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Re: Some answers. [message #8937 is a reply to message #8936] |
Wed, 04 May 2005 11:25 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Poindexter
Messages: 108 Registered: May 2009
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Viscount |
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Hey, Mark, I'm guessing you split one of the long pieces . . . Close. It's hard to describe briefly. I'll look through my photos and make up a small webpage with the procedure on it, if you're really interested. I'm sure you can get one together scratch. It's not an elaborate circuit; and in all honesty, the divided chassis is a cosmetic feature; it's the physical separation of the PS and audio circuit that keep the noise down. I'll help you as much as I can. The chassis is Jarrah on this one, an Ozzie hardwood that's much used for floors and decks. She's a gum tree, mate.  I sometimes use Koa, but not for pieces going out of Hawai'i; it's getting too rare. I sometimes also use Padauk, Zebrano, Wenge. Yah, each tube type will have both a basing type, and a bulb type. These define its physical characteristics, which have to be dealt with by the implementation guy. Aloha, Poinz
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Re: Some answers. [message #8938 is a reply to message #8937] |
Thu, 05 May 2005 17:01 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Mark Williams
Messages: 48 Registered: May 2009
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Baron |
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Hey Poidex, Yes, I'd love to see additional frame construction and wiring details. There's certainly no hurry. Since I travel during the week and am only home on weekends, my projects are often stretched out longer than what I would like. Oh, Jarrah wood. Nice! I've heard some of these tropical woods can be difficult to glue because of the oil content. Are you using any special glue, or regular "carpenter's glue" (alphaic resin)? I'm afraid I'd be stuck using walnut, cherry, or possibly maple. Those are the common ones here, along with oak, but generally I don't favor the grain pattern of oak. I often just stain it black. I was poking around on eBay for 6AQ5's and noticed some Russian ones that were 9 pin, not 7 pin miniatures. Interesting. So, that basing type is important to mind. I had no idea. I just thought a 6AQ5 was the same, with the same pin-outs, etc. no matter what. I'm curious as to why you selected this particular tube since it appears no manufacturer is making them new. Sonics, I assume? Regards, Mark Mark
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Some more answers. [message #8943 is a reply to message #8938] |
Sun, 08 May 2005 21:44 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Poindexter
Messages: 108 Registered: May 2009
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Viscount |
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Jarrah is dry, hard, brittle. It glues up with PVA (I use Titebond II) very well. Walnut, Cherry, Maple are noble woods; do not say 'stuck'. Maple is one of my all time fave woods. The 6P1P is not a 6AQ5, any more than the 6AQ5 is a 6V6. It'a a mystery to me why these two devices have been touted as equivalent on the auction sites; since they do not even have the same basing or envelope. I sympathize; I have been corresponding with a gentleman in G. Britain about his Svet (real, St. Pete) 6AQ5's for a week now, and they are actually not, they're 6P1P's and will not fit my gear. Strange. I did not select this tube, it selected me. I was looking for a line amp tube with lower (about ten) mu, and lower (about 2K) rp, and saw it in the tube manual. Beam tube, but I've been using beam tubes and pentodes in triode since day one, so hey. Looking on the vendor sites, I saw that it shifts typically for $2-5, so how could I lose? First guess, whooda thunk it would be so fab? I got quad of brand-matched quads from Alltronics, and they made de Poinz look so-o smart. Don't tell, now. Poinz
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Got some e-Bay tubes coming... [message #8944 is a reply to message #8943] |
Mon, 09 May 2005 16:06 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Mark Williams
Messages: 48 Registered: May 2009
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Baron |
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Hey Poinz, In addition to my little "TV repair guy" stash of 6AQ5's (don't know how many, if any, of those really work), I won an e-Bay auction yesterday for about dozen of mixed brand 6AQ5's yesterday. Cheap, cheap...only $8.50 plus the shipping. So, I'm all set! Now I just have to get you to reveal any additional construction / wiring secrets, then start ordering stuff. ![](http://www.audioroundtable.com/emoticons/smiley.gif) I will check out Alltronics. Have not heard of them. I figured that those Russian tubes were not really 6AQ5's since they were 9 pin miniatures, not 7 pin miniatures. Appreciate your continuing help and advise! Regards, Mark
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No secrets. [message #8953 is a reply to message #8944] |
Fri, 13 May 2005 23:04 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Poindexter
Messages: 108 Registered: May 2009
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I've decided that a central theme of my commercial offering will be just this. If you're a DIY guy, I'll tell you everything I know about how to get the best out of the circuit. Nothing will be held back, and I hope you will treat me similarly. I do sell these as a (very small) business, and so you may rely upon Wayne (who has demo'd this very piece at The Show) to scold me in public if I huckster the commercial offering in the guise of DIY advice. It's a simple circuit with a simple power supply, as you have seen. It performs in my (not-unbiased) view, remarkably. Monster soundstage, high and natural color of timbre, intergalactic black background, bandwidth (+0, -0.5dB) 16Hz - 150KHz. Don't forget to let me know (preferably through this channel) how you get on. Aloha, Poinz
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Absolute Polarity (Phase) [message #8958 is a reply to message #8953] |
Sun, 15 May 2005 00:49 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Triode_Kingdom
Messages: 13 Registered: May 2009
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Chancellor |
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It was interesting to see a mention of this in the manual. And you're absolutely right, phase (polarity) is not always maintained during recording. In fact, because I nearly always test my new amp/preamp designs in mono, I am painfully aware of just how bad the situation is. Typically, when testing/tweaking new designs, I add both channels of the source (usually CD) through resistors in order to capture all the music. However, I have several CDs for which this technique cannot be used. One example is a Yardbirds CD that appears to have been recorded with the L and R channels exactly 180 degrees out of phase. Either channel alone sounds fine, but when mixed, total output amplitude decreases about 9-10 dB. Several other discs suffer from audible frequency response anomalies when the channels are mixed into mono. This usually manifests itself as a significant reduction of high frequency content. When listening to a particular Steve Miller CD for example, everything above 5 kHz or so virtually disappears when the channels are combined. These defects are more difficult to detect when stereo transducers are used, because cancellation from out-of-phase signals is incomplete (or in the case of headphones, nonexistent). Nevertheless, this issue points out how poorly source material is being produced and processed these days, and how important it is to select programming carefully when evaluating a system. Sorry, I know this doesn't have much to do with the preamp under discussion, it just caught my attention.
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Re: Absolute Polarity (Phase) [message #8960 is a reply to message #8958] |
Sun, 15 May 2005 14:34 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
Poindexter
Messages: 108 Registered: May 2009
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Viscount |
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Yah; in the hippie days, a lot of space rock was intentionally mixed with one stereo channel reversed in polarity to give an acidy sound. At least this you can deal with, if you want to go to the trouble. The problem is multitracked recordings where the individual tracks can be in both polarities, so the stereo final product is irredeemably mixed up. The thing is, in these huge mixing boards, the signal may go through ten or twenty op-amps, which can invert or not, and I don't know if there's any standard for this in the construction of the boards, so the engineer is sort of stuck; how's he to know? It might only be the little purist recordist who uses practically no electronics (and those made by him) between the mike and the tape who can control this. I think it makes a difference, which is why I mention it. It seems to show up most in transients, like drum whacks, which sound more natural if they're in correct absolute polarity. Poinz
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Re: Absolute Polarity (Phase) [message #8969 is a reply to message #8960] |
Mon, 16 May 2005 06:37 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) |
Damir
Messages: 1005 Registered: May 2009
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Illuminati (2nd Degree) |
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On some pro mixing-boards there are phase-meters, but today`s multitrack recordings hardly can be 100% mono-compatible, ( synths, multiefects, samplers, etc). Snare drum recorded with two mics (up & down) must have lower mic out of phase; then recording with more mics must be carefully checked for mics placement/phase, etc.
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