[simon wagstaff]

I recently had the opportunity to purchase a pair of Raidho C1 stand mounted speakers at a price I couldn't pass up. I have always felt that my Gallo Ref 3.5 just might be my "last" speakers but for the price I paid, I figured I could always sell the Raidhos if I wanted to.

My U70 has been relegated to the upstairs system. It just didn't seem like a good match for the U70. They wanted more power, and the tube smoothness seemed to be lost on the Gallos. Using that CDT tweeter I think the high end was just a little too diffuse. I use the power amp section of my Harmon Kardon 990.

Now, I really like the HK990, it has all the features I want. The room correction is a great feature and works well. It also has an electronic crossover for my pair of Infinity IM 1.1 subs. Makes everything seamless. I don't know of any front end piece that does so much so well.

Now, I got the Raidhos and hooked them up to the HK. Sound was very good. I was looking for something that would image like the Gallos but have better image height and more detail. I got this in spades. However, the top end seemed a little etched. I moved the U70 in place, using the pre-outs of the HK990.

Wow!  Image extended all the way from side to side and floor to ceiling. Midrange was so smooth, and the inner detail and depth of image are just remarkable. I don't think I have ever heard a system that commands my attention like this.

However, the Raidho C1 are not that efficient. I lose about 6 db of gain with the U70. With the volume all the way up, it is not very loud, not at all. I will have to go measure with my phone. I don't need to bang the walls, but 6 db more gain would do the trick. It's not a question of power, there is plenty, just a question of maximum volume with the gain all the way up.

Is there any way to get 6db of gain in this system? Next step is to try my Denon AV receiver as a pre-pro. I have done that in the past with the U70 and the results were very good.

I don't really want to revamp my entire front end. and don't know of any piece of two channel gear that will give me the room correction and sub crossovers the way the HK 990 does.

Thanks!

[sfox7076]

You could try to add a tube buffer (well, really a gain stage, not a buffer) or something similar to what Tom Mayer makes as his sound processor.  The Mayer gives you a lot more gain, but I bet one can be made with a 71 tube instead of an 01A and it would give you the gain you want.  It would also a DHT to the front end, which many like.     

[simon wagstaff]

Do you mean something like this?

http://enjoythemusic.com/magazine/equipment/0913/ifi_micro_itube_review.htm

Price is right.

[sfox7076]

Yes.  That can put you 6db higher at the input of the U70.  I have always wanted to try that buffer stage as I have about 50 WE 396As (the same as the 5670s).  Not sure what that will translate to out of the U70.  It is a fine line of over driving/amplifying things. You should also look at what the output impedance is on the pre-outs of your preamp.  should not be an issue, but I always check to make sure that the output isn't too high.  You want 10K or so (lower is fine).  So long as those work, have at it and see what happens.

[simon wagstaff]

Maybe Frank will chime in but I am sure that I am not running out of watts. Shouldn't be overdriving the U70. t also have the U70 crossed over at 80 hz so it would not be getting taxed pushing out bass. I'll be looking to pick one up and try it out. The sound is really quite intoxicating, wonderful match between amp and speakers, just needs a little bit more volume. I could live with it as it is, almost.

[Tom Alverson]

Maybe Frank will chime in but I am sure that I am not running out of watts. Shouldn't be overdriving the U70. t also have the U70 crossed over at 80 hz so it would not be getting taxed pushing out bass. I'll be looking to pick one up and try it out. The sound is really quite intoxicating, wonderful match between amp and speakers, just needs a little bit more volume. I could live with it as it is, almost.

What impedance tap are you using on the amp?  You will get the most power with the tap that best matches the impedance of the speakers.   I would try all the taps and see which one works best with those speakers (regardless of the stated speaker impedance).

[simon wagstaff]

I've tried both the 8 and 16 ohm, no difference in gain.

[Wayner]

Try the 4 ohm tap. The Ultravalve does have a lower gain then Frank's SS or hybrid amps.

If you had an AVA preamp, you wouldn't be having this conversation.......

'ner

[OzarkTom]

Do you mean something like this?

http://enjoythemusic.com/magazine/equipment/0913/ifi_micro_itube_review.htm

Price is right.

 

That is what I use with my Zellatons and DAC Cherry amps. Fantastic!
I love the 3D  circuit.

[simon wagstaff]

Try the 4 ohm tap. The Ultravalve does have a lower gain then Frank's SS or hybrid amps.

Taps will make difference maybe in current, not gain. When Frank makes a dac/pre-amp with room correction and stereo digital crossover I'll be the first to buy, especially if it has the bridge circuit for the u70 built in

Ozark, notice a difference, loss in transparency? I have so much right now a small loss is not a concern.

If you had an AVA preamp, you wouldn't be having this conversation.......

'ner

[Wayner]

The taps will affect your speakers response and behavior and you may see some increased power.

[simon wagstaff]

I need gain, not more power. I have the iFi on order but also wanted to pass along the information I found on this. There is a bit of activity for tube buffer stages, to put in some of that tube magic. Well, I don't need tube magic, I need 6 db of the cleanest gain I can find. There is a little bit of criticism on the iFi for a slight loss of transparency. I poked around and found some information on a solid state buffer from Burson Audio, from about 2006. I sent an e-mail to the company and this was their reply:

Hi John,

I think you will like our new "buffer". : ) It features our new V5 audio opamp technology and it is very transparent.  I can't give away too much details yet but please stay in touched over the next few weeks.  We'll firstly introduce a 3.5mm to stereo version and then introduce the RCA to RCA version which is what you need. : )

Best regards,

Alex



Burson Audio| www.BursonAudio.com | info@bursonaudio.com
Supreme Sound Audio| www.SSAudio.com.au | opamp@bursonaudio.com
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[avahifi]

Simon, our Transcendence 10 RB vacuum tube preamp is what you need.  It sounds great with an Ultravalve amp.  It uses a single 6922/6Dj8 tube per channel with multiple regulated power supplies and has a base price of $899.

Frank

[simon wagstaff]

Hi Frank,

Thanks for taking the time to reply. Hope your recovery is going well. A new preamp doesn't help, I need a DAC and more importantly a sub crossover and at least bass EQ, though I do like the room correction. Complete HT pass through  (including subs) is a requirement as well.

Sorry for posting another company. 6 dB gain is what I need, in between my HK990 and U70.

[simon wagstaff]

Just thought I would post another quick update. iFi tube buffer is in the chain, with 6db gain. Bought on E-bay slightly used for $180.00, perfect.

I remain amazed at the difference in sound between my HK990 power amp section and the U70. The difference was not that significant with my Gallo Ref 3.5 and I left Gallos running with the HK990 power amp and they were capable of providing plenty of goosebumps.

I can barely stand to listen to the Raidhos with the HK990. With the U70 now there is enough gain to make me happy, though I am not getting mega volume, perhaps in the low 80's db as measured by the sound level meter on my phone, Plenty loud, though I wouldn't mind a little more volume, I can live with it. The Raidhos are specified at 89 db efficiency so not too bad.

I have to say though that the midrange transparency, soundstage (both width and especially depth) and high end are now just superb. Perhaps better than anything I have heard, or can remember hearing.

The U70 and the Raidho C1 are a great match.

[simon wagstaff]

Just a little update, in case anybody is interested. I got the iFi Tube. It added usable gain, but still not enough, and introduced too much loss of transparency. Decided to just go for it and picked up a Marantz 7702MK II pre-processor. Plenty of gain, more than enough. The fronts are boosted by 10 db. I reduced gain all around by 3db just to give me some headroom.

Sounds is very good, not the ultimate transparency that might be available, but very, very good. I think my monster interconnect between the pre-pro and U70 is part of the problem. I have a Morrow Audio 2.5 m interconnect on order, on the advice of a friend.

The HK990 is now moved upstairs. I am surprised at it's low gain structure, and how good my Gallos sounded with it, and how bad the Raidhos sounded with it.

The Marantz has independant EQ for my pair of subs. I run the crossover fairly high, 120 hz. Plenty of volume, I am very pleased.

The U70 and Raidho speakers are an excellent match.

[charmerci]

Sounds is very good, not the ultimate transparency that might be available, but very, very good. I think my monster interconnect between the pre-pro and U70 is part of the problem. I have a Morrow Audio 2.5 m interconnect on order, on the advice of a friend.

I have the least expensive Morrow connects. They sounds fine. He says that it needs hundreds of hours of break-in and the sound changes until it finally settles in - could even sound worse. Frankly, I hadn't noticed it. Though they are connected only from my AVA DAC to Odyssey pre-amp.

[simon wagstaff]

I understand that he offers a break in service. I am just going to wing it and see for myself about the break in. Likely fresh out of the box they still won't sound as bad as the Monster.

[charmerci]

I understand that he offers a break in service. I am just going to wing it and see for myself about the break in. Likely fresh out of the box they still won't sound as bad as the Monster.

It's something like 96 and 240 hours, so you still have to "break it in." He recommends 400-500 hours. But as I said, I couldn't hear any diff.

[charmerci]

Simon,


I bought the 1.1's in early Aug. Just recently, I did notice a change in the sound - my only change since I put them in. Everything seemed to "soften" up. It has been around 500 hours of use like Morrow says.


So when you get them, it'd be interesting if you did keep a track of how many hours you listen to them. He recommends not plugging and unplugging them during break-in.


This is the first time I've ever noticed a change in a component, break-in-wise.