Flea powered (sub10w) Class A Solid State Power amplifier required. But do they exist?

[cjfrbw]

First Watt SIT-1 or SIT-2 with tube buffer/preamp (or not to taste). 10 watts/ch, don't think they get that hot. Don't think I have heard anybody including died in the wool big horn guys who haven't loved them. They also like a lot of the other First Watt offerings, too.

Used market only these days, but they do crop up from time to time.

The 5-8 watt ACA amps from Pass DIY are single ended, cheap by high end standards, and worth a stab. Nelson Pass says he listens to these when he is noodling at his work bench. There has been a lot of hate from the objectivists due to measurements, but end users love them. Clones are routinely available on ebay.

 

[Audiophile Bill]

What are you doing below 70hz?

Twin DB1’s. But not 70hz. In room mine were measuring flat to c.45hz, so the DB.1’s are rolled off at 45hz with a 12db slope...[/QUOTE]

Which driver do you have in your mid bass? That seems to be well beyond physics fo the size of that horn. It is the Thunderbolt mid bass right?

Anyway I digress. Personally I would chat to Kevin but I think he’ll point you in the direction of a 300b amp. Are you sure no SET amps are suitable - it would be a natural pairing. What SETs did you try?

 

[Thetiminator]

I’ve tried a pile of valve amps. Sets, otl’s, the lot...from £2k to £20k. I didn’t like any of them. Every time I switched back to my Class D’s there was a sigh of relief. They were clearer, more detailed, quieter, had better attack and massively better bass than every valve amp I tried. To be fair some of the sets did have a touch better midrange but the cons far out weighed the pros. So I’m done with valves and wouldn’t entertain them.

Kevin recommends the Sugden IA4 for SS, just bypassing the pre section and use it as a power amp. But at 33w per channel it’s way more than I need. Hence the question if there was something on the market with just a few watts.

 

[Thetiminator]

Sorry Bill I missed part of your post. Well they weren’t flat to 45hz, more like 52hz but they were only down around 6db from 52hz to 45hz which I don’t mind as I prefer a tighter, lighter, faster sound in the bass.

The drivers are Vitavox compression drivers (AK157 IIRC) and the horn is ‘inspired’ by the Thunderbolt. Paul Messenger measured them at -5db at 45hz, which is more or less exactly what they measured in my room...

 

[Audiophile Bill]

Sorry Bill I missed part of your post. Well they weren’t flat to 45hz, more like 52hz but they were only down around 6db from 52hz to 45hz which I don’t mind as I prefer a tighter, lighter, faster sound in the bass.

The drivers are Vitavox compression drivers (AK157 IIRC) and the horn is ‘inspired’ by the Thunderbolt. Paul Messenger measured them at -5db at 45hz, which is more or less exactly what they measured in my room...[/QUOTE

Nice. The Ak157 is a 15” cone based driver not a compression driver. You should have the S2 in your radial horn though, which is a compression driver of course

 

[Thetiminator]

Yes of course doh. I think mine has the S5 driver as it’s the Statesman spec....

 

[Audiophile Bill]

Yes of course doh. I think mine has the S5 driver as it’s the Statesman spec....

Either way sounds like a really cool system. What sources do you use? You are UK based - what county?

Best.

 

[Thetiminator]

Either way sounds like a really cool system. What sources do you use? You are UK based - what county?

Best.

Custom made source with all the usual power supplies and Uptone trappings...Boulder 1012 pre/dac (the best piece of HiFi I’ve ever had) and at the minute Temple Audio monos with the Supercharger power supplies, those little buggers are incredible for the money...seen off some pretty exotic stuff...

I’m in N. Ireland....for my sins....

 

[christoph]

Living Voice Air Partners

Nice
I do own a pair of Air Scouts

 

[Thetiminator]

Nice
I do own a pair of Air Scouts

We’re in a very small club then! Did you do much in the way of amp swapping or just using SETs?

 

[Alrainbow]

Hi everyone
I use 106db horns so realistically I’m only ever using a watt or so. I’ve tried many valve amps but didn’t really get on with any of them SQ wise (plus my system is running 12-14 hours per day).

At present I’m using some little Class D things as a stop gap which do sound great, but the ultra high damping factor can make the system sound a touch lean with some material. I would just like a little more meat on the bones, especially in the LF’s.

So ideally I’d like a really low powered SS Class A amp with only a few watts to avoid the heat etc. But I haven’t come across any. Is there such a thing and does anyone have any first hand experience?

Best small watt Class A ever built is the ML2 , vastly superior to anything first watt ..


https://www.marklev.com/2013/04/ml-2-monophonic-class-power-amplifier.html?m=1

 

[jeff1225]

I used the First Watt J2, F3 and the SIT monos on my 106 db Avantgarde. Zero noise and excellent sound.

 

[Alrainbow]

I used the First Watt J2, F3 and the SIT monos on my 106 db Avantgarde. Zero noise and excellent sound.

The first watt amps as good as they work on your horns , dont have the flow and drive like an ML2 , this would not be noticeable in your setup , because you are not using your First watt to drive or provide the bass .

In a full range system as the OP , the ML2 will fill out the bass as he is looking for with plenty tone and flow ..


My 2c

 

[jeff1225]

The first watt amps as good as they work on your horns , dont have the flow and drive like an ML2 , this would not be noticeable in your setup , because you are not using your First watt to drive or provide the bass .

In a full range system as the OP , the ML2 will fill out the bass as he is looking for with plenty tone and flow ..


My 2c

I've not heard the ML2 so I cannot comment. What First Watt amps have you tried? The models vary greatly.

 

[BruceD]

I've not heard the ML2 so I cannot comment. What First Watt amps have you tried? The models vary greatly.

I have in an HQD setup and can verify the ML2's remain nearly unequaled today in sonic presentation--

You need to hear them driving Quad 57's absolute bliss !--possibly rated in one of the top 3 Audio Amplification products of the last 50 years.

IMHO

BruceD

 

[christoph]

The first watt amps as good as they work on your horns , dont have the flow and drive like an ML2 , this would not be noticeable in your setup , because you are not using your First watt to drive or provide the bass .

In a full range system as the OP , the ML2 will fill out the bass as he is looking for with plenty tone and flow ..


My 2c

I think I read somewhere that the ML2 is a ticking timebomb because some essential parts (output transistors?) are not available anymore.
Is this fact or myth?

 

[Alrainbow]

I think I read somewhere that the ML2 is a ticking timebomb because some essential parts (output transistors?) are not available anymore.
Is this fact or myth?

Not sure if the original outputs are available but there are surly suitable replacements ( 2N5884/6 for eg ) and the ML2 is a very robust design if serviced accordingly..

BTW , John Curl the original designer is still with us ...

 

[Hear Here]

Hi everyone
I use 106db horns so realistically I’m only ever using a watt or so. I’ve tried many valve amps but didn’t really get on with any of them SQ wise (plus my system is running 12-14 hours per day).

At present I’m using some little Class D things as a stop gap which do sound great, but the ultra high damping factor can make the system sound a touch lean with some material. I would just like a little more meat on the bones, especially in the LF’s.

So ideally I’d like a really low powered SS Class A amp with only a few watts to avoid the heat etc. But I haven’t come across any. Is there such a thing and does anyone have any first hand experience?

I've arrived at this thread rather late, but I'm in a similar situation to you, but I'm viewing it in a rather different way.

My speakers are 104 dB with new ones on order of 107 dB. I used to use "flea-power" SETs of between 5 (PX25) and 28 (845) watts but made a decision to move to SS a couple of years ago. Initially I was looking for low power amps, mainly Class A, but I was disappointed with the sound, so I looked at others irrespective of nominal power.

Ideally you want low gain or better still adjustable gain but these are rare features. In the end I've chosen a Class D of 150 watts, but I can set (using the app) an upper Volume limit of say -20 dB. Hopefully this will prevent possible damage to the speakers if I carelessly place a book on the remote control volume up button!

I can only suggest that you worry less about the nominal output of your amp and concentrate on its sound through your speakers. I did try a 400 watt amp (bought to power electrostatics), but its S/N ratio was poor. Other amps of up to 200 watts have been absolutely no problem at all.

If you really want a low powered non-D amp, look at Bakoon 13r (25 watts). Or a bit more powerful, the dinkly little AGD Audion monos. They may look like SETs but in fact thay are Class D using Galium Nitride chips rather than silicon. They are both on my Must Try list. Oh yes another - Valvet S2se (12 watts).

You mentioned Sugden IA4. Well I had the Sugden FPA-4 which appears to be the power amp version of the IA4 from the same Pasterclass Series. Frankly it was rather dull and lacking in any excitement factor. The other Class A I had (still have) is the much better Accuphase A-36. This is an exceptionally refined amp - complete with gain switch for up to -12 dB attenuation in output. Peter

 

[Thetiminator]

I've arrived at this thread rather late, but I'm in a similar situation to you, but I'm viewing it in a rather different way.

My speakers are 104 dB with new ones on order of 107 dB. I used to use "flea-power" SETs of between 5 (PX25) and 28 (845) watts but made a decision to move to SS a couple of years ago. Initially I was looking for low power amps, mainly Class A, but I was disappointed with the sound, so I looked at others irrespective of nominal power.

Ideally you want low gain or better still adjustable gain but these are rare features. In the end I've chosen a Class D of 150 watts, but I can set (using the app) an upper Volume limit of say -20 dB. Hopefully this will prevent possible damage to the speakers if I carelessly place a book on the remote control volume up button!

I can only suggest that you worry less about the nominal output of your amp and concentrate on its sound through your speakers. I did try a 400 watt amp (bought to power electrostatics), but its S/N ratio was poor. Other amps of up to 200 watts have been absolutely no problem at all.

If you really want a low powered non-D amp, look at Bakoon 13r (25 watts). Or a bit more powerful, the dinkly little AGD Audion monos. They may look like SETs but in fact thay are Class D using Galium Nitride chips rather than silicon. They are both on my Must Try list. Oh yes another - Valvet S2se (12 watts).

You mentioned Sugden IA4. Well I had the Sugden FPA-4 which appears to be the power amp version of the IA4 from the same Pasterclass Series. Frankly it was rather dull and lacking in any excitement factor. The other Class A I had (still have) is the much better Accuphase A-36. This is an exceptionally refined amp - complete with gain switch for up to -12 dB attenuation in output. Peter

Thanks Peter that’s very helpful, particularly re Sugden. There’s more and more using a Class D with horns nowadays....for some reason they just seem to work...the excellent S/N/R’s is always a good start....

 

[Atmasphere]

I’ve tried a pile of valve amps. Sets, otl’s, the lot...from £2k to £20k. I didn’t like any of them. Every time I switched back to my Class D’s there was a sigh of relief. They were clearer, more detailed, quieter, had better attack and massively better bass than every valve amp I tried. To be fair some of the sets did have a touch better midrange but the cons far out weighed the pros. So I’m done with valves and wouldn’t entertain them.

We make a little OTL, the S-30, that might do the job. It has speed and bandwidth, being full power from 2Hz to 100KHz. You can run it with less than the full complement of power tubes as well. These days we've been equipping them with a new rectifier to prevent buzz on really high efficiency speakers like the AvantGarde and such.

I've been playing around a lot with some smaller vintage solid state amps that at first blush seem well out of their league for something like this. But I've found that they can be tweaked and I've gotten several of them to sound quite nice. So- go ahead and laugh because this does sound funny, but they were made by Radio Shack as low powered integreted amps, mostly in the 1970s. The ones I think are worth a look all employ a similar 4-transistor circuit. It operates single-ended right up to the output transistors themselves. The output is capacitively coupled. The circuit generates a fair amount of 2nd harmonic and so as long as you don't push them hard, they sound smooth like a tube amp. The best of them is the Realistic SA-175C. The SA100C is a second best (although quite rare; the 'C' bit is important), followed by the SA-101. These amps are simple and cheap, but I've used them with fairly high efficiency loudspeakers and if they are properly refurbished, they are quiet. Bandwidth on the top is is good- the power amp sections easily go well past 100KHz. The bottom end isn't so good; they are bandwidth limited on purpose. But if you are using subs that might be of no consequence. Radio Shack's smallest amp, the SA-10, used a similar circuit (unless you get one of the later ones- it was in production for over 20 years) and only makes about 1 watt (and has a surprising following with 'DIY/midfi collectors'??). All of these are integrated amps; the loudness contour has to be defeated and if used as a power amp some other mods done to provide a preamp input, but they are easy to work on and dirt cheap. I use a refurbished SA-175 in my bedroom system, driving some high efficency full range speakers supplemented by a sub. As long as I never drive the amp anywhere near full power (its plenty loud with no need for that); it is smooth, detailed and 3D, does not seem 'slow' and lacks the typical solid state glare that causes tubes to still be in production.