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The Menace


n_maher
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It wasn't really my intention to invite name suggestions.
I like how everyone (yes, including me) is ignoring this (I knew this when I posted, but saying something "...doesn't have a name yet" is like a girl walking into a room and saying, "I'm horny" -- you're not really asking for recommendations, but you'll still get some).

Conversely, you're going to ignore them all right back and name it something that isn't like anything in this thread. Of course, we could make that really hard for you.

The Menace A

The Menace AA

The Menace AAA

The Menace AAB

...

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It's similar, but different.

If you can, try a 6H30 for the driver, run reasonably hot, like 18-20ma. For a dynamic and fast sound, it can't be beat when coupled with a 307A. A perfect "foil" to the 307A which I found a little "understated" and "slow" sounding when driven by a 6SN7.

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If you can, try a 6H30 for the driver, run reasonably hot, like 18-20ma. For a dynamic and fast sound, it can't be beat when coupled with a 307A. A perfect "foil" to the 307A which I found a little "understated" and "slow" sounding when driven by a 6SN7.

Since you did not feel it was worth your time to fill in any profile details, can you help us put your comments into context? Letting us know the source, amp and headphones would be a good start. :palm:

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Since you did not feel it was worth your time to fill in any profile details, can you help us put your comments into context? Letting us know the source, amp and headphones would be a good start. :palm:

Sorry, I was purposely trying to avoid hijacking this thread. Just throwing a suggestion out there having tried about 10 or so different driver tubes with the 307A last year. (I went through a DHT head amp "phase" before heading back to high gm/mu spud tubes, which is pretty much where I started.) My best results with the 307A were choke loading it, parafeed output with a pair of Peerless TL-404's, driven by a choke or CCS loaded 6H30. Tent labs filament supplies. Active grid bias circuit for the output tubes, rather than self-bias cathode resistor.

Sources:

Analogue: SME 30/2 turntable, SME Series V tone-arm, Koetsu Urishi cartridge

Digital: Sonic Frontiers Transport 3 CD transport & Processor 3 D/A processor

Digital: Logitech Transporter

Phones:

Senn HD-650's (a couple of pairs, one with Cardas cable which is normally my weapon of choice.)

Grado RS-1

Grado GS-1000

ATH W5000

JVC HA-DX1000

(I think the above list of phones is correct at the time I was "voicing" and using the 307A amp.)

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If you can, try a 6H30 for the driver, run reasonably hot, like 18-20ma. For a dynamic and fast sound, it can't be beat when coupled with a 307A. A perfect "foil" to the 307A which I found a little "understated" and "slow" sounding when driven by a 6SN7.

I appreciate the input but the design is set so what you see is what you get.

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I appreciate the input but the design is set so what you see is what you get.

No problemo! :) Just throwing a suggestion out there and not trying to take your thread off at a tangent.

One other thing that has got me a little curious and in no way is a criticism, but it seems that the way you work is that you take a design, buy the parts, build it and it's done. There isn't an intermediate stage where you breadboard and "fiddle" with the design and component choices before finalizing a build and punching a chassis?

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There isn't an intermediate stage where you breadboard and "fiddle" with the design and component choices before finalizing a build and punching a chassis?

Nope, I'm not the designer so me fiddling is a bad idea. Also, I'm not building something that hasn't already gone through a lot of tweaking or isn't at least something that someone I trust has gone through before. It's a one-off but has well formed roots. I also happen to be one of those people who can't stand endless tweaking, cap/resistor rolling, etc. I'm of the opinion that doing so is just a waste of time and yields differences best quantified by "I can't remember what it sounded like before so it must be better".

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Nope, I'm not the designer so me fiddling is a bad idea. Also, I'm not building something that hasn't already gone through a lot of tweaking or isn't at least something that someone I trust has gone through before. It's a one-off but has well formed roots.

OK, I understand that.

I also happen to be one of those people who can't stand endless tweaking, cap/resistor rolling, etc. I'm of the opinion that doing so is just a waste of time and yields differences best quantified by "I can't remember what it sounded like before so it must be better".

cap/resistor rolling - that's not quite what I meant by design and component choices. For me the whole DHT headphone amp experience was a chance to evaluate DHT filament heating with AC, DC voltage regulated, DC current regulated and the Tent VCS module. The differences between "sound" when using various supply methods on the DHT filaments are not subtle, even more so with a headphone amp. Likewise, evaluating and tuning "sound" using a choke or CCS on the driver stage and grid chokes instead of resistors on the output tubes. Swapping a carbon film resistor for a tant, or switching one poly cap for the latest and greatest, currently being raved about cap, wasn't quite what I meant. That is the great thing about DIY, being able to experiment. But I take your point, anyway! ;)

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So there's no plans for a commercial product? That would be the best reason not to reveal the schematic.

There are no current plans to build the amp that I'm building in the commercial realm but just because it isn't a 1:1 translation doesn't mean it's open source. That said, some of the information contained on the schematic may be viewed as proprietary or at the very least not something Pete feels like giving away. I honestly didn't ask because it's his choice and one I'll certainly abide by as I'm sure everyone else here would if placed in the same position.

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Back on to the Lite build progress.

Last night I decided that I was going to try and hunt and kill the persistent buzz that the amp had in the left channel. With some help from Colin and Ari we'd narrowed down the list of likely candidates to either the big choke on the top panel or the floating filaments (and perhaps their routing). I had also decided to order up one of Antek's steel transformer covers to try and limit the EMF from the power trafo.

So first up was testing the choke orientation and location. By simply removing the two mounting bolts I was able to move the choke significantly further away from the output transformers and also rotate it freely. Unfortunately this had 0 affect on the noise.

Next up was biasing the heaters above ground which essentially amounted to creating a voltage divider off of B+ and connecting one side of the heater wiring to this. As a part of this operation I also decided to parallel the heater secondaries to better balance the current on the low voltage windings. This will also allow me to run stupid output tubes like the 6336 and 6528. So I created the divider using a ~60k and 27k resistor to create a 50V reference point and tied one leg of the parallel secondaries to this point. Colin has further recommended that I bypass the lower resistor with a 100uf cap which I'll do some time over the next few days. Finally I rerouted the heater wiring after the bias point to run away from the CCS components and as far from the input stage as possible. I also used some of LessEMF's M

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