Last Questions
Thanx for the advice on the vol. issue.
Some last questions refering to attached image.
These are final voltage and current values, basically the same for both amps. I just want to confirm that all are exceptable, especially the currents in EL34's.
1)Can I leave the 59mA and 61mA as is, or will it be better to reduce them?
2)I measured Vout over a 8ohm load, with a 100Hz sine wave applied. It started to clip at 35Vpp. This translates to 76W. Does this mean that the amp, can actually deliver 76W max. or do I reason/understand incorrect?
Thanx for all assistance and further suggestions.
Thanx for the advice on the vol. issue.
Some last questions refering to attached image.
These are final voltage and current values, basically the same for both amps. I just want to confirm that all are exceptable, especially the currents in EL34's.
1)Can I leave the 59mA and 61mA as is, or will it be better to reduce them?
2)I measured Vout over a 8ohm load, with a 100Hz sine wave applied. It started to clip at 35Vpp. This translates to 76W. Does this mean that the amp, can actually deliver 76W max. or do I reason/understand incorrect?
Thanx for all assistance and further suggestions.
Attachments
Basics!!!
JDeV, here is a lesson for you in basic electrical calculations:
V=I.R
P=V.I
Vrms=Vp x 0.707
Vavg=Vp x 0.637
XL=2 x 3.14 x F x L
XC=1/(2 x 3.14 x F x C)
Learn these, remember them, and stop asking stupid questions.
(Just had to do that to myself to wake-up abit )
JDeV said:I did understand correct, just did not think correct (basics, basics, basics...)
JDeV, here is a lesson for you in basic electrical calculations:
V=I.R
P=V.I
Vrms=Vp x 0.707
Vavg=Vp x 0.637
XL=2 x 3.14 x F x L
XC=1/(2 x 3.14 x F x C)
Learn these, remember them, and stop asking stupid questions.
(Just had to do that to myself to wake-up abit
)
EC8010
Hi EC8010
I looked at these caps at this site, and others. It seems like you must buy a set of 20 of them. Unfortunately, here in Africa 1 cannot use Paypal or any other money transfer system yet. Would you be interested to exchange 2 of those caps for a CD of your choice, which I can order from Amazon or CDNOW (luckilly they except credit card transactions online) and have delivered to your address? If so please contact me on e-mail.
Thanx
JDeV
EC8010 said:
Hi EC8010
I looked at these caps at this site, and others. It seems like you must buy a set of 20 of them. Unfortunately, here in Africa 1 cannot use Paypal or any other money transfer system yet. Would you be interested to exchange 2 of those caps for a CD of your choice, which I can order from Amazon or CDNOW (luckilly they except credit card transactions online) and have delivered to your address? If so please contact me on e-mail.
Thanx
JDeV
Inconsistent.
Normally, I would be very cautious about upsetting CR time-constants, but you've already changed your output transformers, which are the critical parts with respect to the coupling capacitors. Why not change your coupling capacitors to 100nF, and see if it affects the bass adversely? If it doesn't, then the Teflons can be considered.
Normally, I would be very cautious about upsetting CR time-constants, but you've already changed your output transformers, which are the critical parts with respect to the coupling capacitors. Why not change your coupling capacitors to 100nF, and see if it affects the bass adversely? If it doesn't, then the Teflons can be considered.
Thanks Bas Horneman - your schematic got me here via Google!I bought a "3 year old pair of Mullard 20 mono blocks" from a diy-er who had built them from new components in 1990. I rate them as a bargain at 590.00 British pounds in 1994.
They sound fabulous.
They have solid-state rectification - so I note tube_dude's comment that tube rectification might be an improvement.
One of the mono blocks ceased working (instantly switched off when it smelt waxy burning!). An expert instantly over the phone directed me to R20 and R21 at the EL34's and that solved the problem (practically I used two 1Kohm resistors in parallel in place of the impossible to find 470ohm resistor.
I ran them with all Golden Dragon (Tube-Shop.com tubes) and have tried Groove tubes on the EL34's which made negligable difference. However using Siemens as the 12AX7's has inspired me to try all Siemens throughtout which should be in the mail as I write and I will be trying different brands of 12AX7's
As inputs I have a Fisher 100B FM Tube Tuner and a 1993 Arcam Delta CD player. With the all Golden Dragon tubes the Fisher was so superior to the Arcam that I kept buying the CD that I had heard on the radio only to be dissappointed when it was played as a CD! With the Siemens 12AX7's the Arcam has jumped a notch.
I am well happy with my "Mullard 20" but as a caution would add that I am not a tube Expert.
Hi,
Not that I want to burst a bubble but:
Chances are that all common tubetypes branded Siemens as per 1978 are actually made for them and no different from the former-Yugoslavian Ei tubes.
That's not to say they're no good, they were excellent, just that there's no need to spend big money on a brandname alone.
The Siemens 12AX7As have long flat plates and the Siemens EL34s had the typical Ei exhaust tip at the top as opposed to flat and rounded.
Cheers,
Not that I want to burst a bubble but:
Chances are that all common tubetypes branded Siemens as per 1978 are actually made for them and no different from the former-Yugoslavian Ei tubes.
That's not to say they're no good, they were excellent, just that there's no need to spend big money on a brandname alone.
The Siemens 12AX7As have long flat plates and the Siemens EL34s had the typical Ei exhaust tip at the top as opposed to flat and rounded.
Cheers,
Fdegrove
I believe you are probably right regarding the authenticity of the Siemens 12AX7's.
It is a case of so few factories, so many brand names.
However I am enjoying auditioning different tube brands in the Mullard 20. I found Westinghouse good for rock and the Mullard (testing weak on a tube tester) sounds really good. I stray into a new topic zone.
I believe you are probably right regarding the authenticity of the Siemens 12AX7's.
It is a case of so few factories, so many brand names.
However I am enjoying auditioning different tube brands in the Mullard 20. I found Westinghouse good for rock and the Mullard (testing weak on a tube tester) sounds really good. I stray into a new topic zone.
The amp is a keeper and the next purchase is an EF86 upgrade.
Tuberolling awhile...I took a good look at the 12AX7 "Siemens". The plate is unusual in that it is not two pieces of metal samwiched together but a single piece of metal curved at the wide end with three circular(cooling?) holes (and corresponding sets of holes at the opposite end before the join. It is a short plate having remarkable similarities to an RFT brand 6AQ8 but the construction looks far more refined. I do not have an RFT 12AX7 for comparison.
Do you have any suggestions for brand preference on the EF86's?
Tuberolling awhile...I took a good look at the 12AX7 "Siemens". The plate is unusual in that it is not two pieces of metal samwiched together but a single piece of metal curved at the wide end with three circular(cooling?) holes (and corresponding sets of holes at the opposite end before the join. It is a short plate having remarkable similarities to an RFT brand 6AQ8 but the construction looks far more refined. I do not have an RFT 12AX7 for comparison.
Do you have any suggestions for brand preference on the EF86's?
globe said:
From my own experience, I used the RCA EF86, Sovtek and Mullard's. Listening mostly to jazz and classical, the Mullard is my 1st preferance by far.
For the EL34 I used Electro Harmonics and Svetlana. Svetlana being superior.
Also a good upgrade is to use high grade caps for coupling (C10 and C11 - on Bas Horneman circuit) - I tried Solen and Auricap here, with Auricap sounding the best. Surely there will be even better then this
Enjoy !
C10 and C11 are now highlighted on the Bas Horneman circuit as candidates for an Auricap.
Meanwhile I will be trying tubes various in the EF86 position and will take JDev's advice on trying Mullards. I will report back - it could take a month.
1. Instead of EF86 can I use E80F or 6084's?
2. Instead of 12AX7 can I try 5751's?
Incidentally I should make the admission that I nearly chose the username "dry-joint"! I dont have the practical ability but I sure do have the ears that appreciate the quest.
Meanwhile I will be trying tubes various in the EF86 position and will take JDev's advice on trying Mullards. I will report back - it could take a month.
1. Instead of EF86 can I use E80F or 6084's?
2. Instead of 12AX7 can I try 5751's?
Incidentally I should make the admission that I nearly chose the username "dry-joint"! I dont have the practical ability but I sure do have the ears that appreciate the quest.
Hi,
You can but for as long as you can find good quality EF86s you'd be probably better of using those.
While E80Fs and 6084s will almost certainly "work" they're not exact equivalents.
Most of the Mullard EF86s that are still available NOS are actually made in Holland by Philips. Basically almost any EF86 branded by a Philips subsidiary will be very close to original Philps Holland:
ADAZAM, MAZDA, Dario, Valvo to name a few.
Try it.
A lot of NOS 5751s sound better than current production 12AX7As.
Cheers,
You can but for as long as you can find good quality EF86s you'd be probably better of using those.
While E80Fs and 6084s will almost certainly "work" they're not exact equivalents.
Most of the Mullard EF86s that are still available NOS are actually made in Holland by Philips. Basically almost any EF86 branded by a Philips subsidiary will be very close to original Philps Holland:
ADAZAM, MAZDA, Dario, Valvo to name a few.
Try it.
A lot of NOS 5751s sound better than current production 12AX7As.
Cheers,
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