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Affordable Valve Company

FAQ (Frequently Asked Questions)

How does Affordable Valve Company valve / tube  amplifier compare with other valve / tube amplifiers ?

The most important and expensive part of the valve / tube amplifier
are the transformers (the 3 black lump of metal at the rear of the amplifier)
Our amplifier are the amplifier on the left, with the BIGGER transformer.
You might recognize our competitor on the right, with the SMALLER transformer
Even our GBP £250 amplifier got bigger transformers !
The most important and expensive part of the valve / tube amplifier
are the transformers (the 3 black lump of metal at the rear of the amplifier)
Our amplifier are the amplifier on the left, with the BIGGER transformer.
You might recognize our competitor on the right, with the SMALLER transformer


19 December 2003 Comments : I have a pair of Quad 11 modified by Concordant over 10 yrs ago..Over the last year I have had some reliability probs,and now believe after 10 yrs revalving is needed .I am therefore thinking of replacing them..Your range looks great altho they are integrated and therefore my system would need some cable changes to suit. What would you reccomend to replace my Quads. I use qua 57 as speakers. Am looking for the smooth valve sound but should have good detailing and crisp treble.

We suggest that the big valves might need replacemsnt after 2 or 3 years (for 3 hours use a day) (maybe 2,500 housr to 3,500 hours of hard use.  Longer, if you are not guitar players, who trashes their valves ! )
When the "bass slam" disappears, it is time to replace the valves.

Our integrated amplifiers are "loosely diguised" power amplifier with a "passive" volume control + "passive" selecrotr switch, WITHOUT horrivble remote control Integhraterd Circuits, that contains dozons of horiible transistors !

Most people are usally rude about most old "Control Unit" preampluifier for the Quad II or Leak Stereo 20,
so it will be a worthwhile changing your cables.  If you do not believe me, read the "Classic Section" of Hi Fi World magazine !

One of our customers also had relaibility problem with his old Quad II.
Anything that is 40 year old will have reliabilty problems !
Even your 40 year old wife (or husband) will have relaiblity problems !
This is his testimonial.

  Turntable used was Garrard 401 & 301  & Rega RB300 & Audio Technica AT5 moving coil cartridge

  Loudspeakers used was Spendor S6 (expensive)

  Customer's previous amplifier was Quad II & Denon AVC-A1SE

  How did the sound quality of our model EL34 Silver compare with your previous amplifier?

Comment from Affordable Valve Company - I believe that Mr A S
is saying that our EL34 amplifier is "better all round" to the Quad II,
because Mr A S kept our EL34 amplifier, after the 1 month home trial.
          After using Quad II, the sound is more defined with sharper
          imagery, in fact better all round.  The Denon is best left
          for AV only sound.

  Other comments (optional)
          Nice to hear what music is about, soul and feeling, O
          have a new soul mate with the EL34 Silver Series 4.
          Value for money is outstanding.

                                   Mr A S of Stroud   2003

If the customer already had a Quad II valve amplifier, why did he buy another valve amplifier ?
The customers Quad II valve amplifier was very old, and it needed some repairs.  Some Quad II valve amplifier are 40 years old, and nothing last forever !  The customer took out 1 month home trial on our valve amplifier to see how our valve amplifier sound like.

Why do you need to renovate Quad II amplifier ?

The big valves will last about 3 years.  If you do not have enough bass, try replacing the old valves.
Our replacement cost for a set of 4 big Russian Svetlana EL34 valves and 4 small American military 5670 valves is sold at a "service to customer" price of £50.

The "typical" electrolytic capacitors will only last 2,000 hours at 85 degrees centigrade.
It will last much longer, if it was cooler.  But it will not last 40 years !


Even if you buy a mint unused Quad II, you still need to change the electrolytic capacitors !
Electrolytic capacitors do not last very long, if you do not use it !  You have to "charge it up" on a regular basis to keep it in good condition !  This is one of the odd quirks of electrolytic capacitors !

The "traditional" carbon resistors can change it's resistance to half or double the original value. 


Even if you buy a mint unused Quad II, you still need to change the resistors !
The "traditional" carbon resistors will change value, even if you do not use it !
This is one of the reason why modern equipment have stopped using the "traditional" carbon resistors.

"Sensible" "no nonsense" replacement resistors only cost a few pence, but the labour cost will be much more !
Please do not waste money on overpriced, over hyped resistors that cost a few pounds.  Unless you have speakers that cost a few thousand pounds, you will be better off spending the money on a few CD or records !

If you are lucky, it will cost about £150 for the work + £50 for the carriage for collection and delivery.

Reasons why our EL34 valve amplifier can compete with the Quad II valve amplifier.

1. Our EL34 valve amplifier is a 40 watt amplifier and the Quad II is a 15 watt amplifier.
    If you like listening to loud music in a large room, the extra power will help.

2. We use bigger "output transformer" and "fixed bias" to give twice as much "bass power" and better bass control.
     The bigger "output transformer" will cope better with LOUD DEEP bass note, producing less distortion,
     when there is a LOUD DEEP bass note AND human voices AT THE SAME TIME,
     so human voices are also improved !

3. We use bigger "mains transformer" that runs cooler, and makes the sound just a little bit more "open", a little bit more natural, and less like "processed Hi Fi". It is not a huge difference, but it is 5 times more than any change of cable.

 Like Naim and "Border Patrol", we believe that we can improve the sound by adding a more powerful power supply.
This is why the "mains transformers" on our £600+ amplifiers are huge.

4. Like Musical Fidelity, we believe in "chokes" for the power supply. Our amplifier have 1 Henry choke for the power supply.  1 Henry "choke" is the "choke" equivalent to a gigantic 1,000,000 microfarad capacitor !
   (Electronic hobbyist should note that the "mF" marking on capacitors means microfarad, and not millifarad !)

5. Like Naim, we believe in the "shortest signal path", without bass controls, treble controls, balance control, etc.

    Our amplifier has the "shortest signal path", and it is essentially a "power amplifier" with a "passive" volume control and "passive" selector switch WITHOUT horrible remote control IC (Integrated Cuits) cinatining doezens of horrible transistors.

   Quad 22 preamplifier for the Quad II has bass control, treble control, balance control, filter, etc, which can affect the sound (even when you set these controls to neutral).

    Page 90 of the September 2003 Issue of "Hi Fi World" describe the Quad 22 preamplifier for Quad II as "cloudy and vague sound"  I think that the reason for this adverse comment is the Quad 22 has a lot extra capacitors, extra resistors, extra wiring for the bass control, treble control, balance control and filter. I think that all of these extra components will affect the sound.

6. Like most modern valve amplifiers,
    we use "triode valves" for our input and driver valves. "Triode valves" have low output impedance and low distortion.
    Quad II uses "pentode valves" with high output impedance and higher distortion (before feedback).
    In most cases, it is a bad idea to use low powered "pentode valves", with high output impedance,
    to drive the high "miller capacitance" of the power valves.
    There may be reasons why it is possible for the Quad II to use "pentode valves" to drive the power valves,
    but there is still the problem of a high "open loop" distortion (before applying "negative feedback").

    The "characteristic curves" for Pentodes looks suspiciously like "chracterisc curse" for transistors !
    If you like the sound of transistors, youl will probably like penthodes !

    Modern valbe amplifier connect up EL34 penthodes in "unltra leaner" mode
     or "triode connection" mode to make the penthods behave more like a Triode
    (without the irritaing problems of 300B Triodes !)

7. The EL34 penthoide valves are connected in the "Ultra Linear" mode, which makes it behave        50% as good as a Triode valve.
    (Our more expensive KT88 amplifiers are "Triode Connected".)

8. PROFESSIONALLY RESTORED Quad II will sound better than many transistor amplifiers.
    But Quad II is not perfect.  Nothing in this world is perfect, and Quad II can be beaten by other valve amplifiers.
    How good is the Quad II ?  Is the legend about Quad II justified ?  I think that you should read page 90 of the September 2003 issue of "Hi Fi World" that describe the Quad II as "deliciously fluid and lyrical voice. In other respects though, it sound hopelessly dated.  Low power and hard to partner properly"

    Our EL34 valve amplifier is a 40 watt amplifier and is much more powerful than the Quad II.
    If you have huge speakers and you like listening to loud music in a large room, the extra power of our EL34 will help.

What about the new Quad II-Forty valve amplifier ?

Most modern valve amplifiers use "triode valves" for the "input and driver valves",
for lower distortion, lower output impedance, higher "poles" when driving the following valve, which could lead to better stability of a "feedback" amplifier.

Quad II Forty uses "pentode valves" for the "input and driver valves".
If you have "Golden Ears", this will make the Quad II Forty sound different to most other modern valve amplifiers.

Before you spend £4,000 on the new Quad II-Forty valve amplifier, it would be a good idea to compare the new Quad II-Forty with valve amplifiers from E.A.R. , Conrad Johnson, Audio Research and Affordable Valve Company.

You also have to check that if preamplifier of the new Quad II Forty hums.
The review in "Hi Fi World" magazine said that the preamplifier of the Quad II-Forty hums.
"Hi Fi News" coyly said that the preamplifier of the NEW Quad II Forty was more noisy than the OLD preamplifier for the OLD Quad II.
I shake my head in dispair.  British Hi Fi seems to be going backwards.

Shocking news for ardent Quad fans.
This is a piece of shocking piece of news for Quad fans. There has been a lot of changes in the Quad company.  Quad is owned by 2 Chinese brothers from Hong Kong, and a lot of Quad products are made in a Chinese factory.  Sorry, Quad fans, but Chinese labour is cheap.

If Hi Fi World describe the 15 watt Quad II as low powered, is your amplifier powerful enough ?

The 15 watt Quad II has medium sized transformer can produce 23 watts in the middle frequencies.

Unfortunately, the medium sized transformer can only produce
      4 watts of "bass power" (at 0.5% distortion)
to 10 watts of "bass power" (with more distortion).

The loudest instrument on your CD is usually the Bass drum, so you need "bass power".

Our valve amplifier will produce about twice as much "bass power" as the Quad II,
so our valve amplifier sound louder.

Please read the review from the customer with the
     330 watt £8,000 Chord pre/power
     150 watt £1,400 Musical Fidelity A300
and I hope that that will prove that you do not need 100 watt amplifiers to get good sound.

Continued exposure to loud music will cause permanent damage to your ears.
You can read about Studio Engineers who likes listen at very high level,
and by the time they are 50 year old,
their hearing have been so damaged they cannot work as Studio Engineers.
Young inexperienced Hi Fi Reviewers should learn from this !
It is probably too late for some old Hi Fi Reviwers.

Question from eBay member in January 2005 = How would you expect this amplifier to compare with a Radford ST35 Renaissance valve amp? Do you believe that I would see an improvement and if so, in what way? Jon 
Answer = I cannot find much information about Radford ST 35 or Radford STA-35 renaissance.
I managed to find some information about the old Radford STA-25 and the newish Radford STA-25 Renaissance.
MONEY BACK GUARANTEE (less GBP £60 or  £30, within 30 days) that
most people (with standard taste) ,
except for Hi Fi reviewers (with non standard taste) ,
except for dealers in Internet Forum (disguised as innocent members of the public) that
any of our eBay listings of our standard range (Ultra Linear or Triode Connection)
from GBP £650 to GBP £1000 
will EASILY sound better than old or newish Radford STA-25.
Our eBay listings for our 'Triode Connected' range will give much more realistic human voices, and sweeter treble, and should sound even better
The 25 in the Radford STA-25 name implies that it is only 25 watts,
with a small 25 watts transformer, rather than 35 watts. 
It will be interesting to see if it can produce 35 watts of loud deep bass at 20 hertz.
I believe that our transformers are bigger and better
because one of our customers auditioned the older Radford STA 25,
but felt the old Radford STA-25 was not that much better 
than his old , but famous transistor pre / power amplifiers.
The customer bought the older version of
our GBP £1400 KT88 Triode connected valve / tube amplifier in our eBay listing.
This ebay listing for GBP £1,000 HIGH END "KT88 TRiode Connection" valve / tube amplifiers
is ALMOST as good as
our ebay listing for GBP £1,400 ULTRA HIGH END "KT88 Triode Connection" valve / tube amplifiers
our ebay listing for GBP £1,150 ULTRA HIGH END "EL34 Triode Connection" valve / tube amplifiers
If your Radford STA-35 Renaissance is similar to the Radford STA-25 Renaissance,
and my information is correct,
who does not charge hundreds of pound for a few days work. 
I can suggest the following modifications ...
Improve the power supply with a choke / inductor.
Our eBay listing for our GBP 460 amplifier has a 'inductor / choke regulated' power supply
Design out the Zener diodes from the circuit, using the circuit diagram of the old Radford model.
SERIOUS transistor amplifier designers will NEVER used Zener diodes, which produces a fair amount of noise. SERIOUS transistor amplifier designers might use specially selected LOW NOISE transistors or light emitting diodes. Any noise injected into the power supply, or screen grid will affect the amplifier. Connecting a zener diode , that produces a fair amount of noise to the 'control grid' of the upper valve of the ECC88 cascode is NOT a good idea. 
Replace the long tail pair with 2 SIMILAR triodes with SIMILAR characteristics, so that the 'push' will be almost equal to the 'pull'.  It is wrong to use TOTALLY DISSIMILAR pentode + TOTALLY DISSIMILAR triode for the long tail pair.  The pentode was supposed to reduce the 'Miller capacitance', and push the 'pole' upwards.  If that was so, why did the designer add a capacitor to the anode resistor of the previous valve ?
The 2 kiloohm resistor for the tail is much too small, and does NOT approximate to a 'constant current source'.  So, the balance between the pentode driver valve and triode driver valve will be poor, and will introduce unnecessary distortion.  The designer must have found this problem, and tried to correct this problem by using a 2 kiloohm variable resistor for 'a.c. balance', that he can adjust for minimum distortion. This is a great idea, if the customer has a signal generator and distortion meter, when he change the driver valve !  Designs like the Mullard 5-20 solve this problem by using a 82 kiloohm resistor for the tail, that is a better approximation to a 'constant current source (but you might get a problem with 'heat to cathode insulation' 
The pentode driver valves will have VERY HIGH output impedance / plate resistance, and MIGHT NOT be suitable to drive a triode connected power valve. Our driver valves have unusual low plate resistance, and is MUCH MUCH better for driving Triode Connected power valves.  That might explain why our 'Triode Connection' amplifiers sound better than our competitors ' Triode Connection' amplifiers.


EL34 Ultra linear with switch to Triode mode

Comments : Respected, I? d like to know if You sell amplifiers out of EU. If so, let me know some more info about EL34 amps like do some of them is switch able to triode configuration. I like to purchase that one. If none of them has that possibility I'd like to buy EL34 Limm Signature. I also need to know about terms of purchasing EL34 amp: export price, ground shipping cost, cost of insurance. What is the cost of replacement tubes? I'll be grateful for your quick answer.  Slovenia.

Greeting to Slovenia.

About once a month, we get the "telephone" question of 
"Why don't you have a switch that will switch between EL34 Ultra Linear and EL34 Triode mode",
but we have not received this question from Slovenia.

We do not do this because

1. It is a bad idea to have a switch between "Ultra Linear" and "Triode connection".

2. I learn by investigating that the great amplifier designers have done, and copying their ideas !

    I found that 99% of the great POPULAR designs do NOT have a switch between "Ultra Linear" and "Triode Connection".
    A few pieces of cheap wire and a cheap switch, and you you have a "switch able" triode that will be a good selling point.



Read on, and you will see why the old masters have not done this cheap trick.

2.  If you have a switch, you will LONG wires going from the valve , to the switch on the front panel,
     and then to the transformer at the back of the transformer.

     LONG wires will encourage unsuitability / oscillation, picking up of noise, RFI (Radio Frequency Interference), etc 

     Look up any book on valve (or transistor) amplifiers, and you will always find the advice of    KEEPING THE WIRES SHORT !


     This is NOT my "invention" , I am only telling you, what my books tell me !

3. The switch will be switching about 400 volts to 500 volts.

    If you look up any electronic catalogue, you will usually find switch designed fro 250 volts a.c.
    (These switch might be SAFETY TESTED for higher voltage,
but they are NOT designed fro higher voltage.)

    If is really difficult to get switch designed for 500 volts !

    If you do not believe me, look at the switches used in amplifiers with "switch able" triode mode,
    and compare the switches with 250 volt switch from electronic catalogue,
and you will be shocked that
some (but not all) of these amplifiers have a 250 volt switch operating at 500 volts,
and CLAIMS to have CE safety marking !

This is a joke, until somebody gets electrocuted and killed by 500 volts.

4.     The "Miller capacitance" of the power valve "reacting" with the "output resistance (plat resistance)" of the driver valve, will form a high frequency filter (pole).

       The "Miller capacitance" of  " Triode Connection " is much more than "Ultra Linear Connection".

       The high frequency filter (pole) of the "triode connected" valve will be MUCH LOWER than the pole of the "ultra linear" valve.

       It is already a headache trying to get
        "unconditional stability" from "ultra linear" amplifier (with feedback).





The old Masters did NOT produce amplifiers with this "switch",
so I am going to follow the old Masters footsteps,
and NOT produce amplifiers with this "switch".

There is no shame in copying from the best Masters !

5. EL34 is a sensible practical powerful valve for Ultra Linear connection
     (40 watts + 40 watts in our case.)
    Unfortunately EL34 is NOT very good for "Triode Connection" because

          i) EL34 has a "suppresor grid" that gets in the way of the electrons.

             KT88 does NOT have "suppresor grid",
              so KT88 does not have this problem.

         ii)  I have look through MANY Mullard specification for EL34 and I CANNOT find one "characteristic curves" for EL34 "Triode Connection".

             Mullard's book on how to build valve amplifiers using Mullard EL34 , Mullard EL84 ,
             strongly recommend that Mullard EL34 should be used in the "Ultra Linear" mode,
              and EL34 Triode Connection is not so good.

             GEC is so proud that of KT88 "Triode connected" that
              GEC or other manufacturer ALWAYS publish the "characteristic curves" for KT88 "Triode connected".

            The reason for this is that "KT88 Triode Connected" has "characteristic curves" almost like 300B Triode.  If you do not believe me, please look at the "characteristic curves" for KT88 Triode connected and 300B tube !

             GEC also tell us a lot of facts about KT88 "Triode Connected" like power, etc.

             GEC attitude seems to be if you want low distortion, use KT88 "Triode connected",
            and if you want more power and higher distortion, use KT88 "Ultra LInear".

            Mullard attitude is that if you want more power and higher distortion, use EL34 "Ultra Linear",
            but Mullard attitude is do NOT use EL34 "Triode Connected" !

            My "Golden Ears" and the "Golden Ears" of MANY my customers disagree with Mullard.
            Our  BEST RELIABLE Chinese EL34 (guaranteed for 2 years) sound VERY VERY GOOD
            as EL34 Triode Connection IF YOU USE BIG OUTPUT TRANSFORMER.

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