Revox H5 Preamp 'Out' & 'Power in' Purpose & Use

[jamesperrett]

Originally Posted by teetoon

Julie, With all due respect, have you ever connected a domestic graphic eq to a pre-power connection point ? How do you control the volume coming back from the tape deck as the power amp in is direct to the power amp. I know the Revox B77 will have output controls but what if it was a normal cassette deck being used ?

The standard practice is to not connect a tape deck to a graphic equaliser used between a pre and power amp. The tape deck connections on a domestic graphic equaliser are only intended for use when the equaliser can't be used between a pre and power amp and has to be inserted in the tape monitor loop instead.

[ShaunPJarvis]

Originally Posted by teetoon

After doing a bit of research, I am beginning to smell a rat here.

See this: http://audiokarma.org/forums/index.p...lizers.688898/

Dated 2015.

Another here:http://audiokarma.org/forums/index.p...emotes.696145/

I fear the advice is falling on deaf ears. Sorry.

David.

Nope: still listening and getting more confused as the contradictions appear. The strings to which you allude deal with the fact that the H5, my Revox H5 amplifier, wasn't performing as expected/advertised and in the absence of a manual I was seeking advice on what, if any could be done. The answer was finding a remote H210, which, when I received it (guaranteed working as per the eBay vendor) didn't work. Didn't even power up. Fortunately that was sent to a chap in Switzerland from whom I bought an H6 and he repaired it so my amp issues were then resolved. As for this discussion (eq. dbx amp) I am still not sure where I stand other for just reading that someone has a Kenwood GE1000 manual which I would dearly love to have a scanned copy of. NOTE, the amp does have 'pre out' bridged to 'pwr. amp' and as David has said, my eq does have monitoring 'Tape A' 'Tape B'. Please don't judge me. I'm slow AND I cannot put anything read in to practice (experiment) as only I get home every 11 months. This is why I am trying to get it sorted now, before I get home.

[ShaunPJarvis]

David, I too wish this over. Ignoring what Julie M and others have stated inasmuch as, "If your amplifier has a proper insertion point between the preamp and power amplifier, though, you may as well use this, as connecting an equaliser is really its intended purpose," which doesn't agree with your advice as supported by the scan of the GE1000 page, then the correct method according to you and others is to connect the eq. (forget the dbx for the moment as it is secondary and I am going to take yours and David Radio Wrangler advice and try with a view to abandoning it) to the tape loop, eg:-

AMP tape out to EQ Line In,
EQ Line Out to AMP Tape In,
EQ Tape Rec to Tapes Aux Input,
Tapes Output to EQ's Tape Play.

And by this means using the EQ's Rec On/Off button the recorded signal can be either without Eq. adjustment or with, while by alternating between the EQ's 'Line' and 'Tape A' (for example) I will be able to monitor either the tapes input signal or output from the tape signal in the absence of any such button on the amp?

Julie states, "The selected source (tuner, phono, CD player, VCR .....) is fed to the "tape record" outputs. The "tape monitor" switch then selects between this, and the "tape playback" inputs. If your tape recorder has three heads, and its monitor switch is set to "T" for tape, then the signal that returns to the amplifier is what has actually been recorded onto the tape and picked back up from it. When listening to any other source, the tape loop is bypassed." Kindly let me know if this is the case and which "Tape Monitor" switch is being referred to.

I'm really hoping that I have this now as I can see that I am or have pissed people off. I have the same problem with trying to understand the Load Shedding and frequency synching software (designed and interfaced both by the generator and yacht builders) incorporated in my three generator system. I'm a captain and ex lawyer; not an electronics and Hifi systems buff. Sorry.

[cmjones01]

I have some personal experience of connecting graphic equalisers to domestic hi-fi, and have also thought out and designed my own hi-fi amplifier. It seems to me that there are two main schemes for connecting a graphic equaliser, depending on how the amplifier is designed.

Many amplifiers, especially older ones, have no means of disconnecting the preamp from the power amp. They frequently have a connection for a tape recorder, known as a 'tape loop' and a 'tape monitor' button which connects the signal from the tape loop to the speakers. The input selector switch (between CD, tuner, phono and so on) then selects what the tape recorder records. In this situation, teetoon's method is perfect. The tape loop is the only place a graphic equaliser can be connected, and keeping the 'tape monitor' button pressed keeps the graphic equaliser in circuit. However, this loses the facility for connecting a tape recorder, so the graphic equaliser takes over that job. Hence the 'tape A' and 'tape B' selectors on the Kenwood GE1000 and many other equalisers.

Other amplifiers have pre-out and power-in connections, which are a good place to interpose a graphic equaliser. In this case the amplifier's tape loop isn't used for the equaliser, so it's still available for a tape recorder. The 'tape A' and 'tape B' selectors on the graphic equaliser can then be ignored - they're more or less useless.

Regarding tape loops, there are also many amplifiers (including the one I designed) which don't have a 'tape monitor' button. They have 'tape' on the input selector, and a separate switch which selects what the tape recorder records. This means, for example, that it's possible to record a radio program on tape while listening to a CD. In this case, putting the equaliser in the tape loop would be inconvenient: it loses this handy feature, and means that the usual input selection would have to be set to 'tape' all the time, while the record selector (which is usually a smaller or less obvious control) then has to be used to select what you're listening to. With this setup, I'd recommend using the pre-out-power-in connector instead.

I suspect your Revox, being a sophisticated beastie, is probably most similar to this last case, though I've never used one so I can't be sure. There will be a reason, though, why they included the pre-out-power-in connectors. That reason is probably a graphic equaliser.

These are all different choices depending on the design of the amplifier, the requirement for tape recorders, and operational convenience. None of them are wrong. You get to choose.

Chris