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Tj Bassi

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Hi all,

Having relatively little luck in borrowing tube amps to audition with my Requests (currently run with Krell 250m's, bi-wired), lo and behold up comes a pair of pristine ASL Hurricanes for sale locally. The temptation was too much, and after a nod of approval from the wife, the Hurricanes now have a new home :)
I cant wait to get home and try them. Someone on this forum suggested bi-amping the Requests, running the tubes on the panels and the Krells on the woofer, and I want to try that out also. This is going to be so much fun....

Tj
 

twich54

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TJ, Who said men can't have as much fun as women when it comes to shopping !!! Good luck, keep us posted !
 

aliveatfive

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Tj Bassi said:
Hi all,

Having relatively little luck in borrowing tube amps to audition with my Requests (currently run with Krell 250m's, bi-wired), lo and behold up comes a pair of pristine ASL Hurricanes for sale locally. The temptation was too much, and after a nod of approval from the wife, the Hurricanes now have a new home :)
I cant wait to get home and try them. Someone on this forum suggested bi-amping the Requests, running the tubes on the panels and the Krells on the woofer, and I want to try that out also. This is going to be so much fun....

Tj
Tj -
The Hurricanes have had quite a few incarnations from what I've read. The earliest versions were said to be great and then some subsequent versions had parts changes (oil caps?) that made these less desirable. Current production is supposed to be terrific again. You might try to find out when they were made. As I said before, I'd love to hear them on my Summits.
 

Tj Bassi

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This particular pair of Hurricanes are the latest units, just a few months old. They have the newer extruded chassis, standby switch (a nice feature) and protection circuitry. It is my understanding that only a handful of units with the cap problems were shipped in late '03/early '04, which was one of the reasons I avoided picking up a pair back then. The Hurricanes have been on my *wanted* list since their introduction.

Tj
 

Tj Bassi

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Tube advice, please...

I have a few questions before digging in and setting up the Hurricanes, just want to clarify a few points.

My current startup procedure (and recommended by Krell) is to power up the pre-amp, turn the volume all the way down, then power up the amplifiers. The shut down is basically reverse....turn the volume down, power down the amps, power down the preamp. Is this the procedure I should follow with the tube amps?

The hurricane manual gives instructions for setting the bias, but what exactly is 'tube bias' from a technical standpoint? If someone could explain it to me like I was a three-year-old I would appreciate it.....

Can anyone recommend a good supplier for tubes? Each amp uses eight (!) KT88's so I would like to keep a few around.

This is the first set of tube amplifiers I've actually owned, and I have this nervous sort of thing going on. Comes from hanging around with too many solid state guys. They all but have me convinced my Requests are going to go up in flames before the weekend is over.... :(

Thanks guys,
Tj
 

aliveatfive

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Tube bias allows the tube to be conductive (as if a signal were present) at all times. This is to avoid crossover distortion as the signal goes from the positive side of the sine wave to the negative. You will need a digital voltmeter to properly bias your amp. It is not a difficult process, but there are sources of high voltage in the amplifier that can be lethal. If in doubt, consult a tech and have him (or her) do it. BTW - too little bias and you'll get distortion - too much and you'll shorten the lifespan of the tubes.

Adendum: Just thought of this - some amps already have meters built in to set bias. Don't know if this applies to Hurricanes. Consult documentation.
As far as tube selection, you can try "winged C" from Russia (the 6550c will work well in your amp. The new TungSol is also a good sounding tube. Old stock Mullards and TungSols are supposed to be great, but hugely expensive.
 
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Tj Bassi

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The Hurricane does have a built in bias meter. Thank you for the info. I found quite a number of tube suppliers listed in the back of Audio Express. Anyone have a favorite vendor for replacement tubes?

Tj
 

twich54

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Tj Bassi said:
The Hurricane does have a built in bias meter. Thank you for the info. I found quite a number of tube suppliers listed in the back of Audio Express. Anyone have a favorite vendor for replacement tubes?

Tj
Tj, I've had good luck with ; Doug's Tubes and also Charlie Kittleson @ Vacuum Tube Valley.
 

aliveatfive

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Try: TubeDepot.com , thetubestore.com , triodeel.com. I've used these and I can vouch for all of them. Just ordered some cryo-treated Chinese (Valve Art) 6550s from ATSI.com. I'll post when I receive these and try them out.
 

twich54

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aliveatfive said:
Try: TubeDepot.com , thetubestore.com , triodeel.com. I've used these and I can vouch for all of them. Just ordered some cryo-treated Chinese (Valve Art) 6550s from ATSI.com. I'll post when I receive these and try them out.
Thanks also for the other choices !!
 

Tj Bassi

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Added all to my list of suppliers to investigate-thanks! All but one of the output tubes in the Hurricanes are presently Valve Art and the previous owner spoke highly of them. The odd tube is not marked.

TJ
 

Tj Bassi

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Two days with the new amps....

After two days of listening with the new Hurricanes, and then an afternoon of amp-swapping (Hurricanes vs. Krell 250 monos) while auditioning the same tracks, I have walked away with the conclusion that I not only like the tube amps, I love them. On favorite recordings which I know well, the Hurricanes presented a new image; individual instruments were more defined and had a clearer tone, singer's voices came to the front with more clarity. For me, this is the sound that I've longed for but until the purchase of the new amplifiers was unable to obtain.
I ran another test late in the afternoon, bi-amping my Requests with the Hurricanes on the panels and the Krells on the woofer section, but only achieved marginal results; the bass was definitely lacking to the point where I questioned if the woofer sections were actually being driven. They were, but the Krells seem to require more signal from the pre-amp (I am using a Marantz SR9200, internal amp modules disabled). I am sure this combination will shine if I can find a way to control the gain of the individual amps, but it might be beyond the capabilities of the Marantz unit. I could use some feedback on this if anyone has tried this combination before.

All of this is only my personal opinion.....I did not want to start any tube vs. solid state arguments. Most of my equipment was purchased with the intent of setting up a 5.1 HT rig, which it currently is, but I find myself gravitating back towards a dedicated two-channel system. Its equipment like my Requests and the new Hurricanes that make me glad its going in that direction. I cant wait to get more listening time in.....

Tj
 

MiTT

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That's very cool...

I'm glad that you are enjoying the synergy that tubes bring to your Logans. You should post your findings in more detail over on the Recommended Components section of the forum. I'm working on a review of my BAT amp for that area as well.

Happy listening, enjoy your tubes!
 

aliveatfive

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Tj - If you're going to bi-amp with different amps, you really need some kind of level control to balance the output on both sets of amps. I once tried bi-amping with tubes on top and solid state on the bottom. The results were not worth continuing the experiments. (Others have been successful.)

Mitt - I was just about to write Tom to discontinue my suggestion of a "recommended page." Mine has been the only post in there for about 2 weeks. Glad to see you intend to post.
 

Spike

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Tj Bassi said:
After two days of listening with the new Hurricanes, and then an afternoon of amp-swapping (Hurricanes vs. Krell 250 monos) while auditioning the same tracks, I have walked away with the conclusion that I not only like the tube amps, I love them. On favorite recordings which I know well, the Hurricanes presented a new image; individual instruments were more defined and had a clearer tone, singer's voices came to the front with more clarity. For me, this is the sound that I've longed for but until the purchase of the new amplifiers was unable to obtain.
TJ, I'm glad that the Hurricanes work for you. With 200wpc at your fingertips, you need not bi-amp, unless you specifically want the Krells to provide the grip-like control on the bass.
I ran another test late in the afternoon, bi-amping my Requests with the Hurricanes on the panels and the Krells on the woofer section, but only achieved marginal results; the bass was definitely lacking to the point where I questioned if the woofer sections were actually being driven.
Looks like you need to balance the gain between the Hurricanes and the Krells. How'bout trying the Hurricanes in triode mode first, bringing the output power down to 120wpc to see whether that will bring balance to your system.
I looked up the Krell 250 spec on their archive and saw that they are pretty high at ~26db of gain. It's kinda hard to believe that the Krells with 250wpc, and 26db of gain are getting drowned by the 'Canes. Were you bi-amping using the same outputs with an RCA Y-adaptor? How did you hook up the Hurricanes and Krells to the Marantz? Looking at the user-manual of the Marantz, I only saw 1 set of LR outputs for the amplifiers so it looks like you'll need to use an Y-adaptor for bi-amping. To hook up the amplifiers with other connections will NOT give you a real indication of bi-amping using the 'Canes and Krells.
If you are already using Y-adaptors to ensure the same signals are seen at both amps, then you'll need to get an attenuator to dial down the gain at the Hurricanes. You have 2 choices: adjustable or fixed in-line.
The DACT attenuator and Marchand Electronics Attenuators are examples of stepped attenuators where you can manually dial in the amount of attenuation that you'd like.
For a more scientific method, you'll need to contact ASL to get the gain spec for the 'Canes and then buy the in-line attenuation with the right amount of offset to balance the gains between the 'Canes and Krells. For example, if the Canes were spec'ed to have 29db of gain, the you'll need a -3db unit to get 26db of gain at the Canes to match with the 26db spec'ed for the Krells.
An examples of fixed, in-line attenuators can be found at Parts Express Attenuators.

Good luck
Spike
 
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Tj Bassi

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Spike,
As you thought, I split the L/R channels from the Marantz with a good quality Y adaptor, and ran individual cables to the four amps from there.
The Krells seem to need to be pushed harder when compared to other amps to get the same volume. For instance, with the ASL's and my older MA500 monoblocks, a volume control setting of 12~10 was enough to drive the Requests to a suprisingly loud level. With the Krells, you have to raise the volume to about 5 or so to get the same sound.
It could be that bi-amping is this case is not needed, and I'll run more tests to see if its even viable. Being I already own a trio of 250m's it seemed worth the effort to try.

Tj
 

aliveatfive

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Be aware of the following: output power has nothing to do with the given sound level as represented by a volume control. A lower powered amp may have higher gain than a high powered amp. You should use a sound level meter (available at RatShack for cheap) to balance your amps.
 

jjqiv

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Tj Bassi said:
(I am using a Marantz SR9200, internal amp modules disabled). I am sure this combination will shine if I can find a way to control the gain of the individual amps, but it might be beyond the capabilities of the Marantz unit. I could use some feedback on this if anyone has tried this combination before.

Tj
Good God Man! You need a real preamp! The SR9200 is Mid-Fi. A Hurricane is a terrible thing to waste. I'd recommend the auditionning of a Placette Passive Preamp.
 

Tj Bassi

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Your point is well taken but I'm not sure how to properly implement it. Are you saying that in a speaker such as the 'Logans, both the panel and woofer section are driven equally so as to produce the same SPL?
Just to be thorough, I had planned on running one more series of tests, this time with each pair of amps powering the entire speaker, because I've never been conscious of the sound coming from each section in itself. Obviously you can hear the panels; how much the woofer adds to the overall image is what I wanted to take note of.
I will take your suggestion and pick up a meter first, though, just to have viable results.

Tj
 
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