[Allanmarcus]

In my opinion, a properly functioning tube should not be microphonic. The 12AU7 input tube contains all the gain so it will be more susceptible, but there's nothing about the Cracks's topology that makes it more sensitive to microphonics. I have probably a dozen input tubes and maybe 1-2 of them are microphonic.

I think the issue is with external vibrations, like say banging on a keyboard or walking around near the table where the Crack sits. I forgot that I could not keep the Crack on my desk as I hit the keys on the keyboard pretty hard. I keep the crack on a table next to my desk.

I should also mention, and this is more of a personal thing, but I did not like the idea of reaching around the tubes on the top plate to turn the amp on or plug in a cable, or plug in the quarter inch headphone connector. All inputs on mine are on the back, controls are on the front, and my headphone jack is on the side in one inch oak. I do little to add any vibration even if it is just adjusting the separate left and right volume controls.

The way I, and I think most others, orient the crack is to have the volume and jack on the front and the inputs and power on the back. While the input tube is a little close to the volume and jack, I wouldn't say I have to reach around anything to use volume, jack, or power.

 

[Paladin79]

I know the positions and as I said, it is a personal thing just like preferring a separate volume control for each channel. I would be reaching up there twice as much and I would need to put the second control somewhere. I did what felt right for me. Also I did build a stock crack amp and used it to compare to one I began modifying, I wanted to be absolutely sure that none of my changes affected overall sound. After that I pretty well knew the build and went on to modify a few of them.

I did put a blade switch on top in another build but it just controls magic eye tubes and aesthetically it is not meant to be mounted vertically. This is the only photo I have handy but the white blade switch is on the bottom left amp.

I envisioned my build before receiving the kit but that is just the way I think. My third build required some thought but I designed my own circuits. I should not even call this one a Crack amp, I just used a few left over parts from previous builds. It has 8 tubes, not the standard two.

 

[chimney189]

Good day everyone,
I recently purchased a BH Crack w/SB upgrade.
I'm currently using Tung Sol 7236 and Telefunken 12AU7. The sound is a great balance between warmth and clarity, but I'm missing bass slam and punchiness (the bass slam seems near non-existent).

I've been looking for tubes that might help the situation out: https://www.ebay.com/itm/2-MULLARD-...017926&hash=item33e634c724:g:BlIAAOSwxyJav8fc

Has anyone had experience with these tubes?
Impressions?
Thanks!

 

[FunyunBreath]

Good day everyone,
I recently purchased a BH Crack w/SB upgrade.
I'm currently using Tung Sol 7236 and Telefunken 12AU7. The sound is a great balance between warmth and clarity, but I'm missing bass slam and punchiness (the bass slam seems near non-existent).

I've been looking for tubes that might help the situation out: https://www.ebay.com/itm/2-MULLARD-...017926&hash=item33e634c724:g:BlIAAOSwxyJav8fc

Has anyone had experience with these tubes?
Impressions?
Thanks!

The tubes you linked to are 6DJ8 and are not compatible with the Crack at all.

From my experience, the 7236 is the culprit here if you're looking for more bass slam. The 7236 is a very linear sounding tube with fast, well controlled bass, but it's flaw is that the bass lacks depth and slam.

I would look at a Tung Sol 6as7G to replace the 7236. And if you like that sound and want a more expensive variant with better sound, look at the Tung Sol 5998.

FWIW I've rolled almost all the higher-end tubes in my crack and my favorite combination is the Siemens Chrome Plate 12au7 + Tung Sol 5998

 

[chimney189]

Bendix 6080wb

The tubes you linked to are 6DJ8 and are not compatible with the Crack at all.

From my experience, the 7236 is the culprit here if you're looking for more bass slam. The 7236 is a very linear sounding tube with fast, well controlled bass, but it's flaw is that the bass lacks depth and slam.

I would look at a Tung Sol 6as7G to replace the 7236. And if you like that sound and want a more expensive variant with better sound, look at the Tung Sol 5998.

FWIW I've rolled almost all the higher-end tubes in my crack and my favorite combination is the Siemens Chrome Plate 12au7 + Tung Sol 5998

Thanks for your quick reply, much appreciated!
How does the overall sound signature sound with your favorite combination?
I was also looking at the 7316 ECC186 Amperex? Any impressions with that one?

 

[chimney189]

I also am realizing that the 5998 is a bit too expensive at the moment, are there cheaper alternatives that offer similar sound?

 

[FunyunBreath]

Thanks for your quick reply, much appreciated!
How does the overall sound signature sound with your favorite combination?
I was also looking at the 7316 ECC186 Amperex? Any impressions with that one?

No problem!

Siemens + 5998 is just a great combo with the HD800S. Holographic imaging, wide soundstage, fantastic mids, no sibilance, neutral but with deep bass. I rarely roll any other tubes in my crack at this point if that tells you anything

The Amperex 7316 (mine is a Beckman labeled tube, short plate with halo getter) is my second favorite tube However, 7316 have gotten insane in terms of price and I really don't think they are worth the money. I prefer the Siemens Chrome plate anyways, and they can be found for around $50 easily.

Another great tube to look at that is very reasonably priced is the Sylvania 5814A w/ 3 mica. They have a gorgeous midrange that really makes vocals shine.

 

[FunyunBreath]

I also am realizing that the 5998 is a bit too expensive at the moment, are there cheaper alternatives that offer similar sound?

The Tung Sol 6as7G is basically a 5998 but with a bit less detail. I ordered mine from vacuumtubes.net for $20 a few months back

 

[chimney189]

So, this is what I've found:
https://www.tubedepot.com/products/6as7g-6520
&
https://www.ebay.com/itm/2-Siemens-...epid=0&hash=item239b4f15d0:g:dpAAAOSwKRdamg1Z

 

[chimney189]

Would these be correct?

EDIT: I apologize for the back-and-forth as this would probably be handled better in private messages.

 

[Paladin79]

I like some of the 6as7g tubes, there are plenty of NOS Russian tubes but when you can trust the seller. I like the RCA. I am running one now in fact.

https://www.ebay.com/itm/rca-6as7g-tube/183070395857?epid=0&hash=item2a9fd88dd1:g:TmIAAOSwqfZagSu1

 

[buldogge]

Good day everyone,
I recently purchased a BH Crack w/SB upgrade.
I'm currently using Tung Sol 7236 and Telefunken 12AU7. The sound is a great balance between warmth and clarity, but I'm missing bass slam and punchiness (the bass slam seems near non-existent).

I've been looking for tubes that might help the situation out: https://www.ebay.com/itm/2-MULLARD-...017926&hash=item33e634c724:g:BlIAAOSwxyJav8fc

Has anyone had experience with these tubes?
Impressions?
Thanks!

I like the TS 7236 a lot as a 5998 alternative...especially since they can be picked up for around $25-30!

Have you considered pairing it with a 6SN7?...Maybe a KR V-231 or a NU Black Glass? (need Garage1217 adapter, as well)

I'm running a 7236/TS Mouse Ears combo myself on The Crack/SB (plus choke/diodes/films) and it is quite nice.

There's also the question of which phones you're using, of course. I use mine with T90s and HD700s FWIW.

-Mark in St. Louis

 

[chimney189]

I like the TS 7236 a lot as a 5998 alternative...especially since they can be picked up for around $25-30!

Have you considered pairing it with a 6SN7?...Maybe a KR V-231 or a NU Black Glass? (need Garage1217 adapter, as well)

I'm running a 7236/TS Mouse Ears combo myself on The Crack/SB (plus choke/diodes/films) and it is quite nice.

There's also the question of which phones you're using, of course. I use mine with T90s and HD700s FWIW.

-Mark in St. Louis

I'm using the HD 800S

 

[FunyunBreath]

I have quite a few 6SN7 tubes as well, along with the garage 1217 adapter. Overall they have a much darker sound signature than 12au7 types, which can be quite nice with the HD800. I rarely use them though because they tend to be more prone to microphonics and have a higher noise floor in my crack.

Of the 6sn7's I have, the Tung Sol Mouse Ear, and Sylvania JAN VT-231 are my favorites.

 

[Allanmarcus]

I thought the Tung Sol 7236 was a ruggedized 5998. I also thought, based on reading about them on the Bottlehead forum a little, that they sound the same.

I'm currently using a Tung Sol 7236 and a Telefunken ECC82 (12AU7), and I'm not lacking for bass, but I don't listen to EDM or anything like that.