tube choice for Audible Illusions L1

I have a Audible Illusions L1, and it has humming noise on the left channel. I suspect it is the tube. Also, I would like to smooth the sound a bit more. The recommended and current tube I have is 6h23neb. However, I have someone previously recommends Svetlana 6n1p. I would like to try it out, but it says on the AI FAQ that "6NIP tubes should not be substituted as they require additional filament current and their use will compromise performance."
What does compromise performance means? Does it mean the tube life will decrease? But it won't do any damage on the unit, am I correct?

Also, from the tube store, I can't specify the brand. Is it important to order a specific brand?

Besides the 6h23neb and 6n1p, is there other suggestion that will help smooth out the sound, or make it less harsh?

I can't imagine the harshness you describe is coming from your Audible Illusions preamp. The best person to talk with regarding tubes for your preamp is Art Ferris, the guy that designed it.
Well ... harsh may not be the right word, but maybe due to some of the recording, some song has very strong glare ... I don't know if it is the right word also. Usually when hearing female vocals. The bottom line is, got fatigue after hearing for a while. Some recordings are ok. Anyway ... just want to try out some other tube to see if it will improve the sound to my taste.
You could try older 6h23eb (the ones with the rocket logo) if they are still around. They are a bit softer sounding than the ones made @ Refektor (sp).

I used Siemens 7dj8 in the phono section of a Mod 3a, but never tried them in the line section. Maybe someone here has?

The 7dj8 was durable in the application and had a nice smooth/liquid sound (akin to old production Mullard and Amperex 6dj8's).
You will get much smoother sound with NOS 6922 like Amperex etc. As you are probably aware however, these preamps are tough on tubes and it is not cost effective having to replace NOS tubes every 6-12 months.You might consider some Herbie's Audio Labs tube halos and some different footers. These tweaks can smooth the sound out some.
Thanks. I am reading Joe's tube Lore page. He also recommend the Amperex white label PQ 6922. I found a couple posting on eBay, but it is not matched pair and are expensive, average to be $180. =(

I am very new to tube. So, all those Amperex tubes are old, and can only get from eBay? I tried search the tube store, but can't see any of them.
Get some choice EH6922. Try "The Tubeman". He has cyro'd tightly matched triode pairs available.
Go inside the unit and make sure the Cap dip switches are set to on
the amp you are using may better interface this way.
Also call AI with your serial number and they will
get you the right tubes for that unit
Best Johnnyr
I am reading Joe's tube Lore page. He also recommend the Amperex white label PQ 6922. I found a couple posting on eBay, but it is not matched pair and are expensive, average to be $180. =(
09-24-10: Gte357s


Not for the AI

Special warning to Audible Illusions preamp users:
The one you can say for the Sovtek is that you can run it hard and it can take it - and apparently that’s exactly what AI does. Unfortunately the classic NOS tubes in this family just cant take this kind of treatment and will rapidly fail when used in these units (and some of you guys have the fried tubes to prove it!). So you AI users are probably best off limiting yourselves to the Sovtek, the Russian 6H23N & 6N1P, the 7DJ8 and the E288CC. There may be others the range of tube types and variations is quite literally bewildering but these are the ones I’m aware of that should be able to handle the higher stresses of this brand of preamps. I review the Edicron, Siemens E288CC and 6H23N here but there are other brands for some of these. I’ve seen Phillips E288CCs & Amperex 7DJ8s advertised on some web sites in the past and there are probably others. It might be worth your while chasing them down & evaluating them for yourself to increase the number of alternatives for use in your AI.
I am very confused. So, the Amperex 6922 is not good? From the AI FAQ, it says:

"Only "mil-spec, low-noise" 6922, 6DJ8, 7308 or European E88CC tubes are recommended for use in Modulus preamplifiers.

Previous production Modulus M2, M3, M3a and L1 preamplifiers used Russian 6922 tubes. While quality and sonic performance of these tubes were excellent for several years it is unfortunate that current-production from the Sovtec/Reflector factory does not have the same sonic identity and a high percentage prematurely fail.

Current production Modulus M3a and L2 Preamplifiers use a Russian Military Type 6922 with "Grey Plates" and have excellent sonics and reliability.

Similar tubes which have different technical specs should not be used.

7DJ8 tubes require higher filament voltage and performance is marginal.

6NIP tubes should not be substituted as they require additional filament current and their use will compromise performance."

So, the 7D8J and 6N1P conflict with Joe's comment. And Joe said 6922 is not suitable? ... So, the remaining choice are:

6h23n, 6DJ8, 7308, E288CC ?
Previous production Modulus M2, M3, M3a and L1 preamplifiers used Russian 6922 tubes.
09-24-10: Gte357s


You have the L1 correct?

09-24-10: Audioconnection
Go inside the unit and make sure the Cap dip switches are set to on
the amp you are using may better interface this way.
Also call AI with your serial number and they will
get you the right tubes for that unit
Best Johnnyr
Sounds like good advice.

09-24-10: Theduke
Get some choice EH6922. Try "The Tubeman". He has cyro'd tightly matched triode pairs available.
Also good advice
A good rugged tube.

The 6DJ8, 6922 and 7308 are a family of tubes that are interchangeable in most audio applications. The E88CC is the European name for the 6922. The 7DJ8 is a little higher voltage version of the 6DJ8. Unfortunately NOS versions of these tubes are expensive and will probably not last very long in your preamp.

This discussion is only going to get more confusing. Get in touch with one of the tube sellers recommended here or in other threads and take his advice. That is the cheapest and easiest way for you to find tubes that will give you the best sound you can get at a price you can afford.
thanks for the advice. I will try turn on the cap. It is currently turn off based on recommendation from AI. It won't hurt to try turn it back on. Actually, what is that cap thing?

Also, the Electro-Harmonix-6922 seems worth a try. Not expensive, and it says it may help to remove some of the harshness.

My friend came over and he have a better word to describe other than harsh. It is "dry". It is hard to describe, but when he said this word, I feel it describes the sound.

The Siemens 7dj8's were still going strong in my friends Mod 3A four years after we put them in the phono section.

Philips (euro) 7dj8's are $50 each @ Upscale and per their ad copy they are fine for use in the AI 3.

I have been using an L1 for the past 3 years and currently have the 6h23neb tubes installed and they sound fine to me. I have had them installed for about a year. Before that, when I bought my L1 it came with RCA brand 6DJ8 tubes (made in Germany)which were supposedly made by Siemens in the 60's or 70's. I changed them after 2 years of listening (a lot)just to try something different. I really can't say one is better than the other but they both sound great to me.
Some people on these forums like to indicate that any and all preamps made by AI eat tubes. In my case I certainly haven't found that to be the case so yours may be like mine and not go through tubes.

When you say the sound is dry, I'm surprised no one asked what source, amplifier, and speakers you were using as this could make a lot of difference. One thing about the AI preamps that is different from many others is the fact that they are phase inverting. This means (according to the AI owners manual)that you should switch the red and black speaker cables at your speakers so the red cable is connected to black speaker connector and the black cable is connected to the red speaker connector. Doing this may help but only do it with everything turned off so you don't inadvertantly touch them together and damage you amplifier.

I assume you don't have an owners manual for your preamp. I bought one from AI after I bought my L1 and it took F O R E V E R to get it. If you would like a copy, send me an e-mail with your mailing address and I will send you a copy. It's pretty simple and may help answer some of your questions.

Good Luck.

Hi Dekay,

How does the Siemens 7dj8 sound in the M3A? Would it help to smooth things out a bit compared to other tubes? I have ordered Electroix-Harmonix 6922. Any experience how they would compared?
Only tried 7dj8's in the phono section (1983 Reflektor 6h23's were used in the line stage).

The phono was more open/liquid sounding with 7dj8's VS 6h23's.

Someone in the forums suggested this combo/placement.

Try searching here and @ audioasylum to see if anyone is using 7dj8's in an L1, or in the line section of a 3 or 3A.

If so, I would go with the Euro Philips @ Upscale as the price is OK and they are smoother sounding than Siemens, and Tunsram.

I tried Telefunken 7dj8 as well, but suspect they were not good examples of the tube.
PS: Experimenting with the internal switches and popping in new EH tubes may do the trick. I'd wait and see.
Greetings Gte357s
What amp and cd player speakers are you using
the dip switches for Caps on should sound more neutral
have you done this yet?
Its easy don't worry you cant hurt anything
just mute the pre amp when you do it
Did you invert both speakers Plus with the Minus as in the manual?
Please let us know what you hear.
Best Johnnyr
I tried to turn on the capacitors, my immediate impression is that it sounds thin, and not as musical. It seems it is easier on listening though. But it then sounds closer to the Rotel I have before ...

Try using the "Aux" input and see if you can hear a difference. I think the other inputs have a series resistor in the signal path.

You might also want to try "Main Out #2" which has a 470 ohm resistor in series. To quote the manual "This corrects for anomalies i.e., tube "glare" that are exhibited in some brands of tubes. If you are running a long length (over 15 feet) of interconnect, it is best to use Main Out #1"

I use the "Aux" input for CDs, "Main Out #1", and the capacitor DIP switches are set to OFF.

I currently have a pair of 6H23P-EB tubes that Upscale Audio calls "Type 3" that sound really nice. I've also used a pair of Matsushita 6DJ8 that sounded pretty good that I bought from Andy at Vintage Tube Services.

Of course, what you are hearing might be a system matching issue.
Here is my system:
Sony Blu ray player, Maverick audio DAC (not using the tube buffer), AI L1 preamp, McCormack DNA-1 deluxe amp, B&W CDM9NT speaker.

I am using the Aux input, and Main 1 output. I will try using the Main 2 to see if there is any different.

Also, I have the speaker wire inverted. I have the caps turn off before as recommended by many others. I tried to switch them on last night. I agree that it is more neutral and easier on ears. I will try turning it back on and Main out 2 to see who it sound.
I tried different combination.

Caps on with Main 1 out - harsh or dry
Caps off with Main 1 out - sounds thin, less musical, but easier on listening
Caps on with Main 2 out - it seems it improves the situation a bit, not as harsh. Or according to the manual, it removes tube glare.

I prefer to have caps on and Main 2.

Per the previous owner, the tube is Russia military grade 6h23neb with less than 50 hrs.

I also tried switching the left and right tube, but the buzzing noise is still louder on the left channel, so, it is not because of the tube. It is not a big deal, can't hear it at the sofa.

I am egar to try out the 6922 and see how it sound.
You could have either a bad interconnect on one ch
try swapping them.
A transformer from a CD player or something else located
just inches under or over the pre amps shell could be provoking a hum.
Try moving and or relocating the closely located culprit.
Best Johnnyr
Thanks for the advice. I don't think it is because of the interconnect though. I got the noise since the first day I got this preamp, then I upgrade the interconnect, and the noise is still there. Maybe some capacitor are old? Inside, there is a sticker says it is checked in 96. So, it is a 14 years unit. Is it about time to have a service and replace some capacitor?

I did some more listening, the Main 2 out seems work for me. It remains musical with good sound stage, and the harshness or glare is improved.
I have had L-1 for about 7 years. One day the tubes went bad it made a harsh static kind of sound. I replaced the tubes and all was fine. On the Audible Illusions site they recommend tubes to use and not use. I had a set of brand new Svetlana tubes which I used. I then went on ebay and got some cheap mullards. When I replaced the Svetlana tubes with the Mullard tubes there was a noticeable increase in fullness and base. Also I notice that the highs were less fatiging
i finally got the Electro-Harmonix-6922 and listened for an hour, so far, I like it. it doesn't have the glare as in my previous 6h23neb. I also feel the detail and sound stage are improved
Need help again. I just got the new EH 6922 tube over the weekend, but today, I found out it has very loud hissing sound ... is that the tube is done?
Greetings GTE 357
Trying to save money is sometimes tough.
I would get the serial number so we can have AI get you a low noise gain matched set for that circuit.
This is what I have found to work best. Johnnyr
I emailed Upscale audio, but with no reply. I am disappointed. I even pay extra $10 for the premium, and it says on the web site that this is a tube they would recommend.

But BTW, can I tell if it is the tube comes defective, or it failed prematurely? I hear intermittent hissing sound.
I hear intermittent hissing sound.
10-16-10: Gte357s

That could be a dirty tube socket contact/s. With the preamp turned off try unplugging the tube from the socket and plugging it back in a few times to clean the socket contacts.
I tried plug and unplug several times, and it is still there. And it is not intermittent anymore, it is a continuous hissing sound. I also switch the left and right tube, and the hissing sound move with the tube. By this, I can confirm one of the tube failed. The other is still ok. So, usually, a tube won't fail this fast, is this covered under any warranty?

Sounds like the tube is bad. It can happen with a new tube.... Call Upscale Audio, 909-931-9686. Explain to them the hiss moved from one channel to the other as the bad tube was moved.

You may have to pay a shipping charge. Can't say for sure.
I contacted Upscale audio and they agree to send me a replacement tube. Excellent service, way to go, Upscale.
The Amperex "Orange Globe" are an excellent cost-quality compromise and are likely to last a long time. I have had mine for three years.