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    Mark 3 Rectifier & Mono Preamp

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    TN Allen

    Posts : 124
    Join date : 2013-01-01

    Mark 3 Rectifier & Mono Preamp

    Post by TN Allen on Thu Oct 09, 2014 5:35 pm

    With winter soon to begin, I'm thinking of taking up old projects. One is a Mark 3 mono amp. I've done an upgrade on a ST 70 using a Tube4HiFi board, and a PAS3 upgrade. The ST 70 rectifier tube seems a bit sensitive to our rural Maine current, so, I've bought an octal SD rectifier. I'm wondering if I should consider a permanent SS rectifier for the Mark 3.

    Also, does anyone know of a mono tube preamp kit suitable for a Mark 3?

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    Re: Mark 3 Rectifier & Mono Preamp

    Post by Guest on Thu Oct 09, 2014 6:04 pm

    TN Allen wrote:With winter soon to begin, I'm thinking of taking up old projects. One is a Mark 3 mono amp. I've done an upgrade on a ST 70 using a Tube4HiFi board, and a PAS3 upgrade. The ST 70 rectifier tube seems a bit sensitive to our rural Maine current, so, I've bought an octal SD rectifier.  I'm wondering if I should consider a permanent SS rectifier for the Mark 3.

    Also, does anyone know of a mono tube preamp kit suitable for a Mark 3?

    are you using the MKIII for any particular application, reason I ask is the mono...why not stereo, see if you can pick up another older MKIII on eBay or similar, then you can look at stereo tube preamps, I do not know of any mono units out there, not a big call for them I assume.
    I switched to the Weber Copper Top SS rectifier on all my amps, for the ST70 model WZ34 will suffice, it stands up much better to mains variations and is more 'solid' than a tube rectifier unless you're prepared to pay top dollar these days for NOS tube rectifiers.

    TN Allen

    Posts : 124
    Join date : 2013-01-01

    Re: Mark 3 Rectifier & Mono Preamp

    Post by TN Allen on Thu Oct 09, 2014 6:25 pm

    I occasionally prefer mono, and, I traded an old Dynaco amp for a Tubse4HiFi Mark 3 board kit. I'd also like to try the idea of a single Mark 3 to use with some of the speaker projects I build mono, rather than stereo. Piano for example appeals to me mono, rather than stereo.

    I'll probably use one side of a stereo preamp if I don't find a mono preamp.

    GlacierJohn

    Posts : 38
    Join date : 2014-04-17

    Re: Mark 3 Rectifier & Mono Preamp

    Post by GlacierJohn on Thu Oct 09, 2014 7:10 pm

    TN Allen wrote:I occasionally prefer mono, and, I traded an old Dynaco amp for a Tubse4HiFi Mark 3 board kit. I'd also like to try the idea of a single Mark 3 to use with some of the speaker projects I build mono, rather than stereo. Piano for example appeals to me mono, rather than stereo.

    I'll probably use one side of a stereo preamp if I don't find a mono preamp.

    My old Conrad Johnson PV2 has a stereo-mono switch on it. I'll bet there are other preamps with that same capability. I would think a quality mono only pre amp would be rare if not nonexistent.

    TN Allen

    Posts : 124
    Join date : 2013-01-01

    Re: Mark 3 Rectifier & Mono Preamp

    Post by TN Allen on Thu Oct 09, 2014 7:36 pm

    I've looked for a quality mono preamp. Seems to me something might/ought to exist, but so far, having found nothing, thought I'd ask.

    I have a few older stereo preamps with mono switches, but prefer the elegance of a dedicated mono preamp with a mono power amp. Dynaco sold, contemporaneous to the Mark 3, mono preamps. Perhaps it is time for someone to offer a modern version of these original preamps. Perhaps there may be a market for individual monp preamps with mono block Mark 3s.

    I suggest this as I suspect there may be other geezer ears and brains slightly confused by stereo sound bouncing off the walls of a room, who might like a single point of less confusing sound.

    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: Mark 3 Rectifier & Mono Preamp

    Post by GP49 on Thu Oct 09, 2014 7:59 pm

    Mono is best reproduced by one loudspeaker but a stereo preamp with a switch to blend the channels to mono is perfectly usable and may be preferable if you are playing mono records with a stereo cartridge. Yes, you can parallel the channels at the cartridge but if you are running a "conventional" magnetic cartridge, there will usually result a mismatch with the 47kΩ of each channel of the phono
    stage.

    I even have a couple of Dynaco PAM-1 in storage in the garage. Probably worth more for their Dynaco-Telefunken tubes than on their own!

    TN Allen

    Posts : 124
    Join date : 2013-01-01

    Re: Mark 3 Rectifier & Mono Preamp

    Post by TN Allen on Thu Oct 09, 2014 9:01 pm

    Interesting points, I'll think them over. Surely there must be ways to listen to post mono recordings taking full advantage of their brilliance, using a mono preamp and mono amp.


    stewdan

    Posts : 161
    Join date : 2010-03-07
    Age : 78
    Location : Houston Texas

    Re: Mark 3 Rectifier & Mono Preamp

    Post by stewdan on Fri Oct 10, 2014 12:44 am

    Hi --

    For what it is worth, Heathkit also made a Mono PreAmp (WA-P2) which I have used with a Dynaco Mk3 and a ST-70.

    Like the Pam-1, it plugged into the octal tube socket on the front panel.  

    It sounded pretty good after I replaced caps and resistors that drifted.

    Hope this helps.


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