SS preamp w/ tube amp

awhite1159 · 29th August 2007, 10:38 AM

I currently have a pair of back loaded horns with the Fostex FE208 Sigma drivers being driven by an Adcom GFA5802. The preamp is also an Adcom GFP750. The preamp is/was thier flagship product. I recently purchased a Fountek Altitude 3500 tube amp and it appears that it can be used without a preamp. Would there be any benefit to using my Adcom preamp? Is it advisable not to since it would introduce solid state into the mix? I am new to Tube amps, have experience with vacuum tubes from my Amateur radio days (RF), and eventually will build my own. I purchased this unit just to get my feet wet. I would greatly appreciate any advice.

arnoldc · 29th August 2007, 10:52 AM

My advice to you is to try both ways, and decide what would be best for you. And please let us know what worked best.

ps.

Saw the specs of your 3500, it has 350mV input sensitivity. You might overload it with another stage in front of it, but I'm not sure.

ashok · 29th August 2007, 10:55 AM

Like human beings , each one is unique .
Combination of systems are unique and you really need to try them out the way you want to determine how they will sound in your set up.
A tube circuit anywhere in the chain will leave its footprint . Whether that will be audible as 'tube' sound depends a lot on the other circuitry. Best way is to try it out.
Let us know how your ss preamp sounds with the tube power amp. If you have a super clean ss preamp the sound will be dominated by the behaviour of your tube power amp.

We are waiting.......................

awhite1159 · 29th August 2007, 11:14 AM

I will. Thanks for the replies. When I purchased the ADCOM preamp I was told that it was an extremely good preamp. It also has passive mode which I will probably use when I introduce it into the circuit. I'm not sure if this was just hype in the reviews and from the salesman but I was told this preamp is one of the highest quality sounds but without all the bells and whistles. Very simple front panel; Volume, balance, reverse/stereo/mono, on/off, active/passive. I was also led to believe that this SS preamp was more similiar to tube because of its use of MOSFET. Now as far as the Fountek amp, I was told by Madisound it is great sounding and it also had a good review on Audio Asylum from a gentleman named Kloss.

Thanks.

awhite1159 · 29th August 2007, 11:34 AM

I know this is a tube forum but here is the BLH (2nd of 2) that I have designed and built for use with this amp. With the FE208 Sigma they sound wonderful and highly efficient.

awhite1159 · 1st September 2007, 10:05 AM

Well,

I received my Tube amp mentioned above yesterday. I was skeptical having used SS all my life as to how much better a Vacuum Tube amp could sound. I am absolutely awe-struck with what I am hearing! This amp and my hieff horns are a match made in heaven. I removed the series resistance from the horns since I don't need it anymore. The sound is so much more life-like! I am converted forever! Can this amp sound any better? Does it need to break in? It came with Electrovoice tubes. Is it advisable to upgrade them? One of the biggest surprises to me is that the bass seems to be more sustained, more fluent and maybe it is acoustical hallucination but the horns seem to go lower in bass response. I am very happy. My next one is going to be a DIY. I'm hoping the WAF is less of a factor when building amps vs. Big ol' horns...

arnoldc · 1st September 2007, 02:52 PM

I suggest you enjoy it first, be acquainted with the sound. Don't worry about the stock tubes first.

Enjoy.

ray_moth · 1st September 2007, 11:21 PM

As ArnoldC says, enjoy it first. Unless it's a 'pre-loved' unit, there will probably be some change as it beds in (and as you get used to it). Tube rolling is fine if you already have a stock of tubes to try, but it can be a waste of money if you have to buy tubes just for that purpose.

As to whether it will sound better or worse with your SS preamp, you're now in a good position to find out. I wouldn't worry about overloading the amp, since your preamp has its own volume control to prevent that. A lot of music sources that we use these days, such as FM tuners and CD players, already contain SS stages anyway. I believe it's the power amp that gives most of the character to the sound. However, the simpler the signal path the better, so the best preamp is no preamp if you don't need one!

awhite1159 · 2nd September 2007, 01:36 AM

Thanks for the help. Since it has four inputs and the signal sources seem to work fine I agree to keep it simple. The reason I was originally going to put the preamp in the circuit was because of my concern that I would still need my subwoofers for 20-45Hz and it would have provided a second output for the sub amp. I really appreciate the help. There is another forum on a separate system where no one replied to me when I posted the question and someone even went out of thier way to leave me a disparaging, insulting email. I don't think it was that Romy guy. I know this is probably a relatively inexpensive amp and probably not the highest quality sound but I find it's sound to be better than any amp I have ever owned. I'm sure the marriage to the hieff horn helps too. I'll be listening to it while I build the TubeLab SimpleSE.

awhite1159 · 2nd September 2007, 10:26 AM

One thing I forgot to add is that I have experience with vacuum tube builds but only in the RF category. I was into amateur radio when I was younger and had a Novice class license. The unit I used only being allowed to use CW was a Johnson trans with an 807. My father being the pack rat he is kept all my stuff and being into the hobby himself has a ton of old radios, transmitters, and boxes full of old tubes. Tubes have not changed significantly since then have they? Maybe if I do want to roll out the tubes later I can find some good fits?

29th August 2007, 10:38 AM	#1
awhite1159 diyAudio Member Join Date: Jul 2007	SS preamp w/ tube amp I currently have a pair of back loaded horns with the Fostex FE208 Sigma drivers being driven by an Adcom GFA5802. The preamp is also an Adcom GFP750. The preamp is/was thier flagship product. I recently purchased a Fountek Altitude 3500 tube amp and it appears that it can be used without a preamp. Would there be any benefit to using my Adcom preamp? Is it advisable not to since it would introduce solid state into the mix? I am new to Tube amps, have experience with vacuum tubes from my Amateur radio days (RF), and eventually will build my own. I purchased this unit just to get my feet wet. I would greatly appreciate any advice.

29th August 2007, 10:55 AM	#3
ashok diyAudio Member Join Date: Jun 2002 Location: 3RS	Like human beings , each one is unique . Combination of systems are unique and you really need to try them out the way you want to determine how they will sound in your set up. A tube circuit anywhere in the chain will leave its footprint . Whether that will be audible as 'tube' sound depends a lot on the other circuitry. Best way is to try it out. Let us know how your ss preamp sounds with the tube power amp. If you have a super clean ss preamp the sound will be dominated by the behaviour of your tube power amp. We are waiting....................... __________________ AM

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29th August 2007, 10:52 AM	#2
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	My advice to you is to try both ways, and decide what would be best for you. And please let us know what worked best. ps. Saw the specs of your 3500, it has 350mV input sensitivity. You might overload it with another stage in front of it, but I'm not sure.

29th August 2007, 11:14 AM	#4
awhite1159 diyAudio Member Join Date: Jul 2007	I will. Thanks for the replies. When I purchased the ADCOM preamp I was told that it was an extremely good preamp. It also has passive mode which I will probably use when I introduce it into the circuit. I'm not sure if this was just hype in the reviews and from the salesman but I was told this preamp is one of the highest quality sounds but without all the bells and whistles. Very simple front panel; Volume, balance, reverse/stereo/mono, on/off, active/passive. I was also led to believe that this SS preamp was more similiar to tube because of its use of MOSFET. Now as far as the Fountek amp, I was told by Madisound it is great sounding and it also had a good review on Audio Asylum from a gentleman named Kloss. Thanks.

1st September 2007, 10:05 AM	#6
awhite1159 diyAudio Member Join Date: Jul 2007	Well, I received my Tube amp mentioned above yesterday. I was skeptical having used SS all my life as to how much better a Vacuum Tube amp could sound. I am absolutely awe-struck with what I am hearing! This amp and my hieff horns are a match made in heaven. I removed the series resistance from the horns since I don't need it anymore. The sound is so much more life-like! I am converted forever! Can this amp sound any better? Does it need to break in? It came with Electrovoice tubes. Is it advisable to upgrade them? One of the biggest surprises to me is that the bass seems to be more sustained, more fluent and maybe it is acoustical hallucination but the horns seem to go lower in bass response. I am very happy. My next one is going to be a DIY. I'm hoping the WAF is less of a factor when building amps vs. Big ol' horns...

1st September 2007, 02:52 PM	#7
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	I suggest you enjoy it first, be acquainted with the sound. Don't worry about the stock tubes first. Enjoy.

1st September 2007, 11:21 PM	#8
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	As ArnoldC says, enjoy it first. Unless it's a 'pre-loved' unit, there will probably be some change as it beds in (and as you get used to it). Tube rolling is fine if you already have a stock of tubes to try, but it can be a waste of money if you have to buy tubes just for that purpose. As to whether it will sound better or worse with your SS preamp, you're now in a good position to find out. I wouldn't worry about overloading the amp, since your preamp has its own volume control to prevent that. A lot of music sources that we use these days, such as FM tuners and CD players, already contain SS stages anyway. I believe it's the power amp that gives most of the character to the sound. However, the simpler the signal path the better, so the best preamp is no preamp if you don't need one!

2nd September 2007, 01:36 AM	#9
awhite1159 diyAudio Member Join Date: Jul 2007	Thanks for the help. Since it has four inputs and the signal sources seem to work fine I agree to keep it simple. The reason I was originally going to put the preamp in the circuit was because of my concern that I would still need my subwoofers for 20-45Hz and it would have provided a second output for the sub amp. I really appreciate the help. There is another forum on a separate system where no one replied to me when I posted the question and someone even went out of thier way to leave me a disparaging, insulting email. I don't think it was that Romy guy. I know this is probably a relatively inexpensive amp and probably not the highest quality sound but I find it's sound to be better than any amp I have ever owned. I'm sure the marriage to the hieff horn helps too. I'll be listening to it while I build the TubeLab SimpleSE.

2nd September 2007, 10:26 AM	#10
awhite1159 diyAudio Member Join Date: Jul 2007	One thing I forgot to add is that I have experience with vacuum tube builds but only in the RF category. I was into amateur radio when I was younger and had a Novice class license. The unit I used only being allowed to use CW was a Johnson trans with an 807. My father being the pack rat he is kept all my stuff and being into the hobby himself has a ton of old radios, transmitters, and boxes full of old tubes. Tubes have not changed significantly since then have they? Maybe if I do want to roll out the tubes later I can find some good fits?

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