Hey all sorry if this has been covered before but I’m looking at buying some of Herbie’s Tube Dampers. It seems to me that I need the Ultrasonix Rx-9 to fit the BHK Pre and Monoblock tube sizes? Can someone confirm they fit OK? Also is it the Ultrasonix Rx-9 I need or the equivalent HAL-O III-9? Thanks.
Here’s the link to Herbie’s tube dampers, and size chart. RX-9s fit most nine pin tubes such as 6DJ8, 6922, 7308, 12AU7, 12AT7, 12AX7, etc
I sometimes use a 12AT7 input tube in my tubed headphone amp. The RX-9 fits correctly.
The Halo variant is supposedly better for heat. I have only used the RX and entry level versions.
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Thanks that is what I was thinking. Do you have any BHK amps? I just want to make sure they will fit in those because I have heard people say that some tube dampers don’t fit in them.
I don’t have a BHK, but if you go to the System Photos thread, post #1776, there is a picture of my headphone amp. The two outside tubes are 12B4A with RX-9s affixed. They fit snug. The tubes are vertical glass. Conversely, my 1626 tubes have a bottle shape and have to be positioned just right. You use 12AU7s in the BHK, correct?
I added this photo. The center input tube is a 12A_7 family tube?
Also, his fit chart was correct for all my tubes: Novals, octals, and small bottle 1626.
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Thanks. I think you are misunderstanding. The BHK’s have a more unconventional arrangement where there is a little door that goes on over the tubes - that is what I was wondering about - apparently it won’t shut with some dampers. Beautiful system BTW and thanks for trying to help, I should have been more clear in my question.
@drarifakhtar - Be very carful with the Rx-9 on the BHK AMPS. They fit great on the BHKPRE; however, the BHK250/300 it is very tight. I used the SS-9 on the BHK250; below is my post w/ pics on the BHKPRE & BHK250. I then transferred the one set from BHK250 to one BHK300 and bought the other set of SS-9 dampeners. The wheel diameter is a tad smaller and fits well. You don’t want to touch the door or opposing wall with the dampener wheel.
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Thank you this is what I was after. I will bookmark this for when Herbie’s shop opens again. So basically I will need to use the SS9 for the BHK300s (and RX9 is OK for the pre). Glad I found out before ordering the more expensive ones!
@drarifakhtar - yes, the reason I jumped all over it… The Rx-9 may just squeeze in there; however, I did not want to take the chance. IMHO, didn’t look like it would fit. I captured it in pics because it is a judgement thing and pics helps…
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I’m using a pair of herbies ss9 dampers my bhk preamp. You need to sit then with the open segment facing the back of the preamp as there there is quite a tight space between the tubez and the vertical boards that sit adjacent to them. I always remove or place them on the tubes with the power off. I usually slide turn about 2cm down or 2/3 of the length of the tube. I never run my preamp without them
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@JMK - I’m using the Rx-9 for PRE and SS-9 for BHK300s… Preamp is tricky, need to make sure there is no touching of the dampener. The BHK300s are even trickier cause of the door and wall they are between. I would not use the Rx-9 on the BHK300; however, the BHKPRE is doable. This link has pics I took.
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2 options for the bhk preamp then.
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@JMK - Yeah, I took pictures for that reason. I wanted to make it clear you could fit them; however, very tight as you pointed out. It was a good move with the “special” tubes. My BHK250 sounded great and my BHK300s have about 300hrs on them and are unfolding nicely…
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Here’s a picture of the two side by side. The SS-9 looks to be maybe 1/8" shorter than the
RX-9 when they’re stood on end.
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Thanks that is useful. It seems the white rings on the RX9 are slightly wider (maybe just my eyes?) but those little black rings make the big difference.
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The wheels are pretty close in diameter, but the O-Rings clearly make the RX overall diameter wider.
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Yes when I look again it seems it is the black O rings that are increasing the diameter and the white rings are probably the same size (diameter).
@netspecht-2 - very good, better way to express the difference; direct comparison with photos too… 
It is the Rx-9 rings around the wheel that make it wider. It is deceptive because at an angle they look very close until you realize the o-ring is what determines the fit and area needed to accommodate the Rx-9. The reason I had a pic of the Rx-9 mounted on the tube and indicating it works showing sufficient room 360 degrees around. It is not just the circumference, it is the o-ring inner that expands the circumference greater than the pic you are showing.
Yeah, you might fit the Rx-9 on the BHK300; however, you are taking a chance. The risk/reward was too great…
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Yes the price difference is big and since I’m in the UK I’ll have the added “bonus” of customs charges too! Once the shop reopens I’ll go with the cheaper rings for the BHK300 and just get the RX9 for the pre.
The SS rings are about .04 inches smaller. Like you thought, its basically the black o-ring that increases the diameter.
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@netspecht-2 - now think of the inner section of the o-ring and how it will increase the circumference when installed. You have to consider that too. So, yes with a 6in caliper (mine digital), you get the difference. Man, that is old school analog caliper… so cool… looks like 3/64” wider… 1/8 is 0.125, 1/16 = 0.0625”… yeah… 3/64 = 0.048ish… not a hell of a lot bigger… I might have risked it; however, did not have them side by side… 
Thanks for the numbers, it lays it right out for @drarifakhtar. I would risk it… However, the SS-9 are excellent.
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