matheusrhi
New Head-Fier
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- Aug 17, 2013
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Hi, the Muse TU-20 could drive my AKG K240 Sextett 600 ohms?
Thank you!
Thank you!
Hi, the Muse TU-20 could drive my AKG K240 Sextett 600 ohms?
Thank you!
Thank you. I was in doubt because I did not find enough information on the maximum output impedance. I want to buy a low cost amplifier and found interesting the TU-20.
I also drew attention Bravo V1 and V2. Could tell me which would be better worth between TU-20, Bravo V1 or V2 (or any other)?
There was a distinct difference when lowering the bias from 7,2 to 6,3 V. Maybe some nice distorsion that gave the sound an edge disappeared. Riding that voltage close to the border may be the trick. I don't have an oscilloscope, but someone who has could probably find the right setting.
In the meantime I got myself some op amps (cheap from Hong Kong) and a tube to try out next week.
Hi MDR30 (and others), sorry for resuming an old thread, but it seems this is the only one in HF related to the Muse TU-20.
I've one of this tube amps on its way and I'd like to order a couple of opamps to roll with it.
Any impression on the 3 ones that you have listed above ?
One more noob question on the substitute opamp: to replace the existing NE5532, should I go for the adapters which have only 1 one opamp mounted on top (http://www.ebay.com/itm/1-Pieces-AD797AR-SOIC-to-DIP-Op-amp-replace-NE5534-/120757516362?pt=LH_DefaultDomain_0&hash=item1c1db5784a) or the ones with 2 opamps solder on top and bottom faces (http://www.ebay.com/itm/120757521995?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649) ?
Thanks for your help.
Go for the ones in my pics. AD825 and AD797 are one channel op amps (if I remember correctly) so you need double assemblies. I've moved on from this amp so can't really remember the difference of the op amps but I notice I kept the AD825 in the amp.
However, I think a change to the ECC86 tube would make a bigger difference as this was designed for a lower plate voltage, for use in car radios in the late 1950s, and would work better in this circuit. You can probably find it at a good price on ebay, but you need to adjust the bias voltage as described in this thread (which really goes for the op amps as well).
Thanks for the help.
As main tube amp, I already have a Little Dot MK II, with some mods to run 6922/6dj8 tubes (and 12AU7 /12AX7 too). So on tube side I have already some spare ones to be rolled in the Muse.
The TU-20 is actually a "downgrade", in the sense that I needed a cheaper amp to be able to start practicing with opamp rolling (which I never did before) and some easy board mods (e.g. capacitors upgrades). I was able to get it for quite a cheap price, so I preferred to go for this one instead of the Indeed G2 / G3 (even if these 2 have a much wider story for modding in rockgrotto forum). And if I break it, I still have a nice metal case
By the way, the amp is still on its way, so it will take a bit before practicing with these mods.
I actually have that little amp with me on the road. I carry a Corda 2Stepdance with me and it is my favorite potable amp. The HD800 sounds good with everything. This little tube amp was just a toy to play with. The AD797AR and my APEX tube sounded best, with a clean bias setting. I find the impedance match is better with the line in ports on the back. I have placed poly bi-pass caps across every capacitor to reduce noise and replaced the power supply with a much better unit. I think I got the best I can get it to sound, and have not really played with it much. There really isn't enough power to drive the tube to it's potential other then over modulation.
Also soldered a ground lead. It locks between back plate and box.
Just got my TU-20 on Christmas' Eve. After a short audition out of a Fiio X3 it sounds ok, but just after third volume notch it gets quite noisy (humming).
As possible mitigations I saw the suggestions in previous posts:
- grounding (as in the picture above). Question 1: how is the is the ground lead connected to the case ? Can I just screw it to the closest case screw (e.g. the one next to the black "foot" in the picture above) ?
- improved wall-wart with a more powerful one. Question 2: the power supply included with my TU-20 is a 12V - 3A, while in previous posts there are suggestions to use a 12V -2.5A one. Isn't the one already included with my amp powerful enough ? If not (as real power could be different from the one on the label), how can I measure its actual power ? I just got a multimeter, but not sure how to use it for this check on a wall-wart.
Thanks
Sorry for my noob questions, but I'm just learning "on the field" how to tweak this amp