Messages

361

Tape Project Machines / Re: First Tape Project by Bottlehead RS1500

« on: April 16, 2007, 08:45:07 PM »

three questions:

it is not clear whether the price is for the deck only or it includes the amp, remote and cabinet.

what are the dimensions and weight (approximate is ok to me) of this puppy?

will the alignment be done also to the 4 track and recording heads?

thanks,

xavier

362

Service Resources / Re: Liberman Sound , SF bay area

« on: April 13, 2007, 09:34:15 AM »

how much did he charge?

363

General Discussion / Re: Good luck in your tape venture...

« on: April 13, 2007, 08:07:03 AM »

Oh, I think you're insane. But I also think that you need insane people to achieve great things!

xavier

364

Tape Project Machines / Re: RS1500 rework developments

« 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")?

365

Tape Project Machines / Re: RS1500 rework developments

« on: April 12, 2007, 09:37:40 AM »

Any idea of prices yet?

xavier

366

Suggestion Box / Re: Stravinsky Pulcinella/Apollon-Argo

« on: March 26, 2007, 09:26:59 AM »

It'd better be good!

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=ADME:B:EOIBSAA:US:11&Item=140098172820

367

Reel to Reel Tape Machines / Re: Can a Dolby emphasis curve be constructed passively?

« on: March 02, 2007, 09:49:45 AM »

You got my idea. I know that using a "full time" HF roll off could cause some tapes to sound dull. I've read, however, that some people consider that you can listen to Dolby-B tapes without a decoder. I was hoping there could be a middle point. Maybe a variable circuit where you can select the level of attenuation and adjust it depending on the tape you're listening to?

I follow your DIY point. Typically what would be the size of a Dolby B board? What voltage does yours require?

Thanks,

xavier

368

Reel to Reel Tape Machines / Re: Getting the feet wet with head alignment

« on: March 02, 2007, 09:41:24 AM »

Let me add that you shouldn't make ANY adjustments to a headblock just for the heck of it.  Take a good look at the wear pattern on each head.  This will give you a good idea about how correct the existing head height, zenith and azimuth adjustments are.  If everything looks good then leave alone. 

How can one determine wear visually?

If you're serious about tape setup, the machine to have is the Sound Technology 1500A.

I googled and found these: The Sound Technology 1500A was a microprocessor-controlled audio measurement test system. According to an ad in 1981, the unit was conceived to be the ultimate precision test instrument for tape recorder analysis. It was designed around advanced microprocessor hardware, and showed the user ?the whole story on an integral CRT with adjustment cursor.?

Applications of the system included tape recorder mechanical and electronic performance checks; thorough phono cartridge analysis; one-third octave spectral analysis; acoustical room analysis, including mic and loudspeaker measurements; evaluation of audio quality for VTRs; and research and development for the audio tape manufacturer.

The RS1500 service manual has a good section on head alignment, describing what each of the many screws on the headblock adjusts. The order they suggest is head height, azimuth, tilt (aka zenith), contact and tangency (aka wrap). After those are done one should check phase alignment.

I already purchased my own copy!

But before doing any of this one should make sure the tape path adjustments are dialed in. On an RS1500 that can require a lot of little shims that aren't readily available, and it helps to have some good measuring sticks.

Although I haven't done any measurements my deck seems to be very well in this regard. The tape runs centered on every part of the trail.

Thanks all for your comments. I'm learning a lot and hopefully others will be as well by having access to these threads.

Xavier

369

Reel to Reel Tape Machines / Can a Dolby emphasis curve be constructed passively?

« on: March 01, 2007, 09:09:13 PM »

I know that the Dolby NR system curve varies according to the signal level and to get it 100% correct you would need a Dolby processor or chip but what are the thoughts of emulating the curve passively (or actively modifing a tube preamp)? Could it be done? It would be a nice way of listening to Dolby tapes without old SS Dolby units.

Xavier Cortes

370

Service Resources / Re: Pinch Roller refurbishing

« on: February 28, 2007, 04:05:57 PM »

I was just kidding. You've already bid more than my reserve price!

371

Service Resources / Re: Pinch Roller refurbishing

« on: February 28, 2007, 10:06:23 AM »

Now that I have snagged a decent (ARPO) tension gauge for myself on e-bay I'll share ;^)> One name you guys want to keep in mind is Correx.

Hey Doc,

I guess you don't wan't me bidding on this one?

http://cgi.ebay.com/Correx-Gramm-Gage-Haag-Streit-A-G_W0QQitemZ270093837029QQihZ017QQcategoryZ25272QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

372

Prerecorded Tapes / Re: Level problems with pre-records??

« on: February 28, 2007, 09:15:50 AM »

Very late night yesterday I read Steve's post and I got off the bed to clean the the head with strong emphasis on the edges. Wow, immediate results. Both channels pretty much in balance now. I didn't have a chance to do an extensive testing but I can assure you that things really improved.

There's still some less output from the left channel but you have to make an effort to detect it. I may need to do some more cleaning and try cleaning taking the headblock off for better access to the edges. Maybe I'll even try some naphta (would zippo lighter fluid work?). Anyway I seem to be in the right track.

Hey Steve: You'da man!

373

Reel to Reel Tape Machines / Getting the feet wet with head alignment

« on: February 27, 2007, 12:12:17 PM »

Following a discussion on the prerecorded tapes category I thought I'd start a new thread on head alignment for newbies. I want to get a first grasp of how to align the heads on my RS1500, particularly the 4 track head which is giving me problems with a volume difference of close to 3dB between channels.

Here's what I've learned/understand/think so far:

Azymuth is the most critical of the planes to align on a head. It refers to the alignment of the heads perpendicular to the direction of the tape. If you don't get this one right both tracks will be played out of phase. To adjust azymuth you need three things: an alignment tape with a 16 kHz track, a dual trace oscilloscope to compare the output from both heads using the mentioned track and your deck's service manual to find out what screw/screws to adjust to align the head. The idea here is to get the output from both heads as similar as possible.

If your deck has VU meters you could use both instead of the dual trace oscilloscope to compare levels in case you don't have an oscilloscope (although I'm not sure if the test frequency would be the same). This method being for sure a compromise. Or better yet, you can sum the outputs from both heads creating a mono signal and compare the output level. Since azimuth misalignment will cause cancellation at high frequencies you are aiming to the highest reading.

Zenith is the alignment of the head in the same plane as the tape. If you don't have it right the tape will not contact all of the head but rather will be closer to the top or the bottom part. Here you can use the same test track and you want to maximize output from the heads. Zenith misadjustement should affect both channels equally or in a very similar way if the other planes are aligned.

Wrap  / Head height / Tape-to-head-contact usually don't misalign unless you replace the head so I won't get into them.

When doing adjustments at the tape heads a non magnetic screwdriver is recommended.

Hopefully I'm not oversimplfying things and confusing people here. If I am please forgive me!

Xavier Cortes

374

Reel to Reel Tape Machines / Re: RS1500 hub adapter spacers

« on: February 27, 2007, 09:17:40 AM »

I received the original adapters sent to me by the tech who sold me the deck. I haven't tested as I'm only using plastic reels for the moment but is nice to have them :>). I will ask someone to transcript them to pdf to use them as templates for reproducing them. If anyone is interested I'll speed up the process. Otherwise it will take sometime but eventually I'll post the template here.

Xavier Cortes

375

Prerecorded Tapes / Re: Level problems with pre-records??

« on: February 27, 2007, 09:12:50 AM »

I'm having the same imbalance problem on my RS1500. It happens on the 4 track head and apparently not on the 2 track head although I have to do more extensive testing. Imbalance can be as much as 3dB based on the meter readings. I cleaned the heads but the problem is still there. The tech who sold me the deck assures he checked for alignment and that it must be a head cleaning issue. He has been very helpful and offered that if I can't correct the problem I can send him the headblock for him to align it.

If I take the headblock off, however, I might as well send it to JRF magnetics for a full service. What do you think?

The deck is in very good condition mechanically from what I can tell. Runs very smoothly and silently and most of all, aside from the balance issue it sounds very, very, good. However if the balance issue arises from a misalignment head, well, it can only sound better right?

Xavier Cortes