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Author Topic: Eros Connection to Revox B77  (Read 1151 times)

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Offline kevemaher

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Eros Connection to Revox B77
« on: March 09, 2017, 09:30:14 PM »
Hi, just joined. Seriously looking at the Eros. I have a B77 4 track 3-3/4 and 7-1/2 ips. Records and plays well. Very basic questions:

1. What inside the B77 do I connect the Eros input to? I have the B77 repair manual. I am very tech savvy (I repair and align analog FM tuners). I plan to do the work myself.
2. Can I connect the Eros output directly to a line input on my preamp (Levinson 38s) just as I connect my phono preamp?

Thanks!
Kevin

Offline Doc B.

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Re: Eros Connection to Revox B77
« Reply #1 on: March 10, 2017, 04:59:41 AM »
1) You will need to connect the Eros to the play head. This usually means finding the cable attached to the play head, disconnecting it from the internal repro amp, and extending/reterminating it so it can be connected to the input of the Eros. Every case is a little different and I have not done this mod to a B77. So I'm afraid I can't be any more specific.

2)Yes, it connects to a line level input on your control preamp, just like a phono preamp would.

I will also mention that the EQ settings are NAB and IEC1. NAB will work with most all 7.5ips tapes. It will also work with 3.75 ips tapes, but it's slightly off on the HF response, the HF turnover for NAB 7.5 being 50uS and the turnover for 3.75 being 90uS. What this means is the top end at 3.75 ips will sound a little bit rolled off.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline kevemaher

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Re: Eros Connection to Revox B77
« Reply #2 on: March 11, 2017, 08:06:26 PM »
Wow! Thanks for the fast reply.
Does the eros provide both eqs? How? Switchable?
I don't mind a bit HF roll-off.
Kevin

Offline Doc B.

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Re: Eros Connection to Revox B77
« Reply #3 on: March 12, 2017, 05:48:08 AM »
Yes there is a switch for the two eq settings.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Viking

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Re: Eros Connection to Revox B77
« Reply #4 on: August 24, 2018, 10:28:50 AM »
Good evening, i am new to this forum and to tape in general. Have recently bought a Revox B77  15 ips 2 track, ccir and strongly consider to buy an Eros.  I read that the interconnect cables are recommend to be 1 meter or less. In my case it have to be 1,5 meter from the Eros to my  preamp.  I have to add that i have been in contact with John French and he offered me to build a Flux Magnetic tape playback head.
A little bit more information about my gear:
I use a vacuum tube(6922 tubes) preamp with these technical characteristics:
Input line 200mV/10V Max 100 K
Frequency response 20 H-200 KHZ  @ 600 ohms
Maximum outputlevel 20V roms
Signal/noise ratio 110 dB

1) Does an Eros in combination with the B77 and my preamp work fine ?
2) Do i have to bias the tubes in the Eros when changing them  ?
3) Since i have too little  technical skills, do you still build Eros or is it only available as a kit ?

I will be grateful for answers.

Thanks

Regards
Hans

« Last Edit: August 25, 2018, 03:10:10 AM by Viking »
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Offline Paul Birkeland

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Re: Eros Connection to Revox B77
« Reply #5 on: August 26, 2018, 05:44:34 AM »
Good evening, i am new to this forum and to tape in general. Have recently bought a Revox B77  15 ips 2 track, ccir and strongly consider to buy an Eros.  I read that the interconnect cables are recommend to be 1 meter or less. In my case it have to be 1,5 meter from the Eros to my  preamp.
Can you tell us more about your cables?  The recommendation is to keep the cable capacitance down (to maintain good treble response), so some 1.5M cables are going to be just fine while other 1M cables may roll off the top end a little.
I have to add that i have been in contact with John French and he offered me to build a Flux Magnetic tape playback head.
That is a very, very good idea!


1) Does an Eros in combination with the B77 and my preamp work fine ?
Yes, these are ideal electrical circumstances for an Eros.

2) Do i have to bias the tubes in the Eros when changing them  ?
Nope, all the biasing is automatic.
3) Since i have too little  technical skills, do you still build Eros or is it only available as a kit ?
I have been building kits for folks who don't quite have the time or desire to do so themselves.  You can e-mail me at pb(at)bottlehead(dot)com

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Viking

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Re: Eros Connection to Revox B77
« Reply #6 on: August 28, 2018, 08:09:31 AM »
Thanks for your anwers. Sorry for late response. The following technical information i have about
the interconnect cables i will use are:
- 2 conductors. 5N silver copper alloy strands each channel.
- Insulation for each conductor- thin wall extruded Teflon
- Effective gauge size per channel- 22 awg.
- Shield- braided 5N silver plated OFC
- Outer jacket- extruded teflon
- Geometry-internal twisted

Electrical characteristics:
- Nom. capacitance 18.1 pF/ft DC
- Nom. conductor DC resistance- 20.1  «omega»/1000 ft ( Didn’t find the symbol)
- Nom. inductance- 0.12  «microfarad» /ft (Didn’t find the symbol)
The plugs are Neutrik ProFi RCAs.
I will need 2 pairs of cables. They will be from the same manufacturer.

Forgot to ask the dimension of the Eros.

Thanks
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Offline Paul Birkeland

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Re: Eros Connection to Revox B77
« Reply #7 on: August 28, 2018, 08:15:43 AM »
That's reasonably low capacitance, I wouldn't be too concerned about HF rolloff under those conditions.

The Eros base is about 9" x 11", and I'd plan to have 8" of height if possible for breathing room.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Viking

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Re: Eros Connection to Revox B77
« Reply #8 on: August 28, 2018, 08:59:02 AM »
The cables between the B77  and Eros only need to be  3 feet. The Eros will be placed under the B77, but with much air between.
The cables  from the Eros and my preamp can possible be 4 feet and that will perhaps be better ?(Less chance for HF roll off)
A last question: Can you or someone recommend a service tech in the USA  who also custom upgrade the B77. ( Direct wiring from playback head, by- passing unnecessary electronic etc.) Want to use this deck  as a playback unit only. ( Prerecorded mastertapes).
« Last Edit: August 28, 2018, 10:12:54 AM by Viking »
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Offline Tom-s

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Re: Eros Connection to Revox B77
« Reply #9 on: August 28, 2018, 09:29:14 AM »
High Frequency rolloff.

Edit: Base height on most kits is 4".

Offline Viking

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Re: Eros Connection to Revox B77
« Reply #10 on: August 28, 2018, 09:37:29 AM »
Thanks Tom for your answers i found  HF  via google, therefore i edit my post, but you were quicker
than me :)
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