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retro soulman
12-31-2018, 01:23 AM
Hello! Happy holidays to all of you, with health and hapiness
Well im very happy with the sound of my JBL system, but i want to make a big change on the amp that drives my hf horns and tweeters. My system is biamped with a 2 way bss crossover and i use a passive one just for the tweeters , the speakers are the jbl 4530 loaded with jbl k140, on mid horns i got the 2445 on 2390 lenses and a 2402 tweeter. The amp for the lows is a crown psa2 and for the mid & highs a Sound Valves vta70. The sound of the system is very warm and detailed with nice soundstage . Im very pleased but i want to remove the tube amp from the system. I just want to be full solid state. Even if i found a amp with the same sound with the sound valves but in solid state ill be happy! So, any suggestions for an amp with that warm but detailed sound that will not change the character of my speakers much? Class a? Mosfet? Any brands? I see that in japan accuphase is popular with horns but i think they are a little bright for horns, same with bryston. Small krell? ML? I would also like to be close to the rest age of my system. Best regards!!

Mr. Widget
12-31-2018, 12:35 PM
Hello! Happy holidays to all of you, with health and hapiness
Well im very happy with the sound of my JBL system, but i want to make a big change on the amp that drives my hf horns and tweeters. My system is biamped with a 2 way bss crossover and i use a passive one just for the tweeters , the speakers are the jbl 4530 loaded with jbl k140, on mid horns i got the 2445 on 2390 lenses and a 2402 tweeter. The amp for the lows is a crown psa2 and for the mid & highs a Sound Valves vta70. The sound of the system is very warm and detailed with nice soundstage . Im very pleased but i want to remove the tube amp from the system. I just want to be full solid state. Even if i found a amp with the same sound with the sound valves but in solid state ill be happy! So, any suggestions for an amp with that warm but detailed sound that will not change the character of my speakers much? Class a? Mosfet? Any brands? I see that in japan accuphase is popular with horns but i think they are a little bright for horns, same with bryston. Small krell? ML? I would also like to be close to the rest age of my system. Best regards!!I would go with a small Class A amp, vintage or new. The Bedini 25watt stereo amp is excellent and affordable if you can find one. There are numerous others as well.


Widget

Mitchco
12-31-2018, 04:28 PM
Happy New Year!
If you are handy with a soldering iron, Nelson Pass Class A single ended mosfet design (https://diyaudiostore.com/products/amp-camp-amp-kit?variant=7072933085218) kit has a wonderful tube like sound and works well with compression drivers.

I use these on JBL 4722's 2453h-SL CD (https://www.computeraudiophile.com/ca/ca-academy/audiolense-digital-loudspeaker-and-room-correction-software-walkthrough-r682/) and sound smooth, but detailed. They are a good match for compression drivers due to their low voltage gain, so you don't need to pad them down, just a protection cap for turn off thump. The stock Meanwell power supply is low noise - I have to put my ear near the mouth of the waveguide to hear a faint hiss.

Good luck with whatever you choose!

retro soulman
12-31-2018, 10:23 PM
Yeap 60 watts are more than enough for me ! What i want is good sound and safe operation. My 35wpc of my tube watts are enough but i wouldnt say no ti 60wpc !

HCSGuy
01-01-2019, 09:29 PM
Happy New Year!
If you are handy with a soldering iron, Nelson Pass Class A single ended mosfet design (https://diyaudiostore.com/products/amp-camp-amp-kit?variant=7072933085218) kit has a wonderful tube like sound and works well with compression drivers.

I use these on JBL 4722's 2453h-SL CD (https://www.computeraudiophile.com/ca/ca-academy/audiolense-digital-loudspeaker-and-room-correction-software-walkthrough-r682/) and sound smooth, but detailed. They are a good match for compression drivers due to their low voltage gain, so you don't need to pad them down, just a protection cap for turn off thump. The stock Meanwell power supply is low noise - I have to put my ear near the mouth of the waveguide to hear a faint hiss.

Good luck with whatever you choose!

Thanks for the motivation! I have a pair of the Amp Camp kits that have been sitting around for some months, unbuilt - I'm remodeling my music room, but am hopeful that I'll have time to fit in an amp build between finishing the remodel and Spring chores starting - glad to hear you like them:)

RMC
01-03-2019, 03:28 PM
Hi Retro Soulman,

Best wishes for the new year to yourself also.

I'm a small size amp lover for a number of reasons, one being for the flexibility they allow me to have.

There's not a whole lot of small Pro amps left in the new gear market, but here's a few suggestions to look at. I tend to prefer Pro ones over more "exotic" brands like Krell, Levinson, Pass, etc. for practical reasons.

Note that Bryston isn't mentioned here by me because Earl has already commented elsewhere about a couple of issues with these, also with the use of HF drivers...

MOSFET? Sure why not. The only one I know of that still exists new, plus that I will possibly purchase in the new year, is the Rolls RA 200 studio amp. Don't know if available in Europe, you would need to check with them (rolls.com). They have other smaller ones but not MOSFET as I recall. I remember in the old days when these were more popular, MOSFET amps were said to overload more gracefully than conventional ones. In case you want to read two small paragraphs from someone who knows about MOSFET circuit design and its advantages, let me know I'll post them with reference (and its not even from Rolls).

Crest Audio PA 150 or IPS 150 are other options, though they might have been discontinued recently. However, there could still be some units available in the local distribution system. Another one to check.

Ashly SRA series models 2075 (2 channels) or 4075 (4 channels). I purchased recently two 2150 from that same series.

All the above are convection cooled, so no fan noise, and use one rack space, except for Rolls RA 200 at two rack spaces. Best regards,

Richard

retro soulman
01-03-2019, 08:35 PM
Hi Retro Soulman,

Best wishes for the new year to yourself also.

I'm a small size amp lover for a number of reasons, one being for the flexibility they allow me to have.

There's not a whole lot of small Pro amps left in the new gear market, but here's a few suggestions to look at. I tend to prefer Pro ones over more "exotic" brands like Krell, Levinson, Pass, etc. for practical reasons.

Note that Bryston isn't mentioned here by me because Earl has already commented elsewhere about a couple of issues with these, also with the use of HF drivers...

MOSFET? Sure why not. The only one I know of that still exists new, plus that I will possibly purchase in the new year, is the Rolls RA 200 studio amp. Don't know if available in Europe, you would need to check with them (rolls.com). They have other smaller ones but not MOSFET as I recall. I remember in the old days when these were more popular, MOSFET amps were said to overload more gracefully than conventional ones. In case you want to read two small paragraphs from someone who knows about MOSFET circuit design and its advantages, let me know I'll post them with reference (and its not even from Rolls).

Crest Audio PA 150 or IPS 150 are other options, though they might have been discontinued recently. However, there could still be some units available in the local distribution system. Another one to check.

Ashly SRA series models 2075 (2 channels) or 4075 (4 channels). I purchased recently two 2150 from that same series.

All the above are convection cooled, so no fan noise, and use one rack space, except for Rolls RA 200 at two rack spaces. Best regards,

Richard

I dont know if the "pro" solution is a good idea to drive the horns because thats where is all the resolution and character of the speaker. I had try a small bgw 100b, good mids but not good highs, also a small bryston 2b, good sound but no character (and some hiss ). I believe a class a amp will be the closest thing in sound to my tube power amp!

Ian Mackenzie
01-04-2019, 04:36 AM
I would have a look over on Diyaudio Store. If you can’t solder get a friend to help.

Aside from the Amp Camp design the Aleph 30 is a nice diy option. This is a very smooth and clean SE class A mosfet amp.

Nelson Pass has a number of impressive amps under his First Watt brand that would be excellent.

I suggest you send him an email. He always replies and is very helpful.

pos
01-04-2019, 06:59 AM
I am using the THX AAA 789 on my D2430K, and it does wonders! :bouncy:

bubbleboy76
01-08-2019, 12:54 AM
I am using the THX AAA 789 on my 476Mg, and it does wonders! :bouncy:

BMWCCA
01-08-2019, 05:14 AM
I dont know if the "pro" solution is a good idea to drive the horns because thats where is all the resolution and character of the speaker. I had try a small bgw 100b, good mids but not good highs, also a small bryston 2b, good sound but no character (and some hiss ). I believe a class a amp will be the closest thing in sound to my tube power amp!
Since you're already a happy Crown user, why not try a D75A or D45 for the high-end? They are very clean, easily available at affordable prices around the world, and I think they sound great. Just a suggestion. I like them so much I have about three of each . . . just because! I even carry one and an iPod in the car in case I run across speakers that need testing.

jbl4ever
01-10-2019, 12:27 AM
Nice little Class A amps.
http://www.monarchy-audio.com/SE100_MK2_Main_Frame.htm

baldrick
01-10-2019, 02:31 AM
I am using the THX AAA 789 on my D2430K, and it does wonders! :bouncy:

You actually mean the headphone amp??

pos
01-10-2019, 07:03 AM
You actually mean the headphone amp??
That’s right :)

speakerdave
01-10-2019, 12:41 PM
If powering compression drivers without a passive high pass circuit between amp and speaker, a protection capacitor is always a good idea. If using the ACA Pass diy class A amplifier a protection cap would be required, since it generates a turn off thump. It's small, and no problem for a woofer, but I would not want to expose an expensive CD diaphragm to it.

Dr.db
02-25-2019, 12:20 PM
When using an amp directly coupled to a high sensitivity horndriver, what spec is most important to look at?
Is it the Signal-to-Noise ratio?
Which value is sufficient to keep it quiet? 90db a-weighted?


I would go with a small Class A amp, vintage or new. There are numerous others as well.


Widget

Could you list the ones that are available new please?


@ Pos & Bubbleboy:

Does the THX AAA 789 really handle an 8ohm load of a compressiondriver? It looks like it is only specifid for 16ohms minimum...
Have you driven these with serious spl levels yet? Or are these only suitable for moderate listening levels?

Mr. Widget
02-25-2019, 08:02 PM
Could you list the ones that are available new please?
The Pass Labs XA25 is likely one of the best amps ever made for this application.

https://www.passlabs.com/amplifier/xa25

https://www.stereophile.com/content/pass-laboratories-xa25-power-amplifier

https://6moons.com/audioreviews2/passlabs3/1.html


Widget

pos
02-25-2019, 08:05 PM
@ Pos & Bubbleboy:

Does the THX AAA 789 really handle an 8ohm load of a compressiondriver? It looks like it is only specifid for 16ohms minimum...
Have you driven these with serious spl levels yet? Or are these only suitable for moderate listening levels?

8 ohm nominal (so around 6 ohm min for a typical JBL compression driver) is definitely too low for that amp.
A LPUHP amp would be a better match.

The THX is the perfect match for a 16 or 32 ohm compression driver, and will let you reach 105dB SPL/1m no problem after constant directivity equalization (on sinusoidal signals, and much more on real-world signals given the typical spectral power distribution of music).

Dr.db
02-27-2019, 07:03 AM
Thanks ;)

Dr.db
02-28-2019, 02:48 AM
8 ohm nominal (so around 6 ohm min for a typical JBL compression driver) is definitely too low for that amp.


The JBL 2441 is rated 16ohms, but I think in reality itīs rather 8ohm or am I wrong? Would this work with this THX headamp?

pos
02-28-2019, 09:18 AM
16 ohm JBL compression drivers have a minimum impedance of around 12 ohm in the passband (Re might be lower, but is irrelevant here).

Bubbleboy is running his 16 ohm 476Mg with the THX. I think he uses the SE output.

Dr.db
02-28-2019, 11:45 AM
Thanks ;)
Sounds like it should be fine...

Dr.db
03-06-2019, 02:32 AM
Today I have tested my two amps directly with my compressiondrivers.
- NAD C275 (2*150w rms)
- NAD C245 (4*35w rms)

The Setup was as followed:
- NAD C165 Pre-amp
- NAD C275 or C245 amp
- protection cap
- JBL 2446 or 2405
So there was no active crossover connected...

Results NAD C275:
I could here some subtle noise at 2 feet distance, with more distance it was dead silent.
Than I used the variable input and put the gain with the level-meters of the amp completly down. This decreased the noise further, but just a little. I would have thought this to be of bigger impact.

Results NAD C245:
I could here noise until 7 feet distance, with more distance it was almost silent.
The C245 hasnīt got any level-meters to adjust the gain.

To sum this up, I was impressed by the much oversized NAD C275! At normal listening distances it was 100% silent, no noise at all. The C275 is an affordable amp, so this made me rather confident to find another silent amp for horns without spending big cash.
But I was rather dissapointed with the NAD C245, as it was much more noisy. Actually I planed to use this 35watt amp for my horns, but itīs to noisy.

.

Now Iīm wondering if amplifiers or crossovers are the usual suspects with producing noise?
In my understanding it all sums up, because itīs like a chain... But is it rather hard to find a silent amp or a silent crossover?
Which device is more prone to produce noise :confused:

.

How about putting some resistors infront of the compression-drivers?
This would reduce the sensitivy and therefor the vulnerability for picking up noise.
But this would mean using more passive devices in an active system :(

.

Ian Mackenzie
03-06-2019, 01:07 PM
Your on the right track.

Noise masks resolving power.

The issue with noise becomes increasingly more apparent with active EQ of horns by boosting high frequencies.

Padding back a horn with an Lpad can be an effective means of improvement in the signal to noise ratio.

rusty jefferson
03-06-2019, 07:55 PM
It looks like the C245 has 35 db of gain and the C275 only has 29 db of gain. That explains the difference in noise between the two.

The C165 preamp has about 12 db of gain. That's probably high for efficient horn speakers. I prefer no gain/low gain (6 db) preamps with amplifiers in the 25-30 db of gain range, and high efficiency speakers. I like no system noise if possible.

Mr. Widget
03-06-2019, 08:49 PM
I like no system noise if possible.:yes:



Widget

pos
03-07-2019, 12:08 AM
Agreed, gain matching is very important, so you have to check both the gain of the amp and the level of your source/DAC.
Ideally you will want a 0dBFS signal to produce the maximum level you will ever require, and always keep the attenuator of the amp at maximum position for better tracking between channels.
You can use passive attenuators between your source and amp (xlr pads, etc.).

For the record, the THX 789 amp has three gain settings: -10dB/0dB/+10dB for the single ended output, and -4dB/+6dB/+16dB for the differential one :)

Dr.db
03-07-2019, 01:06 PM
Good to know, thanks for the backround.

I have no quality active-crossover at the moment to try, just some noisy M553...
Now Iīm wondering if amplifiers or active-crossovers are the usual suspects with producing noise?
Which device is more prone to produce noise?