple bass reflex to me.

A lot of good threads on this subject here.

http://www.hostboard.com/forums/sear...earchid=373727

[dbale]

I discussed cabinet size with Bill H. when I ordered my 604-8H-IIIs.
I asked about using them in the flamenco cabs I have,Bill felt that I would be disappointed if I were to use a cab that small.
Bill suggested 6-6.5 cu ft. as his favorite alignment,SH III size.
Having room for almost any size cabinet I told Bill I was looking at building altec 620 or the SH V cabinets.He said they would
give a more extended bass over a 6 cu ft cab.
After spending sometime with the 604s in 620 cabs I can say that I'm very satisfied.

Iconic Speaker Manufacturing - Stonehendge Page

[GM]

Was this box a simple ported design, or an MLTL?

I would go active crossover and have no aversion to a little active assist for lows, as it's easy to do. I'd like to hear opinions about this.

My digging around the net turned up remarks that the HIII horn is a clone of the later Urei 813/815 unit, minus the foam.

-- so is wrapping felt around the mouth sufficient, or necessary? This assumes it actually is a clone of the Urei horn.

Simple reflex.

More bass = bigger box tuned to Fs with Vb = Vas required to get a T/S max flat alignment down to Fb = Fs and due to the driver?s specs this usually requires some EQ and/or corner loading.

Being a decades long fan of tower/column alignments, I recommend a MLTL of at least 9 ft^3 tuned to Fs with a 30? wide baffle and preferably 60?+ tall with the driver spaced down to average listening ear height.

Maybe, but if so, it?s minus the ports to allow some of the cone?s output to reinforce the horn?s lower BW similar in concept to Tom Danley?s Unity/Synergy horns.

It?s a simple radial horn, so ideally needs some damping around/over the mouth to damp down its eigenmodes from reflecting back to the throat. How dense will need to be arrived at empirically.

GM

[Skywave-Rider]

Hey Skywave ! The 604's IMO will benefit from a cabinet a little larger than 6 cu.ft.If you can stand the larger footprint.9 cu.ft seems to be optimum for the 604 like a 620 cabinet.I never heard of the Milestone.It looks like it may have been geared for the Japanese market.That cab looks like a simple bass reflex to me.

A lot of good threads on this subject here.

http://www.hostboard.com/forums/sear...earchid=373727

Thanks, Altec Best! Nice to see you. I have been off the forums for a long time. Living in Tokyo, that's why I heard the Milestones. Altecs and vintage JBLs are very common here. I think 9 cu ft is not possible. I am going to look at some models and compare the Altec to the Beyma regarding box requirements. I could not get that link you posted to work.

I discussed cabinet size with Bill H. when I ordered my 604-8H-IIIs.
I asked about using them in the flamenco cabs I have,Bill felt that I would be disappointed if I were to use a cab that small.
Bill suggested 6-6.5 cu ft. as his favorite alignment,SH III size.
Having room for almost any size cabinet I told Bill I was looking at building altec 620 or the SH V cabinets.He said they would
give a more extended bass over a 6 cu ft cab.
After spending sometime with the 604s in 620 cabs I can say that I'm very satisfied.

Iconic Speaker Manufacturing - Stonehendge Page

Thanks, dbale. It's good to know that GPA likes the smaller size.

Simple reflex.

More bass = bigger box tuned to Fs with Vb = Vas required to get a T/S max flat alignment down to Fb = Fs and due to the driver’s specs this usually requires some EQ and/or corner loading.

Being a decades long fan of tower/column alignments, I recommend a MLTL of at least 9 ft^3 tuned to Fs with a 30” wide baffle and preferably 60”+ tall with the driver spaced down to average listening ear height.

Maybe, but if so, it’s minus the ports to allow some of the cone’s output to reinforce the horn’s lower BW similar in concept to Tom Danley’s Unity/Synergy horns.

It’s a simple radial horn, so ideally needs some damping around/over the mouth to damp down its eigenmodes from reflecting back to the throat. How dense will need to be arrived at empirically.

GM

Thanks, GM. I have been learning a small amount about MLTL alignments. Not enough to ask intelligent questions, yet. After I look at models I am going to have to see what I can do to get the most useful low end in the smaller package. The roll off at the low side is important for integration with subs.

Regarding the horn, thanks for the info. I never thought to apply the Danley concept to the slots in the Urei horn. That makes sense. I wonder if GPA would customize that feature into an order. It's not easy for me to call there, and I know emailing is a waste of time, so I'll have to find a way to talk to him.

What models MLTL alignments? Does WinIsd?

[GM]

Thanks, GM.

I wonder if GPA would customize that feature into an order.

What models MLTL alignments? Does WinIsd?

You?re welcome!

Dunno, it may still be currently patented.

Martin King?s MathCad software is best overall AFAIK, but may no longer be available, so AkAbak is gaining popularity along with Hornresp, though it can?t do offset vents, only drivers, so pretty limited. There?s this new one, but haven?t tried it, though some familiar with these others praise it highly, so may be your best bet overall: Transmission Line Modelling Software - diyAudio


GM