DIY HiFI Supply amplifiers

[selfaddict]

I think I have found myself a great pre and mono block amplifiers which should work very well with my current speakers. Even if I ever decided to go for DIY horns in the future, there amps should work well. So they seem to be future proof, but are they fool proof?

LD91 SET Mono Block Amp

Tram 2 - DHT OTL Linestage

Would assembling these amplifiers be suitable for first time DIY's or should I do the right thing and buy them ready made and tested?

[lurcher]

The DIY HiFi stuff is great, there are a lot of folk on their forums to help. And Brian is always helpful. Should be good for a first time built if you take care and read before soldering.

[John]

I heard a few of their amps; very good

[selfaddict]

Hi John.

How would you describe the sound of these amplifiers? Did you hear the pre and mono blocks together or on their own? I am just trying to find out how the sound compares to Art Audio Diavolo.


I heard a few of their amps; very good


Another thing is the gain versus output power, which I am struggling to understand :scratch:. Are these in any way interlinked or totally separate issues? Does the pre+power amp gain just depends how much gain is achieved on the pre amplifier or does the gain increase on the power amp as well? I have seen power amps which can be ordered with low or normal gain( Audio Note UK) so I assume there is gain on the power amps as well.

In my current system I have way too much gain and need to use 30db attenuators to get the pre to 11 o'clock volume setting . One option would be to use passive pre, but I am afraid that I would loose some of the 'slam' that the active pre brings to my system.

I have been looking DIY amplifier kits that use 2A3 valves and did found Bottlehead kit (thanks Nick), but DIY HiFI Supply kits just feel somehow more suitable.

[John]

Vic of Trans Fi uses the Django and 300b Monos on the same driver you use. I think with that driver you need as clean a amp as you can get as those drivers are extremly revealing and the amp do there jobs right away. DIY Supplies can build them for you too at not to much extra cost.
Its hard to tell within the conext of somone else system but I liked them and Vic has not thought about changing them since he got them which says a lot

[lurcher]

The power amp will have a voltage gain (in dB) and will also have a max output power. The two are connected.

Lets say, we have a 6W (power output) amplifier. To produce 6W into a 8 ohm load (loudspeaker) it will need to output 6.9v

V = SQRT( Power * Load Resistance).

So if the amplifiers need a input of 1.5v to achieve full power, it needs 1.5v in for 6.9v out, thats a voltage ratio of 4.6, or as dB thats 13.2dB

VdB = 20 * LOG( Vout / Vin ).

So this amplifier has a power out of 6W, and a voltage gain of 13.2dB

Now if your signal source is a CD, then the peak voltage from a CD will be 2v, so in theory a passive preamp (unity gain) will provide enough voltage to drive the power amp to full power. And if a active preamp is used, I would look for one with a gain ratio of between 1 and 2, or a dB gain of 0dB to 6dB.

[selfaddict]

Great info, many thanks :clap:

If these amps work great with Vic's Bastanis Atlas, that is as good as demoing them myself. If I remember right Vic did upgrade the drivers to Chrystals, so they would be even more revealing and natural that basic Bastanis wideband drivers I am currently using.




Vic of Trans Fi uses the Django and 300b Monos on the same driver you use. I think with that driver you need as clean a amp as you can get as those drivers are extremly revealing and the amp do there jobs right away. DIY Supplies can build them for you too at not to much extra cost.
Its hard to tell within the conext of somone else system but I liked them and Vic has not thought about changing them since he got them which says a lot

[selfaddict]

Many thanks for this info Nick :respect:.

It took awhile, but I am starting to understand how to interpret this :rolleyes:.

Currently I have Art Audio Diavolo power amplifier which has output power of 13W. Bastanis are working on 16 ohm load for my understanding. So the required output will be 14.4V. Did I got this right?

How do I know what is the required input voltage for the amplifier to achieve full power? Is this same figure as input sensitivity, which is 350mv on Diavolo?








The power amp will have a voltage gain (in dB) and will also have a max output power. The two are connected.

Lets say, we have a 6W (power output) amplifier. To produce 6W into a 8 ohm load (loudspeaker) it will need to output 6.9v

V = SQRT( Power * Load Resistance).

So if the amplifiers need a input of 1.5v to achieve full power, it needs 1.5v in for 6.9v out, thats a voltage ratio of 4.6, or as dB thats 13.2dB

VdB = 20 * LOG( Vout / Vin ).

So this amplifier has a power out of 6W, and a voltage gain of 13.2dB

Now if your signal source is a CD, then the peak voltage from a CD will be 2v, so in theory a passive preamp (unity gain) will provide enough voltage to drive the power amp to full power. And if a active preamp is used, I would look for one with a gain ratio of between 1 and 2, or a dB gain of 0dB to 6dB.

[John]

Yes same drivers as you he also got the Chrystals
You will only need the passive to drive the speakers due to the high sensetivity

[lurcher]

How do I know what is the required input voltage for the amplifier to achieve full power? Is this same figure as input sensitivity, which is 350mv on Diavolo?

It would be yes, I would assume that means you only need 350mv for full power output. So they are more sensitive than I would design to.

[selfaddict]

So my current power amp has output power of 13W and voltage gain of 32.3db.

VdB = 20 * LOG(14.4V / 0.35V )
VbB = 32.3db

No wonder I need to use 30db attenuators with the 10db(if I remember right, pair of 12AX7's) gain of Eastern Electric Avant preamp.

So really I would be better of just upgrading my volume pot from Alp to DACT attenuator and same with the input selectors and see what happens :).


It would be yes, I would assume that means you only need 350mv for full power output. So they are more sensitive than I would design to.

[duo(2)]

Hello,

i have the DIYhifisupply LD91 mkII ( newest edition) and the Tram2 pre , And the " The vinyl song" mm LCR Riaa
i have build the monos and the Riaa my self, the Tram2 i ordered bulid by DIYhifisupply

it´s all very nice components, and VERY good value for the money
But there is a few things you should know before ordering,
first and most important, it seems like they are a little to fast in putting there products
on the marked, and once they are on the marked, and people begin finding "faults" or ways to better them, they start improving them ( and thats good!)- but often without remembering to edit the build manuals - this can be a very very bad experience, especially if you are new to DIY.
secondly, when i ordered the TRAM2 ready build,it took + 2 months before i recived it
:-(

but besides this, they are really a good match to the amazing Bastanis
you will get a very reveling, dynamic, rich sound,
and the 2 amps match fine in gain and sensetivety