TP-028, Nat Adderley's Work Song is now available

Author Topic: RS1500 rework developments  (Read 18110 times)

Offline docb

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RS1500 rework developments
« on: March 13, 2007, 11:38:05 PM »
I've spent the last week or two working up a rational procedure for refurbing and (hopefully) improving the performance of the RS 1500.

A couple of areas that seem to be most critical for best performance are the coplanar positioning of the tape path components and subsequent head alignment, and the proper spool brake tension in both winding directions.

The tape path is quite critical in these machines. Unfortunately it is also easily misaligned from bumps and dings. A careful visual alignment using some established reference points is a starting point for static alignment, and the bulk of the alignment adjustment is made with shims. Once the visual alignment is complete the travel of the tape over the rollers, guides and heads and the tape pack position need to be observed. Any necessary final adjustments will show themselves more clearly as the tape moves. I have found that if the tape path aligment is done with enough care some sources of friction in the tape path can be removed and some guide surfaces can be replaced with lower friction materials. This seems to bring out a subtle improvement in dynamics.

Following this the head block can be removed and a careful visual positioning of the heads can be done. From there the headblock is replaced and alignment with a calibration tape is usually pretty easy.

Before any of this is done, however, the brake tension must be adjusted. I have worked with several different machines now, ranging from minty low hours units to beat up old dogs. One thing is consistent with the machines I have worked with - it seems you can't set the tension to the spec in the manual, regardless of how new the stock felt brake pads look. I spent quite a few hours testing different brake lining materials and I can happily say that I have found a material that seems to hit the tension spec in both directions, dead on. I have worked up a procedure for rebuilding stock brakes with this material. It's remarkable how much better an RS1500 works with the proper brake tension. The tension rollers never pop up at stop (which is critical for being able to stay seated on your lazy butt when you're using the IR remote) and the reels stop very quickly at runout. With the tape kept in good tension the pack seems to come out better when you stop and start a lot too.

Now that I'm finally getting a blow by blow listing of the steps of the refurb process together and I should be able to start developing pricing.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline mstcraig

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Re: RS1500 rework developments
« Reply #1 on: March 14, 2007, 08:25:20 PM »
Again, forgive me if this has been addressed. Can I assume that you will, at some point in the future, be offering Technics machines for sale that are all modified and "turn-key"? I would be very interested to see what you are asking for these. Or, can someone send you a machine they own already and have you do your magic to them? Lastly, any more news on what rooms The Tape Project will be demonstrating in for the upcoming Stereophile show? Craig
Craig Sypnier
(Magnepan, VPI, Sumiko, Shure,
Belles Research, ReVox (A-77 and B-77), Scully 280-B, Teac A-2300SD, Nordost)

Offline docb

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Re: RS1500 rework developments
« Reply #2 on: March 14, 2007, 11:12:45 PM »
Yes to both. We will offer machines for sale when we can find them (we have small stockpile now) and we will also do refurbs and upgrades on customer machines. I will have some shipping crates made that can be used by customers to ship a machine to us and return it. The customer will have the option of purchasing the shipping crate or returning it.

I'll try to come up with a list of things to look for when checking the condition of a machine that one is thinking about purchasing. Some things that commonly need work like brakes are an easy and relatively inexpensive repair/upgrade, while bent and broken guides, arms and motors are not necessarily easy to replace. Other commonly or broken worn parts shouldn't be too expensive to fix and I will try to find reasonable current production replacements for them - the head selector switch comes to mind. And of course head wear makes a big difference in the value of a machine. I hope that folks will be patient in their search and get a fair deal. I've seen a few folks pretty frustrated by "mint" machines that were a wreck, "new in the box" headblocks with completely shot heads, and more than one machine that was shipped cross country with only a little popcorn thrown in the box.

We should have copies of the first four albums for demo at the Sterophile show, and possibly a few other treats...
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline docb

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Re: RS1500 rework developments
« Reply #3 on: March 27, 2007, 05:40:01 PM »
Here's the latest update -

I have just wrapped up the design of the remote control receiver cabinet. For me cabinets are one of the PITA jobs in this business, but I think I came up with a pretty functional setup. The remote box will be 1U tall (1.75") rack style, and will sit above the RS1500. There will be a row of cutouts in the faceplate, of the symbols for Rew, Stop, Pause, Play, FF. These will be centered between the two reels, and light when you hit the corresponding button. There will be no Record button on the remote. You will have to use the Record button on the machine, as we don't want anyone yelling at us for accidentally recording over a Tape Project tape.

I have also been casting about for improved tension roller arm return springs. I have some off the shelf stock to try. So far so they seem to be great, but if they don't pan out in the long run I will have some custom ones made.

This afternoon I am working up a new power entry panel for the back of the RS1500. The plan is to loose the silly battery jack and whimpy power cord, and put in a new panel with an IEC connector and two NEMA three prong outlets, so you can plug the tube preamp and the remote wall wart into them and have just one $27K 1-1/4" diameter yak fur lined neutronium power cord coming off the cabinet if you like.

Lew Hardy is making us some dovetailed walnut rack cabinets to house the RS1500, IR remote receiver, tube repro amp and VU meter cabinet. I'm trying to make this as modular as possible so folks can add things as they wish. Meantime you can use blanking panels where the future upgrades will fit.

Oh yeah, about that VU meter. PJ got a bee in his bonnet and we will be making a truly useful, accurate standalone VU meter setup that can be used with the RS1500 project or in your studio.

OK, I gotta start pulling my stuff together for the trip south to test the duplicating setup. I'll be here sporadically for a few days.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline scully280

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Re: RS1500 rework developments
« Reply #4 on: March 27, 2007, 09:32:09 PM »
Doc,
Will the VU meters be buffered?  Old school VU meters have a lousy sound and I had a pet peeve in past days to buffer them where they were put across outputs.  Also I like the power cord re-work, I think I'll start brushing the fur on my spare cord for correct magnetic orientation.
Richard Lane
Scully280

Offline docb

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Re: RS1500 rework developments
« Reply #5 on: March 27, 2007, 09:37:51 PM »
Yes, they will be buffered and use precision op amps. PJ looked at the circuits that were around and said "shoot, we can do way better than that." We will also have switching so that one can sum and difference the two for phase and level adjustments.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline docb

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Eureka! Tape path mods
« Reply #6 on: April 01, 2007, 11:04:39 AM »
I'm in San Francisco with Paul and Michael this week. One of the cool things about this (besides dinner at Original Joes) is that I get the opportunity to try new product developments on Paul's mastering system, which has been dubbed the Big Magnifying Glass. The combo of that system and Paul's and Michael's super acute hearing gives me just about the best double check possible for mods that seemd to produce an improvement on my own system.

To cut to the chase, we did quite a bit of comparision of the stock tape guide setup and my modified setup. The modded setup is designed to make the tape path setup more like the original isolated loop design of the 3M M59 and M79 machines. On Paul's system this was an easily discernable improvement. More stable sounding, cleaner, more focused, all the things one would hope to hear if the tape is traveling with as little friction as possible.We all signed off on this mod as part of the RS1500 modfication we will offer.

It's rather a tweaky mod to do, starting with a very systematic adjust and check, adjust and check, over and over kind of process to get all of the tape path guides, rollers and heads in dead on alignment. It's time consuming, but well worth it. Once the tape path has been made as true as possible and the tape is packing as flat and well centered as possible I make some changes to the fixed guides in terms of the number of them and the materials that the tape rides over. Once it's all dialed in the sound is cleaner, the tape packs great in both play and fast wind, and in fast wind it spools like a mother.

We tried a few other things including A/Bing the stock head vs. the Flux Magnetics extended response head with this new tape path setup. The stock head is very good, but the extended response head is like "Ahhhhh..." Bass is certainly more extended sounding, but I also perceive the same kind of sonic improvement that one gets from going to premium audio transformers, sweeter but not slower, blacker background but without losing any resolution.

Another experiment was to try Athan urethane pinch rollers. Sorry to say this was not successful. The rollers are very soft compared to the originals, and the sound with them in place was not focused, lacking in articulation - muddy is a good word. So one might guess that the tape is not being as well controlled as it passes through the dual pinch rollers and capstan. Luckily the stock pinch rollers seem to hold up quite well. I will be looking for some alternative replacement rollers, and perhaps experimenting with the roller pressure with the Athan rollers to see if I can get any improvement.

Later yesterday Paul got the 1" machines set up and today we will be making the running masters for the first albums. Monday is slated for our first whack at duping with the new duping line. We are getting so close!
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline docb

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bit by bit
« Reply #7 on: April 11, 2007, 01:54:05 PM »
Lew Hardy of Vivaldi Audio just dropped off the prototype dovetailed walnut rack case today. Beautimous! It's 16U tall and 8" deep, so it will accomodate from top to bottom-

the 1U high IR remote receiver - which I have received the custom front panel for, in bronze with gold engraved lettering to complement the look of the RS1500

the 10U tall RS1500

a 1U ventilated panel to allow for air circulation for

the 2U tube repro amp

the future 2U tall VU meter box

Parts are still pouring in (and man, is the mullah ever pouring out) as I am working to get three prototype machines together for the Stereophile show. I have some great looking Studer/Revox style hub adapters on the way from Europe, a prototype bronze w/ gold engraved lettering repro amp front panel, parts for more repro amps, custom power entry panels, etc., etc.

I'll post pics as things come together.
 
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline xcortes

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Re: RS1500 rework developments
« Reply #8 on: April 12, 2007, 09:37:40 AM »
Any idea of prices yet?

xavier
Xavier Cortes

Offline docb

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Re: RS1500 rework developments
« Reply #9 on: April 12, 2007, 11:38:19 AM »
I'm in the process of sourcing and ordering all sorts parts right now for three prototype mchines that will go to the Stereophile show [insert sound of big vacuum cleaner sucking up Bottlehead's bank account ;^)>] and the picture is beginning to take shape. I promise to put up some pricing as soon as I have a clear picture of the costs involved. It would probably be counterproductive to throw out a premature figure that is too far off from what we end up with as the final price.

 
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline classicrecordings

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Re: RS1500 rework developments
« Reply #10 on: April 12, 2007, 01:20:37 PM »
Will these machines be limited to playback at 15ips, or will they also be able to playback at 7.5ips?

David
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HK Citation 1 Pre-amp, Thorens TD-124, Ortofon 309S arm, SPU cartridges, mono block tube amps, Ars Acoustica LaDiva speakers, and I'm still trying to decide what machine to go with.
http://www.classicrecordings.ca

Offline docb

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Re: RS1500 rework developments
« Reply #11 on: April 12, 2007, 02:39:59 PM »
They will play 3-3/4, 7-1/2 and 15 ips, 1/4 track and 1/2 track, just like a stock RS1500. The only real difference in function will be that the extended response 1/2 track head is optimized for 15 ips rather than 7.5 ips that the stock 1/2 track head is optimized for. The 1/4 track head will remain stock and works great with prerecorded 7-1/2 ips 1/4 track tapes. The outboard repro amp will do NAB and IEC eq, and I'm looking into adding one other custom eq to order, like AES or Nagramaster.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline xcortes

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Re: RS1500 rework developments
« Reply #12 on: April 12, 2007, 04:22:20 PM »
I assume that the machines will keep their recording capabilities?

Also that you can buy only the machine and use a different amp (have you heard about the "Seduction")?

Xavier Cortes

Offline docb

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Re: RS1500 rework developments
« Reply #13 on: April 12, 2007, 06:07:31 PM »
I will not be altering the record circuit at all (as I have no interest in doing this) so it will remain stock in it's functionality. And you can plug anything you want into the tape head output - our repro amp, a modded Seduction, a vintage preamp with tape eq input, a repro amp from Tim, whatever. I will see if I can work out a switching arrangement that would let a person switch between the internal playback electronics and external playback electronics. I suspect that folks won't be going back once they hear a good external repro amp, and I haven't bothered with such a switch in our demo machines because it might add noise.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: RS1500 rework developments
« Reply #14 on: April 14, 2007, 11:45:41 PM »
This is related to my post in the Service Resource forum. As I said there, my RS1500 is working fantastic now but during my visit to Paul's studio, Doc showed me the tape path mods and tweaks he'd been working on. It involved reducing scrape flutter by eliminating friction causing guides that can be done without "if" the rest of the tape path is darn near perfect. He and Michael showed me how it also results in a " tape pack " that, after rewind, looks more like one from playback. Of course now I look at every " un-perfect tape pack " with horror!
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