Renovation of Celestion 66 Studio Monitors

[rodthebod]

Hi Ken

Slightly off topic this but I've just been looking at your amazing projects on your site and the Project turntable with Terminator arm caught my eye, impressive use of parts sourced btw.

I have a Goldring G99 which has been in a cupboard for years, have checked out the various sites and it seems this has potential - using the motor, bearing platter and top plate. When you did your Technics based deck would you say using the plywood plinth reaped benefits over the mass loaded concrete plinth on your other deck? I'm deliberating what kind of plinth to do with the G99, and the tonearm.......
This really took my attention, the Terminator arm you used. I've been looking into making a unipivot tonearm using magnets (not a new concept I know, Schroeder etc) probably 12" but then the parallel tracking air bearing arm principle seems much better and ultimately easier to setup. I remember trying an air bearing arm back in the 1980's - imported from the U.S. I think, in fact I'm pretty sure it was the first one out there - concentric bearing design - noisey pump I remember. I only had it on loan for a limited time because it was in high demand for reviewers etc. but boy did it do things, or rather let the music just come on through. It's funny how you remember vividly when things impress you, or is that old age. Can't remember the manufacturer though.

How does the terminator arm perform, is it easy to setup, has it any querks? The end solution certainly makes for a nice compact and clever design, that appeals to me, even though I'm building whacking great big 66 speakers with 12" drivers which are the largest I've ever had, always used 5.25" drivers in the past.

[walpurgis]

Don't cannibalise the G99. If you want bits, GL75 items will do the same job and can be bought fairly cheaply. The G99 and G88 turntables are appreciating classic units and well worth keeping complete. They sound superb as they are anyway. Just bung yours in a good base/plinth with a decent arm and you'll have a top class deck! It'll be worth quite a lot of money.

[rodthebod]

Thanks for that Geoff

Worth a few quid, wow! it's been stuffed on a cupboard for years, but I've had the thing working with the Transcriptors Fluid arm that was on it and an old Shure V15 Mk2, I'm waiting for a new stylus gauge to turn up so had to guess tracking weight, but yes it plays really quite well. I had to put it on some foam as it was so susceptible to airbourne vibration, (and it's on a wall shelf) It's totally original in the Goldring Teak thin plywood plinth, date on the green underside of top plate is 1968. Runs pretty consistently at 33/1/3 considering its not been used for so long it's quite amazing, they really knew how to build these things.

You're right, and I'd rather not rip something apart that's working well and original and worth a bit in that condition which should only appreciate.

I know someone local who has a Lenco L75 with matching arm totally original, I think they would sell it, what are they worth?
Any suggestion on plinth material, I'm quite keen on this air bearing arm concept, or am I being too ambitious.

Cheers
Rod

[walpurgis]

Not bought from ebay, a sensible price for a GL75 is maybe between £100 and £150 depending on condition.

G99 units have been fetching £400 to £500 lately and the Fluid arm is worth getting on for the same these days. Even a good V15II will fetch a pretty penny now.

To get all the 'ins and outs' for Lenco turntables, you really need to visit the Lenco Heaven specialist forum.

[Qwin]

Yeh, don't do to much to the G99, which is a nice looking and decent sounding deck. I think a nice wood plinth is all you need.

The concrete worked well, but was just too damn heavy, the deck was heavier than a 3'x2' paving slab and awkward to position and adjust.
The plywood deck is no lightweight though and I like it, coupled with the Isonoe feet it works well.

Terminator Arm
I was having a lot of problems with end of side distortion (ESD) with my Technics arm, I even drew up an alignment protractor using the Technics geometry, which is slightly different to the usual bunch. It helped but I wasn't happy. I also looked at the Schroeder arm and even bought some of the materials to start the project, when I came across the Terminator design. The sled moves horizontally on an air cushion, like a hovercraft and the arm is slung below this using two pivot points for vertical movement. The combination works very well, and you get consistent results across the whole of the record, which was cut using a linear tracking device anyway. There is full adjustment available, even azimuth and it is different, but not difficult, to set up, you can adjust VTA on the fly to easily find the cartridge sweet spot. Once you have got used to the setting up procedure, it is very quick and easy to set up a new cartridge. It is a very capable arm and would do justice to cartridges way above of my upper price point. It uses a fish tank air pump, which I have mounted in the next room, so the very slight hum is not a problem for me. Some folks build a soundproof box to put the pump in and hide it in a wall unit or other furniture cupboard, near to the turntable.
Check out Vics site and the genuine testimonials for this great arm http://www.trans-fi.com/terminatortonearm.htm

[Macca]

Hi Martin

That's the one, Mini T, should have known Paradise is the phono pre, I'm just about to build an EAR based phono myself. What exactly happened when the 66's asked to be fed?

Hi Rod

IIRC we had been using an Avondale amp with the 66s. and getting a really good sound. I went out to the bar, came back and asked 'what has changed? It just wasn't right anymore, especially the bass which was just wrong. I'd guess this was simply down to a lack of power rather than the type of design.

[rodthebod]

Thanks for the feedback again Ken, the air bearing parallel tracking concept really is attractive, all other methods with pivot arms are a compromise. I remember the parallel tracking arm from about 30 years ago and the final track on that favourite LP was the best surprise, it always seemed to loose its sparkle with a 9" pivot based arm.

Hi Martin, even better news this, I have as my solid state amps a pair of Les's (Avondale) RMS T65 power amps, not sure how they compare to his latest offerings (Voyagers I believe) but they really drive hard into my Revelation 2 speakers with carbon fibre drivers, more than you can stand! I am looking forward to using the refurbed 66's with my EL84 Leak TL12+ monos though, hopefully there's enough grunt.

Ken, back on the 66's did you try picking out the original HF caps which are bundles and try them close to what the capacitance should be, ie remove some, when I measured them with a friends meter they all had increased their capacitance drastically. Or would they just sound 'muddy' compared to Ansar's? I'm waiting for a new capacitance/inductance meter to arrive from China - taking ages, once I have it I'll try it out. I checked the Hi-Fi collective site out for alcaps, there are two types one is RAW and the other PLAIN, plain ones being much more expensive, which ones do I use - it'll be the pricey ones won't it? There doesn't seem a supplier that does ansar/alcaps and mundorf e-caps together, postage costs to Malta are silly sometimes from some suppliers so I'm hoping for sensible costs.

[Qwin]

My original film caps in the HF section measured the closest to spec of any on the board.
The reason I changed them, is that they were an early film cap and not as good as a modern Polypropylene.
The originals were a bit grainy, the humble Ansar replacements were smoother and more transparent.

I have a cheap Chinese L and C meter, I use it for ball park only on inductance, it gives different readings for instance if you switch from Hi to low range and generally reads hi compared to the Dayton Audio Test System (DATS) I use and trust. It's a lot closer on capacitance.

The Mundorf ECaps come in two versions as you point out. The Plain are the best sounding and are Low Loss (LL) even a large value of say 33uf is only about £3 so not too expensive.
Some of the original Elcaps in my circuit were marked LL for low loss, check yours and replace like for like.
The large value big can in the signal path of the bandpass filter was Low loss. This if nothing else, must be a "Plain" version ECap or the mid range quality will suffer and as stated previously you can throw in a couple of % of PP to make the total value, but no more than 5%, less is more!
Stick with Alcap Lytics from Falcon for the pair of 72uF caps in the Low pass filter. Mundorf don't do that value anyway so you would have to pair up several which would cost more. Falcon are now the only supplier of Alcaps that I know of. Crincklewood Electronics do the Ansar but not the other two and HFC only do the Mundorf ECaps. Its getting harder and harder to source parts, even in the UK, you can't get 1% mills resistors here, I have to get them from the States, HFC only do them at 5% tolerance and they cost a lot. Just means I have to wait, some arrived today that I ordered in November. These are to complete the passive element of the crossover on my semi active project, they will be soldered in place tomorrow. I seem to spend half of my project time waiting for bits, got my coils from the Netherlands, but still waiting on some items from Hong Kong expected any time from mid December to Mid January!

Note: Just to be clear Elcaps/Alcaps/ECaps are three different things but all are Bipolar Lytics. Ansar Supersound are Film caps (Polyprops).

[rodthebod]

It is proving to be messy at best to get the components, still at least they are available judging from the sites thanks to your recommendations Ken. I'm just holding off ordering until I work out if its worth popping in a couple of good audio grade caps in my Leak TL12 + monos. They have caps fitted from about 25 years ago, I've replaced the main smoothing caps as they were failing but I need some advice on whether its a good idea to use more modern caps elsewhere - maybe its best to leave well alone until something fails, they seem to be working well since renewing all the valves?
I've also double checked the original circuit diagram and there seems to be a couple of 50uf caps missing on my amps.

[rodthebod]

Hi Ken

Could I just quiz you on the virtues of external crossovers for the 66's, I have external boxes for the RMS Revelation 2's speakers I have and never really thought much about it, always keeping speaker connections close to the source (power amps) and leaving the main runs to the speakers, usually 3m. I know that inductors don't like magnetic fields and are influenced by them so it's a good idea to keep the crossovers as far away from the larger driver magnets as practicably possible. Did you ever compare the sound of the crossovers when they were external to when you mounted the boards behind the EBR?

I know originality is important but as I'm building new cabinets from scratch it may be the way to go....