Many thanks again NealJ, I can assure you, I'm even more of a novice!
I'll defo check that Tangents website.
Heh! My memory is working just fine! The original MS specs back then used a different standard, and it's that misleading figure that comes up on web searches. The sensitivity of the Pageants won't be more than 90dB, using the standard 2.83V (1Watt into 8 Ohms) input. I have one of the old digest format Hifi Choice magazines with measurements somewhere... I also owned a pair back in the day, and the DSB208 is a nice drive unit.
Hi Max. Congratulations with your build. Many of the Meanwell power supplies have an adjustable output range. So, it might be possible to adjust your Meanwell to give 24V (if you want that) with a small trim pot. Give us the model number and we can check that, or you should easily spot the trim pot. However 1.5V extra will probably not make much difference.
For an 'uninitiated' like me... what prevents one from turning the ACA into a Headphone AMP? I mean... if I were to control the volume through a PRE, what is it 'not good', or at least 'not optimal' in driving a Headphone with a Power Amp such as the ACA?
Is it just that you would need to drop the volume down considerably on the PRE, therefore perhaps affecting sound quality? Is it just not something used often because of the lack of volume control?
I'm curious (and, as may now be obvious, preparing to build a Whammy :O
)
Thanks, best regards,
Rafa.
Is it just that you would need to drop the volume down considerably on the PRE, therefore perhaps affecting sound quality? Is it just not something used often because of the lack of volume control?
I'm curious (and, as may now be obvious, preparing to build a Whammy :O
)Thanks, best regards,
Rafa.
Sorry Toaster, didn't mean to offend, I was just going on printed spec.
I have been amassing DSB208 units for a while, as I've always liked the speakers but found that seventies' design of broad (wide and shallow) as opposed to the narrow and deep designs of today to have a papery bass.
So... I've decided to redesign the cabinets, hence amassing the drive units.
I was told (on this forum) not to mess with the volume of the cabinets or indeed the porting.
B*llsh*t
You may remember, with the exception of the tweeters, which I seriously doubt are affected by cabinet design in the same way as the bass/mid units, the three speakers in the range ALL used the same drive units and varied greatly in cabinet size and porting.
I was not convinced that the Festivals were the best as some claim, though I've only owned the carnivals and pageants.
So... in keeping with a nod to the design of the Q Acoustics Concept 20's, I'm going to redesign the cabintes, heavily braced and with a gel liner as the above speakers have.
Who knows what they'll sound like?
Who cares? It's just a bit of fun!
Rafa,
There is nothing wrong with using the ACA as a headphone amp in all honesty. You can get more gain too if needed by adjusting the feedback resistor. The output impedance is low enough for all headphones, particularly those that are difficult to drive (ie 30 ohms, etc...). Have at it if you want! Just wire a 10K Alps pot or equivalent and away you go.
Most headphone amps are 8-15dB in gain.
The ACA should have GOBS of power for pretty much any headphone setup. The only thing to see is if the noise is low enough (I think it is 15 uV with the Meanwell 24V, which is low but not uber low. The best I’ve seen is 1uV from other headphone designs).
A good experiment is to hook up an ACA to a pair of Klipschorns. If it’s quiet there, then you’re good!
Best,
Anand.
There is nothing wrong with using the ACA as a headphone amp in all honesty. You can get more gain too if needed by adjusting the feedback resistor. The output impedance is low enough for all headphones, particularly those that are difficult to drive (ie 30 ohms, etc...). Have at it if you want! Just wire a 10K Alps pot or equivalent and away you go.
Most headphone amps are 8-15dB in gain.
The ACA should have GOBS of power for pretty much any headphone setup. The only thing to see is if the noise is low enough (I think it is 15 uV with the Meanwell 24V, which is low but not uber low. The best I’ve seen is 1uV from other headphone designs).
A good experiment is to hook up an ACA to a pair of Klipschorns. If it’s quiet there, then you’re good!
Best,
Anand.
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For an 'uninitiated' like me... what prevents one from turning the ACA into a Headphone AMP? I mean... if I were to control the volume through a PRE, what is it 'not good', or at least 'not optimal' in driving a Headphone with a Power Amp such as the ACA?
Is it just that you would need to drop the volume down considerably on the PRE, therefore perhaps affecting sound quality? Is it just not something used often because of the lack of volume control?
I'm curious (and, as may now be obvious, preparing to build a Whammy :O
Thanks, best regards,
Rafa.
Hello Rafa, as far as I am concerned a preamp is a preamp. We can define it further as a separate component in the chain carrying the signal from the source to the speakers. This chain contains an origin for the signal (your CD player, computer, what have you), it contains an amp and speakers. Between the amp and the source, you can insert any number of components as you may need or wish to insert for any reason you may want to insert them. There are, of course, a pile of interconnects involved. Now, while it is true that all of these modify the signal to some degree, the final product is what you and your ears have to evaluate: Does it sound good, is it detailed, is the musical stage nice and lifelike?
I believe the amp and the speakers are the keys to the music you hear. Everything else just produces the signal and processes it to some degree, including the interconnects, before it gets to the amp. You can make all kinds of adjustments to your setup, most importantly the volume must be adjusted, and then judge the results with your own ears. You cannot go by what someone else says it sounds like or should sound like, your ears are the final judge of your setup. If it pleases you then it does not matter how many components you have placed between the source and the amp.
The concept of signal purity and of minimalistic handling of the source are valid concepts, however, it takes a lot of time, effort, and money, to realize these. If you saw the movie "Gandhi" there was a scene where one of the rich people supporting Gandhi was telling a reporter: "You cannot imagine how expensive it is to keep him living in poverty."
If you want fine music and can get it from a cheap headphone amp used as a preamp, using its volume control to adjust the level, before sending it to your amp and speakers, then that is exactly what you should do.
Personally, I am a lot more interested in posts that talk about changing the value of the input resistor of the ACA as a way to increase the power output of the amp, than upon a discussion of the merits or lack of merits of any kind of intermediate components used.
I am not going to make any changes, now. I do have second ACA unit i still need to build in spare time. Since i will use both units for monoblock operations i might need to adjust output voltage to match both supplies.
Model number of the Meanwell is GST120A24.
Thx,
Max
hooked up mine to a pair of Klipsch Cornwall and it’s *dead* quiet
can’t say the same about my beloved 2A3 SET
Well if the output MOSFET fails, yes, you have problems.
Fortunately that doesn’t happen often, but to minimize the fear, build something to protect that is sonically transparent like Neurochrome’s Guardian 86, which also mutes the output on turn on in addition to DC voltage protection.
Many of the highest quality headphone amps in the market are actually small power amps and are meant for less efficient headphones with low impedances.
But if your headphones are 300-600 ohms (Sennheiser 600 series or similar) I would suggest a different design such as Whammy, XRK’s designs, etc...
But this is an ACA thread and experimentation is part of the experience!
Thanks plsvn for the confirmation!
Best,
Anand.
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last time when I glanced ACA schematic , there still was that big honking cap on output ..... it'll not prevent damage made by short circuit between headphones , but it will prevent DC to get to headphones
Indeed! DC voltage protection vs DC current protection!
That being said, the turn on pop will not exist with a Guardian 86, but honestly I don’t mind the turn on pop (with speakers) and if you use them as monoblocks with bridged outputs, there is no turn on pop as there is no voltage differential on the output upon turn on anymore.
If you use it as a stereo amplifier, and you use headphones, that turn on pop can become annoying very fast
Or don’t wear your headphones for the 1st two seconds!
Best,
Anand.
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And there you go! I should have mentioned that from the start: 300 Ohm Sennheiser HD600 is, precisely, the headphones that are arriving tomorrow! So ok, I'll do the Whammy and forget about the ACA-headphone amp!
Thanks Anand,
Rafa.
Thanks for sharing. Can you give us an idea of the efficiency of the ESS drivers?
Thanks,
Anand.
Also using ACA's (1.1) to drive large format 4" JBL 2453h-SL compression drivers from 650 Hz - 20 kHz. Sensitivity: 113 dB SPL, 2.83V (1W) @ 1m (3.3 ft)
No padding, just a protection cap. With the original 19V bricks a bit noisy, but recently replaced with the Meanwell 24V supplies and re-biased. Dead silent, with the faintest hiss only when the ear is right up to the compression driver. The Meanwell supplies are excellent!
Did I mention the sound quality?
No padding, just a protection cap. With the original 19V bricks a bit noisy, but recently replaced with the Meanwell 24V supplies and re-biased. Dead silent, with the faintest hiss only when the ear is right up to the compression driver. The Meanwell supplies are excellent!
Did I mention the sound quality?
Below is a graph comparing ACA V1.6 with 24V rail THD with 4 and 8 Ohm loads. The AP analyzer doesn't want to do this, when you change the load impedance for the power calculation, (so it displays Watts on the horizontal axis) it clears the previous graph. You have to capture two graphs and overlay them in Paint. Sorry, I only have one channel at the moment so I can't do balanced or bridge configuration.
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