Martin F1 Bass Box

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   Hi Guy'sthe F1B is/was a front loaded single folded design with a rather large phaseplug in front of the 18"/4"VC (Celestion to my memory). This might look like a 'letterbox' loaded design, but is'nt. 
The efficiency is very high compared to other 18" bin designs of similar outside dimensions and exhibits quite a flat Power response, since Dave (Martin) quite favoured that. Sound wise the bin has quite a considerable 'kick' to it... The impulse is quite staggering with the right amplification.
Kind regards
a1olsen
(Dave's 'apprentice' at the time)

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a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 21 October 2009 at 1:26am
	Hi Guy's the F1B is/was a front loaded single folded design with a rather large phaseplug in front of the 18"/4"VC (Celestion to my memory). This might look like a 'letterbox' loaded design, but is'nt. The efficiency is very high compared to other 18" bin designs of similar outside dimensions and exhibits quite a flat Power response, since Dave (Martin) quite favoured that. Sound wise the bin has quite a considerable 'kick' to it... The impulse is quite staggering with the right amplification. Kind regards a1olsen (Dave's 'apprentice' at the time)

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 21 October 2009 at 1:33am
	Msg. for Ibex. The F2B utilized OEM ATC's with 100mm/4" Voice coils, bout 15mm copper edge wound coil in 7mm gab, massive ferrite magnet and double half roll surround on a curvy linear cone. Look for something similar with at least 3% efficiency. A JBL 2225H should do a good job here, even though it has a ribbed straight cone. Kind regards a1olsen

Robbo Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 05 December 2005 Location: Shropshire Status: Online Points: 4297	Post Options Post Reply Quote Robbo Report Post Thanks(0) Quote Reply Posted: 21 October 2009 at 8:22am
	[QUOTE=a1olsen]Hi Guy's the F1B is/was a front loaded single folded design with a rather large phaseplug in front of the 18"/4"VC (Celestion to my memory). This might look like a 'letterbox' loaded design, but is'nt. The efficiency is very high compared to other 18" bin designs of similar outside dimensions and exhibits quite a flat Power response, since Dave (Martin) quite favoured that. Sound wise the bin has quite a considerable 'kick' to it... The impulse is quite staggering with the right amplification. Kind regards a1olsen (Dave's 'apprentice' at the time) [/QUOTE I have seen what I thought to be F1B cabinets with grilles removed and they look identical to the bass section of a VRS1000 with the three circular ports so I have always assumed over the years that they were the same internally---From what you are saying, they could not be F1B cabinets----In that case what Martin Audio cabinets were they?

Ibex Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 27 May 2009 Status: Offline Points: 1013	Post Options Post Reply Quote Ibex Report Post Thanks(0) Quote Reply Posted: 21 October 2009 at 5:51pm
	a1olsen, a noble point that you are sharing your knowledge you have made in corporation with dave martin! Does this phaseplug of the F1B look similar to the one from mykey's Brute 45? Did the phaseplug operate to extend the upper cut-off frequency? Was a lot of processing required to get a flat response down to 50 Hz? Did they work in singles too or was it necessary to stack them? What about the horn path length of the F1B in comparison to the F2B, because the F2B had a cut-off of 38Hz. I would assume that it was shorter than in the case of the F2B? Are there any non-processed response plots available of these cabs? aussehen I dread that the Celestion 18" isn't available any more. What would a adequate replacement driver be? Sorry annoying you with a armada of questions! I'm a real fan of those designs of the days when I was young!

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 23 October 2009 at 12:26am
	Hi Ibex, I worked at Martin Audio with/under Dave Martin as R&D Engineer for about a year and a half starting in August 1990... The original plans for the F1 system was a bit 'hit and miss'... The top was sort of a 'given' being the top section out of the VRS1000 ie. Martin OEM ATC 12" 3" voice coil mid with phase plug and an OEM EV DMT 1A 1.4" compression driver. (There was actually a trap install box of this concept as well, but i think with a 1" JBL2425 like the VRS 800) Dave had tried to come up with a sort of compact sized bass bin with an 18" in it, since Turbo was quite rolling with their TSE118 & TMS4. He was not to happy with the initial test's and results and as a 'stop gap' solution in the form of a couple of proto reflex 2x15" OEM ATC loaded bass bins was devised. I think it was even on the IBT show at olympia 1991... There was how ever a couple of proto 18 bin's 'luring' back at Martin's High Wycombe R&D side chambers (it was actually the walkway down to production. At an inspired R&D moment in new solution for the bin was coined/devised - it needed a phase plug ! (and no it's not like Your attached drawing suggests - it's more like a slightly larger TSE 118 with a more true exponential flare (Dave believed strongly in this for power response reasons), broken into easier manufacturable sections with the added benefit of a phase plug arrangement in front of the driver. Remember that we where not able nor willing to challenge the Turbo Bass patent, very much in force at the time, so we had to come up with something slightly original. The result was extremely promising (it sent the rep from Chameleon amps straight to the loo for a throw - ) and we actually got hold of a TSE-118 for comparison - the new Martin design was quite a lot more efficient and with a lot more and stronger impact in the mid bass region. That then got productionized into the F1B. You are however quite right about the bass section of VRS 800 and 1000 - that was a short 18 horn with transmission line assisted bass reflex (Oh Dave loved that phrase!) In reality it ment the backside signal of the 18" ran all the way to the top of the box before coming down again behind the front, to end in reflex openings at the top of the short flare at the bottom of the box. It actually worked very well and extended the bass responsee considerably, but a bit on the cost of ultimate bass sound impulse impact. The VRS boxes was also made in a more horizontal format (ala TMS3) and they where called RS. The for the time very good Celestion driver is only avaliable second hand - it was a 4" VC double spider long throw design and was also used in the 2x18 reflex loaded Sub extension box for the F2. I think it was a 4 legged chassis... BUT the gd news is that Celestion do make a modern 4080? FTR equivalent which is very good to! Hope this answers some of your questions (otherwise 'bring some more on' - I will try and answer as memory and honour permits...) a1olsen

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 23 October 2009 at 12:57am
	Hi Ibex just gone through your questions again.. I think I have in a sort of 'round about way' told why the bin incorporates a plug... Yes the MX-4 came in a specially deviced version for the F1 incl. protective HP and Bass enhancement. BUT NO! the box was quite good for 50Hz on it's own. like with any Martin bins it was like 'the folk's over there' loves it - the more the merrier! I remember a club in East Wycombe got kitted out with a number of these bins - I think 4 a side and that was an absolutely awesome experience! It was so physical - as only an old Martin system is - talk about shakin your body man!!! The path length is actually quite similar to the F2B, but the implementation somewhat different since the F2B employs 'letter box' loading and is a bit of 2 front 2 front 'saxophone shaped horns. The response plot's is the intellectual property of Martin Audio. IE: Martin never published a curve in those days, not that we did not do loo roll long B&K graphs on now vintage B&K 'steam machine' equipment, but that was the ethos of the day. I do remember that only the Benelux distributor ever having been allowed to have a look at the LE700 response curve. Do not forget - this is/was not hi-fi, but ment to part of the creative process of making and reproducing music, so the responses could in between look a bit 'peculiar' and therefore be under grave danger of misinterpretation in the wrong hands and/or heads... But all the electronic controllers came with a meticulous measured B&K graph on top of them. These controllers was also configured over a minimum of 48 Hours 'burn in' time, to prevent less failures 'in the field'. a1olsen

Ibex Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 27 May 2009 Status: Offline Points: 1013	Post Options Post Reply Quote Ibex Report Post Thanks(0) Quote Reply Posted: 24 October 2009 at 5:16pm
	Hi a1olsen! Honor is due to you! Sincere gratitude for your special supply! I'm very pleased to have the oportunity to talk to you as you have been a former Martin Audio employee! You have to know, I really look up to you! Why have you been only for one and a half year engineering for Dave Martin? What are you doing nowadays? I really have no clue how this F1B phaseplug would look like. Would you be so kind to explain or draw a thumbsketch? Does the VRS1000 utilize a phaseplug to? What are the advantages or disadvantages to a letterbox design? The transmission line assisted bass reflex design of the VRS1000 sounds interesting to me. Is it similar to the voigt pipe principle? What's the benefit of such a construction? Never tried to model somthing like this before. Sorry, but what do you mean with '2 front 2 front saxophone shaped horns'? What would you prefer: one F2B or two F2B? Many thanks for your driver recommendations!!! ps: sorry for the armada of questions, bootlicking and my bad english

Cyklist Members Profile Send Private Message Find Members Posts Add to Buddy List Young Croc Joined: 14 December 2007 Location: Ireland Status: Offline Points: 711	Post Options Post Reply Quote Cyklist Report Post Thanks(0) Quote Reply Posted: 24 October 2009 at 6:56pm
	great thread great info a1olsen would also like to know more about the phase plug.
	purple monkey dishwasher

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 25 October 2009 at 4:19am
	Hallo chaps, and tnx for the kind words Ibex. Some of my current 'doings' can be seen in working format (an upgrade is due this winter..) at: www.geocities.com/blueluti I have been working on 'perfecting' that 18" bin concept since that 1st Martin implementation and a mk2 version under my own CSW banner is currently under way - the 1st 8 C118Bmk2 beta bins is currently being manufactured. This also incorporates a plug, but is much different to the Martin one, which I hope You can accept I for Intellectual property rights issues (belongs to Martin Audio) can't revile the true nature of. The purpose of plug is to enhance the sound impact of the bin and also smoothe some of the frequency response... The VRS's does not really need plugs due to the way the 18 is loaded on to the relatively short horn. I'm affraid I'm not familiar the Voigt principle... Please enlighten? The attempt description of the F2B is from a cut through view of the horn parts of the box. Loading of bass drivers in bin is a bit of a matter of taste I suppose? With or without plug vs. letter box vs. side loading - It sort of comes down to the inevitable (hopefully enlightened) chosen compromises against wished performance parameters most speaker designs have to abide by... I would personally depending of application naturally, prefer a couple of F1B's... They would be easier to handle by one man and the combined effort of the 2 18's will in the Martin case IMHO outshine the F2B... I hope this will suffice for now and send best wishes to the Alpine regions in particular. PS: On a very side line note: Did You know that Chevin amps production is now managed from Austria? Cheers a1olsen

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 25 October 2009 at 4:37am
	Oh, and since You ask Ibex... Martin Audio was at the time I worked there in a sort of transition phase - having just been sold by Dave to the Tannoy/Goodmans group and the working atmosphere was in between a bit questionable... I have also had the pleasure of working for Turbosound for 3years, (where the 1st task was to set up their in house R&D), after Funktion One had just seen the day of light. I suppose my CV is quite interesting reading to some... I have since consulted for various Companies and done me own stuff... Cheers a1olsen PS: I do ski quite well by the by... (even though it's a while ago last)

james folkes Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 08 January 2005 Location: United Kingdom Status: Offline Points: 3064	Post Options Post Reply Quote james folkes Report Post Thanks(0) Quote Reply Posted: 25 October 2009 at 10:53am
	arghh, safari browser crash ate my lengthy reply! i've just been looking at the bass cabinet designs on the cluinn site and realised who you are... hello sven! i've got some questions about obscure mx4 system controller configurations too, if you can remember anything about them! i run a modular pa consisting of 215 mkIIs, m600 philis and 2441 loaded bi-radials with bullets on top, a little ict rig and two stacks of f2. i recently bought some mx4 controllers which were set up as F1SDE, we thought this meant crossover points of 1k5, 200/220/250 (depending on what was flavour of the month when it was made, for my money i prefer the lower points on my speakers, f2b and 215 mkII honk a bit at 250) and then an overlapping sub channel which has been delayed to time align 2 x 18" reflex with the horns it will sit alongside. f1 with subs, delay and eq... we thought, presumably the eq is for the hf horn on f1? i really like these crossovers by the way, excellent sound quality, good limiters, nice construction, they might even be marginally nicer than my (admittedly slightly tired) fds360s, they certainly wipe the floor with digital lms units in my price range. my f2r are configured with f2m, f2h and 2 x f2v, although the last mile split of the hf is handled by a dedicated crossover card in the pulse 4 x 300 that powers them (6k3 if i remember correctly). the pulse crossover card has options for a cd horn eq, but i'm not so sure f2 horns even are constant directivity, i thought they were a modified conical with an exponential termination... clearly doing some actual measurements would go a lot further than idle speculation, but i don't get the chance often enough. can you tell me anything more about this mx4 configuration? can i use it the way i have been or do i need to start making up new cards? what is the overlap of the sub, if any? are the top cabs delayed to the bass bins or is it just the subs, or is it not even that? i've spoken to a few people at martin and they couldn't help, unfortunately anyone who worked on f2 has long since flown the nest. james.
	mardy hippy.

a1olsen Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 18 March 2009 Location: London Status: Offline Points: 62	Post Options Post Reply Quote a1olsen Report Post Thanks(0) Quote Reply Posted: 25 October 2009 at 12:57pm
	Hi James, you are quite right - the MX-4 is a mighty fine unit! Designed by a true genius (and godfather 4 most) of the so called pro audio business: Tim Issacs. One of the really nice features besides the obvious configurable is the sound as U mention especially when the limiters start working - they are as gd as unhearable and certainly a hell of a lot better than the RMS ones employed by the company in potters bar... Tim explained that it's due to a 2stage time constant configured around a differential fet gain cell... Now there's a nice line 4 the PUB -oder? Would have been good if Martin had been bothered to send You my way and on a possible consultancy tender would have been even nicer! I resently picked up a MX-2 smaller brother x-over and after a bit of 'Dr' O'ing, with some fresh slopes, capacitors and upgraded IC's, it really came into an enhanced classs of it's own, drriving my own small 'Club system', comprising top boxes and subs. The configuration for the Martin F1 is very similar to F2. It's only the eq (separate plug-in card) which to memory should be different. The EV 1.4-5 inch exit comp. driver has quite a nasty edge surround resonance peak around 13k, so that is addressed be a quite severe notch filter in excess of 10dB's, together with the CD lift for the horn/driver combination. Likewise there's some eq to the Bass bin combined with HP LF over excursion protection. The actual x-over frequencys should be 250Hz and 1k I presume. the 12" certainly does not give much output over 1k2 so it should be quite likely. But mind U - all is only -dB points, since Dave believed that right... I would 2day do things quite differently (and I do!), but that would for best result require re measuring the individual responses on the system and then do some quite heavy manoeuvres in LEAP V or AKABAK. This I would not do for free I'm afraid - sorry - trying to make a living as well in between U know... Best free advice I can probably commit to, is to suggest (providing U R reasonably proficient with analogue active x-over work of course or 'dial it up' on a digital meat mincer perhaps?), that you try employing say L-R -6dB slopes instead? That should take care of some of ur exclaimed 'hunkyness' with some luck. Otherwise I'm ambly happy to assist in a professional capacity at my CSW set-up in Manor House, North London. I have over the years acquired some B&K mics, preamps and an HP 2ch real time FFT Dynamic Signal Analyser plus the these day necessary PC equipment for documentation purposes. But I happily confes to do most things by hopefully 'experienced ear', before starting all the machinery... It's music and reinforced sound we are trying to do something with after all - ain't it? Cheers for now Sven R. Olsen aka 'Dr' O aka a1olsen aka a1greatdane etc. (help Ur selves pls.) PS: I personally wouldn't bother much with those 2x18 reflex 'things' - but would prefer more bins to create enough mouth area for serious low extension... With enough F1B's it should literally 'take Ur breath away'!