2. amps-preamps
  3. 187969-170624

surprising comparison of tube preamps

Hi and thanks for your help. I have been using an ARC LS25 II preamp going into a Mcintosh Mc462 amp. One source is a turntable going into a Parasound JC3+ phono pre. When the ARC broke, I tried a Bottlehead Crack headphone amp as a preamp. I was very surprised to see how beautifully this worked. Really rich sound. Maybe it was less accurate (could not do a direct comparison with the LS25), but it was certainly great to listen to, for my taste. I looked into this some and wondered if the lush sound came from the fact that the Bottlehead was using a simple SET OTL circuit, compared to the hybrid circuit in the LS 25. Still you would think that the ARC unit, costing so much more, would sound better.  I am wondering if people have an explanation for this but, more importantly, have been looking into getting a very simple tube pre to use for the phono part of the system. Mapletree audio sells a simple preamp that I believe is a SET OTL (are all preamps OTL?). Al  Freundorfer, the designer and owner, kindly agreed to make me a modified version to test. Some circuits, including a buffer he sells, have the ability to adjust the 'warmth' and extent of tube sound - he would build this into his amp for me (it is available on some of his other products). Is this a good idea? Could I reproduce the effect I heard with the Bottlehead? Not sure how those 'warmth adjusters' work. Thanks a lot for your help.

arhgef
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o_holter
956 posts
 

Note that, in my other systems, testing with the OTL headphone amp as part of the sound chain, the chain has been like this:

Source (DAC) - > Jade - > preamp -> amp.

In my main system, however, I had to connect this way;

Source (phono riaa + preamp) - > Jade - > amp.

I was not able to insert Jade as the first gain stage.

Something is wrong when it is connected as the last gain stage. I tap on a tube in Jade and hear scratching noise in the speakers. So the sound impression, described above, may be misleading. Maybe this isn't a fair playground for Jade. Connecting a headphone amp as the last gain stage, with output to the amps, is not the right way. Even if it works fine as the first gain stage.

mahgister's avatar
mahgister
12,741 posts
 

Exactly my experience too...

Thanks..

So my experience is that inserting a good tube preamp into the amplification chain depends on the quality of the rest of the gain stages in the chain. For example, the Jade easily beats small s-state amps in  active speakers, from my testing so far (low to mid price). But if the other gain stages are in fact of comparable or higher quality than the Jade, the effect can be zero, or reversed

ghdprentice
6,435 posts
 

I have a headphone amp that is powerful enough to be a headphone amp or an integrated amp and power speakers. The Woo WA5.

pindac's avatar
pindac
2,449 posts
 

As you are adding Build Your Own Amp's into the discussion, I feel you should be made aware of the Pass Designed Korg B1 Pre-Amp'.

I have referenced its usage on quite a few occasions within this forum. 

This is not a Phono Pre Amp, but personal experience of it in use with a Vinyl Source on a variety of systems has shown the Sources in use to have a presentation that has exceptional attraction.

mbmi's avatar
mbmi
447 posts
 

The 4K , Audio-GD HE1 XLR....10 tubes, it’s own Regenerative Power supply. Sings with Any Amp I put it with... Simply a fantastic sounding PRE !     Caution:  It's a Monster.

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