Bottlehead Forum

Bottlehead Kits => Eros Tape => Topic started by: mchurch on July 16, 2011, 05:21:53 AM

Title: Tape Deck Modifications
Post by: mchurch on July 16, 2011, 05:21:53 AM
I am a newbie to this area but I wanted to know if there is any guidance information available from the members as to how modify the tape deck to use the EROS. I am assuming that I will have to re-wire the heads to go direct to the input of the EROS. It appears that the only mods will be to playback so can I still use the record functions. Any information would be appreciated. My equipment is currently a Revox B77 and a Teac X1000R .


Title: Re: Tape Deck Modifications
Post by: Paul Joppa on July 16, 2011, 10:27:22 AM
The Eros is derived from the Tube Repro high-end design, and has similar input capabilities. You can see more at

From that page:

"The Tube Repro is designed as a versatile tape head preamp that works well with medium to high inductance playback heads. It has been developed from the start as the perfect match to Flux Magnetics Extended Response playback heads. ... Most any modern tape recorder, once modified to direct output from the playback heads, will work with the Repro."

Tape heads, like phono cartridges, come in a variety of impedance and voltage levels; any tube amp will be designed for medium to high output heads. Head sensitivity is rated by impedance, and 200 to 700mH is a typical range for tube preamps. It's best to be sure your tape heads are compatible before re-wiring you tape deck (!)
Title: Re: Tape Deck Modifications
Post by: Doc B. on July 17, 2011, 05:00:59 AM
A B77 will work fine. Not 100% sure about the TEAC, but there are very few tape decks that use low impedance heads, so it's probably a safe bet that it will work fine.
Title: Re: Tape Deck Modifications
Post by: mchurch on July 17, 2011, 06:11:13 AM
Thanks Paul & Doc;

I will look into the impedance of the Teac heads to see where they fall. I am just trying to formulate a build plan before I start to modify one or both of the decks. I just wasn't sure how the tape head amps would be connected to the heads. I want to keep the number of connections to the minimum so I might hardwire the heads to connectors the would plug into the playback amp.


Title: Re: Tape Deck Modifications
Post by: PS2500 on July 26, 2013, 11:18:09 PM
I'd be very interested to hear about any project to connect an Eros with a TEAC X1000R (or an A4300). I have it in mind to do such a project in future, but have only built a Crack headphone amp so far, and I have no particular expert knowledge for something that would be considerably more technically demanding.
Title: Re: Tape Deck Modifications
Post by: PS2500 on November 22, 2013, 02:45:11 AM
I'm about ready for my next Bottlehead project and not sure I can run to the expense of a BeePre just yet. One amp that has been in my sights for a while is the somewhat cheaper Eros for tape decks.

If anyone has the patience to explain - perhaps as they would to a 5-year old child - how the connection is implemented between the Eros and the tape heads, it would be a great help. And perhaps to others considering taking this path, too.

Ideally I would like to run the connection so that I can plug an interconnect from the Eros directly to the back panel output on the tape deck (a TEAC X1000R is my  probable candidate), rather than some kind of patching onto the front. However, I am unsure about how challenging the internal modification work required for the deck itself would be. I've replaced drive belts in a TEAC, but beyond that, never done anything other than get the deck open and do a little cleaning.

Any other advice on challenges/pitfalls (and hey, advantages) of taking on this project would be most welcome. I really don't know much about it other than the basic principle behind it, of bypassing the deck's internal electronics in favour of an offboard amp. (I have read everything I could find on this site about it though.)
Title: Re: Tape Deck Modifications
Post by: Doc B. on November 22, 2013, 07:09:40 AM
Locate the playback head. Figure out which cables are attached to it. Trace where they connect to the internal electronics of the deck. Disconnect them from there. Reattach them to RCA jacks you have added on the back panel of the deck.

You will loose meter function in playback by doing this unless you make a y cable coming from the Eros output and connect one pair from the y to the line level input on the back of the deck and monitor the line in. I don't find that a big deal because the only real use for a meter in playback is head alignment and a scope is much better for that job. But people who can't figure out that this would be the case like to blame me for it. Record will still meter properly which is what really matters
Title: Re: Tape Deck Modifications
Post by: PS2500 on November 23, 2013, 09:54:00 PM
Thanks for the reply! I have no doubt more questions will follow...