[oneinthepipe]

Maybe you could just cut the nipples off the tops of the tubes so they'll fit without needing to mess around with spacers or anything? 

I'd rather see them poke through like this   

I like that too. 

I like that too.  A machine shop would cut the holes for a nominal price, I think.

[robinje]

Maybe you could just cut the nipples off the tops of the tubes so they'll fit without needing to mess around with spacers or anything? 

I'd rather see them poke through like this   

I like that too. 

I like that too.  A machine shop would cut the holes for a nominal price, I think.

Or you could just whip out a drill with the appropriate size bit, measure carefully, and do it yourself!  I personally wouldn't do it, though, as I'd likely drill the holes in the wrong spot or otherwise mangle the cover in some other way. 

[jmc207]

If someone does drill holes and gets it right, they could make a template for the rest of us. Or, a small, thin aluminum plate (painted black) could be crafted with the proper on-center measurement for the tube sockets. Then this plate could be affixed over more roughly-cut holes in the actual case. Might could make this thick enough so that the tops of the tubes would be protected. Just some ideas.

[turkey]

Maybe you could just cut the nipples off the tops of the tubes so they'll fit without needing to mess around with spacers or anything? 

I'd rather see them poke through like this   

That kind of thing always makes me wonder if they got a deal on on the chassis or something. Maybe next time they can use a chassis that actually fits. 

[turkey]

You could come pretty close by cutting some cardboard to match the height between the chassis and the underside of the cover. Then wrap the cardboard around the original tubes and lightly chalk the upper edge of the cardboard. Gently lower the cover down and you should get chalk circles showing where the tubes are. You'll be able to mark the centers pretty easily from here so you'll know where to center the pilot on  the hole saw.

Measure the new tubes to see how wide they are and then add maybe 1/4" to give clearance. Choose the appropriate hole saw.

Having said that, I'd probably find a local machine shop that was willing to do it. Most of them are looking for work anyway and will make you a deal. They will also do things like chamfer the holes a bit so that nobody slices their finger open on a sharp edge or something.

Frank has given a lot of details on how hard he (and now Wayner too) work on designing good metal chassis. AVA equipment has very nice metalwork.

So spend a few extra bucks to make sure any modifications match the quality of the original work.

[jmc207]

Now, I just decided to post to remind myself that Frank's original idea with the spacers does work well and is quick, easy, and not expensive at all. Could spend more time listening instead of dreaming up different ways to cut holes in the chassis. We'll see.

[tgp06]

It will be a little tough cutting/punching holes in a cosmetically acceptable manner due to the existing slots.

[jmc207]

Yeah, that's why cutting holes may not be worth it for many. However, if some sort of round rubber gasket (?) of the appropriate size could be obtain to cover the rough edges it would work. Don't know exactly what those are called but I seen them, with a u-channel on the outside edge that fits over the edges of the opening.

Or, the aforementioned little top-plate idea could cover up the edges as well.

[Art_Chicago]

Drilling should be done instead of cutting/punching, i think. Also, the positions of the holes could be determined from the preamp layout (schematic), e.g. a certain distance from the front edge and a certain distances from  the right or left edge of the cover. Frank should be able to point at the exact tube locations, IMHO. I do not know if drilling could be done with the existing slots, though.

[MarkM]

Tubes are on order.  I'm going to punch out the holes for now and search for round covers, something similar to how Emperical Audio moddified the Dac60 into thier own Spoiler dac. 

They moddified the cover in a similar fashion.(for cooling I believe)

Black chase nipples might work.

[turkey]

Or you could just get Insight+ equipment that doesn't need toobs and holes in the covers. 

[turkey]

Digi-Key as suggested. 

Painted black as suggested. 

I think I'm fine with the looks. Tubes extended through the top would be very cool looking tho.
                                                                                                                                          

That really doesn't look bad at all. It's not going to even be that noticeable from a distance. It's also 100% reversible if you ever have to sell it. (That's something to consider for most folks.)

[martyo]

Yes, I'm across the room form the gear, the lighting is usually pretty subdued...........

And if I ever do decide to sell it, it's reversible.

[martyo]

Will anyone be running them with the covers off? I think that looks cool, too.

Brain, are you going to give them a listen?

[oneinthepipe]

I ordered a few NOS Mazda tubes, which are shorter than the standard height 6CG7 tubes, and they might fit in the DAC and preamp without any modification.  They are purported to be good tubes, but I plan to compare them to the RCA clear tops when I get some.  I should receive the Mazda tubes by the end of the week.

NOS Mazda 6CG7 tubes are available from Upscale Audio for $40.00 each and from "Uncle Ned", formerly of Triode Electronics, for $29.95 each, including shipping within the U.S.

There is also a used pair of Mazda 6CG7 on sale here on AC for $50.00 (a good deal, IMO, and I am still tempted to buy them).

http://www.audiocircle.com/index.php?topic=72242.msg686767#msg686767

[oneinthepipe]

The Mazda 6CG7 tubes are exactly (more or less)      the same height as the 6N1P tubes, and the T8 preamp cover fits without any adjustments.

The T8 sounds smoother and much quieter and with more low end with the Mazda 6CG7 tubes than with the 6N1P tubes, but the low end might not be as tight as the Insight SL's low end.  However, on Led Zepplin's The Rain Song, I thought that I heard some low notes that I hadn't heard before with either the T8/6N1P or the Insight SL.  The notes were faint, and I initially thought that there wasn't too much bass output, but I realized that I was listening to any earlier portion of the track, before the bass kicks in.  I went back and listened to the track several times to be certain.  I don't think that this should be possible, however, and I attribute this to psychacoustics or bad memory or whatnot because the Insight SL plays flat to a very low frequency.  Strings and vocals are nice.  There is a lot of growl to growly vocals and a lot of twang to twangy strings.  There seems to be something missing, however.  Maybe there is less in the upper frequencies, which makes these tubes sound quieter, but my listening skills are not developed enough to really know. 

I can't do a side-by-side comparison because I don't have two T8 preamps.  Nonetheless, OgOgilby, who lives nearby, has a T8 DAC, and maybe we can subjectively compare two dissimilarly-tubed T8 DACs side-by-side. 

Eventually, I will compare the Mazda tubes with the RCA clear tops, and maybe I will be able to describe the sound better.

[martyo]

Thanks OITP.
 

There is a lot of growl to growly vocals and a lot of twang to twangy strings.

Good description, nicely put.
Which amp were you using? I look forward to your tube comparison.
My experience with NOS tubes, generally speaking, is that many of them, while having sweeter mid's than current production tubes, don't have the extension or definition at the frequency extremes. Not so with Telefunkens and the best Seimens, they are very linear, but Brimars for example, have a "killer" midrange, but are rolled off at the freq. extremes, and a little fat in the lowest bass they have. (Talking about 12AT7's)

I started out with the EH's in the preamp. When I added the NOS RCA's to the DAC, the sound was richer yet, and the low end even stronger but with a little less definition. Maybe over the weekend I'll reverse the tubes. My brother says he would run the NOS in the pre and the current EH's in the DAC, we'll see.

[martyo]

Oh yeah OITP, would appreciate front-to-back impressions when you've had more time to listen.......

[MarkM]

The EH6CG7  tubes have been run in for about 24 hrs and my very brief listening take is bass definition is not as deep.  Bass guitar notes and kick drum seem to be on the lighter side.  Nice vocals, perhaps a row or two back compared with the 6n1p.  I like the mid-range.  Treble is nicely balanced, not as forward.  In my system, this might not be a bad thing.   Some of my friends think my system can be bright at times.

I only listened for a quick 30 minutes last night and plan on giving the tubes a good drive over the next week.   I have the EH 6CG7 tubes in my Ultra preamp and usually use the low gain for digital sources, will mix it up this weekend to get a true feel for the tubes.
Tubes are matched for low noise and micro.



 

[martyo]

Thanks Mark, enjoy the "drive" over the weekend and let us know what you hear.
I'm surprised about the bass, but your other impressions track with mine.