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Title: Switching out the HRM Post by: Corinthian on October 22, 2009, 08:41:29 AM I understand the correct way to use an HRM is: clean/clean with PAB/overdrive with PAB - never overdrive without PAB because then the signal would be going through two sets of EQs. (I say 'never', of course if it sounds good then no reason not to!) I was wondering if there was a way to switch out the HRM EQ when the PAB not activated to give another useful channel. Big job? More trouble than its worth? Not a good idea? There must be a reason it hasn't been done. Title: Re: Switching out the HRM Post by: bluesfendermanblues on October 22, 2009, 08:47:14 AM I your amp is a standard HRM-amp with high plates, then its a brilliant idea to add a relay to make the second EQ switchable, If you also make the input of the OD switchable between 'HRM-input-OD' and standard 220k input.
Its not as obvious with a BluesMaster amp, since it uses different plate values, which (to my best knowledge) are not used in other D-style amps. Title: Re: Switching out the HRM Post by: Corinthian on October 22, 2009, 08:53:45 AM I your amp is a standard HRM-amp with high plates, then its a brilliant idea to add a relay to make the second EQ switchable, If you also make the input of the OD switchable between 'HRM-input-OD' and standard 220k input. Cool! Would the result be the same as a non-HRM ODS? Or are there more differences between the two amps than this? Does anyone know anyone who has done something similar? I understand this in theory but I'd need a layout to follow if I were to do it for real. Title: Re: Switching out the HRM Post by: mcinku on October 23, 2009, 01:00:48 PM The best way is to add another preamp tube and build a proper nonHRM circuit than switch between those. If you do everything with one tube (whic is possible), than you need to compromise a little and perhaps the result will not be the best.
This amp is doing it the right way... http://www.carolannamps.com/odseries.htm (http://www.carolannamps.com/odseries.htm) ;) Title: Re: Switching out the HRM Post by: Corinthian on October 24, 2009, 07:32:24 AM Mcinku, that's interesting. I hear those Carol Ann amps really sing. It's somewhat over-complicating it though I think - the thought was more about a small mod to take advantage of something that's already there, rather than building a whole new preamp channel. Title: Re: Switching out the HRM Post by: bluesfendermanblues on October 24, 2009, 10:53:10 AM Mcinku, that's interesting. I hear those Carol Ann amps really sing. It's somewhat over-complicating it though I think - the thought was more about a small mod to take advantage of something that's already there, rather than building a whole new preamp channel. My point exactly! - just use a relay set up like this: - Pole1 switches the INPUT of the OD between HRM and standard/Non-HRM input - Pole2 switches the output of the OD to go through the HRM tone stack or bypass Quite simple and no additional tubes. |