Friday, October 21, 2016

Aragon Preamp

Recently I've been using the Aragon preamp merely as a source selector, just using the unbuffered tape outputs, with no AC power being provided to the unit.  However, looking at the schematic, there are 2k output resistors to the tape outputs so it's not 100% transparent.  With my low cap cables that likely makes a negligible difference, but when convenient I'm going to bypass those resistors.

I prefer the Aragon preamp as source selector to the DB Systems selector simply because the Aragon is a big heavy box which doesn't move when you turn the knob.  It also looks very cool, is very heavy, and has wonderful chassis mounted jacks.  I wouldn't say that it sounds any better than the DB Systems selector though.  I thought them about the same, but the 2k resistors would darken it somewhat.

I'd always thought the Aragon 28k preamp to have a slightly "dark" sound through the main outputs also when I was using them--though they seemed to measure as perfectly as anything.  Well now I see that a darkened sound might compliment the Aragon 8008BB power amp, which I'm finding (now) to have a (somewhat excessive) brassy top end.  I'm going to be examining the Aragon and other amplifiers technically this weekend, following a week of A/B/X testing last week.  I did not reliably hear differences according to a simple ABX test, but I still strongly believe the differences I hear anyway.  The basic differences are that the Krell is the best sounding and has sweet and entirely unagressive highs, next the Carver TFM-24 which was designed to sound like a tube amp, next the Parasound HCA-1500A which was slightly brighter than the Krell but very transparent--perhaps the most transparent, and the Aragon which is sounding transparent but harsh at times.  Kudos to John Atkinson, still one of my favorite audio reviewers though I often criticize him, who admitted recently he hadn't heard a difference in an ABX test.

A great test disc is the Tchaikovsky Pathetique on RCA Living Stereo hybrid CD.  Just after 10 minutes into track one, there are some biting violin riffs that can be positively strident with some amplifiers.  It sounds more or less OK on Koss ESP-950 electrostatic headphones, which produce the most  transparent and accurate sound I have.

I'm not sure if I like the Aragon preamp circuit at all, but it's apparently the same as in Aurum preamps (in Aurum they use 2 per channel because it's a balanced preamp).  It looks like a miniature power amplifier all bipolar with feedback and adjusted bias.

Here's a discussion on modifying the Aragon Aurum preamp.  It includes a crucial section on how to do the bias adjustment on all Aragon preamps.

I've been thinking of modding mine in a few ways, adding balanced inputs and outputs and making the selector deal with that.  The balanced outputs would be pseudo-balanced with ground as the negative.

That would allow me to hook up balanced device(s) and run balanced to Lavry ADC, rather than doing an unbalanced conversion right at the Lavry input jacks with adapters.  Then I could insert the ABX test box and since it would have balanced inputs and outputs there would be minimal degradation.

It would also allow me to have a polarity reverse switch on the Aragon (or the ABX).

But it would have been better with the balanced already designed in.

I would use the line amplifier only when doing gain adjustments on devices for ABX comparison.  Otherwise I'd just use the unamplified tape selector.

But doing that kind of modification, I almost might just as well get a fresh chassis, and indeed I've been looking at the many interesting clone preamp chassis on ebay.

No comments:

Post a Comment