Space Echo sound on sound

[Rene Schmitz]

At 14:15 21.11.1997 +0100, you wrote:
>Hi!
>
>Wasn't there a Space Echo that could do Sound-On-Sound ?
>I have the RE-201 model, which cannot do it.
>
>I tried to short the erease head (with 470 Ohm to prevent damage),
>and I got the desired loooong delay (30sec.) indeed.
>But this also disables the HF bias for the recording head, and
>so new sounds go to the tape distorted. Sure, I could control the
>HF current to the erease head *only*, but then, wouldn't the HF bias
>in the recording head still partly erease the previous material ???
>(not at all sure about that - anybody knows for sure?)

I recommend you should try sticking a piece of selfadhesive plastic film  
on the record head!
Many people in the early days of electronic music did it like that, when
they wanted
sound on sound recording, and as you say the previous recorded material gets
partially 
erased.

>Before I go on experimenting, I need schematics of commercial units
>that have this feature built-in. Preferably Roland models, if there are
>any,
>but others are welcome too. What would I have to look for?
>
>JH.
>
>PS.: This was a mail I sent to Looper's Delight - I thought I include it
>as
>it was:
>
>************************************************************************
>*************
>
>I think I should build a switch into my Roland RE-201 Space to disable
>the HF oscillator that feeds the earease head.
>
>The RE-201 is a tape echo with a tape loop of a few meters. It's
>intended to
>produce short echoes with a distance of a few centimeters between record
>and playback heads; the long loop is just to prevent the tape from
>wearing
>out too soon.
>
>Which makes me think of several modifications:
>
>(1) disable the earease head. Would add new sound to old sound (after
>      the _long_ delay of the whole tape length), but no idea to which
>amount,
>      compared with previous recordings. (?)
>
>(2) probably it would be an improovement to make the hf current thru the
>      erease head _variable_, and fade previously stored signals out by
>      partially deleting it. (Again, no idea what this would do to
>frequency
>      response or distortion of a partly ereased signal ... any clues ?)
>
>(3) Now this would be a tough one (and I think I would not dare to do
>      this to my "mint condition vintage space echo" (;->) ): Exchange
>      the location of the heads:
>      (a) original order: tape comes from storage box,
>                                     passes erease head,
>                                     passes recording head,
>                                     passes several playback heads,
>                                     dissapears into storage box.
>      (b) suggested new order:
>                                     tape comes from storage box,
>                                     passes playback head and (plays
>what has been rcorded
>                                          half a minute before)
>                                     passes erease head,
>                                     passes recording head,
>                                     passes remaining playback heads
>(still usable for normal echo
>                                          operation, only with one tap
>less than before)
>                                     dissapears into storage box.
>
>This last one looks *very* tempting ! The feedback would then be
>established
>electronically, with all its accuracy and possibillities. (I love to put
>my latest
>toy, a frequency shifter, into a delay's feedback loop !).
>
>Please tell me what you think.
>Things like that must have been done before! Especially (3) would be
>interesting.
>Anybody to share his experience ?
>
>JH.
>
>