[mlundy57]

I'm looking at replacing my power amp and am not sure whether a tube amp would be a good fit and if so which one.

First, a little about the speakers the amp will be driving. They are two part, full range open baffle speakers. The OB mid/tweeter modules are GR-Research Wedgies. The open baffle bass modules each have two 12" GR-Research direct servo drivers powered by Rythmik A370PEQ amps. The crossover between the Wedgies and the bass modules is at 200Hz. The power amp will only be driving the Wedgies which have a sensitivity of 94.5dB. 

In front of the power amp is a DODD Audio Battery Powered Tube Buffer (0 Gain) with an output impedance of 130 Ohms.

My DAC, a Pulse X Infinity, has an output of 2V.

My listening position would be 6-9ft from the speakers in a small or medium room, six feet in a small (11ft x 13ft) room and 9ft in a medium (15ft x 20ft) room. My normal listening level is 72-78dB at the listening position with peaks around 90dB.  Very rarely I might want to listen to something louder but in those recordings the really loud parts tend to be in the bass such as the TELARC recording of the 1812 Overture.

As a point of reference, I am currently driving the Wedgies with the power amp section of a NAD C372 SS stereo amp. I also have two tube amps, an OddWatt PoddWat 5wpc dual monoblock and a Jolida JD-801A. Both of these amps are integrated whereas I am wanting a separate power amp either stereo or monoblocks. I am not adverse to used equipment either.

Whichever amp I get I would like it to be able to do justice to these speakers, buffer and DAC. Now for the questions:

With the bass units being driven by solid state amps is a tube amp for the Wedgies a good idea or should I stick with solid state for both halves of the speakers?

If a tube is a viable option, what would some recommendations be and why?

Thanks for you help

Mike

[Hugh]

Mike,

I think it's a good idea to keep the bass units driven with solid state and with an 94.5 dB, you'd probably need only around 15-20W amp for the rest of the speaker.

There should be plenty of tube amp options available.

Good luck.

Hugh

[I.Greyhound Fan]

Give a listen to the AVA Ultra Valve tube amp.  It sounds great, has had great reviews, puts out a strong 35wpc and it has a 30 day money back guaranty and excellent customer service.  The price was recently lowered as well.

http://www.avahifi.com/index.php?option=com_content&view=article&id=250&Itemid=235

http://www.theabsolutesound.com/articles/audio-by-van-alstine-ultravalve-power-amplifier-salk-sound-songtower-qwt-loudspeaker-tas-204/

http://www.tonepublications.com/review/ava-ultravalve-vacuum-tube-amplifier/

[mlundy57]

Mike,

I think it's a good idea to keep the bass units driven with solid state and with an 94.5 dB, you'd probably need only around 15-20W amp for the rest of the speaker.

There should be plenty of tube amp options available.

Good luck.

Hugh

Hugh,

Thanks for the input.

Just to clarify, the GR-Research/Rythmik Direct-Servo 12" drivers and A370PEQ amps are designed to work together. So the top half, whether tube or solid state, has to blend with the solid state bottom half.

Mike

[Early B.]

What's your budget????

With your setup, I'd try a good tube amp. I would imagine that the good ones aren't cheap, though. If money is a concern, I would think that a decent SS amp (100 watts or less) would be less costly than a really good 25 - 50 watt amp. You should be able to pick one up for less than a grand. For a tube amp, twice that.

I also have your bass modules and I'm waiting on a pair of 98 dB speakers, but I won't consider changing out my 300wpc SS amp for budget reasons.   

I'm assuming you really enjoy your setup and plan to keep it for a while. Go for the best (that means spend more than you can afford).

[Tyson]

Tubes work their magic best in exactly this kind of setup.  Whichever you choose, find out the input impedance of the amp and plug it into the calculator near the bottom of this page:

http://www.carstereo.com/help/Articles.cfm?id=1

After you put in the tube amp's input impedance, play around with capacitor values till you get a rolloff around 150hz.  Then put a capacitor of that value calculated between your preamp and your tube amp.  Since the value of the cap will be very small, you can splurge on something of excellent quality. 

This will remove the bass before it gets to the amp, so the amp will never see a bass load, which means you can use an even lower powered and less expensive amp.  Personally I like EL84 and EL34 based amps, unless you are willing to splurge for an SET.

[G Georgopoulos]

If the zout of the amp is =<1/10th the load impendance i would recommend any amp (tube/solid state),beware of tube amps with high zout they sound s***.

[Captainhemo]

Mike, just curious, have you tried the  Buffer paired with the 801A  yet ?

You will not need much  power to drive the Wedgies to the levels you are looking for.
My speakers are between 91-92 db and my  50wpc  rated JD302CRC was more than enough. II only set my bias current to  .035A and Michael Allen told methe plates  are run at 460V, so that's actually only about 32 wpc, I never had to push the amp in my 18' x 12' room.

As you know, I'm now playing with  much less power , still no  issues

jay

[mlundy57]

Give a listen to the AVA Ultra Valve tube amp.  It sounds great, has had great reviews, puts out a strong 35wpc and it has a 30 day money back guaranty and excellent customer service.  The price was recently lowered as well.

http://www.avahifi.com/index.php?option=com_content&view=article&id=250&Itemid=235

http://www.theabsolutesound.com/articles/audio-by-van-alstine-ultravalve-power-amplifier-salk-sound-songtower-qwt-loudspeaker-tas-204/

http://www.tonepublications.com/review/ava-ultravalve-vacuum-tube-amplifier/

Thanks, I'll check those out. The rel problem is that I have no way of listening to different options before I buy.

What's your budget????

With your setup, I'd try a good tube amp. I would imagine that the good ones aren't cheap, though. If money is a concern, I would think that a decent SS amp (100 watts or less) would be less costly than a really good 25 - 50 watt amp. You should be able to pick one up for less than a grand. For a tube amp, twice that.

I also have your bass modules and I'm waiting on a pair of 98 dB speakers, but I won't consider changing out my 300wpc SS amp for budget reasons.   

I'm assuming you really enjoy your setup and plan to keep it for a while. Go for the best (that means spend more than you can afford).

My budget is flexible. If I just buy another amp it is probably under $1,000 which would necessitate a used amp to get the most for the money. If I sell something, like my 3 x 8" servo H-Frames and HX-300 amps or one of my other amps then I would have more money to put towards a new amp.

The power amp I am currently using to drive the Wedgies puts out 150wpc. This is such overkill for the Wedgies that it is difficult to dial in the listening volume. The quickest tap I can give the remote either raises the volume too high or lowers it too much. I'm looking for a match that would have my normal listening levels driving the amp at about 30% power and max listening levels driving the amp at about 50% power.  I don't want the amp to get close to clipping or to have to operate in the part of it's power band where distortion increases dramatically.

I do really enjoy the setup.

Tubes work their magic best in exactly this kind of setup.  Whichever you choose, find out the input impedance of the amp and plug it into the calculator near the bottom of this page:

http://www.carstereo.com/help/Articles.cfm?id=1

After you put in the tube amp's input impedance, play around with capacitor values till you get a rolloff around 150hz.  Then put a capacitor of that value calculated between your preamp and your tube amp.  Since the value of the cap will be very small, you can splurge on something of excellent quality. 

This will remove the bass before it gets to the amp, so the amp will never see a bass load, which means you can use an even lower powered and less expensive amp.  Personally I like EL84 and EL34 based amps, unless you are willing to splurge for an SET.

Tyson,

Good idea. I already have two of these filters built for two of my amps. One filter is for an input impedance of 50 kOhms and the other for 100 kOhms. The caps in each filter are Sonicap Platinums but the values are set to roll of at 80Hz.

Also, I have read that performance wise, 1 tube watt is equal to 2 SS watts though I do not understand why this would be. It seems that since a watt is a measurement of power 1 should equal 1 and 2 = 2.

If the zout of the amp is =<1/10th the load impendance i would recommend any amp (tube/solid state),beware of tube amps with high zout they sound s***.

Thanks

Mike, just curious, have you tried the  Buffer paired with the 801A  yet ?

You will not need much  power to drive the Wedgies to the levels you are looking for.
My speakers are between 91-92 db and my  50wpc  rated JD302CRC was more than enough. II only set my bias current to  .035A and Michael Allen told methe plates  are run at 460V, so that's actually only about 32 wpc, I never had to push the amp in my 18' x 12' room.

As you know, I'm now playing with  much less power , still no  issues

jay

Jay,

I have not paired the buffer with the 801A. All the inputs on the 801A go through the preamp. It does not have the HT by-pass that the later model 801's have. Also, when I first got it I talked to Michael about getting it upgraded he told me that even with the HT by-pass circuit, the signal still went through the preamp.  This would defeat the purpose of the buffer.

If it could be modified in such a way as to separate the preamp from the power amp so that I could use just the power amp section and not have to go through the preamp, like the NAD C372, I would go that route at least for now while I saved up in case I found something I liked better.

Mike

[I.Greyhound Fan]

You can trial that AVA tube amp for 30 days.

[mlundy57]

You can trial that AVA tube amp for 30 days.

That would work if (1) I had enough money to buy 3 or 4 different amps, compare them then keep the one I liked best and return the others and (2) I didn't feel that would be taking advantage of the companies I didn't choose.  Buying them one at a time, returning each one then rebuying the one I liked best would also be taking advantage. 

If the companies had demo programs where they loaned out an amp (with a refundable deposit to insure the amp's return) with the full understanding up front that it would be returned then I would do that since I wouldn't be taking advantage of anybody.

Mike

[Hugh]

I like your style Mike.

I wish more people would be as honest.

That would work if (1) I had enough money to buy 3 or 4 different amps, compare them then keep the one I liked best and return the others and (2) I didn't feel that would be taking advantage of the companies I didn't choose.  Buying them one at a time, returning each one then rebuying the one I liked best would also be taking advantage. 

If the companies had demo programs where they loaned out an amp (with a refundable deposit to insure the amp's return) with the full understanding up front that it would be returned then I would do that since I wouldn't be taking advantage of anybody.

Mike

[Captainhemo]

Jay,

I have not paired the buffer with the 801A. All the inputs on the 801A go through the preamp. It does not have the HT by-pass that the later model 801's have. Also, when I first got it I talked to Michael about getting it upgraded he told me that even with the HT by-pass circuit, the signal still went through the preamp.  This would defeat the purpose of the buffer.

If it could be modified in such a way as to separate the preamp from the power amp so that I could use just the power amp section and not have to go through the preamp, like the NAD C372, I would go that route at least for now while I saved up in case I found something I liked better.

Mike

Mike, contact Bill Baker at response Audio,  I know he has converted a few 302/502 Jolidas to be strictly  amps, not  sure if has done any 801's. Might be worth checking into. 

jay

[JonnyFive]

If the companies had demo programs where they loaned out an amp (with a refundable deposit to insure the amp's return) with the full understanding up front that it would be returned then I would do that since I wouldn't be taking advantage of anybody.

Reminds me of that quotation in Clear and Present Danger with Harrison Ford:
 
-We'd like to rent the helicopter.
-It's not for rent, but you can buy it. 
-How much is that?
-Two million dollars.
-Ok, my pilot and I will just need to take it for a test drive.
-Sure I'll just need a deposit.
-How much is that?
-Two million dollars.

If an amp is $2k and you put a $500 deposit on it, what motivation is there to return it?  Many of them would be stolen with little the vendor can do it about it.  You can try them with a deposit, it's just the deposit is the same as the selling price.  IMO, float them on some credit cards, return the ones you don't want, and pay the month of interest for the peace of mind you'll have from making the right choice.

[sunnydaze]

Buy used.  Listen.  If you like it, great.  If not, sell.
Repeat.

Buy smart and you will lose little, if anything.  Just a lil time and effort on the buy and sell.
You'll have fun along the way, and will be getting stuff that is "better" than your new gear budget allows.  Especially in the current slow environment in which I see some incredible used deals. 

No guarantees in audio, but you get to try it in your own setup, at your own leisure.  Some upfront research will narrow the field and better your odds at stumbling upon a synergistic gem at a great price.

I've been doing exactly this for over 20 years.  Not only has it allowed me to sample a greater volume of gear vs buying new,  it has allowed me to play in a pricier sandbox.  And I can do so without losing my shirt on the resell.  When one buys new and pays near list, it's hard to shed a loser and incur the 30 to 50% loss!!   Buying used means one is less committed to the gear for financial reasons, and it's easier to pivot into good sound.

[mlundy57]

Reminds me of that quotation in Clear and Present Danger with Harrison Ford:
 
-We'd like to rent the helicopter.
-It's not for rent, but you can buy it. 
-How much is that?
-Two million dollars.
-Ok, my pilot and I will just need to take it for a test drive.
-Sure I'll just need a deposit.
-How much is that?
-Two million dollars.

If an amp is $2k and you put a $500 deposit on it, what motivation is there to return it?  Many of them would be stolen with little the vendor can do it about it.  You can try them with a deposit, it's just the deposit is the same as the selling price.  IMO, float them on some credit cards, return the ones you don't want, and pay the month of interest for the peace of mind you'll have from making the right choice.

Never said how much the deposit would be. I would expect it to be like the loaner tools from AutoZone. The deposit is the cost of the tool, in this case the cost of the amp, when you return the tool you get your deposit back. 

Floating the expense on a credit card would still violate my rule #2 above. To me it is one thing to do that with a large publicly owned company that expects such practices, builds it into their marketing plans and has pockets deep enough to absorb the expense (I have actually had a clothing manufacture tell me to do that with their products when buying mail order) but quite another when dealing with a small privately owned company that doesn't have deep pockets and are offering the return policy as a guarantee of their workmanship and not as a marketing strategy. When an item is returned like that it can't be sold to somebody else as a new unit. It has to be marked down as a demo unit or sold as B stock, especially if it was scratched so there goes the profit margin.  As someone who operates a single owner LLC myself, I know how tight things can be.

[mlundy57]

Buy used.  Listen.  If you like it, great.  If not, sell.
Repeat.

Buy smart and you will lose little, if anything.  Just a lil time and effort on the buy and sell.
You'll have fun along the way, and will be getting stuff that is "better" than your new gear budget allows.  Especially in the current slow environment in which I see some incredible used deals. 

No guarantees in audio, but you get to try it in your own setup, at your own leisure.  Some upfront research will narrow the field and better your odds at stumbling upon a synergistic gem at a great price.

I've been doing exactly this for over 20 years.  Not only has it allowed me to sample a greater volume of gear vs buying new,  it has allowed me to play in a pricier sandbox.  And I can do so without losing my shirt on the resell.  When one buys new and pays near list, it's hard to shed a loser and incur the 30 to 50% loss!!   Buying used means one is less committed to the gear for financial reasons, and it's easier to pivot into good sound.

That's a viable idea. I wonder how close the performance of an older model is to that of the current offering but it would allow me to buy amps I could never afford new.

And upfront research is what this thread is all about 
 

[tull skull]

I am curious more than anything else but have you tried the oddwatt in the setup? Is it because you really want to keep the Dodd in your system? I would love to know your thoughts on the oddwatt as I was thinking of possibly looking into their preamp.

It would seem to me that one of your integrateds would be the path of least resistance unless you feel they are not up to the task or are set on including the Dodd.

I would also agree to look for used. Try to have fun! Amps that came to mind would be a First Watt or one of Steve Deckert's amps. The First Watts are over $1k though.

You are so good with projects though, why not consider one of the tubelab amp kits? I think you could come up with something pretty spectacular!

[sebrof]

IMO, float them on some credit cards, return the ones you don't want, and pay the month of interest for the peace of mind you'll have from making the right choice.

Just my opinion...
I suppose you could justify doing that if you're buying from Best Buy or a big chain where returns are factored in as the cost of doing business.
But I certainly would not suggest doing this with the guys mentioned so far in this thread; they make and sell small quantities. I'm sure each return hurts, and their policy is assuming the buyer has done his homework and has the intention of keeping the unit. Buying 3 and returning 2 is not cool, IMO.

[sebrof]

Double post